Live recombinant Salmonella Typhi vaccines constructed to investigate the role of rpoS in eliciting immunity to a heterologous antigen.

Directory of Open Access Journals (Sweden)

Huoying Shi

2010-06-01

Full Text Available We hypothesized that the immunogenicity of live Salmonella enterica serovar Typhi vaccines expressing heterologous antigens depends, at least in part, on its rpoS status. As part of our project to develop a recombinant attenuated S. Typhi vaccine (RASTyV to prevent pneumococcal diseases in infants and children, we constructed three RASTyV strains synthesizing the Streptococcus pneumoniae surface protein PspA to test this hypothesis. Each vector strain carried ten engineered mutations designed to optimize safety and immunogenicity. Two S. Typhi vector strains (chi9639 and chi9640 were derived from the rpoS mutant strain Ty2 and one (chi9633 from the RpoS(+ strain ISP1820. In chi9640, the nonfunctional rpoS gene was replaced with the functional rpoS gene from ISP1820. Plasmid pYA4088, encoding a secreted form of PspA, was moved into the three vector strains. The resulting RASTyV strains were evaluated for safety in vitro and for immunogenicity in mice. All three RASTyV strains were similar to the live attenuated typhoid vaccine Ty21a in their ability to survive in human blood and human monocytes. They were more sensitive to complement and were less able to survive and persist in sewage and surface water than their wild-type counterparts. Adult mice intranasally immunized with any of the RASTyV strains developed immune responses against PspA and Salmonella antigens. The RpoS(+ vaccines induced a balanced Th1/Th2 immune response while the RpoS(- strain chi9639(pYA4088 induced a strong Th2 immune response. Immunization with any RASTyV provided protection against S. pneumoniae challenge; the RpoS(+ strain chi9640(pYA4088 provided significantly greater protection than the ISP1820 derivative, chi9633(pYA4088. In the pre-clinical setting, these strains exhibited a desirable balance between safety and immunogenicity and are currently being evaluated in a Phase 1 clinical trial to determine which of the three RASTyVs has the optimal safety and

Role of RpoS in virulence and stress tolerance of the plant pathogen Erwinia carotovora subsp. carotovora.

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Andersson, R A; Kõiv, V; Norman-Setterblad, C; Pirhonen, M

1999-12-01

The plant-pathogenic bacterium Erwinia carotovora subsp. carotovora causes plant disease mainly through a number of extracellular plant-cell-wall-degrading enzymes. In this study, the ability of an rpoS mutant of the Er. carotovora subsp. carotovora strain SCC3193 to infect plants and withstand environmental stress was characterized. This mutant was found to be sensitive to osmotic and oxidative stresses in vitro and to be deficient in glycogen accumulation. The production of extracellular enzymes in vitro was similar in the mutant and in the wild-type strains. However, the rpoS mutant caused more severe symptoms than the wild-type strain on tobacco plants and also produced more extracellular enzymes in planta, but did not grow to higher cell density in planta compared to the wild-type strain. When tested on plants with reduced catalase activities, which show higher levels of reactive oxygen species, the rpoS mutant was found to cause lower symptom levels and to have impaired growth. In addition, the mutant was unable to compete with the wild-type strain in planta and in vitro. These results suggest that a functional rpoS gene is needed mainly for survival in a competitive environment and during stress conditions, and not for effective infection of plants.

Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora.

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Santander, Ricardo D; Monte-Serrano, Mercedes; Rodríguez-Herva, José J; López-Solanilla, Emilia; Rodríguez-Palenzuela, Pablo; Biosca, Elena G

2014-12-01

Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

The Cyclic AMP-Vfr Signaling Pathway in Pseudomonas aeruginosa Is Inhibited by Cyclic Di-GMP

DEFF Research Database (Denmark)

Almblad, Henrik; Harrison, Joe J; Rybtke, Morten

2015-01-01

infection give rise to rugose small colony variants (RSCVs), which are hyper-biofilm-forming mutants that commonly possess mutations that increase production of the biofilm-promoting secondary messenger cyclic di-GMP (c-di-GMP). We show that RSCVs display a decreased production of acute virulence factors...... as a direct result of elevated c-di-GMP content. Overproduction of c-di-GMP causes a decrease in the transcription of virulence factor genes that are regulated by the global virulence regulator Vfr. The low level of Vfr-dependent transcription is caused by a low level of its coactivator, cyclic AMP (c......AMP), which is decreased in response to a high level of c-di-GMP. Mutations that cause reversion of the RSCV phenotype concomitantly reactivate Vfr-cAMP signaling. Attempts to uncover the mechanism underlying the observed c-di-GMP-mediated lowering of cAMP content provided evidence that it is not caused...

The stationary phase sigma factor, RpoS, regulates the production of a carbapenem antibiotic, a bioactive prodigiosin and virulence in the enterobacterial pathogen Serratia sp. ATCC 39006.

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Wilf, Nabil M; Salmond, George P C

2012-03-01

Serratia sp. ATCC 39006 (S39006) is a Gram-negative bacterium that is virulent in plant (potato) and invertebrate animal (Caenorhabditis elegans) models. It produces two secondary metabolite antibiotics, a prodigiosin and a carbapenem, and the exoenzymes pectate lyase and cellulase. We showed previously that deletion of the RNA chaperone Hfq abolished antibiotic production and attenuated virulence in both animal and plant hosts. Hfq and dependent small RNAs (sRNAs) are known to regulate the post-transcriptional expression of rpoS, which encodes σ(S), the stationary phase sigma factor subunit of RNA polymerase. An S39006 hfq deletion mutant showed decreased transcript levels of rpoS. Therefore, in this study we investigated whether the phenotypes regulated by Hfq were mediated through its control of rpoS. Whereas loss of Hfq abolished prodigiosin and carbapenem production and attenuated virulence in both C. elegans and potato, characterization of an S39006 rpoS mutant showed unexpectedly elevated prodigiosin and carbapenem production. Furthermore, the rpoS mutant exhibited attenuated animal pathogenesis, but not plant pathogenesis. Additionally, a homologue of the Hfq-dependent sRNA, RprA, was identified and shown to regulate prodigiosin production in a manner consistent with its role in positively regulating translation of rpoS mRNA. Combined, these results demonstrate that Hfq regulation of secondary metabolism and plant pathogenesis is independent of RpoS and establishes RpoS and RprA as regulators of antibiotic production.

14 CFR 91.151 - Fuel requirements for flight in VFR conditions.

Science.gov (United States)

2010-01-01

... begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed— (1) During the day, to fly after that for at least 30 minutes; or (2) At night, to fly after that...

Visible laser and UV-A radiation impact on a PNP degrading Moraxella strain and its rpoS mutant.

Science.gov (United States)

Nandakumar, Kanavillil; Keeler, Werden; Schraft, Heidi; Leung, Kam T

2006-07-05

The role of stationary phase sigma factor gene (rpoS) in the stress response of Moraxella strain when exposed to radiation was determined by comparing the stress responses of the wild-type (WT) and its rpoS knockout (KO) mutant. The rpoS was turned on by starving the WT cultures for 24 h in minimal salt medium. Under non-starved condition, both WT and KO planktonic Moraxella cells showed an increase in mortality with the increase in duration of irradiation. In the planktonic non-starved Moraxella, for the power intensity tested, UV radiation caused a substantially higher mortality rate than did by the visible laser light (the mortality rate observed for 15-min laser radiation was 53.4 +/- 10.5 and 48.7 +/- 8.9 for WT and KO, respectively, and 97.6 +/- 0 and 98.5 +/- 0 for 25 s of UV irradiation in WT and KO, respectively). However, the mortality rate decreased significantly in the starved WT when exposed to these two radiations. In comparison, rpoS protected the WT against the visible laser light more effectively than it did for the UV radiation. The WT and KO strains of Moraxella formed distinctly different types of biofilms on stainless steel coupons. The KO strain formed a denser biofilm than did the WT. Visible laser light removed biofilms from the surfaces more effectively than did the UV. This was true when comparing the mortality of bacteria in the biofilms as well. The inability of UV radiation to penetrate biofilms due to greater rates of surface absorption is considered to be the major reason for the weaker removal of biofilms in comparison to that of the visible laser light. This result suggests that high power visible laser light might be an effective tool for the removal of biofilms. (c) 2006 Wiley Periodicals, Inc.

ClpP deletion causes attenuation of Salmonella Typhimurium virulence through mis-regulation of RpoS and indirect control of CsrA and the SPI genes

DEFF Research Database (Denmark)

Knudsen, Gitte Maegaard; Olsen, John E.; Aabo, Søren

2013-01-01

, suggesting the repression of invasion was directed through RpoS. The expression of the csrA virulence regulator was increased in the ΔclpP mutant and decreased in the rpoS : : amp and ΔclpP/rpoS : : amp mutants, indicating that ClpP affects the csrA expression level as well. Thus, this study suggests...... the proteolytic component ClpP, the stationary phase regulator RpoS and the carbon-storage regulator CsrA. However, the mechanism behind the ClpP regulation is not fully understood. To elucidate this we examined differentially expressed genes in a ΔclpP mutant compared with WT using global transcriptomic analysis...... that ClpP affects SPI1 expression and thereby virulence indirectly through its regulation of both RpoS and CsrA....

Crl binds to domain 2 of σ(S) and confers a competitive advantage on a natural rpoS mutant of Salmonella enterica serovar Typhi.

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Monteil, Véronique; Kolb, Annie; Mayer, Claudine; Hoos, Sylviane; England, Patrick; Norel, Françoise

2010-12-01

The RpoS sigma factor (σ(S)) is the master regulator of the bacterial response to a variety of stresses. Mutants in rpoS arise in bacterial populations in the absence of stress, probably as a consequence of a subtle balance between self-preservation and nutritional competence. We characterized here one natural rpoS mutant of Salmonella enterica serovar Typhi (Ty19). We show that the rpoS allele of Ty19 (rpoS(Ty19)) led to the synthesis of a σ(S)(Ty19) protein carrying a single glycine-to-valine substitution at position 282 in σ(S) domain 4, which was much more dependent than the wild-type σ(S) protein on activation by Crl, a chaperone-like protein that increases the affinity of σ(S) for the RNA polymerase core enzyme (E). We used the bacterial adenylate cyclase two-hybrid system to demonstrate that Crl bound to residues 72 to 167 of σ(S) domain 2 and that G282V substitution did not directly affect Crl binding. However, this substitution drastically reduced the ability of σ(S)(Ty19) to bind E in a surface plasmon resonance assay, a defect partially rescued by Crl. The modeled structure of the Eσ(S) holoenzyme suggested that substitution G282V could directly disrupt a favorable interaction between σ(S) and E. The rpoS(Ty19) allele conferred a competitive fitness when the bacterial population was wild type for crl but was outcompeted in Δcrl populations. Thus, these results indicate that the competitive advantage of the rpoS(Ty19) mutant is dependent on Crl and suggest that crl plays a role in the appearance of rpoS mutants in bacterial populations.

Perspective Tools of the Strategic Management of VFR Tourism Development at the Regional Level

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Gorbunov, Aleksandr P.; Efimova, Ekaterina V.; Kobets, Margarita V.; Kilinkarova, Sofiya G.

2016-01-01

This study is aimed at identifying the perspective tools of strategic management in general and strategic planning of VFR tourism (for the purpose of visiting friends and relatives) at the regional level in particular. It is based on dialectical and logical methods, analysis and synthesis, induction and deduction, the concrete historical and…

[Involvement of the global regulators GrrS, RpoS, and SplIR in formation of biofilms in Serratia plymuthica].

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Zaĭtseva, Iu V; Voloshina, P V; Liu, X; Ovadis, M I; Berg, G; Chernin, L S; Khmel', I A

2010-05-01

Most bacteria exist in the natural environment as biofilms, multicellular communities attached to hard surfaces. Biofilms have a characteristic architecture and are enclosed in the exopolymer matrix. Bacterial cells in biofilms are extremely resistant to antibacterial factors. It was shown in this work that the GrrA/GrrS system of global regulators of gene expression and the sigma S subunit of RNA polymerase (RpoS) play a significant role in positive regulation of biofilm formation in the rhizospheric bacterium Serratia plymuthica IC1270. Inactivation of grrS and rpoS genes resulted in an up to six-to-sevenfold and four-to-fivefold reduction in biofilm formation, respectively. Mutations in the grrS gene decreased the capacity of the bacterium for swarming motility. The splIR Quorum Sensing (QS) system was shown to negatively influence the biofilm formation. Transfer of the recombinant plasmid containing cloned genes splI/splR of S. plymuthica HRO-C48 into S. plymuthica IC1270 cells led to a twofold decrease of their ability to form biofilms. Inactivation of the splI gene coding for the synthase of N-acyl-homoserine lactones in S. plymuthica HRO-C48 resulted in a 2-2.5-fold increase in the level of biofilm formation, whereas the inclusion of plasmid carrying the cloned splI/splR genes into these mutant cells restored the biofilm formation to the normal level. The results obtained demonstrate that the formation of biofilms in S. plymuthica is positively regulated by the GrrA/GrrS and RpoS global regulators and is negatively regulated by the SplIR QS system.

14 CFR 121.349 - Communication and navigation equipment for operations under VFR over routes not navigated by...

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Communication and navigation equipment for... § 121.349 Communication and navigation equipment for operations under VFR over routes not navigated by... receiver providing visual and aural signals; and (iii) One ILS receiver; and (3) Any RNAV system used to...

Exposure to high hydrostatic pressure rapidly selects for increased RpoS activity and general stress-resistance in Escherichia coli O157:H7.

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Vanlint, Dietrich; Rutten, Nele; Govers, Sander K; Michiels, Chris W; Aertsen, Abram

2013-04-15

Exposure to high hydrostatic pressure (HHP) is increasingly being used in food preservation as a non-thermal pasteurization process, and its further implementation necessitates a more thorough understanding of bacterial resistance development and intraspecies variability with regard to inactivation by HHP. In this report, we discovered that exposure to high hydrostatic pressure stress can rapidly select for strongly increased RpoS activity in a hypersensitive Escherichia coli O157:H7 strain (ATCC 43888), leading to a simultaneous increase in HHP and heat resistance. Moreover, the level of RpoS activity correlated well with the original hypersensitivity and the extent of acquired HHP resistance, and extremely HHP-resistant mutants of ATCC 43888 clearly incurred a number of additional RpoS-dependent phenotypes. These findings suggest that implementation of novel processing techniques in the food production chain can readily affect the physiology of food-borne pathogens. Copyright © 2013 Elsevier B.V. All rights reserved.

The response regulator expM is essential for the virulence of Erwinia carotovora subsp. carotovora and acts negatively on the sigma factor RpoS (sigma s).

Science.gov (United States)

Andersson, R A; Palva, E T; Pirhonen, M

1999-07-01

The main virulence factors of Erwinia carotovora subsp. carotovora, the secreted, extracellular cell-wall-degrading enzymes, are controlled by several regulatory mechanisms. We have isolated transposon mutants with reduced virulence on tobacco. One of these mutants, with a mutation in a gene designated expM, was characterized in this study. This mutant produces slightly reduced amounts of extracellular enzymes in vitro and the secretion of the enzymes is also affected. The expM wild-type allele was cloned together with an upstream gene, designated expL, that has an unknown function. The expM gene was sequenced and found to encode a protein with similarity to the RssB/SprE protein of Escherichia coli and the MviA protein of Salmonella typhimurium. These proteins belong to a new type of two-component response regulators that negatively regulate the stability of the Sigma factor RpoS (sigma s) at the protein level. The results of this study suggest that ExpM has a similar function in E. carotovora subsp. carotovora. We also provide evidence that the overproduction of RpoS in the expM mutant is an important factor for the reduced virulence phenotype and that it partly causes the observed phenotype seen in vitro. However, an expM/rpoS double mutant is still affected in secretion of extracellular enzymes, suggesting that ExpM in addition to RpoS also acts on other targets.

Escherichia coli K-12 survives anaerobic exposure at pH 2 without RpoS, Gad, or hydrogenases, but shows sensitivity to autoclaved broth products.

Directory of Open Access Journals (Sweden)

Daniel P Riggins

Full Text Available Escherichia coli and other enteric bacteria survive exposure to extreme acid (pH 2 or lower in gastric fluid. Aerated cultures survive via regulons expressing glutamate decarboxylase (Gad, activated by RpoS, cyclopropane fatty acid synthase (Cfa and others. But extreme-acid survival is rarely tested under low oxygen, a condition found in the stomach and the intestinal tract. We observed survival of E. coli K-12 W3110 at pH 1.2-pH 2.0, conducting all manipulations (overnight culture at pH 5.5, extreme-acid exposure, dilution and plating in a glove box excluding oxygen (10% H2, 5% CO2, balance N2. With dissolved O2 concentrations maintained below 6 µM, survival at pH 2 required Cfa but did not require GadC, RpoS, or hydrogenases. Extreme-acid survival in broth (containing tryptone and yeast extract was diminished in media that had been autoclaved compared to media that had been filtered. The effect of autoclaved media on extreme-acid survival was most pronounced when oxygen was excluded. Exposure to H2O2 during extreme-acid treatment increased the death rate slightly for W3110 and to a greater extent for the rpoS deletion strain. Survival at pH 2 was increased in strains lacking the anaerobic regulator fnr. During anaerobic growth at pH 5.5, strains deleted for fnr showed enhanced transcription of acid-survival genes gadB, cfa, and hdeA, as well as catalase (katE. We show that E. coli cultured under oxygen exclusion (<6 µM O2 requires mechanisms different from those of aerated cultures. Extreme acid survival is more sensitive to autoclave products under oxygen exclusion.

Increase in imported malaria in the Netherlands in asylum seekers and VFR travellers.

Science.gov (United States)

de Gier, Brechje; Suryapranata, Franciska S T; Croughs, Mieke; van Genderen, Perry J J; Keuter, Monique; Visser, Leo G; van Vugt, Michele; Sonder, Gerard J B

2017-02-02

Malaria is a notifiable disease in the Netherlands, a non-endemic country. Imported malaria infections occur regularly among travellers, migrants and visitors. Surveillance data were analysed from 2008 to 2015. Trends in amounts of notifications among risk groups were analysed using Poisson regression. For asylum seekers, yearly incidence was calculated per region of origin, using national asylum request statistics as denominator data. For tourists, denominator data were used from travel statistics to estimate incidence per travel region up to 2012. A modest increase in overall imported malaria notifications occurred in 2008-2015 (from 222 in 2008 to 344 in 2015). Notably, in 2014 and 2015 sharp increases were seen in malaria among travellers visiting friends and relatives (VFR), and in asylum seekers. Of all Plasmodium falciparum infections, most (1254/1337; 93.8%) were imported from Africa; 1037/1337 (77.6%) were imported from Central and West Africa. Malaria in VFR was mostly caused by P. falciparum infection after visiting Ghana (22%) or Nigeria (19%). Malaria in asylum seekers was mostly caused by Plasmodium vivax infection from the Horn of Africa. The large number of notifications in asylum seekers resulted from both an increase in number of asylum seekers and a striking increase of malaria incidence in this group. Incidence of malaria in asylum seekers from the Horn of Africa ranged between 0.02 and 0.3% in 2008-2013, but rose to 1.6% in 2014 and 1.3% in 2015. In 2008-2012, incidence in tourists visiting Central and West Africa dropped markedly. Imported malaria is on the rise again in the Netherlands, most notably since 2013. This is mostly due to immigration of asylum seekers from the Horn of Africa. The predominance of P. vivax infection among asylum seekers warrants vigilance in health workers when a migrant presents with fever, as relapses of this type of malaria can occur long after arrival in the Netherlands.

Role of bolA and rpoS genes in biofilm formation and adherence pattern by Escherichia coli K-12 MG1655 on polypropylene, stainless steel, and silicone surfaces.

Science.gov (United States)

Adnan, Mohd; Sousa, Ana Margarida; Machado, Idalina; Pereira, Maria Olivia; Khan, Saif; Morton, Glyn; Hadi, Sibte

2017-06-01

Escherichia coli has developed sophisticated means to sense, respond, and adapt in stressed environment. It has served as a model organism for studies in molecular genetics and physiology since the 1960s. Stress response genes are induced whenever a cell needs to adapt and survive under unfavorable growth conditions. Two of the possible important genes are rpoS and bolA. The rpoS gene has been known as the alternative sigma (σ) factor, which controls the expression of a large number of genes, which are involved in responses to various stress factors as well as transition to stationary phase from exponential form of growth. Morphogene bolA response to stressed environment leads to round morphology of E. coli cells, but little is known about its involvement in biofilms and its development or maintenance. This study has been undertaken to address the adherence pattern and formation of biofilms by E. coli on stainless steel, polypropylene, and silicone surfaces after 24 h of growth at 37 °C. Scanning electron microscopy was used for direct examination of the cell attachment and biofilm formation on various surfaces and it was found that, in the presence of bolA, E. coli cells were able to attach to the stainless steel and silicone very well. By contrast, polypropylene surface was not found to be attractive for E. coli cells. This indicates that bolA responded and can play a major role in the presence and absence of rpoS in cell attachment.

Phenotype and specificity of T cells in primary human cytomegalovirus infection during pregnancy: IL-7Rpos long-term memory phenotype is associated with protection from vertical transmission.

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Mele, Federico; Fornara, Chiara; Jarrossay, David; Furione, Milena; Arossa, Alessia; Spinillo, Arsenio; Lanzavecchia, Antonio; Gerna, Giuseppe; Sallusto, Federica; Lilleri, Daniele

2017-01-01

Congenital human cytomegalovirus (HCMV) infection is the major cause of birth defects and a precise definition of the HCMV-specific T-cell response in primary infection may help define reliable correlates of immune protection during pregnancy. In this study, a high throughput method was used to define the frequency of CD4+ and CD8+ T cells specific for four HCMV proteins in the naïve compartment of seronegative subjects and the effector/memory compartments of subjects with primary/remote HCMV infection. The naïve repertoire displayed comparable frequencies of T cells that were reactive with HCMV structural (pp65, gB and the pentamer gHgLpUL128L) and non-structural (IE-1) proteins. Whereas, following natural infection, the majority of effector/memory CD4+ and CD8+ T cells recognized either gB or IE-1, respectively, and pp65. The pattern of T cell reactivity was comparable at early and late stages of infection and in pregnant women with primary HCMV infection transmitting or not transmitting the virus to the fetus. At an early stage of primary infection, about 50% of HCMV-reactive CD4+ T cells were long-term IL-7Rpos memory cells, while 6-12 months later, the frequency of these cells increased to 70%, approaching 100% in remote infections. In contrast, only 10-20% of HCMV-specific CD8+ T cells were long-term memory cells up to 12 months after infection onset, thereafter increasing to 70% in remote infections. Interestingly, a significantly higher frequency of HCMV-specific CD4+ T cells with a long-term IL-7Rpos memory phenotype was observed in non-transmitting compared to transmitting women. These findings indicate that immunodominance in HCMV infection is not predetermined in the naïve compartment, but is the result of virus-host interactions and suggest that prompt control of HCMV infection in pregnancy is associated with the rapid development of long-term IL-7Rpos memory HCMV-specific CD4+ T cells and a low risk of virus transmission to the fetus.

A new positive pressure ventilation delivery system: its impact on lung ventilation studies that are technically inadequate or non diagnostic

International Nuclear Information System (INIS)

Bui, C.; Leiper, C.; Lee, K.; Saunders, C.; Dixson, H.; Elison, B.; Bennett, G.; Gibian, T.; Rutland, J.; Tse, V.; Elzein, H.; Babicheva, R.

2000-01-01

Full text: The objective of this study was to evaluate the efficacy and safety of an improved Positive Pressure Ventilation Delivery System (PVDS) in the investigation of Pulmonary Embolism (PE). The major component of PVDS is a commercially available, self-inflating 1.6L Hudson Resuscitator Bag, filled with either oxygen or air (if the patient has CO 2 retention), which is squeezed by the operator to push Technegas from the Technegas Generator Chamber to the patient via the Patient Administration Set synchronously with patient inspiration. 27 spontaneously breathing in-patients (12 males, 15 females, age range 64-89, 21 with chronic airflow limitation), whose conventional lung ventilation images were technically inadequate or non diagnostic, were re-scanned using PVDS within four days after the conventional ventilation study. Randomised blinded visual interpretation of conventional ventilation/perfusion scan vs. PVDS-assisted ventilation/perfusion scan was performed by consensus reading with two experienced observers. In conclusion PVDS was safe and well tolerated. PVDS improved the image quality of the lung ventilation scans in this cohort of patients. This technique has the potential to improve the accuracy of lung scanning in patients with severe lung disease. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

Identification of IbeR as a Stationary-Phase Regulator in Meningitic Escherichia coli K1 that Carries a Loss-of-Function Mutation in rpoS

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Feng Chi

2009-01-01

Full Text Available IbeR is a regulator present in meningitic Escherichia coli strain E44 that carries a loss-of-function mutation in the stationary-phase (SP regulatory gene rpoS. In order to determine whether IbeR is an SP regulator in E44, two-dimensional gel electrophoresis and LC-MS were used to compare the proteomes of a noninvasive ibeR deletion mutant BR2 and its parent strain E44 in the SP. Four up-regulated (TufB, GapA, OmpA, AhpC and three down-regulated (LpdA, TnaA, OpmC proteins in BR2 were identified when compared to E44. All these proteins contribute to energy metabolism or stress resistance, which is related to SP regulation. One of the down-regulated proteins, tryptophanase (TnaA, which is regulated by RpoS in other E. coli strains, is associated with SP regulation via production of a signal molecule indole. Our studies demonstrated that TnaA was required for E44 invasion, and that indole was able to restore the noninvasive phenotype of the tnaA mutant. The production of indole was significantly reduced in BR2, indicating that ibeR is required for the indole production via tnaA. Survival studies under different stress conditions indicated that IbeR contributed to bacteria stress resistance in the SP. Taken together, IbeR is a novel regulator contributing to the SP regulation.

Borrelia burgdorferi requires the alternative sigma factor RpoS for dissemination within the vector during tick-to-mammal transmission.

Directory of Open Access Journals (Sweden)

Star M Dunham-Ems

2012-02-01

Full Text Available While the roles of rpoS(Bb and RpoS-dependent genes have been studied extensively within the mammal, the contribution of the RpoS regulon to the tick-phase of the Borrelia burgdorferi enzootic cycle has not been examined. Herein, we demonstrate that RpoS-dependent gene expression is prerequisite for the transmission of spirochetes by feeding nymphs. RpoS-deficient organisms are confined to the midgut lumen where they transform into an unusual morphotype (round bodies during the later stages of the blood meal. We show that round body formation is rapidly reversible, and in vitro appears to be attributable, in part, to reduced levels of Coenzyme A disulfide reductase, which among other functions, provides NAD+ for glycolysis. Our data suggest that spirochetes default to an RpoS-independent program for round body formation upon sensing that the energetics for transmission are unfavorable.

Effects of exogenous pyoverdines on Fe availability and their impacts on Mn(II) oxidation by Pseudomonas putida GB-1

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Lee, Sung-Woo; Parker, Dorothy L.; Geszvain, Kati; Tebo, Bradley M.

2014-01-01

Pseudomonas putida GB-1 is a Mn(II)-oxidizing bacterium that produces pyoverdine-type siderophores (PVDs), which facilitate the uptake of Fe(III) but also influence MnO2 formation. Recently, a non-ribosomal peptide synthetase mutant that does not synthesize PVD was described. Here we identified a gene encoding the PVDGB-1 (PVD produced by strain GB-1) uptake receptor (PputGB1_4082) of strain GB-1 and confirmed its function by in-frame mutagenesis. Growth and other physiological responses of these two mutants and of wild type were compared during cultivation in the presence of three chemically distinct sets of PVDs (siderotypes n°1, n°2, and n°4) derived from various pseudomonads. Under iron-limiting conditions, Fe(III) complexes of various siderotype n°1 PVDs (including PVDGB-1) allowed growth of wild type and the synthetase mutant, but not the receptor mutant, confirming that iron uptake with any tested siderotype n°1 PVD depended on PputGB1_4082. Fe(III) complexes of a siderotype n°2 PVD were not utilized by any strain and strongly induced PVD synthesis. In contrast, Fe(III) complexes of siderotype n°4 PVDs promoted the growth of all three strains and did not induce PVD synthesis by the wild type, implying these complexes were utilized for iron uptake independent of PputGB1_4082. These differing properties of the three PVD types provided a way to differentiate between effects on MnO2 formation that resulted from iron limitation and others that required participation of the PVDGB-1 receptor. Specifically, MnO2 production was inhibited by siderotype n°1 but not n°4 PVDs indicating PVD synthesis or PputGB1_4082 involvement rather than iron-limitation caused the inhibition. In contrast, iron limitation was sufficient to explain the inhibition of Mn(II) oxidation by siderotype n°2 PVDs. Collectively, our results provide insight into how competition for iron via siderophores influences growth, iron nutrition and MnO2 formation in more complex environmental

Three-dimensional modelling of an embankment built on a soft soil improved with prefabricated vertical drains

OpenAIRE

Venda Oliveira, P.J.; Cruz, R.F.P.M.L.; Lemos, L.J.L.; Almeida e Sousa, J.N.V.

2015-01-01

This work compares the field measurements of a non-symmetric embankment built on a Portuguese soft soil improved with prefabricated vertical drains (PVDs), with the numerical predictions of a 3D modelling where the PVDs are simulated according to the field flow conditions. The change in the permeability with the void ratio and the effect of the smear zone are also included in the numerical analysis. The numerical predictions are compared with the field data in terms of settlement, horizontal ...

Structural characterization of pyoverdines produced by Pseudomonas putida KT2440 and Pseudomonas taiwanensis VLB120.

Science.gov (United States)

Baune, Matthias; Qi, Yulin; Scholz, Karen; Volmer, Dietrich A; Hayen, Heiko

2017-08-01

The previously unknown sequences of several pyoverdines (PVD) produced by a biotechnologically-relevant bacterium, namely, Pseudomonas taiwanensis VLB120, were characterized by high performance liquid chromatography (HPLC)-high resolution mass spectrometry (HRMS). The same structural characterization scheme was checked before by analysis of Pseudomonas sp. putida KT2440 samples with known PVDs. A new sample preparation strategy based on solid-phase extraction was developed, requiring significantly reduced sample material as compared to existing methods. Chromatographic separation was performed using hydrophilic interaction liquid chromatography with gradient elution. Interestingly, no signals for apoPVDs were detected in these analyses, only the corresponding aluminum(III) and iron(III) complexes were seen. The chromatographic separation readily enabled separation of PVD complexes according to their individual structures. HPLC-HRMS and complementary fragmentation data from collision-induced dissociation and electron capture dissociation enabled the structural characterization of the investigated pyoverdines. In Pseudomonas sp. putida KT2240 samples, the known pyoverdines G4R and G4R A were readily confirmed. No PVDs have been previously described for Pseudomonas sp. taiwanensis VLB120. In our study, we identified three new PVDs, which only differed in their acyl side chains (succinic acid, succinic amide and malic acid). Peptide sequencing by MS/MS provided the sequence Orn-Asp-OHAsn-Thr-AcOHOrn-Ser-cOHOrn. Of particular interest is the presence of OHAsn, which has not been reported as PVD constituent before.

The role of each compartment in a two-compartment vertical flow reactor for ferruginous mine water treatment.

Science.gov (United States)

Yim, G J; Cheong, Y W; Hong, J H; Hur, W

2014-10-01

A vertical flow reactor (VFR) has been suggested for remediation of ferruginous mine drainage that passes down through an accreting bed of ochre. However, a VFR has a limited operation time until the system begins to overflow. In this study, a mathematical model was developed as a part of the effort to explore the operation of a VFR, showing dynamic changes in the head differences, ochre depths, and Fe(II)/Fe(III) concentrations in the effluent flow. The analysis showed that VFR operation time extended from 148.5 days to 163 days in an equally divided and to 168.4 days in asymmetrically (0.72:0.28) divided two-compartment VFR, suggesting that an optimum compartment ratio exists that maximizes the VFR operation time. A constant head filtration in the first compartment maximized filtration efficiency and thus prolonged VFR longevity in the two-compartment VFR. Fe(II) oxidation and ochre formation should be balanced with the permeability of the ochre bed to maximize the VFR operation time and minimize the residual Fe(II) in the effluent. Accelerated Fe(II) oxidation affected the optimum ratio of the compartment area and reduced the residual Fe(II) in the effluent. The VFR operation time can be prolonged significantly from 764 days to 3620 days by increasing the rate of ochre formation, much more than by accelerating the Fe(II) oxidation. During the prolonged VFR operation, ochre formed largely in the first compartment, while overflowing mine water with reduced iron content was effectively filtered in the second compartment. These results not only provide a better understanding of VFR operation but also suggest the direction of evolution of two-compartment VFR toward a compact and highly efficient facility integrated with an aerated cascade and with automatic coagulant feeding. Copyright © 2014 Elsevier Ltd. All rights reserved.

Compartment in vertical flow reactor for ferruginous mine water

Science.gov (United States)

Hur, Won; Cheong, Young-Wook; Yim, Gil-Jae; Ji, Sang-Woo; Hong, Ji-Hye

2014-05-01

Mine effluents contain varying concentrations of ferrous ion along with other metal ions. Fe(II) that quickly oxidizes to form precipitates in the presence of oxygen under net alkaline or neutral conditions. Thus, passive treatment methods are designed for the mine water to reside in an open containment area so as to allow simultaneous oxidation and precipitation of Fe(II), such as in a lagoon or an oxidation pond. A vertical flow reactor (VFR) was also suggested to remediate ferruginous mine drainage passing down through an accreting bed of ochre. However, VFR has a limited operation time until the system begins to overflow. It was also demonstrated that two-compartment VFR has a longer operation time than single compartment VFR of same size. In this study, a mathematical model was developed as a part of efforts to explore the operation of VFR, showing dynamic changes in head differences, ochre depth and Fe(II)/Fe(III) concentration in the effluent flow. The analysis shows that Fe(II) oxidation and ochre formation should be balanced with permeability of ochre bed to maximize VFR operation time and minimize residual Fe(II) in the effluent. The model demonstrates that two compartment VFR can have a longer operation time than a single-compartment VFR and that an optimum compartment ratio exists that maximize VFR operation time. Accelerated Fe(II) oxidation significantly affects the optimum ratio of compartment area and reduced residual Fe(II) in the effluent. VFR operation time can be significantly prolonged by increasing the rate of ochre formation not by accelerated Fe(II) oxidation. Taken together, ochre forms largely in the first compartment while overflowed mine water with reduced iron contents is efficiently filtered in the second compartment. These results provide us a better understanding of VFR operation and optimum design criteria for maximum operation time in a two-compartment VFR. Rapid ochre accretion in the first compartment maintains constant hydraulic

Relative Lyapunov Center Bifurcations

DEFF Research Database (Denmark)

Wulff, Claudia; Schilder, Frank

2014-01-01

Relative equilibria (REs) and relative periodic orbits (RPOs) are ubiquitous in symmetric Hamiltonian systems and occur, for example, in celestial mechanics, molecular dynamics, and rigid body motion. REs are equilibria, and RPOs are periodic orbits of the symmetry reduced system. Relative Lyapunov...... center bifurcations are bifurcations of RPOs from REs corresponding to Lyapunov center bifurcations of the symmetry reduced dynamics. In this paper we first prove a relative Lyapunov center theorem by combining recent results on the persistence of RPOs in Hamiltonian systems with a symmetric Lyapunov...... center theorem of Montaldi, Roberts, and Stewart. We then develop numerical methods for the detection of relative Lyapunov center bifurcations along branches of RPOs and for their computation. We apply our methods to Lagrangian REs of the N-body problem....

RpoS plays a central role in the SOS induction by sub-lethal aminoglycoside concentrations in Vibrio cholerae.

Science.gov (United States)

Baharoglu, Zeynep; Krin, Evelyne; Mazel, Didier

2013-01-01

Bacteria encounter sub-inhibitory concentrations of antibiotics in various niches, where these low doses play a key role for antibiotic resistance selection. However, the physiological effects of these sub-lethal concentrations and their observed connection to the cellular mechanisms generating genetic diversification are still poorly understood. It is known that, unlike for the model bacterium Escherichia coli, sub-minimal inhibitory concentrations (sub-MIC) of aminoglycosides (AGs) induce the SOS response in Vibrio cholerae. SOS is induced upon DNA damage, and since AGs do not directly target DNA, we addressed two issues in this study: how sub-MIC AGs induce SOS in V. cholerae and why they do not do so in E. coli. We found that when bacteria are grown with tobramycin at a concentration 100-fold below the MIC, intracellular reactive oxygen species strongly increase in V. cholerae but not in E. coli. Using flow cytometry and gfp fusions with the SOS regulated promoter of intIA, we followed AG-dependent SOS induction. Testing the different mutation repair pathways, we found that over-expression of the base excision repair (BER) pathway protein MutY relieved this SOS induction in V. cholerae, suggesting a role for oxidized guanine in AG-mediated indirect DNA damage. As a corollary, we established that a BER pathway deficient E. coli strain induces SOS in response to sub-MIC AGs. We finally demonstrate that the RpoS general stress regulator prevents oxidative stress-mediated DNA damage formation in E. coli. We further show that AG-mediated SOS induction is conserved among the distantly related Gram negative pathogens Klebsiella pneumoniae and Photorhabdus luminescens, suggesting that E. coli is more of an exception than a paradigm for the physiological response to antibiotics sub-MIC.

Phase contrast MR imaging measurements of blood flow in healthy human cerebral vessel segments

International Nuclear Information System (INIS)

MacDonald, Matthew Ethan; Frayne, Richard

2015-01-01

Phase contrast (PC) magnetic resonance imaging was used to obtain velocity measurements in 30 healthy subjects to provide an assessment of hemodynamic parameters in cerebral vessels. We expect a lower coefficient-of-variation (COV) of the volume flow rate (VFR) compared to peak velocity (v_p_e_a_k) measurements and the COV to increase in smaller caliber arteries compared to large arteries.PC velocity maps were processed to calculate v_p_e_a_k and VFR in 26 vessel segments. The mean, standard deviation and COV, of v_p_e_a_k and VFR in each segment were calculated. A bootstrap-style analysis was used to determine the minimum number of subjects required to accurately represent the population. Significance of v_p_e_a_k and VFR asymmetry was assessed in 10 vessel pairs.The bootstrap analysis suggested that averaging more than 20 subjects would give consistent results. When averaged over the subjects, v_p_e_a_k and VFR ranged from 5.2 ± 7.1 cm s"−"1, 0.41 ± 0.58 ml s"−"1 (in the anterior communicating artery; mean ± standard deviation) to 73 ± 23 cm s"−"1, 7.6 ± 1.7 ml s"−"1 (in the left internal carotid artery), respectively. A tendency for VFR to be higher in the left hemisphere was observed in 88.8% of artery pairs, while the VFR in the right transverse sinus was larger. The VFR COV was larger than v_p_e_a_k COV in 57.7% of segments, while smaller vessels had higher COV.Significance and potential impact: VFR COV was not generally higher than v_p_e_a_k COV. COV was higher in smaller vessels as expected. These summarized values provide a base against which v_p_e_a_k and VFR in various disease states can be compared. (paper)

Environmental Impact Statement for the Modernization and Enhancement of Ranges, Airspace, and Training Areas in the Joint Pacific Alaska Range Complex in Alaska. Volume 1 - Executive Summary, Chapters 1 through 10

Science.gov (United States)

2013-06-01

any impacts on Visual Flight Rules (VFR) and Instrument Flight Rules ( IFR ) air traffic, other existing mitigations would continue to be relevant in...determine specific impacts and mitigation measures to be taken to minimize any impacts on VFR and IFR air traffic, other existing mitigations would...alternatives to determine specific impacts and mitigation measures to be taken to minimize any impacts on VFR and IFR air traffic, other existing

Speech systems for autonomous unmanned aircraft: enabling autonomous unmanned aircraft to communicate in civil airspace

CSIR Research Space (South Africa)

Burger, CR

2011-09-01

Full Text Available (VFR) and Instrument Flight Rules (IFR). Typical local surveillance missions are done under VFR, but almost all passenger- carrying operations are done under IFR. Because many urban surveillance missions take place in close proximity to airline... hubs, IFR capability is required. Rural and peri-urban operations require VFR capability. The levels of control are: o Controlled airspace: In controlled airspace, a controller provides binding instructions to ensure that traffic separation...

Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation.

Science.gov (United States)

Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang

2017-12-01

Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

Due Regard Encounter Model Version 1.0

Science.gov (United States)

2013-08-19

Note that no existing model covers encoun- ters between two IFR aircraft in oceanic airspace. The reason for this is that one cannot observe encounters...encounters between instrument flight rules ( IFR ) and non- IFR traffic beyond 12NM. 2 TABLE 1 Encounter model categories. Aircraft of Interest Intruder...Aircraft Location Flight Rule IFR VFR Noncooperative Noncooperative Conventional Unconventional CONUS IFR C C U X VFR C U U X Offshore IFR C C U X VFR C U

Impact of traveling to visit friends and relatives on chronic disease management.

Science.gov (United States)

Gurgle, Holly E; Roesel, David J; Erickson, Tiffany N; Devine, Emily Beth

2013-01-01

Travelers visiting friends and relatives (VFR) are known to be at high risk of acquiring infectious diseases during travel. However, little is known about the impact of VFR travel on chronic diseases. This was a nonrandomized, retrospective observational study. Patients were adult VFR travelers who received care from an internal medical clinic serving immigrants and refugees. The primary objective was to determine the impact of VFR travel on markers of chronic disease management including: blood pressure, glycosylated hemoglobin, body mass index, serum creatinine, and anticoagulation. Of the 110 VFR travelers in our study, N = 48 traveled to Africa and N = 62 traveled to Asia for a mean duration of 59 (range 21-303) days. Of the 433 counseling points discussed at pre-travel visits, 71% were infectious disease prevention, 16% chronic disease related, and 13% travel safety. A total of 63 patients (57%) reported one or more health problems while traveling. Of these, 35 patients (32%) experienced a problem related to a chronic condition. In comparison, 24 (22%) patients experienced an acute infection. Sixty percent of patients were nonadherent to medications during travel. An average increase in diastolic blood pressure of 3.6 mmHg among patients with hypertension was the only statistically significant change in a chronic disease marker when values before and after travel were compared. Subgroup analysis revealed that travel to Africa and nonadherence to medications were also associated with worsening blood pressure control, and patients traveling to Africa experienced a decrease in body mass index. This study identified a high proportion of problems related to chronic conditions experienced during VFR travel, while pre-travel appointments tended to focus on infectious disease prevention. A greater emphasis on medication adherence and chronic disease management during VFR travel is also needed during pre-travel preparations. © 2013 International Society of

Better-Than-Visual Technologies for Next Generation Air Transportation System Terminal Maneuvering Area Operations

Science.gov (United States)

Prinzel, Lawrence J., III; Bailey, Randall E.; Shelton, Kevin J.; Jones, Denise R.; Kramer, Lynda J.; Arthur, Jarvis J., III; Williams, Steve P.; Barmore, Bryan E.; Ellis, Kyle E.; Rehfeld, Sherri A.

2011-01-01

A consortium of industry, academia and government agencies are devising new concepts for future U.S. aviation operations under the Next Generation Air Transportation System (NextGen). Many key capabilities are being identified to enable NextGen, including the concept of Equivalent Visual Operations (EVO) replicating the capacity and safety of today's visual flight rules (VFR) in all-weather conditions. NASA is striving to develop the technologies and knowledge to enable EVO and to extend EVO towards a Better-Than-Visual (BTV) operational concept. The BTV operational concept uses an electronic means to provide sufficient visual references of the external world and other required flight references on flight deck displays that enable VFR-like operational tempos and maintain and improve the safety of VFR while using VFR-like procedures in all-weather conditions. NASA Langley Research Center (LaRC) research on technologies to enable the concept of BTV is described.

Characterization of volumetric flow rate waveforms at the carotid bifurcations of older adults

International Nuclear Information System (INIS)

Hoi, Yiemeng; Xie, Yuanyuan J; Steinman, David A; Wasserman, Bruce A; Najjar, Samer S; Lakatta, Edward G; Ferruci, Luigi; Gerstenblith, Gary

2010-01-01

While it is widely appreciated that volumetric blood flow rate (VFR) dynamics change with age, there has been no detailed characterization of the typical shape of carotid bifurcation VFR waveforms of older adults. Toward this end, retrospectively gated phase contrast magnetic resonance imaging was used to measure time-resolved VFR waveforms proximal and distal to the carotid bifurcations of 94 older adults (age 68 ± 8 years) with little or no carotid artery disease, recruited from the BLSA cohort of the VALIDATE study of factors in vascular aging. Timings and amplitudes of well-defined feature points from these waveforms were extracted automatically and averaged to produce representative common, internal and external carotid artery (CCA, ICA and ECA) waveform shapes. Relative to young adults, waveforms from older adults were found to exhibit a significantly augmented secondary peak during late systole, resulting in significantly higher resistance index (RI) and flow augmentation index (FAI). Cycle-averaged VFR at the CCA, ICA and ECA were 389 ± 74, 245 ± 61 and 125 ± 49 mL min −1 , respectively, reflecting a significant cycle-averaged outflow deficit of 5%, which peaked at around 10% during systole. A small but significant mean delay of 13 ms between arrivals of ICA versus CCA/ECA peak VFR suggested differential compliance of these vessels. Sex and age differences in waveform shape were also noted. The characteristic waveforms presented here may serve as a convenient baseline for studies of VFR waveform dynamics or as suitable boundary conditions for models of blood flow in the carotid arteries of older adults

Investigation on effectiveness of a prefabricated vertical drain during cyclic loading

International Nuclear Information System (INIS)

Indraratna, B; Ni, J; Rujikiatkamjorn, C

2010-01-01

The effectiveness of prefabricated vertical drains (PVDs) in enhancing the stability of soft soils during cyclic loading was investigated using triaxial cyclic loading tests. Both undrained and with PVD tests were employed to study the associated excess pore pressure and accumulated strain under the repeated loading condition. The loading frequency and cyclic stress ratio have been chosen to be the variables which influence the performance of soft clays. The experimental results illustrate that with PVDs, the excess pore water pressure generation during cyclic loading decreases significantly. It is found that the excess pore water pressure build up depends on both loading frequency and cyclic stress ratio. The excess pore water pressure will increase when each of them is increased. Furthermore, when the loading frequency is 0.1 Hz, the ratio of coefficient of consolidation under cyclic loading to that under static loading is almost one. With the increasing loading frequency, this ratio increases accordingly.

Haemophilus ducreyi Hfq contributes to virulence gene regulation as cells enter stationary phase.

Science.gov (United States)

Gangaiah, Dharanesh; Labandeira-Rey, Maria; Zhang, Xinjun; Fortney, Kate R; Ellinger, Sheila; Zwickl, Beth; Baker, Beth; Liu, Yunlong; Janowicz, Diane M; Katz, Barry P; Brautigam, Chad A; Munson, Robert S; Hansen, Eric J; Spinola, Stanley M

2014-02-11

To adapt to stresses encountered in stationary phase, Gram-negative bacteria utilize the alternative sigma factor RpoS. However, some species lack RpoS; thus, it is unclear how stationary-phase adaptation is regulated in these organisms. Here we defined the growth-phase-dependent transcriptomes of Haemophilus ducreyi, which lacks an RpoS homolog. Compared to mid-log-phase organisms, cells harvested from the stationary phase upregulated genes encoding several virulence determinants and a homolog of hfq. Insertional inactivation of hfq altered the expression of ~16% of the H. ducreyi genes. Importantly, there were a significant overlap and an inverse correlation in the transcript levels of genes differentially expressed in the hfq inactivation mutant relative to its parent and the genes differentially expressed in stationary phase relative to mid-log phase in the parent. Inactivation of hfq downregulated genes in the flp-tad and lspB-lspA2 operons, which encode several virulence determinants. To comply with FDA guidelines for human inoculation experiments, an unmarked hfq deletion mutant was constructed and was fully attenuated for virulence in humans. Inactivation or deletion of hfq downregulated Flp1 and impaired the ability of H. ducreyi to form microcolonies, downregulated DsrA and rendered H. ducreyi serum susceptible, and downregulated LspB and LspA2, which allow H. ducreyi to resist phagocytosis. We propose that, in the absence of an RpoS homolog, Hfq serves as a major contributor of H. ducreyi stationary-phase and virulence gene regulation. The contribution of Hfq to stationary-phase gene regulation may have broad implications for other organisms that lack an RpoS homolog. Pathogenic bacteria encounter a wide range of stresses in their hosts, including nutrient limitation; the ability to sense and respond to such stresses is crucial for bacterial pathogens to successfully establish an infection. Gram-negative bacteria frequently utilize the alternative sigma

Fulltext PDF

Indian Academy of Sciences (India)

2014-07-01

Jul 1, 2014 ... RpoS is a stationary-phase sigma factor which is required for the expression of several ... that happened in laboratory strains over the last six decades in retrospect. Representatives of the two E. coli strains K12 and B ... W3110 but not MG1655 has six nonfunctional genes, namely, rpoS, dcuA, rcsC, gatA, ...

Efficacy of Low-Cost PC-Based Aviation Training Devices

Directory of Open Access Journals (Sweden)

Savern l Reweti

2017-03-01

Full Text Available Aim/Purpose: The aim of this study was to explore whether a full cost flight training device (FTD was significantly better for simulator training than a low cost PC-Based Aviation Training Device (PCATD. Background: A quasi-transfer study was undertaken to ascertain whether a Civil Aviation Authority certified Flight Training Device (FTD was more effective at improving pilot proficiency in the performance of a standard VFR traffic pattern (Overhead Rejoin Procedure than a customised low cost PCATD. Methodology: In this quasi-transfer study, a high fidelity FTD rather than an aircraft was used to test both training and transfer tasks. Ninety-three pilots were recruited to participate in the study. Contribution: The use of PCATDs is now well established for pilot training, especially for Instrument Flight Rules (IFR skills training. However, little substantive research has been undertaken to examine their efficacy for VFR training. Findings: There was no evidence of a pre-test/post-test difference in VFR task perfor-mance between participants trained on the PCATD and the FTD, when post tested on the FTD. The use of both PCATD and FTD demonstrated signifi-cant improvements in VFR task performance compared to a control group that received no PCATD or FTD training. Recommendations for Practitioners\t: We discuss the possibility that low cost PCATDs may be a viable alternative for flight schools wishing to use a flight simulator but not able to afford a FTD. Recommendation for Researchers: We discuss the introduction of improved low cost technologies that allow PCATDs to be used more effectively for training in VFR procedures. The development and testing of new technologies requires more research. Impact on Society: Flight training schools operate in a difficult economic environment with continued increases in the cost of aircraft maintenance, compliance costs, and aviation fuel. The increased utilisation of low cost PCATD’s especially for VFR

Iron-mineral accretion from acid mine drainage and its application in passive treatment.

Science.gov (United States)

Florence, K; Sapsford, D J; Johnson, D B; Kay, C M; Wolkersdorfer, C

2016-01-01

This study demonstrates substantial removal of iron (Fe) from acid mine drainage (pH ≈3) in a passive vertical flow reactor (VFR) with an equivalent footprint of 154 m(2) per L/s mine water and residence times of >23 h. Average Fe removal rate was 67% with a high of 85% over the 10-month trial. The fraction of Fe passing a 0.22 µm filter (referred to here as Fe-filt) was seen to be removed in the VFR even when Fe(II) was absent, indicating that the contribution of microbial Fe(II) oxidation and precipitation was not the dominant removal mechanism in the VFR. Removal rates of Fe-filt in the VFR were up to 70% in residence times as low as 8 h compared with laboratory experiments where much smaller changes in Fe-filt were observed over 60 h. Centrifugation indicated that 80-90% of the influent Fe had particle sizes water was contacted with VFR sludge, the Fe-filt fraction was destabilized, leading to an appreciably higher removal of this fraction. Heterogeneous precipitation and/or aggregation of nanoparticulate Fe(III) precipitates are considered predominant removal mechanisms. Microbial analyses of the mine water revealed the abundance of extracellular polymeric substance-generating Fe-oxidizing bacterium 'Ferrovum myxofaciens', which may aid the removal of iron and explain the unusual appearance and physical properties of the sludge.

Stationary phase expression of the arginine biosynthetic operon argCBH in Escherichia coli

Directory of Open Access Journals (Sweden)

Sun Yuan

2006-02-01

Full Text Available Abstract Background Arginine biosynthesis in Escherichia coli is elevated in response to nutrient limitation, stress or arginine restriction. Though control of the pathway in response to arginine limitation is largely modulated by the ArgR repressor, other factors may be involved in increased stationary phase and stress expression. Results In this study, we report that expression of the argCBH operon is induced in stationary phase cultures and is reduced in strains possessing a mutation in rpoS, which encodes an alternative sigma factor. Using strains carrying defined argR, and rpoS mutations, we evaluated the relative contributions of these two regulators to the expression of argH using operon-lacZ fusions. While ArgR was the main factor responsible for modulating expression of argCBH, RpoS was also required for full expression of this biosynthetic operon at low arginine concentrations (below 60 μM L-arginine, a level at which growth of an arginine auxotroph was limited by arginine. When the argCBH operon was fully de-repressed (arginine limited, levels of expression were only one third of those observed in ΔargR mutants, indicating that the argCBH operon is partially repressed by ArgR even in the absence of arginine. In addition, argCBH expression was 30-fold higher in ΔargR mutants relative to levels found in wild type, fully-repressed strains, and this expression was independent of RpoS. Conclusion The results of this study indicate that both derepression and positive control by RpoS are required for full control of arginine biosynthesis in stationary phase cultures of E. coli.

Iron-mineral accretion from acid mine drainage and its application in passive treatment

Science.gov (United States)

Florence, K.; Sapsford, D.J.; Johnson, D.B.; Kay, C.M.; Wolkersdorfer, C.

2016-01-01

ABSTRACT This study demonstrates substantial removal of iron (Fe) from acid mine drainage (pH ≈3) in a passive vertical flow reactor (VFR) with an equivalent footprint of 154 m2 per L/s mine water and residence times of >23 h. Average Fe removal rate was 67% with a high of 85% over the 10-month trial. The fraction of Fe passing a 0.22 µm filter (referred to here as Fe-filt) was seen to be removed in the VFR even when Fe(II) was absent, indicating that the contribution of microbial Fe(II) oxidation and precipitation was not the dominant removal mechanism in the VFR. Removal rates of Fe-filt in the VFR were up to 70% in residence times as low as 8 h compared with laboratory experiments where much smaller changes in Fe-filt were observed over 60 h. Centrifugation indicated that 80–90% of the influent Fe had particle sizes mine water revealed the abundance of extracellular polymeric substance-generating Fe-oxidizing bacterium ‘Ferrovum myxofaciens’, which may aid the removal of iron and explain the unusual appearance and physical properties of the sludge. PMID:26675674

Use of Weather Information by General Aviation Pilots. Part 2. Qualitative: Exploring Factors Involved in Weather-Related Decision Making

Science.gov (United States)

2008-03-01

fic nstances wthn some gven text, speech, or behavor (Mles & Huberman , 1994). Multple nstances of a sngle factor then consttute a “theme...Aerospace Medcne. Mles, M.B., and Huberman , A.M. (1994). Qualitative data analysis. Thousand Oaks, CA: Sage. Mlgram, S. (2004). Obedience to authority...personal minimum for GA VFR visibility ________ statute miles 12. Your normal personal minimum for GA VFR cloud ceiling ________ feet AGL For

Joint Airspace Control, Doctrine Update 10-06

Science.gov (United States)

2010-05-20

can potentially compromise OPSEC, but can also increase the geographic uncertainty of potential adversaries and may have deterrent or deceptive...provided to IFR and VFR flights in accordance with civil air traffic control regulations. d. Air Corridor/Route (CORRTE). A bi-directional or...have a certain number of instrument flight rules ( IFR ) operations or passenger enplanements. ATC provides separation between VFR and IFR inside

Are Pilots Graduating SUPT Today Meeting AMC’s Current and Future Needs

Science.gov (United States)

2012-02-05

expect. The future operating environment is expected to be characterized by uncertainty , complexity, rapid change and persistent conflict. As...Procedures  Navigation: Visual, VFR, and IFR  Situational Awareness  Task Management  Three-Dimensional Maneuvering Two methods are used...operations under Instrument or VFR to include day / night IFR operations in the terminal and enroute environment. c. The conduct of mission in a

Challenges to providing pre-travel care for travellers visiting friends and relatives: an audit of a specialist travel medicine clinic.

Science.gov (United States)

Rowe, Kate; Chaves, Nadia; Leder, Karin

2017-09-01

Travellers visiting friends and relatives (VFRs) often have complex pre-travel needs. We identified the characteristics, destinations, vaccinations and pre-travel advice provided to VFRs and compared these with non-VFR travellers. The significant differences we found suggest that future research should focus on improving the uptake of recommended interventions in VFR travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Exploiting the Automatic Dependent Surveillance-Broadcast System via False Target Injection

Science.gov (United States)

2012-03-01

IEEE Xplore . 8. Hal Stoen. (2001) VFR Flight. Retrieved February 15, 2012 from http://stoenworks.com/vfr%20flight.html 9. Cohen, B., & Smith, A...7. Gilbert, G. (1973). Historical development of the air traffic control system. IEEE Transactions on Communications, 364-375. Retrieved from...1998. Proceedings., 17th DASC. the AIAA/ IEEE /SAE,2 F44/1- F44/8 vol.2. 10. Livack, G. S., McDaniel, J. I., Battiste, V., & Johnson, W. W. (2000

Pyoverdine synthesis by the Mn(II-oxidizing bacterium Pseudomonas putida GB-1

Directory of Open Access Journals (Sweden)

Dorothy Lundquist Parker

2014-05-01

Full Text Available When iron-starved, the Mn(II-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1, siderophores that both influence iron uptake and inhibit manganese(II oxidation by these strains. To explore the properties and genetics of a PVD that can affect manganese oxidation, LC-MS/MS and various siderotyping techniques were used to identify the peptides of PVDGB-1 and PVDMnB1 as being (for both PVDs: chromophore-Asp-Lys-OHAsp-Ser-Gly-aThr-Lys-cOHOrn, resembling a structure previously reported for P. putida CFML 90-51, which does not oxidize Mn. All three strains also produced an azotobactin and a sulfonated PVD, each with the peptide sequence above, but with unknown regulatory or metabolic effects. Bioinformatic analysis of the sequenced genome of P. putida GB-1 suggested that a particular non-ribosomal peptide synthetase, coded by the operon PputGB1_4083-4086, could produce the peptide backbone of PVDGB-1. To verify this prediction, plasmid integration disruption of PputGB1_4083 was performed and the resulting mutant failed to produce detectable PVD. In silico analysis of the modules in PputGB1_4083-4086 predicted a peptide sequence of Asp-Lys-Asp-Ser-Ala-Thr-Lsy-Orn, which closely matches the peptide determined by MS/MS. To extend these studies to other organisms, various Mn(II-oxidizing and non-oxidizing isolates of P. putida, P. fluorescens, P. marincola, P. fluorescens-syringae group, P. mendocina-resinovorans group and P. stutzerii group were screened for PVD synthesis. The PVD producers (12 out of 16 tested strains were siderotyped and placed into four sets of differing PVD structures, some corresponding to previously characterized PVDs and some to novel PVDs. These results combined with previous studies suggested that the presence of OHAsp or the flexibility of the pyoverdine polypeptide may enable efficient binding of Mn(III.

Pyoverdine synthesis by the Mn(II)-oxidizing bacterium Pseudomonas putida GB-1

Science.gov (United States)

Parker, Dorothy L.; Lee, Sung-Woo; Geszvain, Kati; Davis, Richard E.; Gruffaz, Christelle; Meyer, Jean-Marie; Torpey, Justin W.; Tebo, Bradley M.

2014-01-01

When iron-starved, the Mn(II)-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1), siderophores that both influence iron uptake and inhibit manganese(II) oxidation by these strains. To explore the properties and genetics of a PVD that can affect manganese oxidation, LC-MS/MS, and various siderotyping techniques were used to identify the peptides of PVDGB-1 and PVDMnB1 as being (for both PVDs): chromophore-Asp-Lys-OHAsp-Ser-Gly-aThr-Lys-cOHOrn, resembling a structure previously reported for P. putida CFML 90-51, which does not oxidize Mn. All three strains also produced an azotobactin and a sulfonated PVD, each with the peptide sequence above, but with unknown regulatory or metabolic effects. Bioinformatic analysis of the sequenced genome of P. putida GB-1 suggested that a particular non-ribosomal peptide synthetase (NRPS), coded by the operon PputGB1_4083-4086, could produce the peptide backbone of PVDGB-1. To verify this prediction, plasmid integration disruption of PputGB1_4083 was performed and the resulting mutant failed to produce detectable PVD. In silico analysis of the modules in PputGB1_4083-4086 predicted a peptide sequence of Asp-Lys-Asp-Ser-Ala-Thr-Lsy-Orn, which closely matches the peptide determined by MS/MS. To extend these studies to other organisms, various Mn(II)-oxidizing and non-oxidizing isolates of P. putida, P. fluorescens, P. marincola, P. fluorescens-syringae group, P. mendocina-resinovorans group, and P. stutzerii group were screened for PVD synthesis. The PVD producers (12 out of 16 tested strains) were siderotyped and placed into four sets of differing PVD structures, some corresponding to previously characterized PVDs and some to novel PVDs. These results combined with previous studies suggested that the presence of OHAsp or the flexibility of the pyoverdine polypeptide may enable efficient binding of Mn(III). PMID:24847318

Comparison of Stability of the Results of Orthodontic Treatment and Gingival Health between Hawley and Vacuum-formed Retainers.

Science.gov (United States)

Moslemzadeh, Seyed H; Sohrabi, Aydin; Rafighi, Ali; Farshidnia, Somaieh

2018-04-01

Aim: Retention is one of the stages of orthodontic treatment, which is an attempt to retain teeth in their corrected positions after active treatment with the use of fixed orthodontic appliances. The aim of the present study was to compare the stability of the results of orthodontic treatment and the gingival health between Hawley retainer (HR) and vacuum-formed retainer (VFR) with two different thicknesses. Materials and methods: In this randomized clinical trial, 66 patients undergoing comprehensive orthodontic treatment in a private office were evaluated after completion of treatment. The subjects were randomly assigned to three groups. At the end of orthodontic treatment, the subjects in all the groups received a fixed bonded retainer in the mandible; in the maxilla, group I received an HR, group II received a VFR with a thickness of 1.5 mm, and group III received a VFR with a thickness of 1 mm. The American Board of Orthodontics objective grading system (ABO-OGS) index was used at the end of treatment (before the delivery of the retainers) and 6 months after the use of retainers to evaluate the stability of the results of orthodontic treatment. Gingival index (GI) was used at the two above-mentioned intervals to evaluate gingival health. The ABO-OGS measurements were carried out on dental casts by a clinician who was blinded to the types of retainers the patients wore. Data were analyzed with Statistical Package for the Social Sciences (SPSS) version 20, using proper statistical analyses. Results: Six months after the delivery of retainers, ABO-OGS and GI scores with the 1.5 mm VFR were higher than those in the two other groups, with no significant differences between the three groups. There were no significant differences between the ABO-OGS scores before the delivery of retainers and 6 months after the use of retainers in any of the study groups. In the HR and 1.5 mm VFR groups, there were significant differences in GI scores between the period before the

Statistical Analysis of Pseudomonas aeruginosa Biofilm Development: Impact of Mutations in Genes Involved in Twitching Motility, Cell-to-Cell Signaling, and Stationary-Phase Sigma Factor Expression

DEFF Research Database (Denmark)

Heydorn, Arne; Ersbøll, Bjarne Kjær; Kato, Junichi

2002-01-01

of variance model comprising the four P. aeruginosa strains, five time points (55, 98, 146, 242, and 314 h), and three independent rounds of biofllm experiments. The results showed that the wild type, the DeltapilHIJK mutant, and the rpoS mutant display conspicuously different types of temporal biofilm...... development, whereas the lasI mutant was indistinguishable from the wild type at all time points. The wild type and the lasI mutant formed uniform, densely packed biofilms. The rpoS mutant formed densely packed biofilms that were significantly thicker than those of the wild type, whereas the Deltapil...

Health challenges of young travelers visiting friends and relatives compared with those traveling for other purposes.

Science.gov (United States)

Han, Pauline; Yanni, Emad; Jentes, Emily S; Hamer, Davidson H; Chen, Lin H; Wilson, Mary E; Macleod, William B; Ooi, Winnie W; Kogelman, Laura; Karchmer, Adolf W; Barnett, Elizabeth D

2012-09-01

The study objective was to assess differences in demographics and travel health challenges between youths ≤18 years old traveling internationally to visit friends and relatives (VFRs) compared with those traveling for other purposes (non-VFR). The Boston Area Travel Medicine Network consists of 5 clinics collecting anonymous data from international pretravel consultations. Data on all travelers ≤18 years of age seen between January 2008 and July 2010 were used. VFRs were compared with non-VFRs on demographics, primary language, trip characteristics, travel vaccinations administered, malaria prophylaxis and antidiarrheal medications prescribed. Thirty-five percent (610/1731) listed VFR as their purpose of travel. Almost half of VFRs were travel to countries that were yellow fever holoendemic, had malaria risk and were high-risk for typhoid (44% versus 20%, 39% versus 12%, 25% versus 15%, P travel-related morbidity, healthcare providers should be prepared to give travel advice to parents of VFR infants and children, particularly those US-born VFRs with foreign-born parents, regarding antimalarial and antidiarrheal medications and preventing yellow fever, malaria and typhoid.

Modeling Political Populations with Bacteria

Science.gov (United States)

Cleveland, Chris; Liao, David

2011-03-01

Results from lattice-based simulations of micro-environments with heterogeneous nutrient resources reveal that competition between wild-type and GASP rpoS819 strains of E. Coli offers mutual benefit, particularly in nutrient deprived regions. Our computational model spatially maps bacteria populations and energy sources onto a set of 3D lattices that collectively resemble the topology of North America. By implementing Wright-Fishcer re- production into a probabilistic leap-frog scheme, we observe populations of wild-type and GASP rpoS819 cells compete for resources and, yet, aid each other's long term survival. The connection to how spatial political ideologies map in a similar way is discussed.

Vulvar field resection: novel approach to the surgical treatment of vulvar cancer based on ontogenetic anatomy.

Science.gov (United States)

Höckel, Michael; Schmidt, Katja; Bornmann, Karoline; Horn, Lars-Christian; Dornhöfer, Nadja

2010-10-01

Current local treatment of vulvar cancer is wide tumor excision and radical vulvectomy based on functional anatomy established from the adult and on the view of radial progressive tumor permeation. Standard surgery is associated with a considerable local failure rate and severe disturbance of the patients' body image. Vulvar field resection (VFR) is based on ontogenetic anatomy and on the concept of local tumor spread within permissive compartments. VFR combined with anatomical reconstruction (AR) is proposed as a new surgical approach to the treatment of vulvar cancer. A prospective trial was launched to test the compartment theory for vulvar cancer and to assess safety and effectiveness of the new therapy. In 54 consecutive patients 46 tumors were locally confined to the tissue compartment differentiated from the vulvar anlage. The 8 tumors having transgressed into adjacent tissue compartments of different embryonic origins exhibited signs of advanced malignant progression. 38 patients with vulvar cancer, stages T1-3 were treated with VFR and AR. The perioperative complication rate was low. At 19 (3-50) months follow-up no patient failed locally. 33 patients estimated their body image as undisturbed. Vulvar cancer permeates within ontogenetic tissue compartments and surgical treatment with VFR and AR appears to be safe and effective. Patients should benefit from the new approach as local tumor control is high and the preserved tissue can be successfully used for restoration of vulvar form and function. Confirmatory trials with more patients and longer follow-up are suggested. Copyright © 2010 Elsevier Inc. All rights reserved.

An increase in visceral fat is associated with a decrease in the taste and olfactory capacity.

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Jose Carlos Fernandez-Garcia

Full Text Available Sensory factors may play an important role in the determination of appetite and food choices. Also, some adipokines may alter or predict the perception and pleasantness of specific odors. We aimed to analyze differences in smell-taste capacity between females with different weights and relate them with fat and fat-free mass, visceral fat, and several adipokines.179 females with different weights (from low weight to morbid obesity were studied. We analyzed the relation between fat, fat-free mass, visceral fat (indirectly estimated by bioelectrical impedance analysis with visceral fat rating (VFR, leptin, adiponectin and visfatin. The smell and taste assessments were performed through the "Sniffin' Sticks" and "Taste Strips" respectively.We found a lower score in the measurement of smell (TDI-score (Threshold, Discrimination and Identification in obese subjects. All the olfactory functions measured, such as threshold, discrimination, identification and the TDI-score, correlated negatively with age, body mass index (BMI, leptin, fat mass, fat-free mass and VFR. In a multiple linear regression model, VFR mainly predicted the TDI-score. With regard to the taste function measurements, the normal weight subjects showed a higher score of taste functions. However a tendency to decrease was observed in the groups with greater or lesser BMI. In a multiple linear regression model VFR and age mainly predicted the total taste scores.We show for the first time that a reverse relationship exists between visceral fat and sensory signals, such as smell and taste, across a population with different body weight conditions.

Corrosion protection of PVD and paint coatings for selective solar absorber surfaces

OpenAIRE

Nunes, A.; Carvalho, M. J.; Diamantino, Teresa C.; Fernandes, J. C. S.

2015-01-01

The selective solar absorber surface is a fundamental part of a solar thermal collector, as it is responsible for the solar radiation absorption and for reduction of radiation heat losses. The surface’s optical properties, the solar absorption (á) and the emittance (å), have great impact on the solar thermal collector efficiency. In this work, two coatings types were studied: coatings obtained by physical vapor deposition (PVDs) and coatings obtained by projection with different paints (PCs) ...

Human factors in aviation: Terminal control area boundary conflicts

Science.gov (United States)

Monan, William P.

1989-01-01

Air-to-air conflicts in the vicinity of Terminal Control Area (TCA) boundaries were studied to obtain a better understanding of the causal dynamics of these events with particular focus on human factor issues. The study dataset consisted of 381 Instrument Flight Rules/Visual Flight Rules (IFR/VFR) traffic conflicts in airspace layers above TCA ceiling and below TCA floors; 213 reports of incursions in TCA terminal airspace by VFR aircraft, of which 123 resulted in conflicts; and an additional set of reports describing problems with Air Traffic Control (ATC) services in and around TCAs. Results and conclusions are detailed.

Variable Persister Gene Interactions with (pppGpp for Persister Formation in Escherichia coli

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Shuang Liu

2017-09-01

Full Text Available Persisters comprise a group of phenotypically heterogeneous metabolically quiescent bacteria with multidrug tolerance and contribute to the recalcitrance of chronic infections. Although recent work has shown that toxin-antitoxin (TA system HipAB depends on stringent response effector (pppGppin persister formation, whether other persister pathways are also dependent on stringent response has not been explored. Here we examined the relationship of (pppGpp with 15 common persister genes (dnaK, clpB, rpoS, pspF, tnaA, sucB, ssrA, smpB, recA, umuD, uvrA, hipA, mqsR, relE, dinJ using Escherichia coli as a model. By comparing the persister levels of wild type with their single gene knockout and double knockout mutants with relA, we divided their interactions into five types, namely A “dependent” (dnaK, recA, B “positive reinforcement” (rpoS, pspF, ssrA, recA, C “antagonistic” (clpB, sucB, umuD, uvrA, hipA, mqsR, relE, dinJ, D “epistasis” (clpB, rpoS, tnaA, ssrA, smpB, hipA, and E “irrelevant” (dnaK, clpB, rpoS, tnaA, sucB, smpB, umuD, uvrA, hipA, mqsR, relE, dinJ. We found that the persister gene interactions are intimately dependent on bacterial culture age, cell concentrations (diluted versus undiluted culture, and drug classifications, where the same gene may belong to different groups with varying antibiotics, culture age or cell concentrations. Together, this study represents the first attempt to systematically characterize the intricate relationships among the different mechanisms of persistence and as such provide new insights into the complexity of the persistence phenomenon at the level of persister gene network interactions.

Quantative flow measurement of the vertebro-basilar circulation for positional vertigo by using 2D phase contrast technique

Energy Technology Data Exchange (ETDEWEB)

Tominaga, Satoru; Seo, Toru; Ishikura, Reiichi; Nakao, Norio [Hyogo Coll. of Medicine, Nishinomiya (Japan); Tabuchi, Yukiko

1996-04-01

Quantative measurements of blood flow in the vertebral and basilar arteries were obtained by the 2D phase contrast (2D PC) technique. In phantom study, flow velocity measured with 2D PC correlated well with actual flow velocity. Sixty-six patients were neurologically normal and 20 had positional vertigo due to vertebrobasilar insufficiency (VBI). Mean velocities (MV) were measured by using a transverse plane in the vertebral arteries at the level of C3 and in the basilar arteries at the level of the sella floor. Volume flow rates (VFR) were calculated as the product of MV and the area of the arteries whose diameters were measured on the basis of pixel counting in the histogram of the signal intensity profile. In the normal group, MV of the left vertebral artery and MV and VFR of the basilar artery showed significant declines as age progressed. In the vertigo group, MV and VFR of the basilar artery were significantly lower than in the normal group. It is concluded that 2D PC technique appears to be fast and easy to handle without cardiac gating to assess blood flow in vessels surrounded by bone tissues. (author).

Quantative flow measurement of the vertebro-basilar circulation for positional vertigo by using 2D phase contrast technique

International Nuclear Information System (INIS)

Tominaga, Satoru; Seo, Toru; Ishikura, Reiichi; Nakao, Norio; Tabuchi, Yukiko.

1996-01-01

Quantative measurements of blood flow in the vertebral and basilar arteries were obtained by the 2D phase contrast (2D PC) technique. In phantom study, flow velocity measured with 2D PC correlated well with actual flow velocity. Sixty-six patients were neurologically normal and 20 had positional vertigo due to vertebrobasilar insufficiency (VBI). Mean velocities (MV) were measured by using a transverse plane in the vertebral arteries at the level of C3 and in the basilar arteries at the level of the sella floor. Volume flow rates (VFR) were calculated as the product of MV and the area of the arteries whose diameters were measured on the basis of pixel counting in the histogram of the signal intensity profile. In the normal group, MV of the left vertebral artery and MV and VFR of the basilar artery showed significant declines as age progressed. In the vertigo group, MV and VFR of the basilar artery were significantly lower than in the normal group. It is concluded that 2D PC technique appears to be fast and easy to handle without cardiac gating to assess blood flow in vessels surrounded by bone tissues. (author)

Sizing criteria for a low footprint passive mine water treatment system.

Science.gov (United States)

Sapsford, D J; Williams, K P

2009-02-01

The objective of this paper is to present data from a novel vertical flow mine water treatment system, demonstrate how these data can be used to generate sizing formulae for this technology, and present a comparison between the size of system based on these formulae and those of conventionally designed passive systems. The paper focuses on passive treatment of circum-neutral ferruginous mine waters bearing up to 50 mgl(-1) of iron in either ferrous or ferric form. The Vertical Flow Reactor (VFR) operates by passing mine water down through an accreting bed of ochre, the ochre bed being responsible for the intensification of iron removal by self-filtration and/or autocatalytic iron oxidation and precipitation. Key to the design and operation of the VFR system is the decrease in permeability in this ochre bed over time. The paper demonstrates that the VFR system can remove iron at many times the 10 g/m2/day removal rate - an often employed figure for the sizing of aerobic settling ponds and wetlands. The paper demonstrates that VFRs are viable and novel passive treatment system for mine waters with a smaller footprint than conventional systems.

Mutations Enhancing Amino Acid Catabolism Confer a Growth Advantage in Stationary Phase

Science.gov (United States)

Zinser, Erik R.; Kolter, Roberto

1999-01-01

Starved cultures of Escherichia coli undergo successive rounds of population takeovers by mutants of increasing fitness. These mutants express the growth advantage in stationary phase (GASP) phenotype. Previous work identified the rpoS819 allele as a GASP mutation allowing cells to take over stationary-phase cultures after growth in rich media (M. M. Zambrano, D. A. Siegele, M. A. Almirón, A. Tormo, and R. Kolter, Science 259:1757–1760, 1993). Here we have identified three new GASP loci from an aged rpoS819 strain: sgaA, sgaB, and sgaC. Each locus is capable of conferring GASP on the rpoS819 parent, and they can provide successively higher fitnesses for the bacteria in the starved cultures. All four GASP mutations isolated thus far allow for faster growth on both individual and mixtures of amino acids. Each mutation confers a growth advantage on a different subset of amino acids, and these mutations act in concert to increase the overall catabolic capacity of the cell. We present a model whereby this enhanced ability to catabolize amino acids is responsible for the fitness gain during carbon starvation, as it may allow GASP mutants to outcompete the parental cells when growing on the amino acids released by dying cells. PMID:10482523

ORF Sequence: NC_000913 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available NC_000913 gi|16128606 >gi|16128606|ref|NP_415156.1| RNA chaperone, transcription antiterm...inator, affects expression of rpoS and uspA [Escherichia coli K12] MSKIKGNVKWFNESKGFGFITPEDGSKDVFVHFSAIQTNGFKTLAEGQRVEFEITNGAKGPSAANVIAL

The role of situation assessment and flight experience in pilots' decisions to continue visual flight rules flight into adverse weather.

Science.gov (United States)

Wiegmann, Douglas A; Goh, Juliana; O'Hare, David

2002-01-01

Visual flight rules (VFR) flight into instrument meteorological conditions (IMC) is a major safety hazard in general aviation. In this study we examined pilots' decisions to continue or divert from a VFR flight into IMC during a dynamic simulation of a cross-country flight. Pilots encountered IMC either early or later into the flight, and the amount of time and distance pilots flew into the adverse weather prior to diverting was recorded. Results revealed that pilots who encountered the deteriorating weather earlier in the flight flew longer into the weather prior to diverting and had more optimistic estimates of weather conditions than did pilots who encountered the deteriorating weather later in the flight. Both the time and distance traveled into the weather prior to diverting were negatively correlated with pilots' previous flight experience. These findings suggest that VFR flight into IMC may be attributable, at least in part, to poor situation assessment and experience rather than to motivational judgment that induces risk-taking behavior as more time and effort are invested in a flight. Actual or potential applications of this research include the design of interventions that focus on improving weather evaluation skills in addition to addressing risk-taking attitudes.

Texas RPO workshop implementation project summary.

Science.gov (United States)

2012-05-01

This report documents rural planning organization (RPO) workshops conducted throughout Texas. An RPO is a voluntary organization created and governed by locally elected officials responsible for transportation decisions at the local level. RPOs addre...

Chart Supplements - Aeronautical Information Services Digital Products

Data.gov (United States)

Department of Transportation — The Chart Supplements are searchable by individual airport in PDF format. They contain data on public and joint use airports, seaplane bases, heliports, VFR airport...

Development of performance measures for the assessment of rural planning organizations.

Science.gov (United States)

2011-04-27

In order for the Transportation Planning Board to provide oversight and assistance to the 20 RPOs in the state, they : need effective evaluation criteria and performance measures. The existing measures, including the annual : performance report, do n...

Pilot Domain Task Experience in Night Fatal Helicopter Emergency Medical Service Accidents.

Science.gov (United States)

Aherne, Bryan B; Zhang, Chrystal; Newman, David G

2016-06-01

In the United States, accident and fatality rates in helicopter emergency medical service (HEMS) operations increase significantly under nighttime environmentally hazardous operational conditions. Other studies have found pilots' total flight hours unrelated to HEMS accident outcomes. Many factors affect pilots' decision making, including their experience. This study seeks to investigate whether pilot domain task experience (DTE) in HEMS plays a role against likelihood of accidents at night when hazardous operational conditions are entered. There were 32 flights with single pilot nighttime fatal HEMS accidents between 1995 and 2013 with findings of controlled flight into terrain (CFIT) and loss of control (LCTRL) due to spatial disorientation (SD) identified. The HEMS DTE of the pilots were compared with industry survey data. Of the pilots, 56% had ≤2 yr of HEMS experience and 9% had >10 yr of HEMS experience. There were 21 (66%) accidents that occurred in non-visual flight rules (VFR) conditions despite all flights being required to be conducted under VFR. There was a statistically significant increase in accident rates in pilots with pilots with >10 yr HEMS DTE. HEMS DTE plays a preventive role against the likelihood of a night operational accident. Pilots with limited HEMS DTE are more likely to make a poor assessment of hazardous conditions at night, and this will place HEMS flight crew at high risk in the VFR night domain.

Associations of Maternal Dietary Patterns during Pregnancy with Offspring Adiposity from Birth Until 54 Months of Age

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Ling-Wei Chen

2016-12-01

Full Text Available Most studies linking maternal diet with offspring adiposity have focused on single nutrients or foods, but a dietary pattern approach is more representative of the overall diet. We thus aimed to investigate the relations between maternal dietary patterns and offspring adiposity in a multi-ethnic Asian mother–offspring cohort in Singapore. We derived maternal dietary patterns using maternal dietary intake information at 26–28 weeks of gestation, of which associations with offspring body mass index (BMI, abdominal circumference (AC, subscapular skinfold (SS, and triceps skinfold (TS were assessed using longitudinal data analysis (linear mixed effects (LME and multiple linear regression at ages 0, 3, 6, 9, 12, 15, 18, 24, 36, 48, and 54 months. Three dietary patterns were derived: (1 vegetables-fruit-and-white rice (VFR; (2 seafood-and-noodles (SfN; and (3 pasta-cheese-and-bread (PCB. In the LME model adjusting for potential confounders, each standard deviation (SD increase in maternal VFR pattern score was associated with 0.09 mm lower offspring TS. Individual time-point analysis additionally revealed that higher VFR score was generally associated with lower postnatal offspring BMI z-score, TS, SS, and sum of skinfolds (SS + TS at ages 18 months and older. Maternal adherence to a dietary pattern characterized by higher intakes of fruit and vegetables and lower intakes of fast food was associated with lower offspring adiposity.

Black hole mass measurement using molecular gas kinematics: what ALMA can do

Science.gov (United States)

Yoon, Ilsang

2017-04-01

We study the limits of the spatial and velocity resolution of radio interferometry to infer the mass of supermassive black holes (SMBHs) in galactic centres using the kinematics of circum-nuclear molecular gas, by considering the shapes of the galaxy surface brightness profile, signal-to-noise ratios (S/Ns) of the position-velocity diagram (PVD) and systematic errors due to the spatial and velocity structure of the molecular gas. We argue that for fixed galaxy stellar mass and SMBH mass, the spatial and velocity scales that need to be resolved increase and decrease, respectively, with decreasing Sérsic index of the galaxy surface brightness profile. We validate our arguments using simulated PVDs for varying beam size and velocity channel width. Furthermore, we consider the systematic effects on the inference of the SMBH mass by simulating PVDs including the spatial and velocity structure of the molecular gas, which demonstrates that their impacts are not significant for a PVD with good S/N unless the spatial and velocity scale associated with the systematic effects are comparable to or larger than the angular resolution and velocity channel width of the PVD from pure circular motion. Also, we caution that a bias in a galaxy surface brightness profile owing to the poor resolution of a galaxy photometric image can largely bias the SMBH mass by an order of magnitude. This study shows the promise and the limits of ALMA observations for measuring SMBH mass using molecular gas kinematics and provides a useful technical justification for an ALMA proposal with the science goal of measuring SMBH mass.

Epidemiology of imported malaria among children and young adults in Barcelona (1990-2008

Directory of Open Access Journals (Sweden)

Garcia-Villarrubia Mireia

2011-11-01

Full Text Available Abstract Background Increasing international travel and migration is producing changes in trends in infectious diseases, especially in children from many European cities. The objective of this study was to describe the epidemiology and determine the trends of imported malaria in patients under 20 years old in the city of Barcelona, Spain, during an 18-year period. Methods The study included malaria cases that were laboratory confirmed and reported to the malaria register at the Public Health Agency of Barcelona from 1990 to 2008, residing in Barcelona and less than 20 years old. Patients were classified as natives (born in Spain or immigrants. Differences in the distribution of demographic, clinical characteristics, and incidence per 100,000 person-year evolution were analysed. Natives and immigrants were compared by logistic regression by calculating the odds ratio (OR with a 95% confidence interval (CI and Chi-square for a linear trend (p Results Of the total 174 cases, 143 (82.1% were immigrants, 100 (57.5% were female, 121 (69.5% Plasmodium falciparum, and 108 (62.1% were visiting friends and relatives (VFR as the reason for travel. Among the immigrants, 99 (67.8% were from Equatorial Guinea. Immigrant cases more frequently travelled to Africa than natives (p = 0.02. The factors associated with imported malaria among immigrant residents was travelling for VFR (OR: 6.2 CI 1.9-20.2 and age 15-19 (OR: 3.7 CI 1-13.3. The incidence increased from 1990 to 1999 (p Conclusions The majority of cases of malaria in population less than 20 years in Barcelona were immigrants, travelling to Africa for VFR and Plasmodium falciparum was most frequently detected. The trend analysis of the entire study period did not show a statistically significant decline. It is recommended to be aware of malaria, especially among children of immigrants who travel to their parent's home country for VFR. Better access to pre travel advice should be provided.

14 CFR 91.126 - Operating on or in the vicinity of an airport in Class G airspace.

Science.gov (United States)

2010-01-01

... weather conditions are at or above basic VFR weather minimums, visual contact with the tower is maintained... displays approved light signals or visual markings indicating that turns should be made to the right, in...

Sequence Classification: 288227 [

Lifescience Database Archive (English)

Full Text Available rone, transcription antiterminator, affects expression of rpoS and uspA || http://www.ncbi.nlm.nih.gov/protein/16128606 ... ...Non-TMB Non-TMH Non-TMB TMB Non-TMB Non-TMB >gi|16128606|ref|NP_415156.1| RNA chape

14 CFR 91.129 - Operations in Class D airspace.

Science.gov (United States)

2010-01-01

... at or above basic VFR weather minimums; (ii) Visual contact with the tower is maintained; and (iii) A...) Each pilot operating an airplane approaching to land on a runway served by a visual approach slope...

FA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — An Area Forecast (FA) is a forecast of Visual Flight Rules (VFR) clouds and weather conditions over an area as large as the size of several states.

SigWx-Low

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The low-level graphics product is a forecast of aviation weather hazards, primarily intended to be used as a guidance product for briefing the VFR pilot. The...

Cases of typhoid fever in Copenhagen region: a retrospective study of presentation and relapse.

Science.gov (United States)

Barrett, Freja Cecille; Knudsen, Jenny Dahl; Johansen, Isik Somuncu

2013-08-11

Typhoid fever is a systemic illness which in high-income countries mainly affects travellers. The incidence is particularly high on the Indian subcontinent. Travellers who visit friends and relatives (VFR) have been shown to have a different risk profile than others. We wished to identify main characteristics for travellers infected with S. Typhi considering both clinical and laboratory findings in order to provide for faster and better diagnostics in the future. The outcome of treatment, especially concerning relapse, was evaluated as well. Retrospectively collected data from 19 adult cases of typhoid fever over a 5-year period at the Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre Denmark. The patients were young adults, presenting with symptoms within a month after travelling. 84% were returned from travelling in the Indian subcontinent. 17 out of 19 patients were VFR-travellers. The main symptoms were fever (100%), gastrointestinal symptoms (84%), headache (58%) and dry cough (26%). Laboratory findings showed elevated C-reactive protein (CRP) and lactate dehydrogenase (LDH) in all cases and elevated alanine transaminase (ALAT) in 47% of cases. In primary cases 4 isolates were fully susceptible to ciprofloxacin, the remaining were intermediate susceptible. Relapse occurred in 37% of the cases and only in cases where the patient was infected by a strain with intermediate susceptibility. Better pre-travel counselling should be given to VFR-travellers. The main symptoms and laboratory findings confirm previous findings. The relapse rate was unexpected high and could be correlated to ciprofloxacin-resistance.

Imported malaria among African immigrants: is there still a relationship between developed countries and their ex-colonies?

Directory of Open Access Journals (Sweden)

Muñoz José

2009-05-01

Full Text Available Abstract Background The objective of this study was to compare cases of imported malaria originating from the Spanish ex-colony of Equatorial Guinea (EG with those originating from the rest of Africa (RA. Methods All the African cases detected in Barcelona between 1989 and 2007 were investigated in a retrospective analysis. Clinical-epidemiological variables such as sex, age, visiting friends and relatives (VFR, species, hospital admission and chemo-prophylaxis were compared. Data were analysed by logistic regression, calculating the Odds Ratio (OR and 95% Confidence Intervals (95% CI. Results Of the 489 African patients, 279 (57,1% had been born in EG and 210 (42,9% in the rest of Africa. The cumulative incidence of imported malaria among those from EG was 179.6 per thousand inhabitants, while in those from the RA it was 33.7 per thousand (p visiting friends and relatives (VFR category, and more individuals younger than 15 years or older than 37 years, and more women. They also visited a traveller's health centre more often, had fewer hospital admissions and were less likely to reside in the inner city. Conclusion Cases of imported malaria originating in Africa, are more likely to come from the Spanish ex-colony of EG, and VFR are more likely to be affected. It is recommended that developed countries promote prevention programmes, such as CP advice directed at African immigrants, and develop programmes of cooperation against malaria in their ex-colonies.

Bonded versus vacuum-formed retainers: a randomized controlled trial. Part 1: stability, retainer survival, and patient satisfaction outcomes after 12 months.

Science.gov (United States)

Forde, Katherine; Storey, Madeleine; Littlewood, Simon J; Scott, Paul; Luther, Friedy; Kang, Jing

2017-10-20

There is a shortage of evidence on the best type of retainer. Evaluate upper and lower bonded retainers (BRs) versus upper and lower vacuum-formed retainers (VFRs) over 12 months, in terms of stability, retainer survival, and patient satisfaction. Two-arm parallel group multi-centre randomized controlled clinical trial. Sixty consecutive patients completing fixed appliance therapy and requiring retainers were recruited from 3 hospital departments. They were randomly allocated to either upper and lower labial segment BRs (n = 30) or upper and lower full-arch VFRs (n = 30). Primary outcome was stability. Secondary outcomes were retainer survival and patient satisfaction. A random sequence of treatment allocation was computer-generated and implemented by sealing in sequentially numbered opaque sealed envelopes independently prepared in advance. Patients, operators and outcome could not be blinded due to the nature of the intervention. Thirty patients received BRs (median [Mdn] age 16 years, inter-quartile range [IQR] = 2) and 30 received VFRs (Mdn age 17 years, IQR = 4). Baseline characteristics were similar between groups. At 12 months, there were no statistically significant inter-group differences in post-treatment change of maxillary labial segment alignment (BR = 1.1 mm, IQR = 1.56, VFR = 0.76 mm, IQR = 1.55, P = 0.61); however, there was greater post-treatment change in the mandibular VFR group (BR = 0.77 mm, IQR = 1.46, VFR = 1.69mm, IQR = 2.00, P = 0.008). The difference in maxillary retainer survival rates were statistically non-significant, P = 0.34 (BR = 63.6%, 239.3 days, 95% confidence interval [CI] = 191.1-287.5, VFR = 73.3%, 311.1 days, 95% CI = 278.3-344.29). The mandibular BR had a lower survival rate (P = 0.01) at 12 months (BR = 50%, 239.3 days 95% CI = 191.1-287.5, VFR = 80%, 324.9 days 95% CI = 295.4-354.4). More subjects with VFRs reported discomfort (P = 0.002) and speech difficulties (P = 0.004) but found them easier to clean than those with

Small noncoding RNA GcvB is a novel regulator of acid resistance in Escherichia coli

Directory of Open Access Journals (Sweden)

Jin Ye

2009-04-01

Full Text Available Abstract Background The low pH environment of the human stomach is lethal for most microorganisms; but not Escherichia coli, which can tolerate extreme acid stress. Acid resistance in E. coli is hierarchically controlled by numerous regulators among which are small noncoding RNAs (sncRNA. Results In this study, we individually deleted seventy-nine sncRNA genes from the E. coli K12-MG1655 chromosome, and established a single-sncRNA gene knockout library. By systematically screening the sncRNA mutant library, we show that the sncRNA GcvB is a novel regulator of acid resistance in E. coli. We demonstrate that GcvB enhances the ability of E. coli to survive low pH by upregulating the levels of the alternate sigma factor RpoS. Conclusion GcvB positively regulates acid resistance by affecting RpoS expression. These data advance our understanding of the sncRNA regulatory network involved in modulating acid resistance in E. coli.

A unified REC market and composite RPO scheme for promotion of renewable energy in India

Science.gov (United States)

Shereef, R. M.; Khaparde, S. A.

2017-07-01

In India, uniform price was assigned to renewable energy certificate (REC) irrespective of renewable energy (RE) type, technology, and location. Moreover REC price bands are higher than existing preferential tariff. There are distinct renewable purchase obligations (RPOs) specified for various RE types, whereas there is lack of efficient tools to check RPO compliance. Because of these reasons, REC market stabilisation is getting delayed. This paper proposes a method using plant performance multiplier to convert non-solar and solar REC to single equivalent REC with competitive REC pricing, which can be traded on unified REC market. The method combines solar and non-solar RPOs into a single composite RPO, to make RPO compliance and its checking simple and efficient. A sample illustration of the proposed method is given. The benefits offered by the proposed method in REC pricing, REC trading and RPO compliance are discussed. A comparative economic analysis of present and proposed method is reported.

Solutions Network Formulation Report. Integration of OMI and TES Aerosol Products into the EPA Regional Planning Organizations' FASTNET Aerosol Tracking and Analysis Tool

Science.gov (United States)

Knowlton, Kelly; Andrews, Jane C.

2006-01-01

Every year, more than 280 million visitors tour our Nation s most treasured parks and wilderness areas. Unfortunately, many visitors are unable to see the spectacular vistas they expect because of white or brown haze in the air. Most of this haze is not natural; it is air pollution, carried by the wind often hundreds of miles from its origin. Some of the pollutants have been linked to serious health problems, such as asthma and other lung disorders, and even premature death. In addition, nitrates and sulfates contribute to acid rain formation, which contaminates rivers and lakes and erodes buildings and historical monuments. The U.S. Environmental Protection Agency RPOs (Regional Planning Organizations) have been tasked with monitoring and determining the nature and origin of haze in Class I scenic areas, and finding ways to reduce haze in order to improve visibility in these areas. The RPOs have developed an Internet-based air quality DST (Decision Support Tool) called FASTNET (Fast Aerosol Sensing Tools for Natural Event Tracking). While FASTNET incorporates a few satellite datasets, most of the data utilized by this DST comes from ground-based instrument networks. The problem is that in many areas the sensors are sparsely located, with long distances between them, causing difficulties in tracking haze over the United States, determining its source, and analyzing its content. Satellite data could help to fill in the data gaps and to supplement and verify ground-recorded air quality data. Although satellite data are now being used for air quality research applications, such data are not routinely used for environmental decision support, in part because of limited resources, difficulties with interdisciplinary data interpretation, and the need for advanced inter-agency partnerships. As a result, the validation and verification of satellite data for air quality operational system applications has been limited This candidate solution evaluates the usefulness of OMI

Cases of typhoid fever in Copenhagen region

DEFF Research Database (Denmark)

Barrett, Freja Cecille; Knudsen, Jenny Dahl; Johansen, Isik Somuncu

2013-01-01

Typhoid fever is a systemic illness which in high-income countries mainly affects travellers. The incidence is particularly high on the Indian subcontinent. Travellers who visit friends and relatives (VFR) have been shown to have a different risk profile than others. We wished to identify main...

A comparison between the order and the volume fill rate for a base-stock inventory control system under a compound renewal demand process

DEFF Research Database (Denmark)

Larsen, Christian; Thorstenson, Anders

2008-01-01

The order fill rate (OFR) is sometimes suggested as an alternative to the volume fill rate (VFR) (most often just denoted fill rate) as a performance measure for inventory control systems. We consider a continuous review, base-stock policy, where replenishment orders have a constant lead time...

Survival and expression of acid resistance genes in Shiga toxin-producing Escherichia coli acid adapted in pineapple juice and exposed to synthetic gastric fluid

Science.gov (United States)

Aims: The aim of this research was to examine relative transcriptional expression of acid resistance (AR) genes, rpoS, gadA and adiA, in O157:H7 and non-O157 Shiga toxin-producing Escherichia coli (STEC) serotypes after adaptation to pineapple juice (PJ) and subsequently to determine survival with e...

Decontamination Systems Information and Reseach Program

Energy Technology Data Exchange (ETDEWEB)

Cook, Echol E

1998-04-01

The following paragraphs comprise the research efforts during the first quarter of 1998 (January 1 - March 31). These tasks have been granted a continuation from the 1997 work and will all end in June 1998. This report represents the last technical quarterly report deliverable for the WVU Cooperative Agreement - Decontamination Systems Information and Research Program. Final reports for all of the 1997 projects will be submitted afterwards as one document. During this period, groundwater extraction operations were completed on Task 1.6 - Pilot Scale Demonstration of TCE Flushing Through PVDs at the DOE/RMI Extrusion Plant. The data have been evaluated and graphs are presented. The plot of TCE Concentration versus Time shows that the up-gradient groundwater monitoring well produced consistent levels of TCE contamination. A similar trend was observed for the down-gradient wells via grab samples tested. Groundwater samples from the PVD test pad Zone of Influence showed consistent reductions in TCE concentrations with respect to time. In addition, a natural pulse frequency is evident which will have a significant impact on the efficiency of the contaminant removal under natural groundwater advection/diffusion processes. The relationships between the PVD Extraction Flow Rate versus Cumulative Time shows a clear trend in flow rate. Consistent values between 20 to 30 g.p.m. at the beginning of the extraction duration, to less than 10 g.p.m. by the end of the extraction cycle are observed. As evidenced by the aquifer's diminishing recharge levels, the PVD extraction is affecting the response of the aquifer's natural attenuation capability. Progress was also marked on the Injection and Circulation of Potable Water Through PVDs task. Data reduction from this sequence of testing is ongoing. Work planned for next quarter includes completing the Injection / Extraction of potable water task and beginning the Surfactant Injection and removal task.

75 FR 57376 - Modification of Class B Airspace; Chicago, IL

Science.gov (United States)

2010-09-21

... will ensure a safe flying environment for all aircraft flying in or near Area F. One commenter stated... enables the segregation of those aircraft from non-participating VFR aircraft and enhances safety system... aircraft not in communication with air traffic control. FAA Order 7110.65, Air Traffic Control, prescribes...

Estimates of Potential Increases in Airport Capacity through ATC (Air Traffic Control) System Improvements in the Airport and Terminal Areas

Science.gov (United States)

1987-10-01

departures); and (3) departures-only. A fleet mix typical of most majur airports was selected consisting of 15 percent small aircraft (e.g., Swearingen SW-4...schedules predicated on VFR operations can result in substantial delays when weather conditions force the use of IFR operations. 5.1 Difference Between

Persistence of Escherichia coli O157:H7 in dairy fermentation systems.

Science.gov (United States)

Dineen, S S; Takeuchi, K; Soudah, J E; Boor, K J

1998-12-01

We examined (i) the persistence of Escherichia coli O157:H7 as a postpasteurization contaminant in fermented dairy products; (ii) the ability of E. coli O157:H7 strains with and without the general stress regulatory protein, RpoS, to compete with commercial starter cultures in fermentation systems; and (iii) the survival of E. coli O157:H7 in the yogurt production process. In commercial products inoculated with 10(3) CFU/ml, E. coli O157:H7 was recovered for up to 12 days in yogurt (pH 4.0), 28 days in sour cream (pH 4.3), and at levels > 10(2) CFU/ml at 35 days in buttermilk (pH 4.1). For the starter culture competition trials, the relative inhibition of E. coli O157:H7 in the experimental fermentation systems was, in decreasing order, thermophilic culture mixture, Lactobacillus delbrueckii subsp. bulgaricus R110 alone, Lactococcus lactis subsp. lactis D280 alone, Lactococcus lactis subsp. cremoris D62 alone, and Streptococcus thermophilus C90 alone showing the least inhibition. Recovery of the rpoS mutant was lower than recovery of its wild-type parent by 72 h or earlier in the presence of individual starter cultures. No E. coli O157:H7 were recovered after the curd formation step in yogurt manufactured with milk inoculated with 10(5) CFU/ml. Our results show that (i) postprocessing entry of E. coli O157:H7 into fermented dairy products represents a potential health hazard; (ii) commercial starter cultures differ in their ability to reduce E. coli O157:H7 CFU numbers in fermentation systems; and (iii) the RpoS protein appears to most effectively contribute to bacterial survival in the presence of conditions that are moderately lethal to the cell.

DksA-HapR-RpoS axis regulates haemagglutinin protease production in Vibrio cholerae.

Science.gov (United States)

Basu, Pallabi; Pal, Ritesh Ranjan; Dasgupta, Shreya; Bhadra, Rupak K

2017-06-01

DksA acts as a co-factor for the intracellular small signalling molecule ppGpp during the stringent response. We recently reported that the expression of the haemagglutinin protease (HAP), which is needed for shedding of the cholera pathogen Vibrio cholerae during the late phase of infection, is significantly downregulated in V. cholerae ∆dksA mutant (∆dksAVc) cells. So far, it has been shown that HAP production by V. cholerae cells is critically regulated by HapR and also by RpoS. Here, we provide evidence that V. cholerae DksA (DksAVc) positively regulates HapR at both the transcriptional and post-transcriptional levels. We show that in ∆dksAVc cells the CsrB/C/D sRNAs, required for the maintenance of intracellular levels of hapR transcripts during the stationary growth, are distinctly downregulated. Moreover, the expression of exponential phase regulatory protein Fis, a known negative regulator of HapR, was found to continue even during the stationary phase in ∆dksAVc cells compared to that of wild-type strain, suggesting another layer of complex regulation of HapR by DksAVc. Extensive reporter construct-based and quantitative reverse-transcriptase PCR (qRT-PCR) analyses supported that RpoS is distinctly downregulated at the post-transcriptional/translational levels in stationary phase-grown ∆dksAVc cells. Since HAP expression through HapR and RpoS is stationary phase-specific in V. cholerae, it appears that DksAVc is also a critical stationary phase regulator for fine tuning of the expression of HAP. Moreover, experimental evidence provided in this study clearly supports that DksAVc is sitting at the top of the hierarchy of regulation of expression of HAP in V. cholerae.

Ranking of persister genes in the same Escherichia coli genetic background demonstrates varying importance of individual persister genes in tolerance to different antibiotics

Directory of Open Access Journals (Sweden)

Nan eWu

2015-09-01

Full Text Available Despite the identification of many genes and pathways involved in the persistence phenomenon of bacteria, the relative importance of these genes in a single organism remains unclear. Here, using Escherichia coli as a model, we generated mutants of 21 known candidate persister genes and compared the relative importance of these mutants in persistence to various antibiotics (ampicillin, gentamicin, norfloxacin, and trimethoprim at different times. We found that oxyR, dnaK, sucB, relA, rpoS, clpB, mqsR, and recA were prominent persister genes involved in persistence to multiple antibiotics. These genes map to the following pathways: antioxidative defense pathway (oxyR, global regulators (dnaK, clpB, and rpoS, energy production (sucB, stringent response (relA, toxin–antitoxin (TA module (mqsR, and SOS response (recA. Among the TA modules, the ranking order was mqsR, lon, relE, tisAB, hipA, and dinJ. Intriguingly, rpoS deletion caused a defect in persistence to gentamicin but increased persistence to ampicillin and norfloxacin. Mutants demonstrated dramatic differences in persistence to different antibiotics at different time points: some mutants (oxyR, dnaK, phoU, lon, recA, mqsR, and tisAB displayed defect in persistence from early time points, while other mutants (relE, smpB, glpD, umuD, and tnaA showed defect only at later time points. These results indicate that varying hierarchy and importance of persister genes exist and that persister genes can be divided into those involved in shallow persistence and those involved in deep persistence. Our findings suggest that the persistence phenomenon is a dynamic process with different persister genes playing roles of variable significance at different times. These findings have implications for improved understanding of persistence phenomenon and developing new drugs targeting persisters for more effective cure of persistent infections.

Thermo-Economic Performance Analysis of a Regenerative Superheating Organic Rankine Cycle for Waste Heat Recovery

Directory of Open Access Journals (Sweden)

Zhonghe Han

2017-10-01

Full Text Available The Organic Rankine Cycle (ORC is a promising form of technology for recovering low-grade waste heat. In this study, a regenerative ORC system is established to recover the waste flue gas of 160 °C. Focusing on thermodynamic and economic performance while simultaneously considering the limitations of volume flow ratio (VFR and the effect of superheat, working fluid selection and parameter optimization have been investigated. The optimization of the evaporation temperature is carried out by analyzing the variation of net power output and specific investment cost (SIC. Then, the net power output, specific net power output, total exergy destruction rate, VFR, total capital cost, and levelized electricity cost (LEC are selected as criteria, and a fuzzy multi-criteria evaluation method is adopted to select a more suitable working fluid and determine the optimal degree of superheat. In addition, the preheating coefficient, latent heat coefficient, superheating coefficient, and internal heat coefficient were proposed to explore the effect of working fluid critical temperature on thermal efficiency. Research studies demonstrate that there is an optimal evaporation temperature, maximizing net power output and minimizing the SIC. Isohexane and butane have greater specific net power output due to greater latent heat. A suitable degree of superheat is not only conducive to improving the working capacity of working fluids, but also reduces the VFR, total capital cost, SIC, and LEC for different working fluids. Thus, the system’s thermodynamic and economic performance—as well as the operational stability—are improved. Among the six working fluids, butane exhibits the best comprehensive performance, and its optimal evaporation temperature and degree of superheat are 100 °C and 5 °C, respectively.

A switch from high-fidelity to error-prone DNA double-strand break repair underlies stress-induced mutation.

Science.gov (United States)

Ponder, Rebecca G; Fonville, Natalie C; Rosenberg, Susan M

2005-09-16

Special mechanisms of mutation are induced in microbes under growth-limiting stress causing genetic instability, including occasional adaptive mutations that may speed evolution. Both the mutation mechanisms and their control by stress have remained elusive. We provide evidence that the molecular basis for stress-induced mutagenesis in an E. coli model is error-prone DNA double-strand break repair (DSBR). I-SceI-endonuclease-induced DSBs strongly activate stress-induced mutations near the DSB, but not globally. The same proteins are required as for cells without induced DSBs: DSBR proteins, DinB-error-prone polymerase, and the RpoS starvation-stress-response regulator. Mutation is promoted by homology between cut and uncut DNA molecules, supporting a homology-mediated DSBR mechanism. DSBs also promote gene amplification. Finally, DSBs activate mutation only during stationary phase/starvation but will during exponential growth if RpoS is expressed. Our findings reveal an RpoS-controlled switch from high-fidelity to mutagenic DSBR under stress. This limits genetic instability both in time and to localized genome regions, potentially important evolutionary strategies.

Derivation of confidence intervals of service measures in a base-stock inventory control system with low-frequent demand

DEFF Research Database (Denmark)

Larsen, Christian

We explore a base-stock system with backlogging where the demand process is a compound renewal process and the compound element is a delayed geometric distribution. For this setting it is proven in [4] that the long-run average service measures order fill rate (OFR) and volume fill rate (VFR) are...

Derivation of confidence intervals of service measures in a base-stock inventory control system with low-frequent demand

DEFF Research Database (Denmark)

Larsen, Christian

2011-01-01

We explore a base-stock system with backlogging where the demand process is a compound renewal process and the compound element is a delayed geometric distribution. For this setting it holds that the long-run average service measures order fill rate (OFR) and volume fill rate (VFR) are equal in v...

Aircraft Route Optimization using the A-Star Algorithm

Science.gov (United States)

2014-03-27

Map Cost array allows a search for a route that not only seeks to minimize the distance travelled, but also considers other factors that may impact ...Rules (VFR) flight profile requires aviators to plan a 20-minute fuel reserve into the flight while an Instrument Flight Rules ( IFR ) flight profile

14 CFR 91.707 - Flights between Mexico or Canada and the United States.

Science.gov (United States)

2010-01-01

... Canada and the United States without filing an IFR or VFR flight plan, as appropriate. ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Flights between Mexico or Canada and the... Rules Governing Persons on Board Such Aircraft § 91.707 Flights between Mexico or Canada and the United...

77 FR 45290 - Proposed Modification of Class B Airspace Area; Philadelphia, PA

Science.gov (United States)

2012-07-31

... environment for all users of the ATC system. VFR aircraft wishing to transit the portion of Alert Area A-220... aircraft to operate at higher altitudes. PHL Airport Traffic Control Tower (ATCT) has made a commitment to... enroute airspace areas to reduce aircraft delays and improve system capacity. Costs of the Proposed Action...

Author Details

African Journals Online (AJOL)

Rule, Stephen. Vol 33, No 1 (2003): Tourism and Development in Africa - Articles Visiting Friends & Relatives (VFR): South Africa's most popular form of domestic tourism. Abstract. ISSN: 1995-641X. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL ...

Secure ADS-B: Towards Airborne Communications Security in the Federal Aviation Administration’s Next Generation Air Transportation System

Science.gov (United States)

2014-03-01

76 5.2 Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.3 Recommendations for Future Work...Global Positioning System ICAO International Civil Aviation Organization IFF Identification Friend or Foe IFR Instrument Flight Rules IMO...Instrument Flight Rules ( IFR ). Under VFR, typically used by General Aviation (GA) aircraft operating under 18,000 feet, the pilot is primarily responsible

Pre-Travel Health Preparation of Pediatric International Travelers: Analysis From the Global TravEpiNet Consortium.

Science.gov (United States)

Hagmann, Stefan; LaRocque, Regina C; Rao, Sowmya R; Jentes, Emily S; Sotir, Mark J; Brunette, Gary; Ryan, Edward T

2013-12-01

Children frequently travel internationally. Health-related data on such children are limited. We sought to investigate the demographics, health characteristics, and preventive interventions of outbound US international pediatric travelers. We analyzed data from 32 099 travelers presenting for pre-travel healthcare at the Global TravEpiNet (GTEN), a national consortium of 19 travel clinics, from January 1, 2009 to June 6, 2012. A total of 3332 (10%) of all GTEN travelers were children (traveled mostly for leisure (36%) or to visit friends or relatives (VFR) (36%). Most popular destination regions were Africa (41%), Southeast Asia (16%), Central America (16%), and the Caribbean (16%). Compared with children traveling for leisure, VFR children were more likely to present travel consultation (44% vs 28%), intended to travel for 28 days or longer (70% vs 22%), and to travel to Africa (62% vs 32%). Nearly half of the pediatric travelers (46%) received at least 1 routine vaccine, and most (83%) received at least 1 travel-related vaccine. Parents or guardians of one third of the children (30%) refused at least 1 recommended travel-related vaccine. Most pediatric travelers visiting a malaria-endemic country (72%) received a prescription for malaria chemoprophylaxis. Ten percent of travelers seeking pre-travel healthcare at GTEN sites are children. VFR-travel, pre-travel consultation close to time of departure, and refusal of recommended vaccines may place children at risk for travel-associated illness. Strategies to engage pediatric travelers in timely, pre-travel care and improve acceptance of pre-travel healthcare interventions are needed. © The Author 2013. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Neglected tropical diseases outside the tropics.

Directory of Open Access Journals (Sweden)

Francesca F Norman

Full Text Available BACKGROUND: The neglected tropical diseases (NTDs cause significant morbidity and mortality worldwide. Due to the growth in international travel and immigration, NTDs may be diagnosed in countries of the western world, but there has been no specific focus in the literature on imported NTDs. METHODS: Retrospective study of a cohort of immigrants and travelers diagnosed with one of the 13 core NTDs at a Tropical Medicine Referral Unit in Spain during the period April 1989-December 2007. Area of origin or travel was recorded and analyzed. RESULTS: There were 6168 patients (2634 immigrants, 3277 travelers and 257 VFR travelers in the cohort. NTDs occurred more frequently in immigrants, followed by VFR travelers and then by other travelers (p<0.001 for trend. The main NTDs diagnosed in immigrants were onchocerciasis (n = 240, 9.1% acquired mainly in sub-Saharan Africa, Chagas disease (n = 95, 3.6% in immigrants from South America, and ascariasis (n = 86, 3.3% found mainly in immigrants from sub-Saharan Africa. Most frequent NTDs in travelers were: schistosomiasis (n = 43, 1.3%, onchocerciasis (n = 17, 0.5% and ascariasis (n = 16, 0.5%, and all were mainly acquired in sub-Saharan Africa. The main NTDs diagnosed in VFR travelers were onchocerciasis (n = 14, 5.4%, and schistosomiasis (n = 2, 0.8%. CONCLUSIONS: The concept of imported NTDs is emerging as these infections acquire a more public profile. Specific issues such as the possibility of non-vectorial transmission outside endemic areas and how some eradication programmes in endemic countries may have an impact even in non-tropical western countries are addressed. Recognising NTDs even outside tropical settings would allow specific prevention and control measures to be implemented and may create unique opportunities for research in future.

77 FR 5429 - Proposed Modification of the Atlanta Class B Airspace Area; GA

Science.gov (United States)

2012-02-03

... consisted of lower Class B floors within a reduced radius of 30 NM from the ATL VORTAC as opposed to the... concerns related to the proposed lower Class B airspace floors, particularly in the airspace directly... congestion at lower altitudes due to VFR traffic trying to avoid flying in the Class B airspace area and...

Cross-country VFR crashes: pilot and contextual factors.

Science.gov (United States)

O'Hare, David; Owen, Douglas

2002-04-01

General Aviation (GA) cross-country crashes, particularly those involving weather, continue to be a major source of fatalities, with a fatality rate more than four times greater than for GA crashes in general. There has been much speculation and little solid evidence on the causes of these crashes. We have designed a program of laboratory and database research into the causes of cross-country weather-related crashes including an analysis of air crashes in New Zealand between 1988 and 2000. There were 1308 reported occurrences in this period. We examined in detail 77 crashes where it could be determined that the aircraft was on a cross-country flight. In our first analysis we compared the characteristics of crashes that occurred in response to externally driven failures with crashes where the aircraft continued to be flown at the pilot's discretion up until the point of the crash. Clear differences were found for visibility, altitude, crash severity, and for several pilot characteristics. These differences are highly consistent with those found for previous research on pilot characteristics and crash involvement. In the second analysis we made comparisons between the weather-related and nonweather-related crashes in the discretionary control group and between subcategories of weather-related crashes. These data show that weather-related crashes occur further into the flight and closer to the planned destination than other kinds of cross-country crashes in GA. Pilots involved in these crashes are younger and have more recent flight time than pilots involved in other crashes. Their increased involvement cannot be explained simply by exposure (flight-time) but must be due to other factors.

The increased use of radiation requires enhanced activities regarding radiation safety control

International Nuclear Information System (INIS)

Lee, Yun Jong; Lee, Jin Woo; Jeong, Gyo Seong

2015-01-01

More recently, companies that have obtained permission to use radioactive materials or radiation device and registered radiation workers have increased by 10% and 4% respectively. The increased use of radiation could have an effect on radiation safety control. However, there is not nearly enough manpower and budget compared to the number of workers and facilities. This paper will suggest a counteroffer thought analyzing pending issues. The results of this paper indicate that there are 47 and 31.3 workers per radiation protection officer in educational and research institutes, respectively. There are 20.1 persons per RPO in hospitals, even though there are 2 RPOs appointed. Those with a special license as a radioisotope handler were ruled out as possible managers because medical doctors who have a special license for radioisotope handling normally have no experience with radiation safety. The number of staff members and budget have been insufficient for safety control at most educational and research institutes. It is necessary to build an optimized safety control system for effective Radiation Safety Control. This will reduce the risk factor of safety, and a few RPOs can be supplied for efficiency and convenience

The increased use of radiation requires enhanced activities regarding radiation safety control

Energy Technology Data Exchange (ETDEWEB)

Lee, Yun Jong; Lee, Jin Woo; Jeong, Gyo Seong [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2015-05-15

More recently, companies that have obtained permission to use radioactive materials or radiation device and registered radiation workers have increased by 10% and 4% respectively. The increased use of radiation could have an effect on radiation safety control. However, there is not nearly enough manpower and budget compared to the number of workers and facilities. This paper will suggest a counteroffer thought analyzing pending issues. The results of this paper indicate that there are 47 and 31.3 workers per radiation protection officer in educational and research institutes, respectively. There are 20.1 persons per RPO in hospitals, even though there are 2 RPOs appointed. Those with a special license as a radioisotope handler were ruled out as possible managers because medical doctors who have a special license for radioisotope handling normally have no experience with radiation safety. The number of staff members and budget have been insufficient for safety control at most educational and research institutes. It is necessary to build an optimized safety control system for effective Radiation Safety Control. This will reduce the risk factor of safety, and a few RPOs can be supplied for efficiency and convenience.

Time course of development of posterior vitreous detachments after phacoemulsification surgery.

Science.gov (United States)

Hikichi, Taiichi

2012-10-01

To determine when posterior vitreous detachments (PVDs) develop after phacoemulsification and aspiration combined with foldable intraocular lens implantation. Prospective, consecutive case series. A total of 575 eyes without a PVD preoperatively were studied prospectively and followed for 3 years after uneventful phacoemulsification surgery. All patients underwent a comprehensive ocular examination, including a dynamic vitreous examination using biomicroscopy with and without a preset lens and a preoperative retinal examination on the day of surgery; the day postoperatively; 1 week and 1, 3, 6, and 12 months postoperatively; and every 6 months for 3 years postoperatively. The patients were divided into groups and analyzed on the basis of age and refractive error or axial length. The cumulative incidence rates of eyes that developed PVD for 3 years postoperatively at each postoperative time point. The cumulative numbers and percentages of eyes that developed a PVD were 6 (1.0%), 18 (3.1%), 31 (5.4%), 45 (7.8%), 63 (11.0%), 88 (15.3%), 106 (18.4%), 133 (23.1%), and 172 (30.0%) within 1 week and 1, 3, 6, 12, 18, 24, 30, and 36 months, respectively. Eleven (6.4%) of the 172 eyes in which a PVD developed during the follow-up period had new retinal breaks with or without a retinal detachment. Eight (15.4%) of 52 eyes with lattice degeneration and 3 (2.5%) of 120 eyes without lattice degeneration had retinal breaks associated with a PVD; these percentages were significant (P = 0.003). Development of PVDs seems to accelerate after phacoemulsification and linearly accumulated for 3 years postoperatively. Approximately 6% of eyes with a PVD had retinal breaks and eyes with lattice degeneration had a 6.2-fold higher risk of developing retinal breaks associated with a PVD. Long-term follow-up is needed after phacoemulsification is performed. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

General Plan-Based Environmental Impact Analysis Process Environmental Assessment, Altus Air Force Base

Science.gov (United States)

2009-11-01

Level Lmax Maximum Sound Level LOP Letter of Procedure LTM Long-term monitoring MACA Mid-Air Collision Avoidance MFH Military Family Housing mgd...users. Additionally, the Air Force proactively engages in a program of public outreach to aviators, publishing Mid-Air Collision Avoidance ( MACA ...operating under VFR. The MACA contains information on preferred flight tracks, operational characteristics of high-performance military aircraft, and

Weather in the Cockpit: Priorities, Sources, Delivery, and Needs in the Next Generation Air Transportation System

Science.gov (United States)

2012-07-01

System GSD ----------- NOAA/ESRL/ Global Systems Division IAF ------------- Initial Approach Fix IFR ------------- Instrument Flight Rules IMC... uncertainties . A distillation of our review of the literature and a new detailed analysis of our own leads to the weather factors shown in Figure 1...ratings of weather factors differed between operating in visual flight rules (VFR) and operating in instrument flight rules ( IFR ). In characterizing

Study of the Light Utility Helicopter (LUH) Acquisition Program as a Model for Defense Acquisition of Nondevelopmental Items

Science.gov (United States)

2014-12-01

Local Economic Impact of UH-72A Manufacture ................42  viii e.  EADS’ (Now Airbus Group’s) Suppliers and Subcontractors...Headquarters, Department of the Army IFR instrument flight rules IOTE initial operational test and evaluation IR infrared KO contracting officer kt...instrument flight rules ( IFR ) and visual flight rules (VFR) capabilities, thereby allowing flight at night and under low visibility weather

Identification of speech transients using variable frame rate analysis and wavelet packets.

Science.gov (United States)

Rasetshwane, Daniel M; Boston, J Robert; Li, Ching-Chung

2006-01-01

Speech transients are important cues for identifying and discriminating speech sounds. Yoo et al. and Tantibundhit et al. were successful in identifying speech transients and, emphasizing them, improving the intelligibility of speech in noise. However, their methods are computationally intensive and unsuitable for real-time applications. This paper presents a method to identify and emphasize speech transients that combines subband decomposition by the wavelet packet transform with variable frame rate (VFR) analysis and unvoiced consonant detection. The VFR analysis is applied to each wavelet packet to define a transitivity function that describes the extent to which the wavelet coefficients of that packet are changing. Unvoiced consonant detection is used to identify unvoiced consonant intervals and the transitivity function is amplified during these intervals. The wavelet coefficients are multiplied by the transitivity function for that packet, amplifying the coefficients localized at times when they are changing and attenuating coefficients at times when they are steady. Inverse transform of the modified wavelet packet coefficients produces a signal corresponding to speech transients similar to the transients identified by Yoo et al. and Tantibundhit et al. A preliminary implementation of the algorithm runs more efficiently.

A MAG for the Twenty First Century: Lethal, Lighter, Energy Efficient, and Cheaper

Science.gov (United States)

2010-04-14

implementation of this concept. Since this concept does not create additional commands beyond the VMLA FRS , the plans already underway for 24 TACAIR...rules (VFR/ IFR ) operations. 2. Properly certified to meet acquisition requirements and allow for U.S. Military operation. Systems/capability must...protect .from small arms fire. Self-sealing fuel tanks required. 33. Infrared (IR) suppression for engine(s) 34. Avionics: IFR capable. Dual

aldB, an RpoS-dependent gene in Escherichia coli encoding an aldehyde dehydrogenase that is repressed by Fis and activated by Crp.

Science.gov (United States)

Xu, J; Johnson, R C

1995-06-01

Escherichia coli aldB was identified as a gene that is negatively regulated by Fis but positively regulated by RpoS. The complete DNA sequence determined in this study indicates that aldB encodes a 56.3-kDa protein which shares a high degree of homology with an acetaldehyde dehydrogenase encoded by acoD of Alcaligenes eutrophus and an aldehyde dehydrogenase encoded by aldA of Vibrio cholerae and significant homology with a group of other aldehyde dehydrogenases from prokaryotes and eukaryotes. Expression of aldB is maximally induced during the transition from exponential phase to stationary phase. Its message levels are elevated three- to fourfold by a fis mutation and abolished by an rpoS mutation. In addition, the expression of an aldB-lacZ fusion was decreased about 20-fold in the absence of crp. DNase I footprinting analysis showed that five Fis binding sites and one Crp binding site are located within the aldB promoter region, suggesting that Fis and Crp are acting directly to control aldB transcription. AldB expression is induced by ethanol, but in contrast to that of most of the RpoS-dependent genes, the expression of aldB is not altered by an increase in medium osmolarity.

Gene expression of Escherichia coli in continuous culture during adaptation to artificial sunlight.

Science.gov (United States)

Berney, Michael; Weilenmann, Hans-Ulrich; Egli, Thomas

2006-09-01

Escherichia coli growing in continuous culture under continuous UVA irradiation exhibits growth inhibition with a subsequent adaptation to the stress. Transcriptome analysis was performed during transient growth inhibition and in the UVA light-adapted growth state. The results indicate that UVA light induces stringent response and an additional response that includes the upregulation of the synthesis of valine, isoleucine, leucine, phenylalanine, histidine and glutamate. The induction of several SOS response-genes strongly points to DNA damage as a result of UVA exposure. The involvement of oxidative stress was observed with the induction of ahpCF. Taken together it supports the hypothesis of the production of reactive oxygen species by UVA light. In the UVA-adapted cell population strong repression of the acid tolerance response was found. We identified the enzyme chorismate mutase as a possible chromophore for UVA light-inactivation and found strong repression of the pyrBI operon and the gene mgtA encoding for an ATP-dependent Mg2+ transporter. Furthermore, our results indicate that the role of RpoS may not be as important in the adaptation of E. coli to UVA light as it was implicated by previous results with starved cells, but that RpoS might be of crucial importance for the resistance under transient light exposure.

Hydrothermal Fe-Si-Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

International Nuclear Information System (INIS)

Sun Zhilei; Zhou Huaiyang; Yang Qunhui; Sun Zhixue; Bao Shenxu; Yao Huiqiang

2011-01-01

Highlights: → The Fe-Mn crust in the HHF has seawater contribution, whereas the Fe-Si oxide in the MHF is dominated by hydrothermal fluid → The Nd isotope of diffuse flow Fe-Si-Mn deposits indicates the obvious hydrothermal origin. → The Mn/Fe ratio in hydrothermal deposit may be a good indicator of propagating activities of the Valu Fa Ridge. - Abstract: A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe-Si-Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Moessbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe-Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ΣREE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe-Si-Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.

Duplex formation between the sRNA DsrA and rpoS mRNA is not sufficient for efficient RpoS synthesis at low temperature

Czech Academy of Sciences Publication Activity Database

Hämmerle, H.; Večerek, Branislav; Resch, A.; Bläsi, U.

2013-01-01

Roč. 10, č. 12 (2013), s. 1834-1841 ISSN 1547-6286 Institutional support: RVO:61388971 Keywords : DsrA * Hfq * Riboregulation Subject RIV: EE - Microbiology, Virology Impact factor: 5.377, year: 2013 http://www.ncbi.nlm.nih.gov/pubmed/24448230

Investigating the Significance of VFR Visits to International Students

Science.gov (United States)

Taylor, Ruth; Shanka, Tekle; Pope, Jeff

2004-01-01

Higher education, particularly in the area of international education has exhibited significant growth since the mid-1980s. Whilst it is beginning to attract research from both educational and tourism industry perspectives, the current body of knowledge regarding this market is still quite limited. This is particularly the case in the area of…

Grand Canyon VFR Chart - Aeronautical Information Services Digital Products

Data.gov (United States)

Department of Transportation — The Federal Aviation Administration (FAA) digital-Visual Chart series is designed to meet the needs of users who require georeferenced raster images of a FAA Visual...

VFR Class B Graphics - Aeronautical Information Services Digital Products

Data.gov (United States)

Department of Transportation — These graphics are designed to increase safety and aid pilots in gaining situational awareness within existing and redesigned Class B areas. The graphic provides an...

Tuning Fullerene Intercalation in a Poly (thiophene) derivative by Controlling the Polymer Degree of Self-Organisation

Science.gov (United States)

Paternò, G. M.; Skoda, M. W. A.; Dalgliesh, Robert; Cacialli, F.; Sakai, V. García

2016-10-01

Controlling the nanoscale arrangement in polymer-fullerene organic solar cells is of paramount importance to boost the performance of such promising class of photovoltaic diodes. In this work, we use a pseudo-bilayer system made of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), to acquire a more complete understanding of the diffusion and intercalation of the fullerene-derivative within the polymer layer. By exploiting morphological and structural characterisation techniques, we observe that if we increase the film solidification time the polymer develops a higher crystalline order, and, as a result, it does not allow fullerene molecules to intercalate between the polymer side-chains. Gaining insight into the detailed fullerene intercalation mechanism is important for the development of organic photovoltaic diodes (PVDs).

General Plan-Based Environmental Impact Analysis Process Environmental Assessment Volume 1

Science.gov (United States)

2009-09-01

feet LBP lead-based paint Leq Equivalent Sound Level Lmax Maximum Sound Level MACA Mid-Air Collision Avoidance MFH Military Family Housing MGD...engages in a program of public outreach to aviators, publishing Mid-Air Collision Avoidance ( MACA ) guides at its bases, including Tyndall AFB. These...Consequences Tyndall Air Force Base, Florida September 2009 4-3 airports, are primarily intended for pilots operating under VFR. The MACA contains

Development of Earthquake Emergency Response Plan for Tribhuvan International Airport, Kathmandu, Nepal

Science.gov (United States)

2013-02-01

Prince, Haiti. The consequences for Nepal if a comparable or bigger disaster happens in Kathmandu would likely be worse than in Port–au-Prince because the...procedures adopted in other countries. The framework was made compatible with ICAO standards and TIA’s current existing emergency plan for other...Flight Rules (VFR) in daylight and Instrument Flight Rule ( IFR ). A. Restore Airport Perimeter Security B. Restore Flight Operations a

NextGen UAS Research, Development and Demonstration Roadmap. Version 1.0

Science.gov (United States)

2012-03-15

18. NUMBER OF PAGES 80 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard ...individual COA, UAS may operate under both Visual Flight Rules (VFR) and Instrument Flight Rules ( IFR ), in both special use airspace and non- segregated...National Aeronautics Research and Development Plan,” February 2010 , which cites the importance of integrating UAS into the NextGen NAS and establishes

Oceanic Area System Improvement Study (OASIS). Volume V. North Atlantic, Central East Pacific, and Caribbean Regions Communication Systems Description.

Science.gov (United States)

1981-09-01

system SENEAM Servicies a la Navagacion en el Espacio Aero Mexicano SSB Single side band USB Upper side band VFR Visual flight rules VHF Very-high...working may mitigate many historical problems associated with HF communications. The ambient noise associated with monitoring an HF frequency led to...airports all have their VHF facilities on site. Communications are the responsibility of the Administration de l’Aeroport International Francois

Correlated Encounter Model for Cooperative Aircraft in the National Airspace System; Version 2.0

Science.gov (United States)

2018-05-08

aircraft was in communication with and therefore advised by ATC which would impact the anticipated behavior of the flight: • Discrete Code: The aircraft is...receiving ATC services. This includes aircraft flying under Instrument Flight Rules ( IFR ) and aircraft flying under Visual flight rules (VFR) but...improves the accuracy of the en- counters by ensuring that smoothing, rounding, and interpolation errors do not strongly impact the targeted data in the

Regulatory Network Controlling Extracellular Proteins in Erwinia carotovora subsp. carotovora: FlhDC, the Master Regulator of Flagellar Genes, Activates rsmB Regulatory RNA Production by Affecting gacA and hexA (lrhA) Expression▿

OpenAIRE

Cui, Yaya; Chatterjee, Asita; Yang, Hailian; Chatterjee, Arun K.

2008-01-01

Erwinia carotovora subsp. carotovora produces an array of extracellular proteins (i.e., exoproteins), including plant cell wall-degrading enzymes and Harpin, an effector responsible for eliciting hypersensitive reaction. Exoprotein genes are coregulated by the quorum-sensing signal, N-acyl homoserine lactone, plant signals, an assortment of transcriptional factors/regulators (GacS/A, ExpR1, ExpR2, KdgR, RpoS, HexA, and RsmC) and posttranscriptional regulators (RsmA, rsmB RNA). rsmB RNA produc...

Imported malaria in Auckland, New Zealand.

Science.gov (United States)

Camburn, Anna E; Ingram, R Joan H; Holland, David; Read, Kerry; Taylor, Susan

2012-11-09

To describe the current malaria situation in Auckland, New Zealand. We collected data on all cases of malaria diagnosed in Auckland from 1st October 2008 to 30th September 2009. Enhanced surveillance was arranged with all hospital and community haematology laboratories in the region. Laboratories notified us when a diagnosis of malaria was made. After obtaining informed consent the patient was asked about their travel, prophylaxis taken and symptoms. Laboratory results were collected. There were 36 cases of malaria in 34 patients. Consent could not be obtained from two patients so data is from 34 cases in 32 patients. (One patient had P.falciparum then later P.vivax, the other had P.vivax and relapsed.) There were 24 males and 8 females with a median age of 21 years (range 6 months to 75 years). Eleven of the 32 were New Zealand residents. 8 of these 11 had travelled to visit friends or relatives (VFR) while 3 were missionaries. In this group 6 had P.falciparum, 4 P.vivax and one had both. Twenty-one of the 32 were new arrivals to New Zealand: 11 refugees and 10 migrants. Malaria in Auckland is seen in new arrivals and VFR travellers, not in tourist travellers.

Missile Defense Agency Ballistic Missile Defense System (BMDS): Programmatic Environmental Impact Statement. Volume 1 Final BMDS PEIS

Science.gov (United States)

2007-01-01

coastal area includes shoreline, tidal wetlands, coastal wetlands, and coastal estuaries. 3-3 Exhibit 3-1. Map of Global Biomes Source: Modified...under IFR versus VFR. Using this information, a map of the Region of Influence would be developed for the affected areas , as well as charts detailing...sea turtle nesting areas could disturb buried nests or cover the nests with a sand layer too deep for the hatchlings to escape. Because sea turtle

Antimicrobials, stress and mutagenesis.

Directory of Open Access Journals (Sweden)

Alexandro Rodríguez-Rojas

2014-10-01

Full Text Available Cationic antimicrobial peptides are ancient and ubiquitous immune effectors that multicellular organisms use to kill and police microbes whereas antibiotics are mostly employed by microorganisms. As antimicrobial peptides (AMPs mostly target the cell wall, a microbial 'Achilles heel', it has been proposed that bacterial resistance evolution is very unlikely and hence AMPs are ancient 'weapons' of multicellular organisms. Here we provide a new hypothesis to explain the widespread distribution of AMPs amongst multicellular organism. Studying five antimicrobial peptides from vertebrates and insects, we show, using a classic Luria-Delbrück fluctuation assay, that cationic antimicrobial peptides (AMPs do not increase bacterial mutation rates. Moreover, using rtPCR and disc diffusion assays we find that AMPs do not elicit SOS or rpoS bacterial stress pathways. This is in contrast to the main classes of antibiotics that elevate mutagenesis via eliciting the SOS and rpoS pathways. The notion of the 'Achilles heel' has been challenged by experimental selection for AMP-resistance, but our findings offer a new perspective on the evolutionary success of AMPs. Employing AMPs seems advantageous for multicellular organisms, as it does not fuel the adaptation of bacteria to their immune defenses. This has important consequences for our understanding of host-microbe interactions, the evolution of innate immune defenses, and also sheds new light on antimicrobial resistance evolution and the use of AMPs as drugs.

Pseudomonas aeruginosa AlgR Phosphorylation Status Differentially Regulates Pyocyanin and Pyoverdine Production

Directory of Open Access Journals (Sweden)

Alexander S. Little

2018-01-01

Full Text Available Pseudomonas aeruginosa employs numerous, complex regulatory elements to control expression of its many virulence systems. The P. aeruginosa AlgZR two-component regulatory system controls the expression of several crucial virulence phenotypes. We recently determined, through transcriptomic profiling of a PAO1 ΔalgR mutant strain compared to wild-type PAO1, that algZR and hemCD are cotranscribed and show differential iron-dependent gene expression. Previous expression profiling was performed in strains without algR and revealed that AlgR acts as either an activator or repressor, depending on the gene. Thus, examination of P. aeruginosa gene expression from cells locked into different AlgR phosphorylation states reveals greater physiological relevance. Therefore, gene expression from strains carrying algR alleles encoding a phosphomimetic (AlgR D54E or a phosphoablative (AlgR D54N form were compared by microarray to PAO1. Transcriptome analyses of these strains revealed 25 differentially expressed genes associated with iron siderophore biosynthesis or heme acquisition or production. The PAO1 algR D54N mutant produced lower levels of pyoverdine but increased expression of the small RNAs prrf1 and prrf2 compared to PAO1. In contrast, the algR D54N mutant produced more pyocyanin than wild-type PAO1. On the other hand, the PAO1 algR D54E mutant produced higher levels of pyoverdine, likely due to increased expression of an iron-regulated gene encoding the sigma factor pvdS, but it had decreased pyocyanin production. AlgR specifically bound to the prrf2 and pvdS promoters in vitro. AlgR-dependent pyoverdine production was additionally influenced by carbon source rather than the extracellular iron concentration per se. AlgR phosphorylation effects were also examined in a Drosophila melanogaster feeding, murine acute pneumonia, and punch wound infection models. Abrogation of AlgR phosphorylation attenuated P. aeruginosa virulence in these infection

aldB, an RpoS-dependent gene in Escherichia coli encoding an aldehyde dehydrogenase that is repressed by Fis and activated by Crp.

OpenAIRE

Xu, J; Johnson, R C

1995-01-01

Escherichia coli aldB was identified as a gene that is negatively regulated by Fis but positively regulated by RpoS. The complete DNA sequence determined in this study indicates that aldB encodes a 56.3-kDa protein which shares a high degree of homology with an acetaldehyde dehydrogenase encoded by acoD of Alcaligenes eutrophus and an aldehyde dehydrogenase encoded by aldA of Vibrio cholerae and significant homology with a group of other aldehyde dehydrogenases from prokaryotes and eukaryotes...

Buffer capacity of food components influences the acid tolerance response in Salmonella Typhimurium during simulated gastric passage

DEFF Research Database (Denmark)

Henriksen, Sidsel; Buschhardt, Tasja; Hansen, Tina Beck

2014-01-01

tubes, enabling simultaneous testing of biological triplicates under varying conditions. Surprisingly, we found that less buffered media provided higher protection of Salmonella, compared to media with high buffer capacity. By investigating the relative gene expression of rpoS and ompR encoding for two...... Heart Infusion Broth having a higher buffer capacity. We suggest this to be associated with a varying ability of Salmonella Typhimurium to mount a stationary phase acid tolerance response (ATR) depending on the buffer capacity of the food vehicle....

Imported malaria in an area in southern Madrid, 2005-2008

Directory of Open Access Journals (Sweden)

Rubio José M

2010-10-01

Full Text Available Abstract Background In Spain, malaria cases are mostly due to migrants and travellers returning from endemic areas. The objective of this work was to describe the malaria cases diagnosed at the Severo Ochoa University Hospital (HUSO in Leganés in the south of the Madrid Region from 2005 to 2008. Methods Descriptive retrospective study performed at HUSO. Data sources are registries from the Microbiology Department and malaria cases notified to the Preventive Medicine Department. Analysed parameters were: administrative, demographical, related to the stay at the endemic country, clinical, microbiological diagnosis method, pregnancy, treatment and prophylaxis, co-infections, and days of hospital stay. Results Fifty-seven patients diagnosed with malaria were studied. Case distribution per year was 13 in 2005, 15 in 2006, 15 in 2007 and 14 in 2008. Thirty-three patients were female (57.9% and 24 male (42.1%. Mean age was 27.8 years. Most of the malaria cases were acquired in Nigeria (49.1% and Equatorial Guinea (32.7%. 29.1% of the patients were immigrants who had arrived recently, and 61.8% acquired malaria when travelling to their countries of origin to visit friends and relatives (VFR. Majority of cases were diagnosed between June and September. Microscopy was positive in 39 cases (68.4% immunochromatography in 42 (73.7% and PCR in the 55 cases where performed. Plasmodium falciparum was responsible for 94.7% of the cases. The more frequent symptoms were fever (77.2%, followed by headache and gastrointestinal symptoms (33.3%. Nine cases needed hospital admittance, a pregnant woman, three children, four VFR and an African tourist, but all evolved favourably. Chemoprophylaxis data was known from 55 patients. It was taken correctly in one case (1.8%, in five (9.1% the prophylaxis was improper while the others 49 (89.1% cases had not followed any anti-malarial prophylaxis. Conclusions Children, pregnant women and the VFR have the highest risk to

THE IMPACT OF RPOS DELETION ON ESCHERICHIA COLI BIOFILMS. (R825503)

Science.gov (United States)

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Analysis of Helicopter Mishaps at Heliports, Airports and Unimproved Sites

Science.gov (United States)

1991-01-01

Classif. (of this page) 21. No. of Pages 22. Price Unclassified Unclassified orm DOT IF 1700.7 (8-72) Reproduction of this document is authori~ed...procedure. These mishaps point out the need for adequate clearance on departure. This design issue is coupled with a related operational/ human factors...Time C__________ Other 5 Comav iVF S Time ZoneA6 h 159 Type at Cleerance 160 Ai’uoace, 1 ’None 6 VFR on top 1 Uncontrolled 8 Stage 11 TRSA 1I__ Warning

On the trends of Fukui potential and hardness potential derivatives in isolated atoms vs. atoms in molecules.

Science.gov (United States)

Bhattacharjee, Rituparna; Roy, Ram Kinkar

2014-10-28

In the present study, trends of electronic contribution to molecular electrostatic potential [Vel(r¯)(r=0)], Fukui potential [v(+)f|(r=0) and v(-)f|(r=0)] and hardness potential derivatives [Δ(+)h(k) and Δ(-)h(k)] for isolated atoms as well as atoms in molecules are investigated. The generated numerical values of these three reactivity descriptors in these two electronically different situations are critically analyzed through the relevant formalism. Values of Vel(r¯) (when r → 0, i.e., on the nucleus) are higher for atoms in molecules than that of isolated atoms. In contrast, higher values of v(+)|(r=0) and v(-)|(r=0) are observed for isolated atoms compared to the values for atoms in a molecule. However, no such regular trend is observed for the Δ(+)h(k) and Δ(-)h(k) values, which is attributed to the uncertainty in the Fukui function values of atoms in molecules. The sum of Fukui potential and the sum of hardness potential derivatives in molecules are also critically analyzed, which shows the efficacy of orbital relaxation effects in quantifying the values of these parameters. The chemical consequence of the observed trends of these descriptors in interpreting electron delocalization, electronic relaxation and non-negativity of atomic Fukui function indices is also touched upon. Several commonly used molecules containing carbon as well as heteroatoms are chosen to make the investigation more insightful.

The GacS/A-RsmA Signal Transduction Pathway Controls the Synthesis of Alkylresorcinol Lipids that Replace Membrane Phospholipids during Encystment of Azotobacter vinelandii SW136.

Directory of Open Access Journals (Sweden)

Yanet Romero

Full Text Available Azotobacter vinelandii is a soil bacterium that undergoes a differentiation process that forms cysts resistant to desiccation. During encystment, a family of alkylresorcinols lipids (ARs are synthesized and become part of the membrane and are also components of the outer layer covering the cyst, where they play a structural role. The synthesis of ARs in A. vinelandii has been shown to occur by the activity of enzymes encoded in the arsABCD operon. The expression of this operon is activated by ArpR, a LysR-type transcriptional regulator whose transcription occurs during encystment and is dependent on the alternative sigma factor RpoS. In this study, we show that the two component response regulator GacA, the small RNA RsmZ1 and the translational repressor protein RsmA, implicated in the control of the synthesis of other cysts components (i.e., alginate and poly-ß-hydroxybutyrate, are also controlling alkylresorcinol synthesis. This control affects the expression of arsABCD and is exerted through the regulation of arpR expression. We show that RsmA negatively regulates arpR expression by binding its mRNA, repressing its translation. GacA in turn, positively regulates arpR expression through the activation of transcription of RsmZ1, that binds RsmA, counteracting its repressor activity. This regulatory cascade is independent of RpoS. We also show evidence suggesting that GacA exerts an additional regulation on arsABCD expression through an ArpR independent route.

Role of the interplay between quorum sensing regulator VqsR and the Pseudomonas quinolone signal in mediating carbapenem tolerance in Pseudomonas aeruginosa.

Science.gov (United States)

Viducic, Darija; Murakami, Keiji; Amoh, Takashi; Ono, Tsuneko; Miyake, Yoichiro

2017-06-01

Pseudomonas aeruginosa coordinates its response to environmental conditions through activation of a quorum sensing (QS) system. In this study, we investigated the regulatory interaction between the QS transcriptional regulator VqsR and the Pseudomonas quinolone signal (PQS) through integration of sigma factor RpoS, and we addressed whether one of the pathways controlling carbapenem tolerance can be attributed to VqsR. We demonstrate that vqsR expression at the transcriptional level is regulated by pqsA, pqsR, and pqsE. Assessment of the transcriptional expression of vqsR, lasI, rhlI, and qscR in ΔpqsA and ΔpqsAΔrpoS mutants provided insight into pqsA- and rpoS-dependent regulation of vqsR and vqsR-controlled genes. Exogenously supplemented PQS reversed expression of vqsR and vqsR-controlled genes in the ΔpqsA mutant to wild-type levels, but failed to increase expression levels of lasI and qscR in the ΔpqsAΔrpoS mutant to levels observed in wild-type PAO1. The ΔvqsR mutant showed reduced survival when challenged with carbapenems compared to wild-type PAO1. Introduction of a pqsA mutation into the ΔvqsR mutant completely abolished its carbapenem-sensitive phenotype. We conclude that a regulatory link between PQS and vqsR exists, and that RpoS is important in their interaction. We also demonstrate that VqsR affects carbapenem tolerance. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Iron-regulated transcription of the pvdA gene in Pseudomonas aeruginosa: effect of Fur and PvdS on promoter activity.

OpenAIRE

Leoni, L; Ciervo, A; Orsi, N; Visca, P

1996-01-01

The pvdA gene, encoding the enzyme L-ornithine N5-oxygenase, catalyzes a key step of the pyoverdin biosynthetic pathway in Pseudomonas aeruginosa. Expression studies with a promoter probe vector made it possible to identify three tightly iron-regulated promoter regions in the 5.9-kb DNA fragment upstream of pvdA. The promoter governing pvdA expression was located within the 154-bp sequence upstream of the pvdA translation start site. RNA analysis showed that expression of PvdA is iron regulat...

CT-based compartmental quantification of adipose tissue versus body metrics in colorectal cancer patients

Energy Technology Data Exchange (ETDEWEB)

Nattenmueller, Johanna; Hoegenauer, Hanna; Grenacher, Lars; Kauczor, Hans-Ulrich [University Hospital, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Boehm, Juergen; Ulrich, Cornelia [Huntsman Cancer Institute, Department of Population Health Sciences, Salt Lake City, UT (United States); Scherer, Dominique; Paskow, Michael; Gigic, Biljana; Schrotz-King, Petra [National Center for Tumor Diseases and German Cancer Research Center, Division of Preventive Oncology, Heidelberg (Germany)

2016-11-15

While obesity is considered a prognostic factor in colorectal cancer (CRC), there is increasing evidence that not simply body mass index (BMI) alone but specifically abdominal fat distribution is what matters. As part of the ColoCare study, this study measured the distribution of adipose tissue compartments in CRC patients and aimed to identify the body metric that best correlates with these measurements as a useful proxy for adipose tissue distribution. In 120 newly-diagnosed CRC patients who underwent multidetector computed tomography (CT), densitometric quantification of total (TFA), visceral (VFA), intraperitoneal (IFA), retroperitoneal (RFA), and subcutaneous fat area (SFA), as well as the M. erector spinae and psoas was performed to test the association with gender, age, tumor stage, metabolic equivalents, BMI, waist-to-height (WHtR) and waist-to-hip ratio (WHR). VFA was 28.8 % higher in men (p{sub VFA}<0.0001) and 30.5 % higher in patients older than 61 years (p{sub VFA}<0.0001). WHtR correlated best with all adipose tissue compartments (r{sub VFA}=0.69, r{sub TFA}=0.84, p<0.0001) and visceral-to-subcutaneous-fat-ratio (VFR, r{sub VFR}=0.22, p=<0.05). Patients with tumor stages III/IV showed significantly lower overall adipose tissue than I/II. Increased M. erector spinae mass was inversely correlated with all compartments. Densitometric quantification on CT is a highly reproducible and reliable method to show fat distribution across adipose tissue compartments. This distribution might be best reflected by WHtR, rather than by BMI or WHR. (orig.)

Survival and Filamentation of Salmonella enterica Serovar Enteritidis PT4 and Salmonella enterica Serovar Typhimurium DT104 at Low Water Activity

Science.gov (United States)

Mattick, K. L.; Jørgensen, F.; Legan, J. D.; Cole, M. B.; Porter, J.; Lappin-Scott, H. M.; Humphrey, T. J.

2000-01-01

In this study we investigated the long-term survival of and morphological changes in Salmonella strains at low water activity (aw). Salmonella enterica serovar Enteritidis PT4 and Salmonella enterica serovar Typhimurium DT104 survived at low aw for long periods, but minimum humectant concentrations of 8% NaCl (aw, 0.95), 96% sucrose (aw, 0.94), and 32% glycerol (aw, 0.92) were bactericidal under most conditions. Salmonella rpoS mutants were usually more sensitive to bactericidal levels of NaCl, sucrose, and glycerol. At a lethal aw, incubation at 37°C resulted in more rapid loss of viability than incubation at 21°C. At aw values of 0.93 to 0.98, strains of S. enterica serovar Enteritidis and S. enterica serovar Typhimurium formed filaments, some of which were at least 200 μm long. Filamentation was independent of rpoS expression. When the preparations were returned to high-aw conditions, the filaments formed septa, and division was complete within approximately 2 to 3 h. The variable survival of Salmonella strains at low aw highlights the importance of strain choice when researchers produce modelling data to simulate worst-case scenarios or conduct risk assessments based on laboratory data. The continued increase in Salmonella biomass at low aw (without a concomitant increase in microbial count) would not have been detected by traditional microbiological enumeration tests if the tests had been performed immediately after low-aw storage. If Salmonella strains form filaments in food products that have low aw values (0.92 to 0.98), there are significant implications for public health and for designing methods for microbiological monitoring. PMID:10742199

A Study of Bird Ingestions Into Large High Bypass Ratio Turbine Aircraft Engines.

Science.gov (United States)

1984-09-01

average weights based on ".S _ _ _ L TABLE 2.3 CUMULATIVE DISTRIBUTION OF INCESTION EVENTS FOR REVISED IST and 2ND YEAR Year I Year 2 month £,ant Cue. It...7Q iMIM I MLLS*NIcE r2 UN MU.SA=Yc RSZU54 VIGURI 5-5. IM 31211-524 SWGIM/ ,UVC MOM W 3- ’u bi~ mum riom - * 1-5)5 Us1 CrMN-2 ugh Dowus Turbofan Knein... son time. The following codes refer to entries in Appendix E. AIRCRAFT (AC) WEATHER (WX) 1 - )C8 IFR - Instruent Flight Rules 2 - OClO VFR - Visual

Elucidation of the Vibrio anguillarum genetic response to the potential fish probiont Pseudomonas fluorescens AH2, using RNA-arbitrarily primed PCR

DEFF Research Database (Denmark)

Holmstrøm, Kim; Gram, Lone

2003-01-01

or another V. anguillarum siderophore. On the pJM1 plasmid of V anguillarum serotype O1, a pseudogene designated open reading frame E (ORF E) that contains a frameshift mutation was previously identified. The gene homologous to vibE identified in this study, interestingly, also has significant homology...... to ORF E on the amino acid level and does not possess the frameshift mutation. Thus, the chromosomally encoded vibE homologue could fulfil the role of the inactive plasmid-encoded ORF E pseudogene. Addition of Fe3+ to the system eliminated the growth arrest, and the genes homologous to rpoS and vibE were...

Mode-locking in advection-reaction-diffusion systems: An invariant manifold perspective

Science.gov (United States)

Locke, Rory A.; Mahoney, John R.; Mitchell, Kevin A.

2018-01-01

Fronts propagating in two-dimensional advection-reaction-diffusion systems exhibit a rich topological structure. When the underlying fluid flow is periodic in space and time, the reaction front can lock to the driving frequency. We explain this mode-locking phenomenon using the so-called burning invariant manifolds (BIMs). In fact, the mode-locked profile is delineated by a BIM attached to a relative periodic orbit (RPO) of the front element dynamics. Changes in the type (and loss) of mode-locking can be understood in terms of local and global bifurcations of the RPOs and their BIMs. We illustrate these concepts numerically using a chain of alternating vortices in a channel geometry.

Characteristics and pre-travel preparation of travelers at a Canadian pediatric tertiary care travel clinic: A retrospective analysis.

Science.gov (United States)

Ma, Xiao Wei; Pell, Lisa G; Akseer, Nadia; Khan, Sarah; Lam, Ray E; Louch, Debra; Science, Michelle; Morris, Shaun K

2016-01-01

International travelers are susceptible to a wide spectrum of travel related morbidities. Despite rising number of international travelers in Canada, the demographics, risk profiles, and preventative strategies of high-risk traveler groups, including pediatric travelers visiting friends and relatives (VFRs) are not well described. A descriptive analysis was conducted on pre-travel consultations completed between January 2013 and August 2014 at a large pediatric tertiary care center in Toronto, Canada. Data on demographics, travel characteristics, and pre-travel interventions were extracted from 370 pre-travel consultations. Results were compared between all VFR and non-VFR travelers, as well as between children traveling to visit friends and relatives, for vacation, and for education and/or volunteer purposes. Forty-eight percent of consultations were for children travel to visit friends and/or relatives than for other purposes (29% vs 9%, p travel for >28 days than children traveling for vacation (43% vs 1%, p traveling for education/volunteer purposes (43% vs 21%, p = 0.03). Around half of cVFRs traveled to destinations in Asia (51%). The majority stayed with locals, friends and/or relatives (85%), and nearly all traveled to urban destinations (98%). The most prescribed interventions for children were azithromycin (84%), Dukoral (66%), and the hepatitis A vaccine (60%). Atovaquone/proguanil was the most commonly prescribed antimalarial for children. Children that travel to visit friends and relatives represent a unique travel group and may require specific considerations during pre-travel preparations. Our findings can help develop targeted pre-travel strategies for children VFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of travel in measles outbreaks in Australia - An enhanced surveillance study.

Science.gov (United States)

MacIntyre, C R; Karki, S; Sheikh, M; Zwar, N; Heywood, A E

2016-08-17

Many developed countries, like Australia, maintain a high population level immunity against measles, however, there remains a risk of acquisition of measles in non-immune travellers and subsequent importation into Australia leading to localised outbreaks. In this study, we estimate the incidence of measles and describe characteristics including immunisation and pre-travel health seeking behaviour of notified cases of measles in New South Wales and Victoria, Australia between February 2013 and January 2014. Cases were followed up by telephone interview using a questionnaire to collect information of demographic and travel characteristics. In NSW, the incidence was highest in age group 0-9years (20/million population) whereas in Victoria the highest incidence was observed in 10-19 (23/million population) years group. Out of 44 cases interviewed, 25 (56.8%) had history of travel outside of Australia during or immediately prior to the onset of measles. Holiday (60%) was the main reason for travel with 44% (11/25) reporting visiting friends and relatives (VFR) during the trip. The major reason described for not seeking prior medical advice before travel were "no perceived risk of diseases" (41%) and "previous overseas travel without any problem" (41%). Of the 25 measles cases with recent overseas travel during the incubation period, one reported a measles vaccine prior to their recent trip. Four cases were children of parents who refused vaccination. Twenty out of 25 (80.0%) had attended mass gathering events. Young adults and VFR travellers should be a high priority for preventive strategies in order to maintain measles elimination status. Copyright © 2016. Published by Elsevier Ltd.

Prolonged Stationary-Phase Incubation Selects for lrp Mutations in Escherichia coli K-12

Science.gov (United States)

Zinser, Erik R.; Kolter, Roberto

2000-01-01

Evolution by natural selection occurs in cultures of Escherichia coli maintained under carbon starvation stress. Mutants of increased fitness express a growth advantage in stationary phase (GASP) phenotype, enabling them to grow and displace the parent as the majority population. The first GASP mutation was identified as a loss-of-function allele of rpoS, encoding the stationary-phase global regulator, ςS (M. M. Zambrano, D. A. Siegele, M. A. Almirón, A. Tormo, and R. Kolter, Science 259:1757–1760, 1993). We now report that a second global regulator, Lrp, can also play a role in stationary-phase competition. We found that a mutant that took over an aged culture of an rpoS strain had acquired a GASP mutation in lrp. This GASP allele, lrp-1141, encodes a mutant protein lacking the critical glycine in the turn of the helix-turn-helix DNA-binding domain. The lrp-1141 allele behaves as a null mutation when in single copy and is dominant negative when overexpressed. Hence, the mutant protein appears to retain stability and the ability to dimerize but lacks DNA-binding activity. We also demonstrated that a lrp null allele generated by a transposon insertion has a fitness gain identical to that of the lrp-1141 allele, verifying that cells lacking Lrp activity have a competitive advantage during prolonged starvation. Finally, we tested by genetic analysis the hypothesis that the lrp-1141 GASP mutation confers a fitness gain by enhancing amino acid catabolism during carbon starvation. We found that while amino acid catabolism may play a role, it is not necessary for the lrp GASP phenotype, and hence the lrp GASP phenotype is due to more global physiological changes. PMID:10894750

Autocrine CSF-1R signaling drives mesothelioma chemoresistance via AKT activation

Science.gov (United States)

Cioce, M; Canino, C; Goparaju, C; Yang, H; Carbone, M; Pass, H I

2014-01-01

Clinical management of malignant pleural mesothelioma (MPM) is very challenging because of the uncommon resistance of this tumor to chemotherapy. We report here increased expression of macrophage colony-stimulating-factor-1-receptor (M-CSF/CSF-1R) mRNA in mesothelioma versus normal tissue specimens and demonstrate that CSF-1R expression identifies chemoresistant cells of mesothelial nature in both primary cultures and mesothelioma cell lines. By using RNAi or ligand trapping, we demonstrate that the chemoresistance properties of those cells depend on autocrine CSF-1R signaling. At the single-cell level, the isolated CSF-1Rpos cells exhibit a complex repertoire of pluripotency, epithelial–mesenchymal transition and detoxifying factors, which define a clonogenic, chemoresistant, precursor-like cell sub-population. The simple activation of CSF-1R in untransformed mesothelial cells is sufficient to confer clonogenicity and resistance to pemetrexed, hallmarks of mesothelioma. In addition, this induced a gene expression profile highly mimicking that observed in the MPM cells endogenously expressing the receptor and the ligands, suggesting that CSF-1R expression is mainly responsible for the phenotype of the identified cell sub-populations. The survival of CSF1Rpos cells requires active AKT (v-akt murine thymoma viral oncogene homolog 1) signaling, which contributed to increased levels of nuclear, transcriptionally competent β-catenin. Inhibition of AKT reduced the transcriptional activity of β-catenin-dependent reporters and sensitized the cells to senescence-induced clonogenic death after pemetrexed treatment. This work expands what is known on the non-macrophage functions of CSF-1R and its role in solid tumors, and suggests that CSF-1R signaling may have a critical pathogenic role in a prototypical, inflammation-related cancer such as MPM and therefore may represent a promising target for therapeutic intervention. PMID:24722292

The RNA Chaperone Hfq Is Involved in Stress Tolerance and Virulence in Uropathogenic Proteus mirabilis

Science.gov (United States)

Wang, Min-Cheng; Liaw, Shwu-Jen

2014-01-01

Hfq is a bacterial RNA chaperone involved in the riboregulation of diverse genes via small noncoding RNAs. Here, we show that Hfq is critical for the uropathogenic Proteus mirabilis to effectively colonize the bladder and kidneys in a murine urinary tract infection (UTI) model and to establish burned wound infection of the rats. In this regard, we found the hfq mutant induced higher IL-8 and MIF levels of uroepithelial cells and displayed reduced intra-macrophage survival. The loss of hfq affected bacterial abilities to handle H2O2 and osmotic pressures and to grow at 50°C. Relative to wild-type, the hfq mutant had reduced motility, fewer flagella and less hemolysin expression and was less prone to form biofilm and to adhere to and invade uroepithelial cells. The MR/P fimbrial operon was almost switched to the off phase in the hfq mutant. In addition, we found the hfq mutant exhibited an altered outer membrane profile and had higher RpoE expression, which indicates the hfq mutant may encounter increased envelope stress. With the notion of envelope disturbance in the hfq mutant, we found increased membrane permeability and antibiotic susceptibilities in the hfq mutant. Finally, we showed that Hfq positively regulated the RpoS level and tolerance to H2O2 in the stationary phase seemed largely mediated through the Hfq-dependent RpoS expression. Together, our data indicate that Hfq plays a critical role in P. mirabilis to establish UTIs by modulating stress responses, surface structures and virulence factors. This study suggests Hfq may serve as a scaffold molecule for development of novel anti-P. mirabilis drugs and P. mirabilis hfq mutant is a vaccine candidate for preventing UTIs. PMID:24454905

RPO networking in the digital era: prospects and challenges in the year 2000 and beyond

International Nuclear Information System (INIS)

Baharuddin Aziz

2000-01-01

Crucial activities pertaining to the harnessing of nuclear science and technology and their attendant initiatives, inevitably, are expected to increase as the nation embarks on a development plan to achieve a modern industrial nation status. As such activities/initiatives increase in scope and applications, they also dictate the need to continually assess and upgrade radiation protection and expand the functions of RPOs. This article briefly surveys recent developments in information and communication technologies and attempts to relate the digital era to various aspects of radiation protection. It briefly discusses the implications of the digital era to RPO initiatives and offers suggestions to intensify Radiation Safety networking, management, documentation and the sharing of information. (author)

The in vitro fitness cost of antimicrobial resistance in Escherichia coli varies with the growth conditions

DEFF Research Database (Denmark)

Petersen, Andreas; Aarestrup, Frank Møller; Olsen, John Elmerdahl

2009-01-01

The objective of this study was to investigate the influence of stressful growth conditions on the fitness cost of antimicrobial resistance in Escherichia coli BJ4 caused by chromosomal mutations and plasmid acquisition. The fitness cost of chromosomal streptomycin resistance increased......H and at high-salt concentrations. Strains with an impaired rpoS demonstrated a reduced fitness only during growth in a high-salt concentration. In conclusion, it was demonstrated that bacterial fitness cost in association with antimicrobial resistance generally increases under stressful growth conditions....... However, the growth potential of bacteria with antimicrobial resistances did not increase in a straightforward manner in these in vitro experiments and is therefore probably even more difficult to predict in vivo....

Evaluation of Lipid Metabolism and Nutritional Status in Male Goalball Players

Directory of Open Access Journals (Sweden)

Gawlik Krystyna

2015-12-01

Full Text Available Lipid disorders, obesity and overweight are considered one of the most important modifiable cardiovascular risk factors. Population surveys carried out in Poland have demonstrated a tendency for lipid disorders to occur in 70% and overweight and obesity in more than half of Poles. No such studies have been conducted in groups of people with vision impairment so far. Yet, regular involvement of visually impaired people in sports is likely to reduce cardiovascular risk. Therefore, the authors attempted to evaluate the lipid profile and nutritional status of male goalball players. Thirty two blind or visually impaired male goalball players aged 20 to 45 years participated in the study during which somatic variables (BH, BM, WC, VFR, BMI and the lipid profile (TC, LDL, HDL, TG were evaluated. Overweight was found in 40.6% of athletes, with obesity being at the level of 9.3%. A high correlation was found between visceral fat and the BMI (r=0.7; p<0.001, as well as between visceral fat and WC (r=0.8; p<0.001. Abnormal total cholesterol levels were recorded for LDL (22% of study participants, HDL (17% and triglycerides (13%. Lower levels of individual components of lipid profiles (and higher levels for HDL were found in athletes with a normal BMI. A correlation was found between the BMI and TG (r=0.4, p<0.01, WC and TG (r=0.4, p<0.01, VFR and LDL (r=0.4, p<0.05 and TG (r=0.5, p<0.001. The percentage of overweight and obese subjects with vision impairment was lower compared to the general population of men in Poland, with a more beneficial lipid profile. Regular physical activity of the study participants is likely to have a positive effect on their health.

A profile of travelers--an analysis from a large swiss travel clinic.

Science.gov (United States)

Bühler, Silja; Rüegg, Rolanda; Steffen, Robert; Hatz, Christoph; Jaeger, Veronika K

2014-01-01

Globally, the Swiss have one of the highest proportions of the population traveling to tropical and subtropical countries. Large travel clinics serve an increasing number of customers with specific pre-travel needs including uncommon destinations and preexisting medical conditions. This study aims to identify health characteristics and travel patterns of travelers seeking advice in the largest Swiss travel clinic so that tailored advice can be delivered. A descriptive analysis was performed on pre-travel visits between July 2010 and August 2012 at the Travel Clinic of the Institute of Social and Preventive Medicine, University of Zurich, Switzerland. A total of 22,584 travelers sought pre-travel advice. Tourism was the main reason for travel (17,875, 81.5%), followed by visiting friends and relatives (VFRs; 1,715, 7.8%), traveling for business (1,223, 5.6%), and "other reasons" (ie, volunteer work, pilgrimage, study abroad, and emigration; 1,112, 5.1%). The main travel destination was Thailand. In the VFR group, the highest proportions of traveling children (258, 15.1%) and of pregnant or breastfeeding women (23, 3.9%) were observed. Mental disorders were more prominent in VFRs (93, 5.4%) and in travel for "other reasons" (63, 5.7%). The latter stayed for the longest periods abroad; 272 (24.9%) stayed longer than 6 months. VFR travelers received the highest percentage of yellow fever vaccinations (523, 30.5%); in contrast, rabies (269, 24.2%) and typhoid vaccinations (279, 25.1%) were given more often to the "other travel reasons" group. New insights into the characteristics of a selected and large population of Swiss international travelers results in improved understanding of the special needs of an increasingly diverse population and, thus, in targeted preventive advice and interventions. © 2014 International Society of Travel Medicine.

Increase in imported malaria in the Netherlands in asylum seekers and VFR travellers

NARCIS (Netherlands)

de Gier, Brechje; Suryapranata, Franciska S. T.; Croughs, Mieke; van Genderen, Perry J. J.; Keuter, Monique; Visser, Leo G.; van Vugt, Michele; Sonder, Gerard J. B.

2017-01-01

Malaria is a notifiable disease in the Netherlands, a non-endemic country. Imported malaria infections occur regularly among travellers, migrants and visitors. Surveillance data were analysed from 2008 to 2015. Trends in amounts of notifications among risk groups were analysed using Poisson

Increase in imported malaria in the Netherlands in asylum seekers and VFR travellers

NARCIS (Netherlands)

Gier, B. de; Suryapranata, F.S.; Croughs, M.; Genderen, P.J. van; Keuter, M.; Visser, L.G.; Vugt, M. De; Sonder, G.J.

2017-01-01

BACKGROUND: Malaria is a notifiable disease in the Netherlands, a non-endemic country. Imported malaria infections occur regularly among travellers, migrants and visitors. Surveillance data were analysed from 2008 to 2015. Trends in amounts of notifications among risk groups were analysed using

Pyrrolnitrin and Hydrogen Cyanide Production by Pseudomonas chlororaphis Strain PA23 Exhibits Nematicidal and Repellent Activity against Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Munmun Nandi

Full Text Available Pseudomonas chlororaphis strain PA23 is a biocontrol agent able to suppress growth of the fungal pathogen Sclerotinia sclerotiorum. This bacterium produces an arsenal of exometabolites including pyrrolnitrin (PRN, phenazine (PHZ, hydrogen cyanide (HCN, and degradative enzymes. Production of these compounds is controlled at both the transcriptional and posttranscriptional levels by the Gac-Rsm system, RpoS, PsrA, and the Phz quorum-sensing system. Beyond pathogen-suppression, the success of a biocontrol agent is dependent upon its ability to establish itself in the environment where predation by bacterivorous organisms, including nematodes, may threaten persistence. The focus of this study was to investigate whether PA23 is able to resist grazing by Caenorhabditis elegans and to define the role played by exoproducts in the bacterial-nematode interaction. We discovered that both PRN and HCN contribute to fast- and slow-killing of C. elegans. HCN is well-established as having lethal effects on C. elegans; however, PRN has not been reported to be nematicidal. Exposure of L4 stage nematodes to purified PRN reduced nematode viability in a dose-dependent fashion and led to reduced hatching of eggs laid by gravid adults. Because bacterial metabolites can act as chemoattractants or repellents, we analyzed whether PA23 exhibited attractant or repulsive properties towards C. elegans. Both PRN and HCN were found to be potent repellents. Next we investigated whether the presence of C. elegans would elicit changes in PA23 gene activity. Co-culturing the two organisms increased expression of a number of genes associated with biocontrol, including phzA, hcnA, phzR, phzI, rpoS and gacS. Exoproduct analysis showed that PHZ and autoinducer signals were upregulated, consistent with the gene expression profiles. Collectively, these findings indicate that PA23 is able to sense the presence of C. elegans and it is able to both repel and kill the nematodes, which

Definitions, qualifications and requirements for radiation protection experts, radiation protection officers and radiation workers: results of the 2 nd EUTERP Workshop

International Nuclear Information System (INIS)

Draaisma, Folkert S.; Steen, Jan van der

2008-01-01

Full text: In Europe, a common vision for maintaining competence in radiation protection is emerging, focussing on a common denominator for qualification of radiation protection experts (RPEs) and radiation protection officers (RPOs) and for mutual recognition and mobility of these professionals across the European Union. Therefore, the European Commission, D.-G. Transport and Energy, has launched an initiative to establish a European Radiation Protection Training and Education Platform (EUTERP Platform). The objectives of the Platform can be summarised as: to facilitate the trans national access to vocational education and training; to better integrate education and training into occupational radiation protection infrastructures in the Member, Candidate and Associated States of the European Union. The Platform ensures a permanent dialogue between all involved parties by the use of its web site (www.euterp.eu), by issuing newsletters and by organising workshops. The first workshop has been held in Vilnius, 22-24 May 2007, and resulted in 8 recommendations to the European Commission, the IAEA, IRPA and national authorities. The recommendations were, a.o., dealing with: new definitions for the Radiation Protection Expert (RPE) and the Radiation Protection Officer (RPO), which should be used in the revision of both the EURATOM and the International BSS; developing guidance for a methodology to compare the quality of training courses and training material; developing guidance for a standardized methodology of assessing the recognition of RP professionals as a basis for future mutual recognition, based on a description of roles and duties, education, training and work experience; developing guidance for a formal recognition process of the competence of RPEs and RPOs. The second workshop will be held on 23-25 April 2008, again in Vilnius, and will specifically discuss the above-mentioned proposals for new definitions and guidance material. It is expected that the

Flight management research utilizing an oculometer. [pilot scanning behavior during simulated approach and landing

Science.gov (United States)

Spady, A. A., Jr.; Kurbjun, M. C.

1978-01-01

This paper presents an overview of the flight management work being conducted using NASA Langley's oculometer system. Tests have been conducted in a Boeing 737 simulator to investigate pilot scan behavior during approach and landing for simulated IFR, VFR, motion versus no motion, standard versus advanced displays, and as a function of various runway patterns and symbology. Results of each of these studies are discussed. For example, results indicate that for the IFR approaches a difference in pilot scan strategy was noted for the manual versus coupled (autopilot) conditions. Also, during the final part of the approach when the pilot looks out-of-the-window he fixates on his aim or impact point on the runway and holds this point until flare initiation.

Inhibition and dispersal of Agrobacterium tumefaciens biofilms by a small diffusible Pseudomonas aeruginosa exoproduct(s).

Science.gov (United States)

Hibbing, Michael E; Fuqua, Clay

2012-06-01

Environmental biofilms often contain mixed populations of different species. In these dense communities, competition between biofilm residents for limited nutrients such as iron can be fierce, leading to the evolution of competitive factors that affect the ability of competitors to grow or form biofilms. We have discovered a compound(s) present in the conditioned culture fluids of Pseudomonas aeruginosa that disperses and inhibits the formation of biofilms produced by the facultative plant pathogen Agrobacterium tumefaciens. The inhibitory activity is strongly induced when P. aeruginosa is cultivated in iron-limited conditions, but it does not function through iron sequestration. In addition, the production of the biofilm inhibitory activity is not regulated by the global iron regulatory protein Fur, the iron-responsive extracytoplasmic function σ factor PvdS, or three of the recognized P. aeruginosa quorum-sensing systems. In addition, the compound(s) responsible for the inhibition and dispersal of A. tumefaciens biofilm formation is likely distinct from the recently identified P. aeruginosa dispersal factor, cis-2-decenoic acid (CDA), as dialysis of the culture fluids showed that the inhibitory compound was larger than CDA and culture fluids that dispersed and inhibited biofilm formation by A. tumefaciens had no effect on biofilm formation by P. aeruginosa.

Regional vascular density-visual field sensitivity relationship in glaucoma according to disease severity.

Science.gov (United States)

Shin, Joong Won; Lee, Jiyun; Kwon, Junki; Choi, Jaewan; Kook, Michael S

2017-12-01

To study whether there are global and regional relationships between peripapillary vascular density (pVD) assessed by optical coherence tomography angiography (OCT-A) and visual field (VF) mean sensitivity at different glaucoma stages. Microvascular images and peripapillary retinal nerve fibre layer (pRNFL) thicknesses were obtained using a Cirrus OCT-A device in 91 glaucoma subjects. The pVD was measured at various spatial locations according to the Garway-Heath map, using a MATLAB software (The MathWorks, Natick, Massachusetts). VF mean sensitivity (VFMS) was recorded in the 1/L scale. Global and regional vasculature-function (pVD vs VFMS) relationships were assessed in separate patient groups at mild and moderate-to-advanced stages of glaucoma. The pVDs at superotemporal and inferotemporal regions were significantly associated with corresponding VFMS in mild glaucoma (pglaucoma, there were significant associations between pVD and VFMS, regardless of location. The association between global pVD and VFMS was significantly stronger than that between global pRNFL thickness and VFMS in moderate-to-advanced stage glaucoma (p glaucoma. OCT-A may be useful in monitoring glaucoma at various stages. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Enzyme-mediated quenching of the Pseudomonas quinolone signal (PQS promotes biofilm formation of Pseudomonas aeruginosa by increasing iron availability

Directory of Open Access Journals (Sweden)

Beatrix Tettmann

2016-12-01

Full Text Available The 2-alkyl-3-hydroxy-4(1H-quinolone 2,4-dioxygenase HodC was previously described to cleave the Pseudomonas quinolone signal, PQS, which is exclusively used in the complex quorum sensing (QS system of Pseudomonas aeruginosa, an opportunistic pathogen employing QS to regulate virulence and biofilm development. Degradation of PQS by exogenous addition of HodC to planktonic cells of P. aeruginosa attenuated production of virulence factors, and reduced virulence in planta. However, proteolytic cleavage reduced the efficacy of HodC. Here, we identified the secreted protease LasB of P. aeruginosa to be responsible for HodC degradation. In static biofilms of the P. aeruginosa PA14 lasB::Tn mutant, the catalytic activity of HodC led to an increase in viable biomass in newly formed but also in established biofilms, and reduced the expression of genes involved in iron metabolism and siderophore production, such as pvdS, pvdL, pvdA and pvdQ. This is likely due to an increase in the levels of bioavailable iron by degradation of PQS, which is able to sequester iron from the surrounding environment. Thus, HodC, despite its ability to quench the production of virulence factors, is contraindicated for combating P. aeruginosa biofilms.

Quantification and Minimization of Uncertainties of Internal Target Volume for Stereotactic Body Radiation Therapy of Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Ge Hong [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Department of Radiation Oncology, Henan Cancer Hospital, the Affiliated Cancer Hospital of Zhengzhou University, Henan (China); Cai Jing; Kelsey, Chris R. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yin Fangfang, E-mail: fangfang.yin@duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

2013-02-01

Purpose: To quantify uncertainties in delineating an internal target volume (ITV) and to understand how these uncertainties may be individually minimized for stereotactic body radiation therapy (SBRT) of early stage non-small cell lung cancer (NSCLC). Methods and Materials: Twenty patients with NSCLC who were undergoing SBRT were imaged with free-breathing 3-dimensional computed tomography (3DCT) and 10-phase 4-dimensional CT (4DCT) for delineating gross tumor volume (GTV){sub 3D} and ITV{sub 10Phase} (ITV3). The maximum intensity projection (MIP) CT was also calculated from 10-phase 4DCT for contouring ITV{sub MIP} (ITV1). Then, ITV{sub COMB} (ITV2), ITV{sub 10Phase+GTV3D} (ITV4), and ITV{sub 10Phase+ITVCOMB} (ITV5) were generated by combining ITV{sub MIP} and GTV{sub 3D}, ITV{sub 10phase} and GTV{sub 3D}, and ITV{sub 10phase} and ITV{sub COMB}, respectively. All 6 volumes (GTV{sub 3D} and ITV1 to ITV5) were delineated in the same lung window by the same radiation oncologist. The percentage of volume difference (PVD) between any 2 different volumes was determined and was correlated to effective tumor diameter (ETD), tumor motion ranges, R{sub 3D}, and the amplitude variability of the recorded breathing signal (v) to assess their volume variations. Results: The mean (range) tumor motion (R{sub SI}, R{sub AP}, R{sub ML}, and R{sub 3D}) and breathing variability (v) were 7.6 mm (2-18 mm), 4.0 mm (2-8 mm), 3.3 mm (0-7.5 mm), 9.9 mm (4.1-18.7 mm), and 0.17 (0.07-0.37), respectively. The trend of volume variation was GTV{sub 3D} PVDs for all volume pairs correlated negatively with ETD (r{<=}-0.658, P{<=}.006) and positively with

Imported malaria in a cosmopolitan European city: a mirror image of the world epidemiological situation.

Science.gov (United States)

Millet, Juan Pablo; Garcia de Olalla, Patricia; Carrillo-Santisteve, Paloma; Gascón, Joaquim; Treviño, Begoña; Muñoz, José; Gómez I Prat, Jordi; Cabezos, Juan; González Cordón, Anna; Caylà, Joan A

2008-04-08

International travel and migration have been related with an increase of imported malaria cases. There has been considerable immigration to Barcelona from low-income countries (LIC) in recent years. The objective is to describe the epidemiology and to determine the trends of the disease in Barcelona. Analysis of the cases notified among city residents between 1989 and 2005. Patients were classified as: tourists, voluntary workers, resident immigrants (visiting friends and relatives, VFR) and recently arrived immigrants. An analysis was conducted using the chi2 test and comparison of means. As a measure of association we calculated the Relative Risk (RR) and Odds Ratio (OR) with a Confidence Interval of 95% (CI) and carried out a trends analysis. Of the total of 1,579 imported cases notified, 997 (63.1%) lived in Barcelona city, and 55.1% were male. The mean age of patients was 32.7 years. The incidence increased from 2.4 cases/100,000 in 1989 to 3.5 cases/100,000 in 2005 (RR 1.46 CI:1.36-1.55). This increase was not statistically significant (trends analysis, p = 0.36). In terms of reason for travelling, 40.7% were VFR, 33.6% tourists, 12.1% voluntary workers and 13.6% were recently arrived immigrants. The most frequent species found was Plasmodium falciparum (71.3%), mainly in visitors to Africa (OR = 2.3, CI = 1.7-3.2). The vast majority (82.2%) had had some contact with Africa (35.9% with Equatorial Guinea, a Spanish ex-colony) and 96.6% had not completed chemoprophylaxis. Six deaths were observed, all tourists who had travelled to Africa and not taken chemoprophylaxis (3.9% fatality rate). Over the period studied there is an increase in malaria incidence, however the trend is not statistically significant. Lack of chemoprophylaxis compliance and the association between Africa and P. falciparum are very clear in the imported cases. Most of the patients with malaria did not take chemoprophylaxis.

Imported malaria in a cosmopolitan European city: A mirror image of the world epidemiological situation

Directory of Open Access Journals (Sweden)

Gómez i Prat Jordi

2008-04-01

Full Text Available Abstract Background International travel and migration have been related with an increase of imported malaria cases. There has been considerable immigration to Barcelona from low-income countries (LIC in recent years. The objective is to describe the epidemiology and to determine the trends of the disease in Barcelona. Methods Analysis of the cases notified among city residents between 1989 and 2005. Patients were classified as: tourists, voluntary workers, resident immigrants (visiting friends and relatives, VFR and recently arrived immigrants. An analysis was conducted using the chi2 test and comparison of means. As a measure of association we calculated the Relative Risk (RR and Odds Ratio (OR with a Confidence Interval of 95% (CI and carried out a trends analysis. Results Of the total of 1,579 imported cases notified, 997 (63.1% lived in Barcelona city, and 55.1% were male. The mean age of patients was 32.7 years. The incidence increased from 2.4 cases/100,000 in 1989 to 3.5 cases/100,000 in 2005 (RR 1.46 CI:1.36–1.55. This increase was not statistically significant (trends analysis, p = 0.36. In terms of reason for travelling, 40.7% were VFR, 33.6% tourists, 12.1% voluntary workers and 13.6% were recently arrived immigrants. The most frequent species found was Plasmodium falciparum (71.3%, mainly in visitors to Africa (OR = 2.3, CI = 1.7–3.2. The vast majority (82.2% had had some contact with Africa (35.9% with Equatorial Guinea, a Spanish ex-colony and 96.6% had not completed chemoprophylaxis. Six deaths were observed, all tourists who had travelled to Africa and not taken chemoprophylaxis (3.9% fatality rate. Conclusion Over the period studied there is an increase in malaria incidence, however the trend is not statistically significant. Lack of chemoprophylaxis compliance and the association between Africa and P. falciparum are very clear in the imported cases. Most of the patients with malaria did not take chemoprophylaxis.

New development in the certification of a component radiation protection officer in industrial radiography

International Nuclear Information System (INIS)

Ismail Bahari; Azwar, M.H.; Mohd Pauzi, M.S.

2001-01-01

The appointment of a Radiation protection Officer (RPO) by companies for activities related to the use of Atomic Energy, including Industrial Radiography is mandated under regulation 23 of the Radiation Protection (Basic Safety Standards) Regulations 1988. The regulations categorically requires the appointment of a competent person to help ensure radiation safety at work. Definition of competency has been spelt out in the regulations and this is translated to include having been trained and tested through examination by the AELB and be able to carry out the duties and responsibilities prescribed by the Act and Regulations. This paper discusses the development in the certification of RPO in the field of industrial radiography and what the new RPO certification scheme together with the Certification of RPO standard (LEMI/TEK/44) will do to increase competency as well as the market value of future RPOs. (Author)

78 FR 50313 - Final Additional Airworthiness Design Standards: Night Visual Flight Rules (VFR) Under the...

Science.gov (United States)

2013-08-19

... lights; and (d) Any other colour, including white, for lights not described in sub-paragraphs (a) to (c) of this paragraph, provided the colour differs sufficiently from the colours prescribed in... indicator, as required in CS-VLA 1545 and the significance of the colour coding used on the indicator. (2...

Anaerobic survival of Pseudomonas aeruginosa by pyruvate fermentation requires an Usp-type stress protein

DEFF Research Database (Denmark)

Schreiber, K; Boes, N; Escbach, M

2006-01-01

the induced synthesis of three enzymes involved in arginine fermentation, ArcA, ArcB, and ArcC, and the outer membrane protein OprL. Moreover, formation of two proteins of unknown function, PA3309 and PA4352, increased by factors of 72- and 22-fold, respectively. Both belong to the group of universal stress...... proteins (Usp). Long-term survival of a PA3309 knockout mutant by pyruvate fermentation was found drastically reduced. The oxygen-sensing regulator Anr controls expression of the PPA3309-lacZ reporter gene fusion after a shift to anaerobic conditions and further pyruvate fermentation. PA3309 expression...... was also found induced during the anaerobic and aerobic stationary phases. This aerobic stationary-phase induction is independent of the regulatory proteins Anr, RpoS, RelA, GacA, RhlR, and LasR, indicating a currently unknown mechanism of stationary-phase-dependent gene activation. PA3309 promoter...

An Examination of Visitors’ Interest in Tourist Cards and Cultural Routes in the Case of a Romanian Destination

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Ana ISPAS

2015-10-01

Full Text Available Although tourist cards and cultural routes have been interesting innovations when they were launched on the international tourism market, they are rarely implemented in Romanian tourism destinations, especially in an integrated manner. This paper presents a theoretical model regarding the integration of tourist cards in cultural routes, based on the assumption that tourists who are interested in both products have similar demographic and travel characteristics. The research results outline only the infl uence of tourists’ travel characteristics on their interest to buy cultural routes and tourist cards. Leisure travelers should be the main targeted segment, as their probability to buy such products is higher than in the case of business or VFR (visit friends and relatives tourists. These results can assist the Destination Management Organizations (DMOs regarding the choice of marketing strategies aimed at integrating cultural routes in a tourist card.

β-lactam antibiotics promote bacterial mutagenesis via an RpoS-mediated reduction in replication fidelity

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Gutierrez, A.; Laureti, L.; Crussard, S.; Abida, H.; Rodríguez-Rojas, A.; Blázquez, J.; Baharoglu, Z.; Mazel, D.; Darfeuille, F.; Vogel, J.; Matic, I.

2013-01-01

Regardless of their targets and modes of action, subinhibitory concentrations of antibiotics can have an impact on cell physiology and trigger a large variety of cellular responses in different bacterial species. Subinhibitory concentrations of β-lactam antibiotics cause reactive oxygen species production and induce PolIV-dependent mutagenesis in Escherichia coli. Here we show that subinhibitory concentrations of β-lactam antibiotics induce the RpoS regulon. RpoS-regulon induction is required for PolIV-dependent mutagenesis because it diminishes the control of DNA-replication fidelity by depleting MutS in E. coli, Vibrio cholerae and Pseudomonas aeruginosa. We also show that in E. coli, the reduction in mismatch-repair activity is mediated by SdsR, the RpoS-controlled small RNA. In summary, we show that mutagenesis induced by subinhibitory concentrations of antibiotics is a genetically controlled process. Because this mutagenesis can generate mutations conferring antibiotic resistance, it should be taken into consideration for the development of more efficient antimicrobial therapeutic strategies. PMID:23511474

How effective is aeration with vortex flow regulators? Pilot scale experiments

Science.gov (United States)

Wójtowicz, Patryk; Szlachta, Małgorzata

2017-11-01

Vortex flow regulators (VFR) are used in urban drainage systems as a replacement for traditional flow throttling devices. Vortex regulators are not only very efficient energy dissipators but also atomizers which are beneficial for sewer aeration. A deficit of dissolved oxygen can be a problem in both natural waters and sewerage. Hydrodynamic flow regulators can boost oxygen concentration preventing putrefaction and improving treatment of stormwater and wastewater. We were first to investigate the aeration efficiency of semi-commercial scale cylindrical vortex flow regulators to determine the potential of their application in environmental engineering and to propose modification to enhance the aeration capacity of basic designs. Different device geometries and arrangements of active outlets for both single and double discharge vortex regulators were tested in a recirculating system. In this study, we present a concise review of the current state of our extensive research on the aeration efficiency of vortex flow regulators and their application in sewerage systems.

Estimation of mass transfer parameters in a Taylor-Couette-Poiseuille heterogeneous reactor

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Resende M. M.

2004-01-01

Full Text Available A bench-scale, continuous vortex flow reactor (VFR, with a radius ratio, h, equal to 0.48 and an aspect ratio, G, equal to 11.19 was studied. This reactor may be used in the enzymatic hydrolysis of polypeptides obtained from sweet cheese whey with enzymes immobilized on agarose gel. Operational conditions were 2410 < Re q < 11793 and 30-min residence time for glycerol-water, 14% w/w, 27ºC (Re ax = 1.1 and for water, 38ºC (Re ax = 1.5. Residence time distributions (RTDs were obtained after pulse injections of different tracers (including dyed solid particles. Mass transfer coefficients of a lumped-parameter model of the reactor were estimated from these data. Model fitting to experimental data was accurate. Working conditions were selected so that transport properties of the fluids would be similar to the ones in the actual process at the final stages of whey hydrolysis.

Educating international students about tuberculosis and infections associated with travel to visit friends and relatives (VFR-travel).

Science.gov (United States)

Gibney, Katherine B; Brass, Amanda; Hume, Sam C; Leder, Karin

2014-01-01

International students in Victoria, Australia, originate from over 140 different countries. They are over-represented in disease notifications for tuberculosis and travel-associated infections, including enteric fever, hepatitis A, and malaria. We describe a public health initiative aimed to increase awareness of these illnesses among international students and their support staff. We identified key agencies including student support advisors, medical practitioners, health insurers, and government and professional organisations. We developed health education materials targeting international students regarding tuberculosis and travel-related infections to be disseminated via a number of different media, including electronic and printed materials. We sought informal feedback from personnel in all interested agencies regarding the materials developed, their willingness to deliver these materials to international students, and their preferred media for disseminating these materials. Education institutions with dedicated international student support staff and on-campus health clinics were more easily engaged to provide feedback and disseminate the health education materials than institutions without such dedicated personnel. Response to contacting off-campus medical practices was poor. Delivery of educational materials via electronic and social media was preferred over face-to-face education. It is feasible to provide health education messages targeting international students for dissemination via appropriately-staffed educational institutions. This initiative could be expanded in terms of age-group, geographic range, and health issues to be targeted. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transcriptome analysis of all two-component regulatory system mutants of Escherichia coli K-12.

Science.gov (United States)

Oshima, Taku; Aiba, Hirofumi; Masuda, Yasushi; Kanaya, Shigehiko; Sugiura, Masahito; Wanner, Barry L; Mori, Hirotada; Mizuno, Takeshi

2002-10-01

We have systematically examined the mRNA profiles of 36 two-component deletion mutants, which include all two-component regulatory systems of Escherichia coli, under a single growth condition. DNA microarray results revealed that the mutants belong to one of three groups based on their gene expression profiles in Luria-Bertani broth under aerobic conditions: (i) those with no or little change; (ii) those with significant changes; and (iii) those with drastic changes. Under these conditions, the anaeroresponsive ArcB/ArcA system, the osmoresponsive EnvZ/OmpR system and the response regulator UvrY showed the most drastic changes. Cellular functions such as flagellar synthesis and expression of the RpoS regulon were affected by multiple two-component systems. A high correlation coefficient of expression profile was found between several two-component mutants. Together, these results support the view that a network of functional interactions, such as cross-regulation, exists between different two-component systems. The compiled data are avail-able at our website (http://ecoli.aist-nara.ac.jp/xp_analysis/ 2_components).

Risk factors and pre-travel healthcare of international travellers attending a Dutch travel clinic: a cross-sectional analysis.

Science.gov (United States)

Wieten, Rosanne W; van der Schalie, Maurice; Visser, Benjamin J; Grobusch, Martin P; van Vugt, Michèle

2014-01-01

The number of international travellers is currently estimated to exceed one billion annually. To address travel related health risks and facilitate risk reduction strategies, detailed knowledge of travellers' characteristics is important. In this cross-sectional study, data of a 20% sample of travellers visiting the Academic Medical Center (AMC) travel clinic Amsterdam from July 2011 to July 2012 was collected. Itineraries and protection versus exposure rates of preventable infectious diseases were mapped and reported according to STROBE guidelines. 1749 travellers were included. South-Eastern Asia, South-America and West-Africa were most frequently visited. 26.2% of the population had pre-existing medical conditions (often cardiovascular). Young and VFR travellers had a longer median travel time (28 and 30 days) compared to the overall population (21 days). Young adult travellers were relatively often vaccinated against hepatitis B (43.9% vs. 20.5%, p travellers. Pre-travel guidelines were well adhered to. Young adult travellers had high-risk itineraries but were adequately protected. Improvement of hepatitis B and rabies protection would be desirable, specifically for VFRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Uneven Geography of Tourism in South Africa

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CM Rogerson

2014-01-01

Full Text Available Understanding the spatial dimensions of tourism is one of the core challenges for geographers involved in tourism studies. The aim in this paper is to pursue a geographical analysis of uneven patterns of tourism in South Africa and specifically to unpack the key trends observed in the country's tourism space economy. The analysis is conducted between three groupings of municipalities as destinations or tourism spaces. These three groups are demarcated as the metropolitan areas, the rural spaces of the priority district municipalities, and what is called the intermediate space of the remaining non-priority district municipalities. The findings show the dominance of South Africa's tourism space economy by the metropolitan areas. In addition, the analysis shows these three different tourism spaces exhibit different trajectories in terms of growth performance (numbers of trips, bednights and visitor spend, origin of visitors (domestic versus international and purpose of travel (leisure, business, VFR and other. Interpreting the characteristics of these tourism spaces is an essential first step for improved local tourism planning.

Analysis of general aviation single-pilot IFR incident data obtained from the NASA Aviation Safety Reporting System

Science.gov (United States)

Bergeron, H. P.

1983-01-01

An analysis of incident data obtained from the NASA Aviation Safety Reporting System (ASRS) has been made to determine the problem areas in general aviation single-pilot IFR (SPIFR) operations. The Aviation Safety Reporting System data base is a compilation of voluntary reports of incidents from any person who has observed or been involved in an occurrence which was believed to have posed a threat to flight safety. This paper examines only those reported incidents specifically related to general aviation single-pilot IFR operations. The frequency of occurrence of factors related to the incidents was the criterion used to define significant problem areas and, hence, to suggest where research is needed. The data was cataloged into one of five major problem areas: (1) controller judgment and response problems, (2) pilot judgment and response problems, (3) air traffic control (ATC) intrafacility and interfacility conflicts, (4) ATC and pilot communication problems, and (5) IFR-VFR conflicts. In addition, several points common to all or most of the problems were observed and reported. These included human error, communications, procedures and rules, and work load.

Identification and characterization of Nip, necrosis-inducing virulence protein of Erwinia carotovora subsp. carotovora.

Science.gov (United States)

Mattinen, Laura; Tshuikina, Marina; Mäe, Andres; Pirhonen, Minna

2004-12-01

Erwinia carotovora subsp. carotovora is a gram-negative bacterium that causes soft rot disease of many cultivated crops. When a collection of E. carotovora subsp. carotovora isolates was analyzed on a Southern blot using the harpin-encoding gene hrpN as probe, several harpinless isolates were found. Regulation of virulence determinants in one of these, strain SCC3193, has been characterized extensively. It is fully virulent on potato and in Arabidopsis thaliana. An RpoS (SigmaS) mutant of SCC3193, producing elevated levels of secreted proteins, was found to cause lesions resembling the hypersensitive response when infiltrated into tobacco leaf tissue. This phenotype was evident only when bacterial cells had been cultivated on solid minimal medium at low pH and temperature. The protein causing'the cell death was purified and sequenced, and the corresponding gene was cloned. The deduced sequence of the necrosis-inducing protein (Nip) showed homology to necrosis- and ethylene-inducing elicitors of fungi and oomycetes. A mutant strain of E. carotovora subsp. carotovora lacking the nip gene showed reduced virulence in potato tuber assay but was unaffected in virulence in potato stem or on other tested host plants.

What could the nematodes teach us about radiation protection? Plenty

International Nuclear Information System (INIS)

Doris, I.C.

2006-01-01

Trying to make rational decisions that have far-reaching consequences for both our patients and our profession is difficult, even after we have spent so many of our formative years learning to think and act in a disciplined and logical manner, and taking into account all the available evidence. What do we do when there is no evidence or, at best, very limited evidence? This is a problem that I have had cause to consider several times and in many contexts since undertaking, a few years ago, the role of radiation protection officer (RPO) in my department. Maintaining the ALARA principle ('as low as reasonably achievable') would seem to make common sense. However, in view of the changes occurring in diagnostic imaging, I am concerned as to whether the breadth and depth of our knowledge of radiation's biological effects has kept pace with the changes in clinical practice. Can we apply this time-honoured principle in contemporary radiology? Having experienced, as an RPO, the challenge of applying sound principles of radiation protection, I would like to share some thoughts on the current role and responsibilities of RPOs and the problems they may face in the future. (author)

Regulatory inspection: a powerful tool to control industrial radioactive sources

International Nuclear Information System (INIS)

Silva, F.C.A. da; Leocadio, J.C.; Ramalho, A.T.

2008-01-01

An important contribution for Brazilian development, especially for the quality control of products, is the use of radiation sources by conventional industries. There are in Brazil roughly 3,000 radioactive sources spread out among 950 industries. The main industrial practices involved are: industrial radiography, industrial irradiators, industrial accelerators, well logging petroleum and nuclear gauges. More than 1,800 Radiation Protection Officers (RPOs) were qualified to work in these practices. The present work presents a brief description of the safety control over industrial radioactive installations performed by the Brazilian Regulatory Authority, i.e. the National Commission of Nuclear Energy (CNEN). This paper also describes the national system for radiation safety inspections, the regulation infrastructure and the national inventory of industrial installations. The inspections are based on specific indicators, and their periodicity depends on the risk and type of installation. The present work discusses some relevant aspects that must be considered during the inspections, in order to make the inspections more efficient in controlling the sources. One of these aspects regards the evaluation of the storage place for the sources, a very important parameter for preventing future risky situations. (author)

The Odyssey of the Ancestral Escherich Strain through Culture Collections: an Example of Allopatric Diversification.

Science.gov (United States)

Desroches, M; Royer, G; Roche, D; Mercier-Darty, M; Vallenet, D; Médigue, C; Bastard, K; Rodriguez, C; Clermont, O; Denamur, E; Decousser, J-W

2018-01-01

More than a century ago, Theodor Escherich isolated the bacterium that was to become Escherichia coli , one of the most studied organisms. Not long after, the strain began an odyssey and landed in many laboratories across the world. As laboratory culture conditions could be responsible for major changes in bacterial strains, we conducted a genome analysis of isolates of this emblematic strain from different culture collections (England, France, the United States, Germany). Strikingly, many discrepancies between the isolates were observed, as revealed by multilocus sequence typing (MLST), the presence of virulence-associated genes, core genome MLST, and single nucleotide polymorphism/indel analyses. These differences are correlated with the phylogeographic history of the strain and were due to an unprecedented number of mutations in coding DNA repair functions such as mismatch repair (MutL) and oxidized guanine nucleotide pool cleaning (MutT), conferring a specific mutational spectrum and leading to a mutator phenotype. The mutator phenotype was probably acquired during subculturing and corresponded to second-order selection. Furthermore, all of the isolates exhibited hypersusceptibility to antibiotics due to mutations in efflux pump- and porin-encoding genes, as well as a specific mutation in the sigma factor-encoding gene rpoS . These defects reflect a self-preservation and nutritional competence tradeoff allowing survival under the starvation conditions imposed by storage. From a clinical point of view, dealing with such mutator strains can lead microbiologists to draw false conclusions about isolate relatedness and may impact therapeutic effectiveness. IMPORTANCE Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isolates. Several genes can be impacted, each of them being associated with a typical mutational spectrum. By studying one of the oldest strains available, the ancestral Escherich strain, we were able to

Identification of type II and type III pyoverdine receptors from Pseudomonas aeruginosa.

Science.gov (United States)

de Chial, Magaly; Ghysels, Bart; Beatson, Scott A; Geoffroy, Valérie; Meyer, Jean Marie; Pattery, Theresa; Baysse, Christine; Chablain, Patrice; Parsons, Yasmin N; Winstanley, Craig; Cordwell, Stuart J; Cornelis, Pierre

2003-04-01

Pseudomonas aeruginosa produces, under conditions of iron limitation, a high-affinity siderophore, pyoverdine (PVD), which is recognized at the level of the outer membrane by a specific TonB-dependent receptor, FpvA. So far, for P. aeruginosa, three different PVDs, differing in their peptide chain, have been described (types I-III), but only the FpvA receptor for type I is known. Two PVD-producing P. aeruginosa strains, one type II and one type III, were mutagenized by a mini-TnphoA3 transposon. In each case, one mutant unable to grow in the presence of the strong iron chelator ethylenediaminedihydroxyphenylacetic acid (EDDHA) and the cognate PVD was selected. The first mutant, which had an insertion in the pvdE gene, upstream of fpvA, was unable to take up type II PVD and showed resistance to pyocin S3, which is known to use type II FpvA as receptor. The second mutant was unable to take up type III PVD and had the transposon insertion in fpvA. Cosmid libraries of the respective type II and type III PVD wild-type strains were constructed and screened for clones restoring the capacity to grow in the presence of PVD. From the respective complementing genomic fragments, type II and type III fpvA sequences were determined. When in trans, type II and type III fpvA restored PVD production, uptake, growth in the presence of EDDHA and, in the case of type II fpvA, pyocin S3 sensitivity. Complementation of fpvA mutants obtained by allelic exchange was achieved by the presence of cognate fpvA in trans. All three receptors posses an N-terminal extension of about 70 amino acids, similar to FecA of Escherichia coli, but only FpvAI has a TAT export sequence at its N-terminal end.

Role of hydrogen sulfide in portal hypertension and esophagogastric junction vascular disease

Science.gov (United States)

Wang, Chao; Han, Juan; Xiao, Liang; Jin, Chang-E; Li, Dong-Jian; Yang, Zhen

2014-01-01

AIM: To investigate the association between endogenous hydrogen sulfide (H2S) and portal hypertension as well as its effect on vascular smooth muscle cells. METHODS: Portal hypertension patients were categorized by Child-Pugh score based on bilirubin and albumin levels, prothrombin time, ascites and hepatic encephalopathy. Plasma H2S concentrations and portal vein diameters (PVDs) were compared between portal hypertension patients and control participants, as well as between portal hypertension patients with varying degrees of severity. In addition, we established a rabbit hepatic schistosomiasis portal hypertension (SPH) model and analyzed liver morphology, fibrosis grade, plasma and liver tissue H2S concentrations, as well as cystathionine γ-lyase (CSE) activity and phosphorylated extracellular signal-regulated kinase (pERK)1/2, B cell lymphoma (Bcl)-2 and Bcl-XL expression in portal vein smooth muscle cells, in addition to their H2S-induced apoptosis rates. RESULTS: In portal hypertension patients, endogenous H2S levels were significantly lower than those in healthy controls. The more severe the disease was, the lower were the H2S plasma levels, which were inversely correlated with PVD and Child-Pugh score. Liver tissue H2S concentrations and CSE expression were significantly lower in the SPH rabbit livers compared with the control animals, starting at 3 wk, whereas pERK 1/2 expressions gradually increased 12-20 wk after SPH model establishment. In portal vein smooth muscle cells, increasing H2S levels led to increased apoptosis, while Bcl-2 and Bcl-XL expression decreased. CONCLUSION: H2S prevents vascular restructuring caused by excessive proliferation of smooth muscle cells via apoptosis induction, which helps to maintain normal vascular structures. PMID:24574782

Global transcriptional responses of Pseudomonas syringae DC3000 to changes in iron bioavailability in vitro

Directory of Open Access Journals (Sweden)

Rutzke Michael

2008-12-01

Full Text Available Abstract Background Pseudomonas syringae pv tomato DC3000 (DC3000 is a Gram-negative model plant pathogen that is found in a wide variety of environments. To survive in these diverse conditions it must sense and respond to various environmental cues. One micronutrient required for most forms of life is iron. Bioavailable iron has been shown to be an important global regulator for many bacteria where it not only regulates a wide variety of genes involved in general cell physiology but also virulence determinants. In this study we used microarrays to study differential gene regulation in DC3000 in response to changes in levels of cell-associated iron. Results DC3000 cultures were grown under highly controlled conditions and analyzed after the addition of iron citrate or sodium citrate to the media. In the cultures supplemented with iron, we found that cell-associated iron increased rapidly while culture densities were not significantly different over 4 hours when compared to cultures with sodium citrate added. Microarray analysis of samples taken from before and after the addition of either sodium citrate or iron citrate identified 386 differentially regulated genes with high statistical confidence. Differentially regulated genes were clustered based on expression patterns observed between comparison of samples taken at different time points and with different supplements. This analysis grouped genes associated with the same regulatory motifs and/or had similar putative or known function. Conclusion This study shows iron is rapidly taken up from the medium by iron-depleted DC3000 cultures and that bioavailable iron is a global cue for the expression of iron transport, storage, and known virulence factors in DC3000. Furthermore approximately 34% of the differentially regulated genes are associated with one of four regulatory motifs for Fur, PvdS, HrpL, or RpoD.

Two-stage gene regulation of the superoxide stress response soxRS system in Escherichia coli.

Science.gov (United States)

Nunoshiba, T

1996-01-01

All organisms have adapted to environmental changes by acquiring various functions controlled by gene regulation. In bacteria, a number of specific responses have been found to confer cell survival in various nutrient-limited conditions, and under physiological stresses such as high or low temperature, extreme pH, radiation, and oxidation (for review, see Neidhardt et al., 1987). In this article, I introduce an Escherichia coli (E. coli) global response induced by superoxide stress, the soxRS regulon. The functions controlled by this system consist of a wide variety of enzymes such as manganese-containing SOD (Mn-SOD); glucose 6-phosphate dehydrogenase (G6PD), the DNA repair enzyme endonuclease IV, fumarase C, NADPH:ferredoxin oxidoreductase, and aconitase. This response is positively regulated by a two-stage control system in which SoxR iron-sulfur protein senses exposure to superoxide and nitric oxide, and then activates transcription of the soxS gene, whose product stimulates the expression of the regulon genes. Our recent finding indicates that soxS transcription is initiated in a manner dependent on the rpoS gene encoding RNA polymerase sigma factor, theta s, in response to entering the stationary phase of growth. With this information, mechanisms for prokaryotic coordinating gene expression in response to superoxide stress and in stationary phase are discussed.

Building a complete image of genome regulation in the model organism Escherichia coli.

Science.gov (United States)

Ishihama, Akira

2018-01-15

The model organism, Escherichia coli, contains a total of more than 4,500 genes, but the total number of RNA polymerase (RNAP) core enzyme or the transcriptase is only about 2,000 molecules per genome. The regulatory targets of RNAP are, however, modulated by changing its promoter selectivity through two-steps of protein-protein interplay with 7 species of the sigma factor in the first step, and then 300 species of the transcription factor (TF) in the second step. Scientists working in the field of prokaryotic transcription in Japan have made considerable contributions to the elucidation of genetic frameworks and regulatory modes of the genome transcription in E. coli K-12. This review summarizes the findings by this group, first focusing on three sigma factors, the stationary-phase sigma RpoS, the heat-shock sigma RpoH, and the flagellar-chemotaxis sigma RpoF, as examples. It also presents an overview of the current state of the systematic research being carried out to identify the regulatory functions of all TFs from a single and the same bacterium E. coli K-12, using the genomic SELEX and PS-TF screening systems. All these studies have been undertaken with the aim of understanding the genome regulation in E. coli K-12 as a whole.

What could the nematodes teach us about radiation protection? Plenty

Energy Technology Data Exchange (ETDEWEB)

Doris, I.C. [Hamilton General Hospital, Dept. of Diagnostic Imaging, Hamilton, Ontario (Canada)]. E-mail: doris@hhsc.ca

2006-02-15

Trying to make rational decisions that have far-reaching consequences for both our patients and our profession is difficult, even after we have spent so many of our formative years learning to think and act in a disciplined and logical manner, and taking into account all the available evidence. What do we do when there is no evidence or, at best, very limited evidence? This is a problem that I have had cause to consider several times and in many contexts since undertaking, a few years ago, the role of radiation protection officer (RPO) in my department. Maintaining the ALARA principle ('as low as reasonably achievable') would seem to make common sense. However, in view of the changes occurring in diagnostic imaging, I am concerned as to whether the breadth and depth of our knowledge of radiation's biological effects has kept pace with the changes in clinical practice. Can we apply this time-honoured principle in contemporary radiology? Having experienced, as an RPO, the challenge of applying sound principles of radiation protection, I would like to share some thoughts on the current role and responsibilities of RPOs and the problems they may face in the future. (author)

Diversity and functions of bacterial community in drinking water biofilms revealed by high-throughput sequencing

Science.gov (United States)

Chao, Yuanqing; Mao, Yanping; Wang, Zhiping; Zhang, Tong

2015-06-01

The development of biofilms in drinking water (DW) systems may cause various problems to water quality. To investigate the community structure of biofilms on different pipe materials and the global/specific metabolic functions of DW biofilms, PCR-based 454 pyrosequencing data for 16S rRNA genes and Illumina metagenomic data were generated and analysed. Considerable differences in bacterial diversity and taxonomic structure were identified between biofilms formed on stainless steel and biofilms formed on plastics, indicating that the metallic materials facilitate the formation of higher diversity biofilms. Moreover, variations in several dominant genera were observed during biofilm formation. Based on PCA analysis, the global functions in the DW biofilms were similar to other DW metagenomes. Beyond the global functions, the occurrences and abundances of specific protective genes involved in the glutathione metabolism, the SoxRS system, the OxyR system, RpoS regulated genes, and the production/degradation of extracellular polymeric substances were also evaluated. A near-complete and low-contamination draft genome was constructed from the metagenome of the DW biofilm, based on the coverage and tetranucleotide frequencies, and identified as a Bradyrhizobiaceae-like bacterium according to a phylogenetic analysis. Our findings provide new insight into DW biofilms, especially in terms of their metabolic functions.

DsrA regulatory RNA represses both hns and rbsD mRNAs through distinct mechanisms in Escherichia coli.

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Lalaouna, David; Morissette, Audrey; Carrier, Marie-Claude; Massé, Eric

2015-10-01

The 87 nucleotide long DsrA sRNA has been mostly studied for its translational activation of the transcriptional regulator RpoS. However, it also represses hns mRNA, which encodes H-NS, a major regulator that affects expression of nearly 5% of Escherichia coli genes. A speculative model previously suggested that DsrA would block hns mRNA translation by binding simultaneously to start and stop codon regions of hns mRNA (coaxial model). Here, we show that DsrA efficiently blocked translation of hns mRNA by base-pairing immediately downstream of the start codon. In addition, DsrA induced hns mRNA degradation by actively recruiting the RNA degradosome complex. Data presented here led to a model of DsrA action on hns mRNA, which supports a canonical mechanism of sRNA-induced mRNA degradation by binding to the translation initiation region. Furthermore, using MS2-affinity purification coupled with RNA sequencing technology (MAPS), we also demonstrated that DsrA targets rbsD mRNA, involved in ribose utilization. Surprisingly, DsrA base pairs far downstream of rbsD start codon and induces rapid degradation of the transcript. Thus, our study enables us to draw an extended DsrA targetome. © 2015 John Wiley & Sons Ltd.

Weak Organic Acids Decrease Borrelia burgdorferi Cytoplasmic pH, Eliciting an Acid Stress Response and Impacting RpoN- and RpoS-Dependent Gene Expression

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Daniel P. Dulebohn

2017-09-01

Full Text Available The spirochete Borrelia burgdorferi survives in its tick vector, Ixodes scapularis, or within various hosts. To transition between and survive in these distinct niches, B. burgdorferi changes its gene expression in response to environmental cues, both biochemical and physiological. Exposure of B. burgdorferi to weak monocarboxylic organic acids, including those detected in the blood meal of fed ticks, decreased the cytoplasmic pH of B. burgdorferi in vitro. A decrease in the cytoplasmic pH induced the expression of genes encoding enzymes that have been shown to restore pH homeostasis in other bacteria. These include putative coupled proton/cation exchangers, a putative Na+/H+ antiporter, a neutralizing buffer transporter, an amino acid deaminase and a proton exporting vacuolar-type VoV1 ATPase. Data presented in this report suggested that the acid stress response triggered the expression of RpoN- and RpoS-dependent genes including important virulence factors such as outer surface protein C (OspC, BBA66, and some BosR (Borreliaoxidative stress regulator-dependent genes. Because the expression of virulence factors, like OspC, are so tightly connected by RpoS to general cellular stress responses and cell physiology, it is difficult to separate transmission-promoting conditions in what is clearly a multifactorial and complex regulatory web.

Several Hfq-dependent alterations in physiology of Yersinia enterocolitica O:3 are mediated by derepression of the transcriptional regulator RovM.

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Leskinen, Katarzyna; Pajunen, Maria I; Varjosalo, Markku; Fernández-Carrasco, Helena; Bengoechea, José A; Skurnik, Mikael

2017-03-01

In bacteria, the RNA chaperone Hfq enables pairing of small regulatory RNAs with their target mRNAs and therefore is a key player of post-transcriptional regulation network. As a global regulator, Hfq is engaged in the adaptation to external environment, regulation of metabolism and bacterial virulence. In this study we used RNA-sequencing and quantitative proteomics (LC-MS/MS) to elucidate the role of this chaperone in the physiology and virulence of Yersinia enterocolitica serotype O:3. This global approach revealed the profound impact of Hfq on gene and protein expression. Furthermore, the role of Hfq in the cell morphology, metabolism, cell wall integrity, resistance to external stresses and pathogenicity was evaluated. Importantly, our results revealed that several alterations typical for the hfq-negative phenotype were due to derepression of the transcriptional factor RovM. The overexpression of RovM caused by the loss of Hfq chaperone resulted in extended growth defect, alterations in the lipid A structure, motility and biofilm formation defects, as well as changes in mannitol utilization. Furthermore, in Y. enterocolitica RovM only in the presence of Hfq affected the abundance of RpoS. Finally, the impact of hfq and rovM mutations on the virulence was assessed in the mouse infection model. © 2016 John Wiley & Sons Ltd.

The Presence of Behavioral Traps in U.S. Airline Accidents: A Qualitative Analysis

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Jonathan Velazquez

2018-01-01

Full Text Available Behavioral traps are accident-inducing operational pitfalls aviators may encounter as a result of poor decision making. The Federal Aviation Administration (FAA identifies the existence of twelve of these negative pilot behaviors. These are: Peer Pressure; Get-There-Itis; Loss of Situational Awareness; Descent Below the Minimum En Route Altitude (MEA; Mind Set; Duck-Under Syndrome; Getting Behind the Aircraft; Continuing Visual Flight Rules (VFR into Instrument Conditions; Scud Running; Operating Without Adequate Fuel Reserves; Flying Outside the Envelope; and Neglect of Flight Planning, Preflight Inspections, and Checklists. The purpose of this paper was to study the nature of their occurrence in the airline domain. Four Subject Matter Experts (SMEs analyzed 34 National Transportation Safety Board (NTSB accident reports. The SMEs were able to identify many pilot actions that were representative of the behavioral traps. Behavioral traps were found in all accidents with Loss of Situational Awareness and Neglect of Flight Planning, Preflight Inspections, and Checklists dominant. Various themes began to emerge, which played important roles in many accidents. These themes included Crew Resource Management (CRM issues, airline management and fatigue. The findings of this study indicated that behavioral traps were prevalent in airline accidents including habitual noncompliance by pilots. Attitude management training is recommended.

New Stereo Vision Digital Camera System for Simultaneous Measurement of Cloud Base Height and Atmospheric Visibility

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Janeiro, F. M.; Carretas, F.; Palma, N.; Ramos, P. M.; Wagner, F.

2013-12-01

Clouds play an important role in many aspects of everyday life. They affect both the local weather as well as the global climate and are an important parameter on climate change studies. Cloud parameters are also important for weather prediction models which make use of actual measurements. It is thus important to have low-cost instrumentation that can be deployed in the field to measure those parameters. This kind of instruments should also be automated and robust since they may be deployed in remote places and be subject to adverse weather conditions. Although clouds are very important in environmental systems, they are also an essential component of airplane safety when visual flight rules (VFR) are enforced, such as in most small aerodromes where it is not economically viable to install instruments for assisted flying. Under VFR there are strict limits on the height of the cloud base, cloud cover and atmospheric visibility that ensure the safety of the pilots and planes. Although there are instruments, available in the market, to measure those parameters, their relatively high cost makes them unavailable in many local aerodromes. In this work we present a new prototype which has been recently developed and deployed in a local aerodrome as proof of concept. It is composed by two digital cameras that capture photographs of the sky and allow the measurement of the cloud height from the parallax effect. The new developments consist on having a new geometry which allows the simultaneous measurement of cloud base height, wind speed at cloud base height and atmospheric visibility, which was not previously possible with only two cameras. The new orientation of the cameras comes at the cost of a more complex geometry to measure the cloud base height. The atmospheric visibility is calculated from the Lambert-Beer law after the measurement of the contrast between a set of dark objects and the background sky. The prototype includes the latest hardware developments that

The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments

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Loza-Correa, Maria; Sahr, Tobias; Rolando, Monica; Daniels, Craig; Petit, Pierre; Skarina, Tania; Valero, Laura Gomez; Dervins-Ravault, Delphine; Honoré, Nadine; Savchenko, Aleksey; Buchrieser, Carmen

2014-01-01

Summary Legionella pneumophila uses aquatic protozoa as replication niche and protection from harsh environments. Although L. pneumophila is not known to have a circadian clock, it encodes homologues of the KaiBC proteins of Cyanobacteria that regulate circadian gene expression. We show that L. pneumophila kaiB, kaiC and the downstream gene lpp1114, are transcribed as a unit under the control of the stress sigma factor RpoS. KaiC and KaiB of L. pneumophila do not interact as evidenced by yeast and bacterial two-hybrid analyses. Fusion of the C-terminal residues of cyanobacterial KaiB to Legionella KaiB restores their interaction. In contrast, KaiC of L. pneumophila conserved autophosphorylation activity, but KaiB does not trigger the dephosphorylation of KaiC like in Cyanobacteria. The crystal structure of L. pneumophila KaiB suggests that it is an oxidoreductase-like protein with a typical thioredoxin fold. Indeed, mutant analyses revealed that the kai operon-encoded proteins increase fitness of L. pneumophila in competitive environments, and confer higher resistance to oxidative and sodium stress. The phylogenetic analysis indicates that L. pneumophila KaiBC resemble Synechosystis KaiC2B2 and not circadian KaiB1C1. Thus, the L. pneumophila Kai proteins do not encode a circadian clock, but enhance stress resistance and adaption to changes in the environments. PMID:23957615

Curli Fibers Are Highly Conserved between Salmonella typhimurium and Escherichia coli with Respect to Operon Structure and Regulation

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Römling, Ute; Bian, Zhao; Hammar, Mårten; Sierralta, Walter D.; Normark, Staffan

1998-01-01

Mouse-virulent Salmonella typhimurium strains SR-11 and ATCC 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by Western blot analysis and electron microscopy. Concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye Congo red (called the rdar morphotype). Cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgBA(C) and csgDEFG, from S. typhimurium SR-11 revealed the same gene order and flanking genes as in Escherichia coli. The divergence of the curli region between S. typhimurium and E. coli at the nucleotide level is above average (22.4%). However, a high level of conservation at the protein level, which ranged from 86% amino acid homology for the fiber subunit CsgA to 99% homology for the lipoprotein CsgG, implies functional constraints on the gene products. Consequently, S. typhimurium genes on low-copy-number plasmids were able to complement respective E. coli mutants, although not always to wild-type levels. rpoS and ompR are required for transcriptional activation of (at least) the csgD promoter. The high degree of conservation at the protein level and the identical regulation patterns in E. coli and S. typhimurium suggest similar roles of curli fibers in the same ecological niche in the two species. PMID:9457880

An improved method for generating axenic entomopathogenic nematodes.

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Yadav, Shruti; Shokal, Upasana; Forst, Steven; Eleftherianos, Ioannis

2015-09-19

Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophila rpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.

Developing a training program for radiation protection officers in industrial radiography

International Nuclear Information System (INIS)

Kinda, R.

2013-04-01

Non-Destructive Testing employs a variety of techniques which are used to test objects e.g. pipes, vessels, welded joints, castings and other devices for imperfections without interfering with their physical structure. The common methods of testing include magnetic particle, ultrasound, dye penetrant and industrial radiography using gamma emitting radiation sources and electronic x-ray emitting devices. Other methods used are acoustic emission testing, acoustic resonance testing, electromagnetic testing, infrared testing and leak testing. This project work focuses on training of RPOs in the areas where radiation is used, as improper use may lead to high radiation exposure. In order to ensure adequate protection and safety of staff and the public, the Radiation Protection Officers need to be thoroughly trained. With proper training the Radiation Protection Officer will have the ability to interpret legislative instruments and understand the requirements. The RPO will also be able to develop a Radiation Protection Plan and train fellow staff on radiation safety issues. A number of companies currently specialize in Industrial Radiography and this number is growing on a yearly basis. Since the increased use of radiation sources cannot be curbed, training Radiation Protection Officers will improve the radiation safety standards within these companies and promote the safe use of the radiation sources. Therefore this project covers the fundamental elements required to train Radiation Protection Officers in Industrial Radiography. (author)

Regulatory design governing progression of population growth phases in bacteria.

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Agustino Martínez-Antonio

Full Text Available It has long been noted that batch cultures inoculated with resting bacteria exhibit a progression of growth phases traditionally labeled lag, exponential, pre-stationary and stationary. However, a detailed molecular description of the mechanisms controlling the transitions between these phases is lacking. A core circuit, formed by a subset of regulatory interactions involving five global transcription factors (FIS, HNS, IHF, RpoS and GadX, has been identified by correlating information from the well- established transcriptional regulatory network of Escherichia coli and genome-wide expression data from cultures in these different growth phases. We propose a functional role for this circuit in controlling progression through these phases. Two alternative hypotheses for controlling the transition between the growth phases are first, a continuous graded adjustment to changing environmental conditions, and second, a discontinuous hysteretic switch at critical thresholds between growth phases. We formulate a simple mathematical model of the core circuit, consisting of differential equations based on the power-law formalism, and show by mathematical and computer-assisted analysis that there are critical conditions among the parameters of the model that can lead to hysteretic switch behavior, which--if validated experimentally--would suggest that the transitions between different growth phases might be analogous to cellular differentiation. Based on these provocative results, we propose experiments to test the alternative hypotheses.

Regulatory design governing progression of population growth phases in bacteria.

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Martínez-Antonio, Agustino; Lomnitz, Jason G; Sandoval, Santiago; Aldana, Maximino; Savageau, Michael A

2012-01-01

It has long been noted that batch cultures inoculated with resting bacteria exhibit a progression of growth phases traditionally labeled lag, exponential, pre-stationary and stationary. However, a detailed molecular description of the mechanisms controlling the transitions between these phases is lacking. A core circuit, formed by a subset of regulatory interactions involving five global transcription factors (FIS, HNS, IHF, RpoS and GadX), has been identified by correlating information from the well- established transcriptional regulatory network of Escherichia coli and genome-wide expression data from cultures in these different growth phases. We propose a functional role for this circuit in controlling progression through these phases. Two alternative hypotheses for controlling the transition between the growth phases are first, a continuous graded adjustment to changing environmental conditions, and second, a discontinuous hysteretic switch at critical thresholds between growth phases. We formulate a simple mathematical model of the core circuit, consisting of differential equations based on the power-law formalism, and show by mathematical and computer-assisted analysis that there are critical conditions among the parameters of the model that can lead to hysteretic switch behavior, which--if validated experimentally--would suggest that the transitions between different growth phases might be analogous to cellular differentiation. Based on these provocative results, we propose experiments to test the alternative hypotheses.

Enhancement of the synthesis of RpoN, Cra, and H-NS by polyamines at the level of translation in Escherichia coli cultured with glucose and glutamate.

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Terui, Yusuke; Higashi, Kyohei; Taniguchi, Shiho; Shigemasa, Ai; Nishimura, Kazuhiro; Yamamoto, Kaneyoshi; Kashiwagi, Keiko; Ishihama, Akira; Igarashi, Kazuei

2007-03-01

Proteins whose synthesis is enhanced by polyamines at the level of translation were identified in a polyamine-requiring mutant cultured in the presence of 0.1% glucose and 0.02% glutamate instead of 0.4% glucose as an energy source. Under these conditions, enhancement of cell growth by polyamines was almost the same as that in the presence of 0.4% glucose. It was found that synthesis of RpoN, Cra, and H-NS was enhanced by polyamines at the level of translation at the early logarithmic phase of growth (A(540) of 0.15). The effects of polyamines on synthesis of RpoN, H-NS, and Cra were due to the existence of unusual Shine-Dalgarno sequences (RpoN and H-NS) and an inefficient GUG initiation codon (Cra) in their mRNAs. Thus, rpoN, cra, and hns genes were identified as new members of the polyamine modulon. Because most of the polyamine modulon genes thus far identified encode transcription factors (RpoS [sigma(38)], Cya, FecI [sigma(18)], Fis, RpoN [sigma(54)], Cra, and H-NS), DNA microarray analysis of mRNA expressed in cells was performed. At the early logarithmic phase of growth, a total of 97 species of mRNAs that were up-regulated by polyamines more than twofold were under the control of seven polyamine modulon genes mentioned above.

The development of renewable energy power in India: Which policies have been effective?

International Nuclear Information System (INIS)

Schmid, Gisèle

2012-01-01

The International Energy Agency has identified the development of renewable energy sources as a key element to mitigate climate change. At the same time it has projected India to be the second-largest contributor to the increase in global energy demand to 2035. India hence faces a significant challenge to ensure its energy security by diversifying its power generation mix. In the wake of the creation of a Green Climate Fund in Cancun, this paper studies empirically the effect of the introduction of the Electricity Act 2003 and the Tariff Policy 2006, as well as the implementation of feed-in tariffs and minimum quotas on clean electricity sourcing, on the development of grid-connected renewable energy power in nine Indian States over the period 2001–2009. Results suggest that the passing of the Tariff Policy 2006, state-level policies, quantity-based instruments and a greater participation of the private sector have played a key role in promoting the development of installed capacity from renewable energy power in the nine States of the sample. - Highlights: ► First empirical analysis on renewable energy power development in India. ► National and state-level regulation analysis in nine Indian States. ► Use of panel data over the period 2001–2009. ► The Tariff Policy 2006, state-level policies and RPOs have played a key role.

Importance of stress-response genes to the survival of airborne Escherichia coli under different levels of relative humidity.

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Ng, Tsz Wai; Chan, Wing Lam; Lai, Ka Man

2017-12-01

Other than the needs for infection control to investigate the survival and inactivation of airborne bacterial pathogens, there has been a growing interest in exploring bacterial communities in the air and the effect of environmental variables on them. However, the innate biological mechanism influencing the bacterial viability is still unclear. In this study, a mutant-based approach, using Escherichia coli as a model, was used to prove the concept that common stress-response genes are important for airborne survival of bacteria. Mutants with a single gene knockout that are known to respond to general stress (rpoS) and oxidative stress (oxyR, soxR) were selected in the study. Low relative humidity (RH), 30-40% was more detrimental to the bacteria than high RH, >90%. The log reduction of ∆rpoS was always higher than that of the parental strain at all RH levels but the ∆oxyR had a higher log reduction than the parental strain at intermediate RH only. ∆soxR had the same viability compared to the parental strain at all RH levels. The results hint that although different types and levels of stress are produced under different RH conditions, stress-response genes always play a role in the bacterial viability. This study is the first reporting the association between stress-response genes and viability of airborne bacteria.

Genetic basis of growth adaptation of Escherichia coli after deletion of pgi, a major metabolic gene.

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Pep Charusanti

2010-11-01

Full Text Available Bacterial survival requires adaptation to different environmental perturbations such as exposure to antibiotics, changes in temperature or oxygen levels, DNA damage, and alternative nutrient sources. During adaptation, bacteria often develop beneficial mutations that confer increased fitness in the new environment. Adaptation to the loss of a major non-essential gene product that cripples growth, however, has not been studied at the whole-genome level. We investigated the ability of Escherichia coli K-12 MG1655 to overcome the loss of phosphoglucose isomerase (pgi by adaptively evolving ten replicates of E. coli lacking pgi for 50 days in glucose M9 minimal medium and by characterizing endpoint clones through whole-genome re-sequencing and phenotype profiling. We found that 1 the growth rates for all ten endpoint clones increased approximately 3-fold over the 50-day period; 2 two to five mutations arose during adaptation, most frequently in the NADH/NADPH transhydrogenases udhA and pntAB and in the stress-associated sigma factor rpoS; and 3 despite similar growth rates, at least three distinct endpoint phenotypes developed as defined by different rates of acetate and formate secretion. These results demonstrate that E. coli can adapt to the loss of a major metabolic gene product with only a handful of mutations and that adaptation can result in multiple, alternative phenotypes.

Physiological adaptation of Escherichia coli after transfer onto refrigerated ground meat and other solid matrices: a molecular approach.

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Guernec, Anthony; Robichaud-Rincon, Philippe; Saucier, Linda

2012-10-01

Bacteria on meat are subjected to specific living conditions that differ drastically from typical laboratory procedures in synthetic media. This study was undertaken to determine the behavior of bacteria when transferred from a rich-liquid medium to solid matrices, as is the case during microbial process validation. Escherichia coli cultured in Brain-Heart Infusion (BHI) broth to different growth phases were inoculated in ground beef (GB) and stored at 5°C for 12 days or spread onto BHI agar and cooked meat medium (CMM), and incubated at 37°C for several hours. We monitored cell densities and the expression of σ factors and genes under their control over time. The initial growth phase of the inoculum influenced growth resumption after transfer onto BHI agar and CMM. Whatever the solid matrix, bacteria adapted to their new environment and did not perceive stress immediately after inoculation. During this period, the σ(E) and σ(H) regulons were not activated and rpoD mRNA levels adjusted quickly. The rpoS and gadA mRNA levels did not increase after inoculation on solid surfaces and displayed normal growth-dependent modifications. After transfer onto GB, dnaK and groEL gene expression was affected more by the low temperature than by the composition of a meat environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Regulation of the csgD promoter by global regulators HN-S, IHF, and RpoS in E. coli O157:H7 isolates

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Introduction: Curli production is essential for the biofilm formation in E. coli and Salmonella. The control of expression of CsgD, the key regulator of the curli operon, is very complex, and has been shown to be regulated by several global regulators and is influenced by various growth and stress...

Clinical research on the development of posterior vitreous detachments after coaxial microincision phacoemulsification

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Rong Xu

2013-09-01

Full Text Available AIM: To explore the development process of when posterior vitreous detachments(PVDsafter coaxial micro-incision phacoemulsification and aspiration combined with foldable intraocular lens implantation.METHODS: Clinical data of 917 patients with cataract were collected after coaxial microincision phacoemulsification and aspiration combined with foldable intraocular lens implantation. The 917 operating eyes forms observation group and the 917 corresponding normal eyes serve as control group. All patients underwent a comprehensive ocular examination before surgery. The vitreous and retinal condition was tested by B-scan ultrasonography and biomicroscope with a 90-diopter(Dpreset lens after 1 week and 1, 3, 6, and 12 months postoperatively. RESULTS: The incident rate of eyes in the observation group that developed PVD after operation were 8(0.9%, 31(3.4%, 53(5.8%, 78(8.5%, 129(14.1%within 1 week and 1, 3, 6, 12 months, respectively. Ten(7.8%of the 129 eyes in which PVD developed during the one year follow-up period had new retinal breaks with or without a retinal detachment; One(0.1%of the 788 eyes in which a PVD did not developed during the follow-up period had new retinal tear with or without a retinal detachment; these percentages were statistically significant(P=0.009. Eight(14.8%of 54 eyes with lattice degeneration and 2(2.7%of 75 eyes without lattice degeneration had retinal tears associated with a PVD; the difference was statistically significant(P=0.004.CONCLUSION: Development of PVDs seems to accelerate after coaxial microincision phacoemulsification and linearly accumulated for 1 year postoperatively. Approximately 7.8% of eyes with a PVD had retinal tears. Compared with patients having no lattice degeneration, Patients' eyes with lattice degeneration had a 5.5-fold higher risk of developing retinal breaks associated with a PVD. This indicates long-term follow-up is necessary after phacoemulsification is performed.

The Pseudomonas aeruginosa Chp Chemosensory System Regulates Intracellular cAMP Levels by Modulating Adenylate Cyclase Activity

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Fulcher, Nanette B.; Holliday, Phillip M.; Klem, Erich; Cann, Martin J.; Wolfgang, Matthew C.

2010-01-01

Summary Multiple virulence systems in the opportunistic pathogen Pseudomonas aeruginosa are regulated by the second messenger signaling molecule adenosine 3’, 5’-cyclic monophosphate (cAMP). Production of cAMP by the putative adenylate cyclase enzyme CyaB represents a critical control point for virulence gene regulation. To identify regulators of CyaB, we screened a transposon insertion library for mutants with reduced intracellular cAMP. The majority of insertions resulting in reduced cAMP mapped to the Chp gene cluster encoding a putative chemotaxis-like chemosensory system. Further genetic analysis of the Chp system revealed that it has both positive and negative effects on intracellular cAMP and that it regulates cAMP levels by modulating CyaB activity. The Chp system was previously implicated in the production and function of type IV pili (TFP). Given that cAMP and the cAMP-dependent transcriptional regulator Vfr control TFP biogenesis gene expression, we explored the relationship between cAMP, the Chp system and TFP regulation. We discovered that the Chp system controls TFP production through modulation of cAMP while control of TFP-dependent twitching motility is cAMP-independent. Overall, our data define a novel function for a chemotaxis-like system in controlling cAMP production and establish a regulatory link between the Chp system, TFP and other cAMP-dependent virulence systems. PMID:20345659

[New possibilities in emergency medical transportation and emergency services of Polish Medical Air Rescue].

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Gałazkowski, Robert

2010-01-01

In Poland, two types of medical services are accomplished by the Medical Air Rescue (MAR) operating all over the country: emergency transport from the incident scene to hospital and inter-hospital transport. Helicopters or planes are used for this purpose. In 2009, helicopters performed 4359 flights to incidents and 1537 inter-hospital transports whereas planes performed 589 inter-hospital ambulance and 196 rescue flights. MAR operates from 17 bases of the Helicopter Emergency Medical Service (HEMS) and one airbase. Helicopters are mainly used when medical transport is emergent, within the operational region of a given base whereas planes when the distance between the present and target airports exceeds 250 km. In 2008, new modern aircraft were introduced to HEMS-helicopters EC 135. They fulfil all requirements of air transport regulations and are adjusted to visual (VFR) and instrumental (IFR) flights rules, at day and night. The medical cabin of EC 135 is ergonomic and functional considering the majority of rescue activities under life-saving circumstances. It is equipped with ventilator, defibrillator, infusion pumps etc. Defibrillators have 12-lead ECG, E(T)CO2, SpO2, NIBP, and IBP modules. Transport ventilators can work in a variety of ventilation modes including CMV, SIMV, SVV, BILEVEL, PCV, ASB, PPV and CPAP. The purchase of helicopters with modern avionic and medical configuration ensures high quality services of MAR for many years to come.

Intraoperative efficiency of fluorescence imaging by Visually Enhanced Lesion Scope (VELscope) in patients with bisphosphonate related osteonecrosis of the jaw (BRONJ).

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Assaf, Alexandre T; Zrnc, Tomislav A; Riecke, Björn; Wikner, Johannes; Zustin, Jozef; Friedrich, Reinhard E; Heiland, Max; Smeets, Ralf; Gröbe, Alexander

2014-07-01

The purpose of this study was to determine the potential of tissue fluorescence imaging by using Visually Enhanced Lesion Scope (VELscope) for the detection of osteonecrosis of the jaw induced by bisphosphonates (BRONJ). We investigated 20 patients (11 females and 9 males; mean age 74 years, standard deviation ± 6.4 years), over a period of 18 month with the diagnosis of BRONJ in this prospective cohort study. All patients received doxycycline as a fluorescending marker for osseous structures. VELscope has been used intraoperatively using the loss of fluorescence to detect presence of osteonecrosis. Osseous biopsies were taken to confirm definite histopathological diagnosis of BRONJ in each case. Diagnosis of BRONJ was confirmed for every patient. In all patients except one, VELscope was sufficient to differentiate between healthy and necrotic bone by visual fluorescence retention (VFR) and visual fluorescence loss (VFL). 19 cases out of a total of 20 showed no signs of recurrence of BRONJ during follow-up (mean 12 months, range 4-18 months). VELscope examination is a suitable tool to visualize necrotic areas of the bone in patients with bisphosphonate related osteonecrosis of the jaw. Loss of fluorescence in necrotic bone areas is useful intraoperatively as a tool for fluorescence-guided bone resection with relevant clinical interpretation. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Demographics, health and travel characteristics of international travellers at a pre-travel clinic in Marseille, France.

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Aubry, Camille; Gaudart, Jean; Gaillard, Catherine; Delmont, Jean; Parola, Philippe; Brouqui, Philippe; Gautret, Philippe

2012-09-01

With the aim to identify at-risk individuals among a cohort of international travellers, 3442 individuals who sought advice at Marseille travel health centre in 2009 were prospectively included. Demographics, travel characteristics, chronic medical conditions, vaccinations and antimalarial chemoprophylaxis were documented. Chronic medical conditions were reported by 11% of individuals, including hypertension (39%), asthma (20%), thyroid disease (15%) and depression (13%). 4% reported taking a daily medication, and psychotropic and cardiovascular medications were the most commonly used. Older travellers (≥60 years) accounted for 10% of the travellers and the prevalence of chronic medical conditions was 27% in this group. Individuals aged 15 years or less accounted for 13% of the travellers. Age, last minute travel (17%) and neurological and psychiatric diseases were the most frequent factors that influenced Yellow fever vaccination and malaria chemoprophylaxis, with more than one tenth of the travellers reporting at least one risk factor for which adjusted advice may be necessary. Migrants visiting their relatives in their origin country accounted for 14% of travellers and 73% of this group travelled with their family including young children. We demonstrate that a significant proportion of travellers are at-risk (43%) because of their travel conditions (VFR), their age, or their health status, and should be targeted for risk reduction strategies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biochemical Mechanisms and Energy Strategies of Geobacter sulfurreducens for Long- Term Survival

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Helmus, R. A.; Liermann, L. J.; Brantley, S. L.; Tien, M.

2008-12-01

Numerous species of bacteria have been observed to exhibit a growth advantage in stationary phase (GASP) phenotype, indicating that microorganisms starved of an energy source may adapt to allow for long-term survival. Understanding how Geobacter sulfurreducens persists using various metal forms as energy sources and whether a GASP phenotype develops during long-term growth are important for efficient application of this bacterium to sites requiring engineered bioremediation of soluble metals. Thus, we investigated the growth kinetics and survival of G. sulfurreducens. The growth rate of G. sulfurreducens was highest when cultured with soluble iron and generally higher on iron oxide than manganese oxide, suggesting that soluble metal forms are more readily utilized as energy sources by G. sulfurreducens. By monitoring the abundance of G. sulfurreducens in batch cultures for >6 months, distinct growth, stationary, and prolonged starvation phases were observed and a cell density of 105- 106 cells/mL persisted under long-term starvation conditions. The outgrowth of an aged G. sulfurreducens strain co-cultured with a young strain was monitored as a measure of the existence of the GASP phenotype. As the strains aged, the rpoS gene was cloned and sequenced at different stages of growth to identify mutations corresponding to a growth advantage. The results of these studies provide insight into the use of various metal forms for growth by G. sulfurreducens and its ability to persist when starved of energy sources.

The Legionella pneumophila GIG operon responds to gold and copper in planktonic and biofilm cultures.

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Jwanoswki, Kathleen; Wells, Christina; Bruce, Terri; Rutt, Jennifer; Banks, Tabitha; McNealy, Tamara L

2017-01-01

Legionella pneumophila contaminates man-made water systems and creates numerous exposure risks for Legionnaires' Disease. Because copper/silver ionization is commonly used to control L. pneumophila, its mechanisms of metal response and detoxification are of significant interest. Here we describe an L. pneumophila operon with significant similarity to the GIG operon of Cupriavidus metallidurans. The Legionella GIG operon is present in a subset of strains and has been acquired as part of the ICE-βox 65-kB integrative conjugative element. We assessed GIG promoter activity following exposure of L. pneumophila to multiple concentrations of HAuCl4, CuSO4 and AgNO3. At 37°C, control stationary phase cultures exhibited GIG promoter activity. This activity increased significantly in response to 20 and 50uM HAuCl4 and CuSO4 but not in response to AgNO3. Conversely, at 26°C, cultures exhibited decreased promoter response to copper. GIG promoter activity was also induced by HAuCl4 or CuSO4 during early biofilm establishment at both temperatures. When an L. pneumophila GIG promoter construct was transformed into E. coli DH5α, cultures showed baseline expression levels that did not increase following metal addition. Analysis of L. pneumophila transcriptional regulatory mutants suggested that GIG up-regulation in the presence of metal ions may be influenced by the stationary phase sigma factor, RpoS.

Comparative analysis of the survival and gene expression of pathogenic strains Vibrio harveyi after starvation.

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Sun, Jingjing; Gao, Xiaojian; Qun, Jiang; Du, Xuedi; Bi, Keran; Zhang, Xiaojun; Lin, Li

2016-11-01

This study aimed to evaluate the survival and gene expression of Vibrio harveyi under starvation conditions. The microcosms V. harveyi were incubated in sterilized seawater for 4 weeks at room temperature. Overall, the cell numeration declined rapidly about 10 3 CFU/ml during starvation, with a tiny rebound at day 21. Scanning electron microscopy revealed that rod-shaped cells became sphere with a rippled cell surface. By polymerase chain reaction (PCR) assay, nine genes, named luxR, toxR, vhhB, flaA, topA, fur, rpoS, mreB and ftsZ, were detected in the non-starved cells. In the starved cells, the expression levels of the detected genes declined substantially ranging from 0.005-fold to 0.028-fold compared to the non-starved cells performed by reverse transcription quantitative real-time PCR with 16S rRNA as the internal control. In the recovering cells, the expression levels of the detected genes, except luxR and mreB, were upregulated dramatically compared to the wild, especially topA (23.720-fold), fur (39.400-fold) and toxR (9.837-fold), validating that the expressions of both the metabolism and virulence genes were important for growth and survival of V. harveyi. The results may shed a new light on understanding of stress adaptation in bacteria. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Legionella pneumophila GIG operon responds to gold and copper in planktonic and biofilm cultures.

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Kathleen Jwanoswki

Full Text Available Legionella pneumophila contaminates man-made water systems and creates numerous exposure risks for Legionnaires' Disease. Because copper/silver ionization is commonly used to control L. pneumophila, its mechanisms of metal response and detoxification are of significant interest. Here we describe an L. pneumophila operon with significant similarity to the GIG operon of Cupriavidus metallidurans. The Legionella GIG operon is present in a subset of strains and has been acquired as part of the ICE-βox 65-kB integrative conjugative element. We assessed GIG promoter activity following exposure of L. pneumophila to multiple concentrations of HAuCl4, CuSO4 and AgNO3. At 37°C, control stationary phase cultures exhibited GIG promoter activity. This activity increased significantly in response to 20 and 50uM HAuCl4 and CuSO4 but not in response to AgNO3. Conversely, at 26°C, cultures exhibited decreased promoter response to copper. GIG promoter activity was also induced by HAuCl4 or CuSO4 during early biofilm establishment at both temperatures. When an L. pneumophila GIG promoter construct was transformed into E. coli DH5α, cultures showed baseline expression levels that did not increase following metal addition. Analysis of L. pneumophila transcriptional regulatory mutants suggested that GIG up-regulation in the presence of metal ions may be influenced by the stationary phase sigma factor, RpoS.

OxyR-activated expression of Dps is important for Vibrio cholerae oxidative stress resistance and pathogenesis.

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Xiaoyun Xia

Full Text Available Vibrio cholerae is the causative agent of cholera, a dehydrating diarrheal disease. This Gram-negative pathogen is able to modulate its gene expression in order to combat stresses encountered in both aquatic and host environments, including stress posed by reactive oxygen species (ROS. In order to further the understanding of V. cholerae's transcriptional response to ROS, we performed an RNA sequencing analysis to determine the transcriptional profile of V. cholerae when exposed to hydrogen hydroperoxide. Of 135 differentially expressed genes, VC0139 was amongst the genes with the largest induction. VC0139 encodes a protein homologous to the DPS (DNA-binding protein from starved cells protein family, which are widely conserved and are implicated in ROS resistance in other bacteria. Using a promoter reporter assay, we show that during exponential growth, dps is induced by H2O2 in a manner dependent on the ROS-sensing transcriptional regulator, OxyR. Upon entry into stationary phase, the major stationary phase regulator RpoS is required to transcribe dps. Deletion of dps impaired V. cholerae resistance to both inorganic and organic hydroperoxides. Furthermore, we show that Dps is involved in resistance to multiple environmental stresses. Finally, we found that Dps is important for V. cholerae adult mouse colonization, but becomes dispensable in the presence of antioxidants. Taken together, our results suggest that Dps plays vital roles in both V. cholerae stress resistance and pathogenesis.

Cloning and over expression of non-coding RNA rprA in E.coli and its resistance to Kanamycin without osmotic shock.

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Sahni, Azita; Hajjari, Mohammadreza; Raheb, Jamshid; Foroughmand, Ali Mohammad; Asgari, Morteza

2017-01-01

Recent reports have indicated that small RNAs have key roles in the response of the E.coli to stress and also in the regulating of virulence factors. It seems that some small non-coding RNAs are involved in multidrug resistance. Previous studies have indicated that rprA can increase the tolerance to Kanamycin in RcsB-deficient Escherichia coli K-12 following osmotic shock. The current study aims to clone and over-express the non-coding RNA rprA in E.coli and investigate its effect on the bacterial resistance to Kanamycin without any osmotic shock. For this purpose, rprA gene was amplified by the PCR and then cloned into the PET-28a (+) vector. The recombinant plasmid was transformed into wild type E.coli BL21 (DE3). The over expression was induced by IPTG and confirmed by qRT-PCR. The resistance to the kanamycin was then measured in different times by spectrophotometry. The statistical analysis showed that the rprA can increase the resistance to Kanamycin in Ecoli K12. The interaction between rprA and rpoS was reviewed and analyzed by in silico methods. The results showed that the bacteria with over-expressed rprA were more resistant to Kanamycin. The present study is an important step to prove the role of non-coding RNA rprA in bacterial resistance. The data can be the basis for future works and can also help to develop and deliver next-generation antibiotics.

Imported malaria in children in Madrid, Spain, 2007-2013.

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Sánchez, Beatriz Soto; Tato, L M Prieto; Martín, S Guillén; Pérez, E; Grasa, C; Valderrama, S; Augusto, I de; Sierra, M; Ros, M García; Aguado, I; Hortelano, M García López

The majority of malaria cases diagnosed in Europe in the last few years have occurred in people living in non-endemic areas travelling back to their home country to visit friends and relatives (VFRs). Children account for 15-20% of imported malaria, with known higher risk of severe disease. A retrospective multicentre study was conducted in 24 hospitals in Madrid (Spain) including patients under 16 years diagnosed with malaria (2007-2013). A total of 149 episodes in 147 children were reported. Plasmodium falciparum was the species most commonly isolated. Twenty-five patients developed severe malaria and there was one death related to malaria. VFR accounted for 45.8% of our children. Only 17 VFRs had received prophylaxis, and 4 of them taken appropriately. They presented more frequently with fever (98% vs. 69%), a longer time with fever (55 vs. 26%), delay in diagnosis of more than three days (62 vs. 37%), and more thrombocytopenia (65 vs. 33%) than non-VFRs, and with significant differences (pmalaria cases in our study. They seldom took adequate prophylaxis, and delayed the visit to the physician, increasing the length of fever and subsequent delaying in diagnosis. Appropriate preventive measures, such as education and pre-travel advices should be taken in this population. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Performance analysis of a combined organic Rankine cycle and vapor compression cycle for power and refrigeration cogeneration

International Nuclear Information System (INIS)

Kim, Kyoung Hoon; Perez-Blanco, Horacio

2015-01-01

A thermodynamic analysis of cogeneration of power and refrigeration activated by low-grade sensible energy is presented in this work. An organic Rankine cycle (ORC) for power production and a vapor compression cycle (VCC) for refrigeration using the same working fluid are linked in the analysis, including the limiting case of cold production without net electricity production. We investigate the effects of key parameters on system performance such as net power production, refrigeration, and thermal and exergy efficiencies. Characteristic indexes proportional to the cost of heat exchangers or of turbines, such as total number of transfer units (NTU tot ), size parameter (SP) and isentropic volumetric flow ratio (VFR) are also examined. Three important system parameters are selected, namely turbine inlet temperature, turbine inlet pressure, and the flow division ratio. The analysis is conducted for several different working fluids. For a few special cases, isobutane is used for a sensitivity analysis due to its relatively high efficiencies. Our results show that the system has the potential to effectively use low grade thermal sources. System performance depends both on the adopted parameters and working fluid. - Highlights: • Waste heat utilization can reduce emissions of carbon dioxide. • The ORC/VCC cycle can deliver power and/or refrigeration using waste heat. • Efficiencies and size parameters are used for cycle evaluation. • The cycle performance is studied for eight suitable refrigerants. Isobutane is used for a sensitivity analysis. • The work shows that the isobutene cycle is quite promising.

Activation of the Glutamic Acid-Dependent Acid Resistance System in Escherichia coli BL21(DE3) Leads to Increase of the Fatty Acid Biotransformation Activity.

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Woo, Ji-Min; Kim, Ji-Won; Song, Ji-Won; Blank, Lars M; Park, Jin-Byung

The biosynthesis of carboxylic acids including fatty acids from biomass is central in envisaged biorefinery concepts. The productivities are often, however, low due to product toxicity that hamper whole-cell biocatalyst performance. Here, we have investigated factors that influence the tolerance of Escherichia coli to medium chain carboxylic acid (i.e., n-heptanoic acid)-induced stress. The metabolic and genomic responses of E. coli BL21(DE3) and MG1655 grown in the presence of n-heptanoic acid indicated that the GadA/B-based glutamic acid-dependent acid resistance (GDAR) system might be critical for cellular tolerance. The GDAR system, which is responsible for scavenging intracellular protons by catalyzing decarboxylation of glutamic acid, was inactive in E. coli BL21(DE3). Activation of the GDAR system in this strain by overexpressing the rcsB and dsrA genes, of which the gene products are involved in the activation of GadE and RpoS, respectively, resulted in acid tolerance not only to HCl but also to n-heptanoic acid. Furthermore, activation of the GDAR system allowed the recombinant E. coli BL21(DE3) expressing the alcohol dehydrogenase of Micrococcus luteus and the Baeyer-Villiger monooxygenase of Pseudomonas putida to reach 60% greater product concentration in the biotransformation of ricinoleic acid (i.e., 12-hydroxyoctadec-9-enoic acid (1)) into n-heptanoic acid (5) and 11-hydroxyundec-9-enoic acid (4). This study may contribute to engineering E. coli-based biocatalysts for the production of carboxylic acids from renewable biomass.

Activation of the Glutamic Acid-Dependent Acid Resistance System in Escherichia coli BL21(DE3 Leads to Increase of the Fatty Acid Biotransformation Activity.

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Ji-Min Woo

Full Text Available The biosynthesis of carboxylic acids including fatty acids from biomass is central in envisaged biorefinery concepts. The productivities are often, however, low due to product toxicity that hamper whole-cell biocatalyst performance. Here, we have investigated factors that influence the tolerance of Escherichia coli to medium chain carboxylic acid (i.e., n-heptanoic acid-induced stress. The metabolic and genomic responses of E. coli BL21(DE3 and MG1655 grown in the presence of n-heptanoic acid indicated that the GadA/B-based glutamic acid-dependent acid resistance (GDAR system might be critical for cellular tolerance. The GDAR system, which is responsible for scavenging intracellular protons by catalyzing decarboxylation of glutamic acid, was inactive in E. coli BL21(DE3. Activation of the GDAR system in this strain by overexpressing the rcsB and dsrA genes, of which the gene products are involved in the activation of GadE and RpoS, respectively, resulted in acid tolerance not only to HCl but also to n-heptanoic acid. Furthermore, activation of the GDAR system allowed the recombinant E. coli BL21(DE3 expressing the alcohol dehydrogenase of Micrococcus luteus and the Baeyer-Villiger monooxygenase of Pseudomonas putida to reach 60% greater product concentration in the biotransformation of ricinoleic acid (i.e., 12-hydroxyoctadec-9-enoic acid (1 into n-heptanoic acid (5 and 11-hydroxyundec-9-enoic acid (4. This study may contribute to engineering E. coli-based biocatalysts for the production of carboxylic acids from renewable biomass.

Death and cannibalism in a seasonal environment facilitate bacterial coexistence.

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Rozen, Daniel E; Philippe, Nadège; Arjan de Visser, J; Lenski, Richard E; Schneider, Dominique

2009-01-01

Bacterial populations can evolve and adapt to become diverse niche specialists, even in seemingly homogeneous environments. One source of this diversity arises from newly 'constructed' niches that result from the activities of the bacteria themselves. Ecotypes specialized to exploit these distinct niches can subsequently coexist via frequency-dependent interactions. Here, we describe a novel form of niche construction that is based upon differential death and cannibalism, and which evolved during 20 000 generations of experimental evolution in Escherichia coli in a seasonal environment with alternating growth and starvation. In one of 12 populations, two monophyletic ecotypes, S and L, evolved that stably coexist with one another. When grown and then starved in monoculture, the death rate of S exceeds that of L, whereas the reverse is observed in mixed cultures. As shown by experiments and numerical simulations, the competitive advantage of S cells is increased by extending the period of starvation, and this advantage results from their cannibalization of the debris of lysed L cells, which allows the S cells to increase both their growth rate and total cell density. At the molecular level, the polymorphism is associated with divergence in the activity of the alternative sigma factor RpoS, with S cells displaying no detectable activity, while L cells show increased activity relative to the ancestral genotype. Our results extend the repertoire of known cross-feeding mechanisms in microbes to include cannibalism during starvation, and confirm the central roles for niche construction and seasonality in the maintenance of microbial polymorphisms.

Complete genome sequence of the fire blight pathogen Erwinia pyrifoliae DSM 12163T and comparative genomic insights into plant pathogenicity

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Frey Jürg E

2010-01-01

Full Text Available Abstract Background Erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on Asian (Nashi pear and is geographically restricted to Eastern Asia. Relatively little is known about its genetics compared to the closely related main fire blight pathogen E. amylovora. Results The genome of the type strain of E. pyrifoliae strain DSM 12163T, was sequenced using both 454 and Solexa pyrosequencing and annotated. The genome contains a circular chromosome of 4.026 Mb and four small plasmids. Based on their respective role in virulence in E. amylovora or related organisms, we identified several putative virulence factors, including type III and type VI secretion systems and their effectors, flagellar genes, sorbitol metabolism, iron uptake determinants, and quorum-sensing components. A deletion in the rpoS gene covering the most conserved region of the protein was identified which may contribute to the difference in virulence/host-range compared to E. amylovora. Comparative genomics with the pome fruit epiphyte Erwinia tasmaniensis Et1/99 showed that both species are overall highly similar, although specific differences were identified, for example the presence of some phage gene-containing regions and a high number of putative genomic islands containing transposases in the E. pyrifoliae DSM 12163T genome. Conclusions The E. pyrifoliae genome is an important addition to the published genome of E. tasmaniensis and the unfinished genome of E. amylovora providing a foundation for re-sequencing additional strains that may shed light on the evolution of the host-range and virulence/pathogenicity of this important group of plant-associated bacteria.

The membrane protein LasM Promotes the Culturability of Legionella pneumophila in Water

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Laam Li

2016-09-01

Full Text Available The water-borne pathogen Legionella pneumophila (Lp strongly expresses the lpg1659 gene in water. This gene encodes a hypothetical protein predicted to be a membrane protein using in silico analysis. While no conserved domains were identified in Lpg1659, similar proteins are found in many Legionella species and other aquatic bacteria. RT-qPCR showed that lpg1659 is positively regulated by the alternative sigma factor RpoS, which is essential for Lp to survive in water. These observations suggest an important role of this novel protein in the survival of Lp in water. Deletion of lpg1659 did not affect cell morphology, membrane integrity or tolerance to high temperature. Moreover, lpg1659 was dispensable for growth of Lp in rich medium, and during infection of the amoeba Acanthamoeba castellanii and of THP-1 human macrophages. However, deletion of lpg1659 resulted in an early loss of culturability in water, while over-expression of this gene promoted the culturability of Lp. Therefore, these results suggest that lpg1659 is required for Lp to maintain culturability, and possibly long-term survival, in water. Since the loss of culturability observed in the absence of Lpg1659 was complemented by the addition of trace metals into water, this membrane protein is likely a transporter for acquiring essential trace metal for maintaining culturability in water and potentially in other metal-deprived conditions. Given its role in the survival of Lp in water, Lpg1659 was named LasM for Legionella aquatic survival membrane protein.

Habituation of Salmonella spp. at Reduced Water Activity and Its Effect on Heat Tolerance

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Mattick, K. L.; Jørgensen, F.; Legan, J. D.; Lappin-Scott, H. M.; Humphrey, T. J.

2000-01-01

The effect of habituation at reduced water activity (aw) on heat tolerance of Salmonella spp. was investigated. Stationary-phase cells were exposed to aw 0.95 in broths containing glucose-fructose, sodium chloride, or glycerol at 21°C for up to a week prior to heat challenge at 54°C. In addition, the effects of different aws and heat challenge temperatures were investigated. Habituation at aw 0.95 resulted in increased heat tolerance at 54°C with all solutes tested. The extent of the increase and the optimal habituation time depended on the solute used. Exposure to broths containing glucose-fructose (aw 0.95) for 12 h resulted in maximal heat tolerance, with more than a fourfold increase in D54 values. Cells held for more than 72 h in these conditions, however, became as heat sensitive as nonhabituated populations. Habituation in the presence of sodium chloride or glycerol gave rise to less pronounced but still significant increases in heat tolerance at 54°C, and a shorter incubation time was required to maximize tolerance. The increase in heat tolerance following habituation in broths containing glucose-fructose (aw 0.95) was RpoS independent. The presence of chloramphenicol or rifampin during habituation and inactivation did not affect the extent of heat tolerance achieved, suggesting that de novo protein synthesis was probably not necessary. These data highlight the importance of cell prehistory prior to heat inactivation and may have implications for food manufacturers using low-aw ingredients. PMID:11055944

rpoS-Regulated core genes involved in the competitive fitness of Salmonella enterica Serovar Kentucky in the intestines of chickens.

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Cheng, Ying; Pedroso, Adriana Ayres; Porwollik, Steffen; McClelland, Michael; Lee, Margie D; Kwan, Tiffany; Zamperini, Katherine; Soni, Vivek; Sellers, Holly S; Russell, Scott M; Maurer, John J

2015-01-01

Salmonella enterica serovar Kentucky has become the most frequently isolated serovar from poultry in the United States over the past decade. Despite its prevalence in poultry, it causes few human illnesses in the United States. The dominance of S. Kentucky in poultry does not appear to be due to single introduction of a clonal strain, and its reduced virulence appears to correlate with the absence of virulence genes grvA, sseI, sopE, and sodC1. S. Kentucky's prevalence in poultry is possibly attributable to its metabolic adaptation to the chicken cecum. While there were no difference in the growth rate of S. Kentucky and S. Typhimurium grown microaerophilically in cecal contents, S. Kentucky persisted longer when chickens were coinfected with S. Typhimurium. The in vivo advantage that S. Kentucky has over S. Typhimurium appears to be due to differential regulation of core Salmonella genes via the stationary-phase sigma factor rpoS. Microarray analysis of Salmonella grown in cecal contents in vitro identified several metabolic genes and motility and adherence genes that are differentially activated in S. Kentucky. The contributions of four of these operons (mgl, prp, nar, and csg) to Salmonella colonization in chickens were assessed. Deletion of mgl and csg reduced S. Kentucky persistence in competition studies in chickens infected with wild-type or mutant strains. Subtle mutations affecting differential regulation of core Salmonella genes appear to be important in Salmonella's adaptation to its animal host and especially for S. Kentucky's emergence as the dominant serovar in poultry. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

A role for the RNA chaperone Hfq in controlling adherent-invasive Escherichia coli colonization and virulence.

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Karina T Simonsen

Full Text Available Adherent-invasive Escherichia coli (AIEC has been linked with the onset and perpetuation of inflammatory bowel diseases. The AIEC strain LF82 was originally isolated from an ileal biopsy from a patient with Crohn's disease. The pathogenesis of LF82 results from its abnormal adherence to and subsequent invasion of the intestinal epithelium coupled with its ability to survive phagocytosis by macrophages once it has crossed the intestinal barrier. To gain further insight into AIEC pathogenesis we employed the nematode Caenorhabditis elegans as an in vivo infection model. We demonstrate that AIEC strain LF82 forms a persistent infection in C. elegans, thereby reducing the host lifespan significantly. This host killing phenotype was associated with massive bacterial colonization of the nematode intestine and damage to the intestinal epithelial surface. C. elegans killing was independent of known LF82 virulence determinants but was abolished by deletion of the LF82 hfq gene, which encodes an RNA chaperone involved in mediating posttranscriptional gene regulation by small non-coding RNAs. This finding reveals that important aspects of LF82 pathogenesis are controlled at the posttranscriptional level by riboregulation. The role of Hfq in LF82 virulence was independent of its function in regulating RpoS and RpoE activity. Further, LF82Δhfq mutants were non-motile, impaired in cell invasion and highly sensitive to various chemical stress conditions, reinforcing the multifaceted function of Hfq in mediating bacterial adaptation. This study highlights the usefulness of simple non-mammalian infection systems for the identification and analysis of bacterial virulence factors.

Prefabricated Vertical Drain (PVD) and Deep Cement Mixing (DCM)/Stiffened DCM (SDCM) techniques for soft ground improvement

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Bergado, D. T.; Long, P. V.; Chaiyaput, S.; Balasubramaniam, A. S.

2018-04-01

Soft ground improvement techniques have become most practical and popular methods to increase soil strength, soil stiffness and reduce soil compressibility including the soft Bangkok clay. This paper focuses on comparative performances of prefabricated vertical drain (PVD) using surcharge, vacuum and heat preloading as well as the cement-admixed clay of Deep Cement Mixing (DCM) and Stiffened DCM (SDCM) methods. The Vacuum-PVD can increase the horizontal coefficient of consolidation, Ch, resulting in faster rate of settlement at the same magnitudes of settlement compared to Conventional PVD. Several field methods of applying vacuum preloading are also compared. Moreover, the Thermal PVD and Thermal Vacuum PVD can increase further the coefficient of horizontal consolidation, Ch, with the associated reduction of kh/ks values by reducing the drainage retardation effects in the smear zone around the PVD which resulted in faster rates of consolidation and higher magnitudes of settlements. Furthermore, the equivalent smear effect due to non-uniform consolidation is also discussed in addition to the smear due to the mechanical installation of PVDs. In addition, a new kind of reinforced deep mixing method, namely Stiffened Deep Cement Mixing (SDCM) pile is introduced to improve the flexural resistance, improve the field quality control, and prevent unexpected failures of the Deep Cement Mixing (DCM) pile. The SDCM pile consists of DCM pile reinforced with the insertion of precast reinforced concrete (RC) core. The full scale test embankment on soft clay improved by SDCM and DCM piles was also analysed. Numerical simulations using the 3D PLAXIS Foundation finite element software have been done to understand the behavior of SDCM and DCM piles. The simulation results indicated that the surface settlements decreased with increasing lengths of the RC cores, and, at lesser extent, increasing sectional areas of the RC cores in the SDCM piles. In addition, the lateral movements

Posterior Vitreous Detachment as Observed by Wide-Angle OCT Imaging.

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Tsukahara, Mayuka; Mori, Keiko; Gehlbach, Peter L; Mori, Keisuke

2018-04-06

Posterior vitreous detachment (PVD) plays an important role in vitreoretinal interface disorders. Historically, observations of PVD using OCT have been limited to the macular region. The purpose of this study is to image the wide-angle vitreoretinal interface after PVD in normal subjects using montaged OCT images. An observational cross-sectional study. A total of 144 healthy eyes of 98 normal subjects aged 21 to 95 years (51.4±22.0 [mean ± standard deviation]). Montaged images of horizontal and vertical OCT scans through the fovea were obtained in each subject. Montaged OCT images. By using wide-angle OCT, we imaged the vitreoretinal interface from the macula to the periphery. PVD was classified into 5 stages: stage 0, no PVD (2 eyes, both aged 21 years); stage 1, peripheral PVD limited to paramacular to peripheral zones (88 eyes, mean age 38.9±16.2 years, mean ± standard deviation); stage 2, perifoveal PVD extending to the periphery (12 eyes, mean age 67.9±8.4 years); stage 3, peripapillary PVD with persistent vitreopapillary adhesion alone (7 eyes, mean age 70.9±11.9 years); stage 4, complete PVD (35 eyes, mean age 75.1±10.1 years). All stage 1 PVDs (100%) were observed in the paramacular to peripheral region where the vitreous gel adheres directly to the cortical vitreous and retinal surface. After progression to stage 2 PVD, the area of PVD extends posteriorly to the perifovea and anteriorly to the periphery. Vitreoschisis was observed in 41.2% at PVD initiation (stage 1a). Whereas prior work suggests that PVD originates in the perifoveal region and after the sixth decade, our observations demonstrate that (1) PVD first appears even in the third decade of life and gradually appears more extensively throughout life; (2) more than 40% of eyes without fundus diseases at their PVD initiation are associated with vitreoschisis; and (3) PVD is first noted primarily in the paramacular-peripheral region where vitreous gel adheres to the retinal surface and is

CT-based compartmental quantification of adipose tissue versus body metrics in colorectal cancer patients

International Nuclear Information System (INIS)

Nattenmueller, Johanna; Hoegenauer, Hanna; Grenacher, Lars; Kauczor, Hans-Ulrich; Boehm, Juergen; Ulrich, Cornelia; Scherer, Dominique; Paskow, Michael; Gigic, Biljana; Schrotz-King, Petra

2016-01-01

While obesity is considered a prognostic factor in colorectal cancer (CRC), there is increasing evidence that not simply body mass index (BMI) alone but specifically abdominal fat distribution is what matters. As part of the ColoCare study, this study measured the distribution of adipose tissue compartments in CRC patients and aimed to identify the body metric that best correlates with these measurements as a useful proxy for adipose tissue distribution. In 120 newly-diagnosed CRC patients who underwent multidetector computed tomography (CT), densitometric quantification of total (TFA), visceral (VFA), intraperitoneal (IFA), retroperitoneal (RFA), and subcutaneous fat area (SFA), as well as the M. erector spinae and psoas was performed to test the association with gender, age, tumor stage, metabolic equivalents, BMI, waist-to-height (WHtR) and waist-to-hip ratio (WHR). VFA was 28.8 % higher in men (p_V_F_A<0.0001) and 30.5 % higher in patients older than 61 years (p_V_F_A<0.0001). WHtR correlated best with all adipose tissue compartments (r_V_F_A=0.69, r_T_F_A=0.84, p<0.0001) and visceral-to-subcutaneous-fat-ratio (VFR, r_V_F_R=0.22, p=<0.05). Patients with tumor stages III/IV showed significantly lower overall adipose tissue than I/II. Increased M. erector spinae mass was inversely correlated with all compartments. Densitometric quantification on CT is a highly reproducible and reliable method to show fat distribution across adipose tissue compartments. This distribution might be best reflected by WHtR, rather than by BMI or WHR. (orig.)

Representation of planar motion of complex joints by means of rolling pairs. Application to neck motion.

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Page, Alvaro; de Rosario, Helios; Gálvez, José A; Mata, Vicente

2011-02-24

We propose to model planar movements between two human segments by means of rolling-without-slipping kinematic pairs. We compute the path traced by the instantaneous center of rotation (ICR) as seen from the proximal and distal segments, thus obtaining the fixed and moving centrodes, respectively. The joint motion is then represented by the rolling-without-slipping of one centrode on the other. The resulting joint kinematic model is based on the real movement and accounts for nonfixed axes of rotation; therefore it could improve current models based on revolute pairs in those cases where joint movement implies displacement of the ICR. Previous authors have used the ICR to characterize human joint motion, but they only considered the fixed centrode. Such an approach is not adequate for reproducing motion because the fixed centrode by itself does not convey information about body position. The combination of the fixed and moving centrodes gathers the kinematic information needed to reproduce the position and velocities of moving bodies. To illustrate our method, we applied it to the flexion-extension movement of the head relative to the thorax. The model provides a good estimation of motion both for position variables (mean R(pos)=0.995) and for velocities (mean R(vel)=0.958). This approach is more realistic than other models of neck motion based on revolute pairs, such as the dual-pivot model. The geometry of the centrodes can provide some information about the nature of the movement. For instance, the ascending and descending curves of the fixed centrode suggest a sequential movement of the cervical vertebrae. Copyright © 2010 Elsevier Ltd. All rights reserved.

Function and regulation of Vibrio campbellii proteorhodopsin: acquired phototrophy in a classical organoheterotroph.

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Zheng Wang

Full Text Available Proteorhodopsins (PRs are retinal-binding photoproteins that mediate light-driven proton translocation across prokaryotic cell membranes. Despite their abundance, wide distribution and contribution to the bioenergy budget of the marine photic zone, an understanding of PR function and physiological significance in situ has been hampered as the vast majority of PRs studied to date are from unculturable bacteria or culturable species that lack the tools for genetic manipulation. In this study, we describe the presence and function of a horizontally acquired PR and retinal biosynthesis gene cluster in the culturable and genetically tractable bioluminescent marine bacterium Vibrio campbellii. Pigmentation analysis, absorption spectroscopy and photoinduction assays using a heterologous over-expression system established the V. campbellii PR as a functional green light absorbing proton pump. In situ analyses comparing PR expression and function in wild type (WT V. campbellii with an isogenic ΔpR deletion mutant revealed a marked absence of PR membrane localization, pigmentation and light-induced proton pumping in the ΔpR mutant. Comparative photoinduction assays demonstrated the distinct upregulation of pR expression in the presence of light and PR-mediated photophosphorylation in WT cells that resulted in the enhancement of cellular survival during respiratory stress. In addition, we demonstrate that the master regulator of adaptive stress response and stationary phase, RpoS1, positively regulates pR expression and PR holoprotein pigmentation. Taken together, the results demonstrate facultative phototrophy in a classical marine organoheterotrophic Vibrio species and provide a salient example of how this organism has exploited lateral gene transfer to further its adaptation to the photic zone.

Biofilms promote survival and virulence of Salmonella enterica sv. Tennessee during prolonged dry storage and after passage through an in vitro digestion system.

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Aviles, Bryan; Klotz, Courtney; Eifert, Joseph; Williams, Robert; Ponder, Monica

2013-04-01

Salmonella enterica serotypes have been linked to outbreaks associated with low water activity foods. While the biofilm-forming abilities of Salmonella improve its survival during thermal processing and sanitation it is unclear whether biofilms enhance survival to desiccation and gastric stresses. The purpose of this study was to quantify the effect of physiological state (planktonic versus biofilm) and prior exposure to desiccation and storage in dry milk powder on Salmonella survival and gene expression after passage through an in vitro digestion model. Planktonic cells of Salmonella enterica serotype Tennessee were deposited onto membranes while biofilms were formed on glass beads. The cells were subsequently dried at room temperature and stored in dried milk powder (a(w)=0.3) for up to 30 days. Salmonella survival was quantified by serial dilution onto Brilliant Green Agar before desiccation, after desiccation, after 1-day storage and after 30-day storage. At each sampling period both physiological states were tested for survival through a simulated gastrointestinal system. RNA was extracted at the identical time points and Quantitative Real-Time PCR was used to determine relative expression for genes associated with stress response (rpoS, otsB), virulence (hilA, invA, sipC) and a housekeeping gene 16S rRNA. The physiological state and length of storage affected the survival and gene expression of Salmonella within the desiccated milk powder environment and after passage through an in vitro digestion system (pstorage for short periods, however the largest amount of expression occurred in biofilm cells stored for 30 days at aw 0.3, suggesting increased virulence potential. Copyright © 2013 Elsevier B.V. All rights reserved.

Travel-associated disease among US residents visiting US GeoSentinel clinics after return from international travel.

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Hagmann, Stefan H F; Han, Pauline V; Stauffer, William M; Miller, Andy O; Connor, Bradley A; Hale, DeVon C; Coyle, Christina M; Cahill, John D; Marano, Cinzia; Esposito, Douglas H; Kozarsky, Phyllis E

2014-12-01

US residents make 60 million international trips annually. Family practice providers need to be aware of travel-associated diseases affecting this growing mobile population. To describe demographics, travel characteristics and clinical diagnoses of US residents who present ill after international travel. Descriptive analysis of travel-associated morbidity and mortality among US travellers seeking care at 1 of the 22 US practices and clinics participating in the GeoSentinel Global Surveillance Network from January 2000 to December 2012. Of the 9624 ill US travellers included in the analysis, 3656 (38%) were tourist travellers, 2379 (25%) missionary/volunteer/research/aid workers (MVRA), 1580 (16%) travellers visiting friends and relatives (VFRs), 1394 (15%) business travellers and 593 (6%) student travellers. Median (interquartile range) travel duration was 20 days (10-60 days). Pre-travel advice was sought by 45%. Hospitalization was required by 7%. Compared with other groups of travellers, ill MVRA travellers returned from longer trips (median duration 61 days), while VFR travellers disproportionately required higher rates of inpatient care (24%) and less frequently had received pre-travel medical advice (20%). Illnesses of the gastrointestinal tract were the most common (58%), followed by systemic febrile illnesses (18%) and dermatologic disorders (17%). Three deaths were reported. Diagnoses varied according to the purpose of travel and region of exposure. Returning ill US international travellers present with a broad spectrum of travel-associated diseases. Destination and reason for travel may help primary health care providers to generate an accurate differential diagnosis for the most common disorders and for those that may be life-threatening. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effectiveness of intrauterine treatment with cephapirin in dairy cows with purulent vaginal discharge.

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Tison, N; Bouchard, E; DesCôteaux, L; Lefebvre, R C

2017-02-01

The objective of this study was to assess the efficacy of cephapirin intrauterine treatment preceding a timed artificial insemination protocol in lactating dairy cows with purulent vaginal discharges (PVDs). Holstein dairy cows (n = 1247) from 18 herds were enrolled in a controlled randomized clinical trial. At 34 days in milk (DIM; ±7 days), cows had a genital examination (transrectal palpation, vaginoscopy, and uterine bacteriology). They were randomly assigned to either the control group (CONT, no treatment) or the treatment group (CEPH) consisting of 1 intrauterine infusion of 500-mg cephapirin benzathine (RCL) (Metricure, Merck Animal Health, Montreal, Canada) regardless of the uterine health status. All cows were systematically enrolled in a presynch-ovsynch protocol for the first insemination. A second genital examination was made 2 weeks later. Cows that received any systemic or local antibiotics 10 days prior sampling to the end of the synchronization protocol were excluded from the study. Reproductive data of cows were collected for at least 300 DIM, entered in a databank, and validated (health record management software, DSAHR). Pregnancy diagnosis was done by transrectal palpation at the routinely scheduled veterinarian visits. On the basis of the highest sum of sensibility and specificity for pregnancy status at 120 DIM, the optimal cutoff for vaginal discharge score was determined as the presence of cloudy discharge with or without purulent material (PVD+, score 2). With a prevalence of 21.6% at 34 DIM, PVD+ was detrimental to the first-service conception rate (FSCR; PVD+: 26 ± 5%; PVD-: 40 ± 3%; P = 0.02). The negative effect of PVD+ was indicated by a hazard ratio of 0.72 (chi-square = 8.58; P < 0.01; 95% confidence interval = 0.56-0.91). Treatment with cephapirin was associated with a significant improvement of the FSCR in PVD+ cows (PVD+ CEPH: 36 ± 5%, PVD+ CONT: 23 ± 5%; P < 0.05), although it did not produce a

The NlpD lipoprotein is a novel Yersinia pestis virulence factor essential for the development of plague.

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Avital Tidhar

Full Text Available Yersinia pestis is the causative agent of plague. Previously we have isolated an attenuated Y. pestis transposon insertion mutant in which the pcm gene was disrupted. In the present study, we investigated the expression and the role of pcm locus genes in Y. pestis pathogenesis using a set of isogenic surE, pcm, nlpD and rpoS mutants of the fully virulent Kimberley53 strain. We show that in Y. pestis, nlpD expression is controlled from elements residing within the upstream genes surE and pcm. The NlpD lipoprotein is the only factor encoded from the pcm locus that is essential for Y. pestis virulence. A chromosomal deletion of the nlpD gene sequence resulted in a drastic reduction in virulence to an LD(50 of at least 10(7 cfu for subcutaneous and airway routes of infection. The mutant was unable to colonize mouse organs following infection. The filamented morphology of the nlpD mutant indicates that NlpD is involved in cell separation; however, deletion of nlpD did not affect in vitro growth rate. Trans-complementation experiments with the Y. pestis nlpD gene restored virulence and all other phenotypic defects. Finally, we demonstrated that subcutaneous administration of the nlpD mutant could protect animals against bubonic and primary pneumonic plague. Taken together, these results demonstrate that Y. pestis NlpD is a novel virulence factor essential for the development of bubonic and pneumonic plague. Further, the nlpD mutant is superior to the EV76 prototype live vaccine strain in immunogenicity and in conferring effective protective immunity. Thus it could serve as a basis for a very potent live vaccine against bubonic and pneumonic plague.

Role of acetyl-phosphate in activation of the Rrp2-RpoN-RpoS pathway in Borrelia burgdorferi.

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Haijun Xu

2010-09-01

Full Text Available Borrelia burgdorferi, the Lyme disease spirochete, dramatically alters its transcriptome and proteome as it cycles between the arthropod vector and mammalian host. During this enzootic cycle, a novel regulatory network, the Rrp2-RpoN-RpoS pathway (also known as the σ(54-σ(S sigma factor cascade, plays a central role in modulating the differential expression of more than 10% of all B. burgdorferi genes, including the major virulence genes ospA and ospC. However, the mechanism(s by which the upstream activator and response regulator Rrp2 is activated remains unclear. Here, we show that none of the histidine kinases present in the B. burgdorferi genome are required for the activation of Rrp2. Instead, we present biochemical and genetic evidence that supports the hypothesis that activation of the Rrp2-RpoN-RpoS pathway occurs via the small, high-energy, phosphoryl-donor acetyl phosphate (acetyl∼P, the intermediate of the Ack-Pta (acetate kinase-phosphate acetyltransferase pathway that converts acetate to acetyl-CoA. Supplementation of the growth medium with acetate induced activation of the Rrp2-RpoN-RpoS pathway in a dose-dependent manner. Conversely, the overexpression of Pta virtually abolished acetate-induced activation of this pathway, suggesting that acetate works through acetyl∼P. Overexpression of Pta also greatly inhibited temperature and cell density-induced activation of RpoS and OspC, suggesting that these environmental cues affect the Rrp2-RpoN-RpoS pathway by influencing acetyl∼P. Finally, overexpression of Pta partially reduced infectivity of B. burgdorferi in mice. Taken together, these findings suggest that acetyl∼P is one of the key activating molecule for the activation of the Rrp2-RpoN-RpoS pathway and support the emerging concept that acetyl∼P can serve as a global signal in bacterial pathogenesis.

Borrelia burgdorferi requires glycerol for maximum fitness during the tick phase of the enzootic cycle.

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Christopher J Pappas

2011-07-01

Full Text Available Borrelia burgdorferi, the spirochetal agent of Lyme disease, is a vector-borne pathogen that cycles between a mammalian host and tick vector. This complex life cycle requires that the spirochete modulate its gene expression program to facilitate growth and maintenance in these diverse milieus. B. burgdorferi contains an operon that is predicted to encode proteins that would mediate the uptake and conversion of glycerol to dihydroxyacetone phosphate. Previous studies indicated that expression of the operon is elevated at 23°C and is repressed in the presence of the alternative sigma factor RpoS, suggesting that glycerol utilization may play an important role during the tick phase. This possibility was further explored in the current study by expression analysis and mutagenesis of glpD, a gene predicted to encode glycerol 3-phosphate dehydrogenase. Transcript levels for glpD were significantly lower in mouse joints relative to their levels in ticks. Expression of GlpD protein was repressed in an RpoS-dependent manner during growth of spirochetes within dialysis membrane chambers implanted in rat peritoneal cavities. In medium supplemented with glycerol as the principal carbohydrate, wild-type B. burgdorferi grew to a significantly higher cell density than glpD mutant spirochetes during growth in vitro at 25°C. glpD mutant spirochetes were fully infectious in mice by either needle or tick inoculation. In contrast, glpD mutants grew to significantly lower densities than wild-type B. burgdorferi in nymphal ticks and displayed a replication defect in feeding nymphs. The findings suggest that B. burgdorferi undergoes a switch in carbohydrate utilization during the mammal to tick transition. Further, the results demonstrate that the ability to utilize glycerol as a carbohydrate source for glycolysis during the tick phase of the infectious cycle is critical for maximal B. burgdorferi fitness.

Payload hardware and experimental protocol development to enable future testing of the effect of space microgravity on the resistance to gentamicin of uropathogenic Escherichia coli and its σs-deficient mutant

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Matin, A. C.; Wang, J.-H.; Keyhan, Mimi; Singh, Rachna; Benoit, Michael; Parra, Macarena P.; Padgen, Michael R.; Ricco, Antonio J.; Chin, Matthew; Friedericks, Charlie R.; Chinn, Tori N.; Cohen, Aaron; Henschke, Michael B.; Snyder, Timothy V.; Lera, Matthew P.; Ross, Shannon S.; Mayberry, Christina M.; Choi, Sungshin; Wu, Diana T.; Tan, Ming X.; Boone, Travis D.; Beasley, Christopher C.; Piccini, Matthew E.; Spremo, Stevan M.

2017-11-01

Human immune response is compromised and bacteria can become more antibiotic resistant in space microgravity (MG). We report that under low-shear modeled microgravity (LSMMG), stationary-phase uropathogenic Escherichia coli (UPEC) become more resistant to gentamicin (Gm), and that this increase is dependent on the presence of σs (a transcription regulator encoded by the rpoS gene). UPEC causes urinary tract infections (UTIs), reported to afflict astronauts; Gm is a standard treatment, so these findings could impact astronaut health. Because LSMMG findings can differ from MG, we report preparations to examine UPEC's Gm sensitivity during spaceflight using the E. coli Anti-Microbial Satellite (EcAMSat) as a free-flying "nanosatellite" in low Earth orbit. Within EcAMSat's payload, a 48-microwell fluidic card contains and supports study of bacterial cultures at constant temperature; optical absorbance changes in cell suspensions are made at three wavelengths for each microwell and a fluid-delivery system provides growth medium and predefined Gm concentrations. Performance characterization is reported here for spaceflight prototypes of this payload system. Using conventional microtiter plates, we show that Alamar Blue (AB) absorbance changes can assess the Gm effect on E. coli viability, permitting telemetric transfer of the spaceflight data to Earth. Laboratory results using payload prototypes are consistent with wellplate and flask findings of differential sensitivity of UPEC and its ΔrpoS strain to Gm. if σs plays the same role in space MG as in LSMMG and Earth gravity, countermeasures discovered in recent Earth studies (aimed at weakening the UPEC antioxidant defense) to control UPEC infections would prove useful also in space flights. Further, EcAMSat results should clarify inconsistencies from previous space experiments on bacterial antibiotic sensitivity and other issues.

YehZYXW of Escherichia coli Is a Low-Affinity, Non-Osmoregulatory Betaine-Specific ABC Transporter.

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Lang, Shenhui; Cressatti, Marisa; Mendoza, Kris E; Coumoundouros, Chelsea N; Plater, Samantha M; Culham, Doreen E; Kimber, Matthew S; Wood, Janet M

2015-09-22

Transporter-mediated osmolyte accumulation stimulates the growth of Escherichia coli in high-osmolality environments. YehZYXW was predicted to be an osmoregulatory transporter because (1) osmotic and stationary phase induction of yehZYXW is mediated by RpoS, (2) the Yeh proteins are homologous to the components of known osmoregulatory ABC transporters (e.g., ProU of E. coli), and (3) YehZ models based on the structures of periplasmic betaine-binding proteins suggested that YehZ retains key betaine-binding residues. The betaines choline-O-sulfate, glycine betaine, and dimethylsulfoniopropionate bound YehZ and ProX with millimolar and micromolar affinities, respectively, as determined by equilibrium dialysis and isothermal titration calorimetry. The crystal structure of the YehZ apoprotein, determined at 1.5 Å resolution (PDB ID: 4WEP ), confirmed its similarity to other betaine-binding proteins. Small and nonpolar residues in the hinge region of YehZ (e.g., Gly223) pack more closely than the corresponding residues in ProX, stabilizing the apoprotein. Betaines bound YehZ-Gly223Ser an order of magnitude more tightly than YehZ, suggesting that weak substrate binding in YehZ is at least partially due to apo state stabilization. Neither ProX nor YehZ bound proline. Assays based on osmoprotection or proline auxotrophy failed to detect YehZYXW-mediated uptake of proline, betaines, or other osmolytes. However, transport assays revealed low-affinity glycine betaine uptake, mediated by YehZYXW, that was inhibited at high salinity. Thus, YehZYXW is a betaine transporter that shares substrate specificity, but not an osmoregulatory function, with homologues like E. coli ProU. Other work suggests that yehZYXW may be an antivirulence locus whose expression promotes persistent, asymptomatic bacterial infection.

Anaerobic expression of the gadE-mdtEF multidrug efflux operon is primarily regulated by the two-component system ArcBA through antagonizing the H-NS mediated repression.

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Deng, Ziqing; Shan, Yue; Pan, Qing; Gao, Xiang; Yan, Aixin

2013-01-01

The gadE-mdtEF operon encodes a central acid resistance regulator GadE and two multidrug efflux proteins MdtEF. Although transcriptional regulation of gadE in the context of acid resistance under the aerobic growth environment of Escherichia coli has been extensively studied, regulation of the operon under the physiologically relevant environment of anaerobic growth and its effect on the expression of the multidrug efflux proteins MdtEF in the operon has not been disclosed. Our previous study revealed that anaerobic induction of the operon was dependent on ArcA, the response regulator of the ArcBA two-component system, in the M9 glucose minimal medium. However, the detailed regulatory mechanism remains unknown. In this study, we showed that anaerobic activation of mdtEF was driven by the 798 bp unusually long gadE promoter. Deletion of evgA, ydeO, rpoS, and gadX which has been shown to activate the gadE expression during acid stresses under aerobic condition did not have a significant effect on the anaerobic activation of the operon. Rather, anaerobic activation of the operon was largely dependent on the global regulator ArcA and a GTPase MnmE. Under aerobic condition, transcription of gadE was repressed by the global DNA silencer H-NS in M9 minimal medium. Interestingly, under anaerobic condition, while ΔarcA almost completely abolished transcription of gadE-mdtEF, further deletion of hns in ΔarcA mutant restored the transcription of the full-length PgadE-lacZ, and P1- and P3-lacZ fusions, suggesting an antagonistic effect of ArcA on the H-NS mediated repression. Taken together, we conclude that the anaerobic activation of the gadE-mdtEF was primarily mediated by the two-component system ArcBA through antagonizing the H-NS mediated repression.

Anaerobic expression of the gadE-mdtEF multidrug efflux operon is primarily regulated by the two-component system ArcBA through antagonizing the H-NS mediated repression

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Ziqing eDeng

2013-07-01

Full Text Available The gadE-mdtEF operon encodes a central acid resistance regulator GadE and two multidrug efflux proteins MdtEF. Although transcriptional regulation of gadE in the context of acid resistance under the aerobic growth environment of E. coli has been extensively studied, regulation of the operon under the physiologically relevant environment of anaerobic growth and its effect on the expression of the multidrug efflux proteins MdtEF has not been disclosed. Our previous study revealed that anaerobic induction of the operon was dependent on ArcA, the response regulator of the ArcBA two-component system, in the M9 glucose minimal medium. However, the detailed regulatory mechanism remains unknown. In this study, we showed that anaerobic activation of mdtEF was driven by the 798bp unusually long gadE promoter. Deletion of evgA, ydeO, rpoS, and gadX which has been shown to activate the gadE expression during acid stresses under aerobic condition did not have a significant effect on the anaerobic activation of the operon. Rather, anaerobic activation of the operon was largely dependent on the global regulator ArcA and a GTPase MnmE. Under aerobic condition, transcription of gadE was repressed by the global DNA silencer H-NS in M9 minimal medium. Interestingly, under anaerobic condition, while ΔarcA almost completely abolished transcription of gadE-mdtEF, further deletion of hns in ΔarcA mutant restored the transcription of the full length PgadE-lacZ, and P1- and P3-lacZ fusions, suggesting an antagonistic effect of ArcA on the H-NS mediated repression. Taken together, we conclude that the anaerobic activation of the gadE-mdtEF was primarily mediated by the two-component system ArcBA through antagonizing the H-NS mediated repression.

Mechanism of bacterial inactivation by (+-limonene and its potential use in food preservation combined processes.

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Laura Espina

Full Text Available This work explores the bactericidal effect of (+-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS allowed identification of altered E. coli BJ4 structures after (+-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+-limonene. The study of mechanism of inactivation by (+-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+-limonene in food preservation, either acting alone or in combination with lethal heat treatments.

Mechanism of Bacterial Inactivation by (+)-Limonene and Its Potential Use in Food Preservation Combined Processes

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Espina, Laura; Gelaw, Tilahun K.; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego

2013-01-01

This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments. PMID:23424676

Discovery of Salmonella Virulence Factors Translocated via Outer Membrane Vesicles to Murine Macrophages.

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Yoon, Hyunjin; Ansong, Charles; Adkins, Joshua N.; Heffron, Fred

2011-06-01

We have previously shown that the regulators SpvR, FruR, IHF, PhoP/PhoQ, SsrA/SsrB, SlyA, Hnr, RpoE, SmpB, CsrA, RpoS, Crp, OmpR/EnvZ, and Hfq are essential for Salmonella Typhimurium virulence in mice. Here we use quantitative LC-MS-based proteomics profiling of in-frame deletion mutants of these 14 regulators to identify proteins that are coordinately regulated by these virulence regulators and are thus presumably novel factors contributing to Salmonella pathogenesis. Putative candidate proteins from proteomics analysis were determined, which exhibited similar abundance profiles to those of Salmonella pathogenicity island (SPI)-2 type III secretion system (TTSS) proteins. A subset of 5 proteins including STM0082, STM1548, PdgL, STM1633, and STM3595 was selected for further analysis. All 5 proteins were expressed inside macrophage cells and STM0082 (SrfN) was secreted into host cytoplasm. Furthermore, deletion of STM0082 attenuated virulence in mice when administered intraperitoneally as determined by competitive index. srfN transcription was positively regulated by SsrAB, however, secretion was independent of SPI-2 TTSS as well as SPI-1 TTSS and flagella. Proteins including PagK and STM2585A, which are positively regulated by PhoP/PhoQ, have sec signal peptides as predicted for SrfN and were secreted into macrophage cytoplasm regardless of SPI-2 TTSS. Isolation of outer membrane vesicles (OMVs) revealed the presence of SrfN, PagK, and STM2585A inside vesicle compartments. This result is the first case showing delivery of virulence effectors via OMVs in S. Typhimurium. Moreover, Hfq regulation of SrfN translation suggests that small non-coding RNAs may be responsible for regulating effector protein expression.

Global genome response of Escherichia coli O157∶H7 Sakai during dynamic changes in growth kinetics induced by an abrupt downshift in water activity.

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Chawalit Kocharunchitt

Full Text Available The present study was undertaken to investigate growth kinetics and time-dependent change in global expression of Escherichia coli O157∶H7 Sakai upon an abrupt downshift in water activity (aw. Based on viable count data, shifting E. coli from aw 0.993 to aw 0.985 or less caused an apparent loss, then recovery, of culturability. Exponential growth then resumed at a rate characteristic for the aw imposed. To understand the responses of this pathogen to abrupt osmotic stress, we employed an integrated genomic and proteomic approach to characterize its cellular response during exposure to a rapid downshift but still within the growth range from aw 0.993 to aw 0.967. Of particular interest, genes and proteins with cell envelope-related functions were induced during the initial loss and subsequent recovery of culturability. This implies that cells undergo remodeling of their envelope composition, enabling them to adapt to osmotic stress. Growth at low aw, however, involved up-regulating additional genes and proteins, which are involved in the biosynthesis of specific amino acids, and carbohydrate catabolism and energy generation. This suggests their important role in facilitating growth under such stress. Finally, we highlighted the ability of E. coli to activate multiple stress responses by transiently inducing the RpoE and RpoH regulons to control protein misfolding, while simultaneously activating the master stress regulator RpoS to mediate long-term adaptation to hyperosmolality. This investigation extends our understanding of the potential mechanisms used by pathogenic E. coli to adapt, survive and grow under osmotic stress, which could potentially be exploited to aid the selection and/or development of novel strategies to inactivate this pathogen.

Enhancing E. coli tolerance towards oxidative stress via engineering its global regulator cAMP receptor protein (CRP.

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Souvik Basak

Full Text Available Oxidative damage to microbial hosts often occurs under stressful conditions during bioprocessing. Classical strain engineering approaches are usually both time-consuming and labor intensive. Here, we aim to improve E. coli performance under oxidative stress via engineering its global regulator cAMP receptor protein (CRP, which can directly or indirectly regulate redox-sensing regulators SoxR and OxyR, and other ~400 genes in E. coli. Error-prone PCR technique was employed to introduce modifications to CRP, and three mutants (OM1~OM3 were identified with improved tolerance via H(2O(2 enrichment selection. The best mutant OM3 could grow in 12 mM H(2O(2 with the growth rate of 0.6 h(-1, whereas the growth of wild type was completely inhibited at this H(2O(2 concentration. OM3 also elicited enhanced thermotolerance at 48°C as well as resistance against cumene hydroperoxide. The investigation about intracellular reactive oxygen species (ROS, which determines cell viability, indicated that the accumulation of ROS in OM3 was always lower than in WT with or without H(2O(2 treatment. Genome-wide DNA microarray analysis has shown not only CRP-regulated genes have demonstrated great transcriptional level changes (up to 8.9-fold, but also RpoS- and OxyR-regulated genes (up to 7.7-fold. qRT-PCR data and enzyme activity assay suggested that catalase (katE could be a major antioxidant enzyme in OM3 instead of alkyl hydroperoxide reductase or superoxide dismutase. To our knowledge, this is the first work on improving E. coli oxidative stress resistance by reframing its transcription machinery through its native global regulator. The positive outcome of this approach may suggest that engineering CRP can be successfully implemented as an efficient strain engineering alternative for E. coli.

A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella.

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Kato, Akinori; Hayashi, Hironori; Nomura, Wataru; Emori, Haruka; Hagihara, Kei; Utsumi, Ryutaro

2012-10-02

Bacteria integrate numerous environmental stimuli when generating cellular responses. Increasing numbers of examples describe how one two-component system (TCS) responds to signals detected by the sensor of another TCS. However, the molecular mechanisms underlying this phenomenon remain poorly defined. Here, we report a connector-like factor that affects the activity of the CpxR/CpxA two-component system in Salmonella enterica serovar Typhimurium. We isolated a clone that induced the expression of a cpxP-lac gene fusion from a high-copy-number plasmid pool of random Salmonella genomic fragments. A 63-amino acid protein, CacA, was responsible for the CpxA/CpxR-dependent activation of the cpxP gene. The CpxR-activated genes cpxP and spy exhibited approximately 30% and 50% reductions in transcription, respectively, in a clean cacA deletion mutant strain in comparison to wild-type. From 33 response regulator (RR) deletion mutants, we identified that the RssB regulator represses cacA transcription. Substitution mutations in a conserved -10 region harboring the RNA polymerase recognition sequence, which is well conserved with a known RpoS -10 region consensus sequence, rendered the cacA promoter RpoS-independent. The CacA-mediated induction of cpxP transcription was affected in a trxA deletion mutant, which encodes thioredoxin 1, suggesting a role for cysteine thiol-disulfide exchange(s) in CacA-dependent Cpx activation. We identified CacA as an activator of the CpxR/CpxA system in the plasmid clone. We propose that CacA may integrate the regulatory status of RssB/RpoS into the CpxR/CpxA system. Future investigations are necessary to thoroughly elucidate how CacA activates the CpxR/CpxA system.

A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella

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Kato Akinori

2012-10-01

Full Text Available Abstract Background Bacteria integrate numerous environmental stimuli when generating cellular responses. Increasing numbers of examples describe how one two-component system (TCS responds to signals detected by the sensor of another TCS. However, the molecular mechanisms underlying this phenomenon remain poorly defined. Results Here, we report a connector-like factor that affects the activity of the CpxR/CpxA two-component system in Salmonella enterica serovar Typhimurium. We isolated a clone that induced the expression of a cpxP-lac gene fusion from a high-copy-number plasmid pool of random Salmonella genomic fragments. A 63-amino acid protein, CacA, was responsible for the CpxA/CpxR-dependent activation of the cpxP gene. The CpxR-activated genes cpxP and spy exhibited approximately 30% and 50% reductions in transcription, respectively, in a clean cacA deletion mutant strain in comparison to wild-type. From 33 response regulator (RR deletion mutants, we identified that the RssB regulator represses cacA transcription. Substitution mutations in a conserved -10 region harboring the RNA polymerase recognition sequence, which is well conserved with a known RpoS -10 region consensus sequence, rendered the cacA promoter RpoS-independent. The CacA-mediated induction of cpxP transcription was affected in a trxA deletion mutant, which encodes thioredoxin 1, suggesting a role for cysteine thiol-disulfide exchange(s in CacA-dependent Cpx activation. Conclusions We identified CacA as an activator of the CpxR/CpxA system in the plasmid clone. We propose that CacA may integrate the regulatory status of RssB/RpoS into the CpxR/CpxA system. Future investigations are necessary to thoroughly elucidate how CacA activates the CpxR/CpxA system.

Low temperature geomicrobiology follows host rock composition along a geochemical gradient in Lau Basin

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Jason B Sylvan

2013-03-01

Full Text Available The East Lau Spreading Center (ELSC and Valu Fa Ridge (VFR comprise a ridge segment in the southwest Pacific Ocean where rapid transitions in the underlying mantle chemistry manifest themselves as gradients in seafloor rock geochemistry. We studied the geology and microbial diversity of three silicate rock samples and three inactive sulfide chimney samples collected, from north to south, at the vent fields Kilo Moana, ABE, Tui Malila and Mariner. This is the first study of microbial populations on basaltic andesite, which was sampled at Mariner vent field. Silicate rock geochemistry exhibits clear latitudinal trends that are mirrored by changes in bacterial community composition. α-proteobacteria, ε-proteobacteria and Bacteroidetes are most common on a silicate collected from Kilo Moana and their proportions decrease linearly on silicates collected further south. Conversely, a silicate from Mariner vent field hosts high proportions of a unique lineage of Chloroflexi unrelated (<90% sequence similarity to previously recovered environmental clones or isolates, which decrease at ABE and are absent at Kilo Moana. The exteriors of inactive sulfide structures are dominated by lineages of sulfur oxidizing α-proteobacteria, γ-proteobacteria and ε-proteobacteria while the interior of one chimney is dominated by putative sulfur-reducing δ-proteobacteria. A comparison of bacterial communities on inactive sulfides from this and previous studies reveals the presence of a clade of uncultured Bacteroidetes exclusive to sulfidic environments, and a high degree of heterogeneity in bacterial community composition from one sulfide structure to another. In light of the heterogeneous nature of bacterial communities observed here and in previous studies of both active and inactive hydrothermal sulfide structures, the presence of numerous niches may be detected on these structures in the future by finer scale sampling and analysis.

System for synthetic vision and augmented reality in future flight decks

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Behringer, Reinhold; Tam, Clement K.; McGee, Joshua H.; Sundareswaran, Venkataraman; Vassiliou, Marius S.

2000-06-01

Rockwell Science Center is investigating novel human-computer interface techniques for enhancing the situational awareness in future flight decks. One aspect is to provide intuitive displays which provide the vital information and the spatial awareness by augmenting the real world with an overlay of relevant information registered to the real world. Such Augmented Reality (AR) techniques can be employed during bad weather scenarios to permit flying in Visual Flight Rules (VFR) in conditions which would normally require Instrumental Flight Rules (IFR). These systems could easily be implemented on heads-up displays (HUD). The advantage of AR systems vs. purely synthetic vision (SV) systems is that the pilot can relate the information overlay to real objects in the world, whereas SV systems provide a constant virtual view, where inconsistencies can hardly be detected. The development of components for such a system led to a demonstrator implemented on a PC. A camera grabs video images which are overlaid with registered information, Orientation of the camera is obtained from an inclinometer and a magnetometer, position is acquired from GPS. In a possible implementation in an airplane, the on-board attitude information can be used for obtaining correct registration. If visibility is sufficient, computer vision modules can be used to fine-tune the registration by matching visual clues with database features. Such technology would be especially useful for landing approaches. The current demonstrator provides a frame-rate of 15 fps, using a live video feed as background and an overlay of avionics symbology in the foreground. In addition, terrain rendering from a 1 arc sec. digital elevation model database can be overlaid to provide synthetic vision in case of limited visibility. For true outdoor testing (on ground level), the system has been implemented on a wearable computer.

Imported malaria in pregnant women: a retrospective pooled analysis

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Käser, Annina K.; Arguin, Paul M.; Chiodini, Peter L.; Smith, Valerie; Delmont, Jean; Jiménez, Beatriz C.; Färnert, Anna; Kimura, Mikio; Ramharter, Michael; Grobusch, Martin P.; Schlagenhauf, Patricia

2015-01-01

Summary Background Data on imported malaria in pregnant women are scarce. Method A retrospective, descriptive study of pooled data on imported malaria in pregnancy was done, using data from 1977 to 2014 from 8 different collaborators in Europe, the United States and Japan. Most cases were from the period 1991–2014. National malaria reference centresas well as specialists on this topic were asked to search their archives for cases of imported malaria in pregnancy. A total of 632 cases were collated, providing information on Plasmodium species, region of acquisition, nationality, country of residence, reason for travel, age, gestational age, prophylactic measures and treatment used, as well as on complications and outcomes in mother and child. Results Datasets from some sources were incomplete. The predominant Plasmodium species was P. falciparum in 72% of cases. Among the 543 cases where information on the use of chemoprophylaxis was known, 471 (74.5%) did not use chemoprophylaxis or used incorrect or incomplete chemoprophylaxis. The main reason for travelling was “visiting friends and relatives” VFR (48.6%) and overall, most cases of malaria were imported from West Africa (85.9%). Severe anaemia was the most frequent complication in the mother. Data on offspring outcome was limited, but spontaneous abortion was a frequently reported foetal outcome (n = 14). A total of 50 different variants of malaria treatment regimens were reported. Conclusion Imported cases of malaria in pregnancy are mainly P. falciparum acquired in sub-Saharan Africa. Malaria prevention and treatment in pregnant travellers is a challenge for travel medicine due to few data on medication safety and maternal and foetal outcomes. International, collaborative efforts are needed to capture standardized data on imported malaria cases in pregnant women. PMID:26227740

Piecewise linear approximations to model the dynamics of adaptation to osmotic stress by food-borne pathogens.

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Métris, Aline; George, Susie M; Ropers, Delphine

2017-01-02

Addition of salt to food is one of the most ancient and most common methods of food preservation. However, little is known of how bacterial cells adapt to such conditions. We propose to use piecewise linear approximations to model the regulatory adaptation of Escherichiacoli to osmotic stress. We apply the method to eight selected genes representing the functions known to be at play during osmotic adaptation. The network is centred on the general stress response factor, sigma S, and also includes a module representing the catabolic repressor CRP-cAMP. Glutamate, potassium and supercoiling are combined to represent the intracellular regulatory signal during osmotic stress induced by salt. The output is a module where growth is represented by the concentration of stable RNAs and the transcription of the osmotic gene osmY. The time course of gene expression of transport of osmoprotectant represented by the symporter proP and of the osmY is successfully reproduced by the network. The behaviour of the rpoS mutant predicted by the model is in agreement with experimental data. We discuss the application of the model to food-borne pathogens such as Salmonella; although the genes considered have orthologs, it seems that supercoiling is not regulated in the same way. The model is limited to a few selected genes, but the regulatory interactions are numerous and span different time scales. In addition, they seem to be condition specific: the links that are important during the transition from exponential to stationary phase are not all needed during osmotic stress. This model is one of the first steps towards modelling adaptation to stress in food safety and has scope to be extended to other genes and pathways, other stresses relevant to the food industry, and food-borne pathogens. The method offers a good compromise between systems of ordinary differential equations, which would be unmanageable because of the size of the system and for which insufficient data are available

Escherichia coli O157:H7 Acid Sensitivity Correlates with Flocculation Phenotype during Nutrient Limitation

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Kathryn L. Kay

2017-07-01

Full Text Available Shiga toxin producing Escherichia coli (STEC strains vary in acid resistance; however, little is known about the underlying mechanisms that result in strain specific differences. Among 25 STEC O157:H7 strains tested, 7 strains flocculated when grown statically for 18 h in minimal salts medium at 37°C, while 18 strains did not. Interestingly, the flocculation phenotype (cells came out of suspension was found to correlate with degree of acid sensitivity in an assay with 400 mM acetic acid solution at pH 3.3 targeting acidified foods. Strains exhibiting flocculation were more acid sensitive and were designated FAS, for flocculation acid sensitive, while the acid resistant strain designated PAR for planktonic acid resistant. Flocculation was not observed for any strains during growth in complex medium (Luria Bertani broth. STEC strains B201 and B241 were chosen as representative FAS (2.4 log reduction and PAR (0.15 log reduction strains, respectively, due to differences in acid resistance and flocculation phenotype. Results from electron microscopy showed evidence of fimbriae production in B201, whereas fimbriae were not observed in B241.Curli fimbriae production was identified through plating on Congo red differential medium, and all FAS strains showed curli fimbriae production. Surprisingly, 5 PAR strains also had evidence of curli production. Transcriptomic and targeted gene expression data for B201 and B241indicated that csg and hde (curli and acid induced chaperone genes, respectively expression positively correlated with the phenotypic differences observed for these strains. These data suggest that FAS strains grown in minimal medium express curli, resulting in a flocculation phenotype. This may be regulated by GcvB, which positively regulates curli fimbriae production and represses acid chaperone proteins. RpoS and other regulatory mechanisms may impact curli fimbriae production, as well. These findings may help elucidate mechanisms

RpoN Modulates Carbapenem Tolerance in Pseudomonas aeruginosa through Pseudomonas Quinolone Signal and PqsE

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Murakami, Keiji; Amoh, Takashi; Ono, Tsuneko; Miyake, Yoichiro

2016-01-01

The ability of Pseudomonas aeruginosa to rapidly modulate its response to antibiotic stress and persist in the presence of antibiotics is closely associated with the process of cell-to-cell signaling. The alternative sigma factor RpoN (σ54) is involved in the regulation of quorum sensing (QS) and plays an important role in the survival of stationary-phase cells in the presence of carbapenems. Here, we demonstrate that a ΔrpoN mutant grown in nutrient-rich medium has increased expression of pqsA, pqsH, and pqsR throughout growth, resulting in the increased production of the Pseudomonas quinolone signal (PQS). The link between pqsA and its role in carbapenem tolerance was studied using a ΔrpoN ΔpqsA mutant, in which the carbapenem-tolerant phenotype of the ΔrpoN mutant was abolished. In addition, we demonstrate that another mechanism leading to carbapenem tolerance in the ΔrpoN mutant is mediated through pqsE. Exogenously supplied PQS abolished the biapenem-sensitive phenotype of the ΔrpoN ΔpqsA mutant, and overexpression of pqsE failed to alter the susceptibility of the ΔrpoN ΔpqsA mutant to biapenem. The mutations in the ΔrpoN ΔrhlR mutant and the ΔrpoN ΔpqsH mutant led to susceptibility to biapenem. Comparison of the changes in the expression of the genes involved in QS in wild-type PAO1 with their expression in the ΔrpoN mutant and the ΔrpoN mutant-derived strains demonstrated the regulatory effect of RpoN on the transcript levels of rhlR, vqsR, and rpoS. The findings of this study demonstrate that RpoN negatively regulates the expression of PQS in nutrient-rich medium and provide evidence that RpoN interacts with pqsA, pqsE, pqsH, and rhlR in response to antibiotic stress. PMID:27431228

Enhanced/synthetic vision and head-worn display technologies for terminal maneuvering area NextGen operations

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Arthur, Jarvis J., III; Prinzel, Lawrence J., III; Williams, Steven P.; Bailey, Randall E.; Shelton, Kevin J.; Norman, R. Mike

2011-06-01

NASA is researching innovative technologies for the Next Generation Air Transportation System (NextGen) to provide a "Better-Than-Visual" (BTV) capability as adjunct to "Equivalent Visual Operations" (EVO); that is, airport throughputs equivalent to that normally achieved during Visual Flight Rules (VFR) operations rates with equivalent and better safety in all weather and visibility conditions including Instrument Meteorological Conditions (IMC). These new technologies build on proven flight deck systems and leverage synthetic and enhanced vision systems. Two piloted simulation studies were conducted to access the use of a Head-Worn Display (HWD) with head tracking for synthetic and enhanced vision systems concepts. The first experiment evaluated the use a HWD for equivalent visual operations to San Francisco International Airport (airport identifier: KSFO) compared to a visual concept and a head-down display concept. A second experiment evaluated symbology variations under different visibility conditions using a HWD during taxi operations at Chicago O'Hare airport (airport identifier: KORD). Two experiments were conducted, one in a simulated San Francisco airport (KSFO) approach operation and the other, in simulated Chicago O'Hare surface operations, evaluating enhanced/synthetic vision and head-worn display technologies for NextGen operations. While flying a closely-spaced parallel approach to KSFO, pilots rated the HWD, under low-visibility conditions, equivalent to the out-the-window condition, under unlimited visibility, in terms of situational awareness (SA) and mental workload compared to a head-down enhanced vision system. There were no differences between the 3 display concepts in terms of traffic spacing and distance and the pilot decision-making to land or go-around. For the KORD experiment, the visibility condition was not a factor in pilot's rating of clutter effects from symbology. Several concepts for enhanced implementations of an unlimited field

German travelers' preferences for travel vaccines assessed by a discrete choice experiment.

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Poulos, Christine; Curran, Desmond; Anastassopoulou, Anastassia; De Moerlooze, Laurence

2018-02-08

Many travelers to regions with endemic infectious diseases do not follow health authorities' recommendations regarding vaccination against vaccine-preventable infectious diseases, before traveling. The determinants of individual travelers' decisions to vaccinate before traveling are largely unknown. This study aimed to provide this information using a discrete choice experiment (DCE) administered to four types of German travelers: (1) business travelers; (2) travelers visiting friends and relatives (VFR); (3) leisure travelers; and (4) backpackers. A DCE survey was developed, pretested and administered online. It included a series of choice questions in which respondents chose between two hypothetical vaccines, each characterized by four disease attributes with varying levels describing the of risk, health impact, curability and transmissibility of the disease they would prevent (described with four disease attributes with varying levels of risk, health impact, curability and transmissibility), and varying levels of four vaccine attributes (duration of protection, number of doses required, time required for vaccination, and vaccine cost). A random-parameters logit model was used to estimate the importance weights each traveler type placed on the various attribute levels. These weights were used to calculate mean monetary equivalents (MMEs) of changes in each attribute (holding all others constant) and of hypothetical disease-vaccine combinations. All traveler types' choices indicated that they attached the greatest importance to the risk and health impact of disease and to the vaccine cost whereas the other disease and vaccine attributes were less important for their decisions about travel vaccines. An option of not choosing any of the vaccine-pairs presented was rarely selected indicating that travelers' generally prefer to be vaccinated rather than not. The MMEs of changes in vaccine attributes indicated a very high variability between the individual travelers

The position of mefloquine as a 21st century malaria chemoprophylaxis.

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Schlagenhauf, Patricia; Adamcova, Miriam; Regep, Loredana; Schaerer, Martin T; Rhein, Hans-Georg

2010-12-09

Malaria chemoprophylaxis prevents the occurrence of the symptoms of malaria. Travellers to high-risk Plasmodium falciparum endemic areas need an effective chemoprophylaxis. A literature search to update the status of mefloquine as a malaria chemoprophylaxis. Except for clearly defined regions with multi-drug resistance, mefloquine is effective against the blood stages of all human malaria species, including the recently recognized fifth species, Plasmodium knowlesi. New data were found in the literature on the tolerability of mefloquine and the use of this medication by groups at high risk of malaria. Use of mefloquine for pregnant women in the second and third trimester is sanctioned by the WHO and some authorities (CDC) allow the use of mefloquine even in the first trimester. Inadvertent pregnancy while using mefloquine is not considered grounds for pregnancy termination. Mefloquine chemoprophylaxis is allowed during breast-feeding. Studies show that mefloquine is a good option for other high-risk groups, such as long-term travellers, VFR travellers and families with small children. Despite a negative media perception, large pharmaco-epidemiological studies have shown that serious adverse events are rare. A recent US evaluation of serious events (hospitalization data) found no association between mefloquine prescriptions and serious adverse events across a wide range of outcomes including mental disorders and diseases of the nervous system. As part of an in-depth analysis of mefloquine tolerability, a potential trend for increased propensity for neuropsychiatric adverse events in women was identified in a number of published clinical studies. This trend is corroborated by several cohort studies that identified female sex and low body weight as risk factors. The choice of anti-malarial drug should be an evidence-based decision that considers the profile of the individual traveller and the risk of malaria. Mefloquine is an important, first-line anti-malarial drug

Characteristics of HIV infected individuals traveling abroad. Results from the +REDIVI Collaborative Network.

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Pérez-Molina, Jose A; Martinez-Perez, Angela; Serre, Nuria; Treviño, Begoña; Ruiz-Giardín, José Manuel; Torrús, Diego; Goikoetxea, Josune; Echevarría, Esteban Martín; Malmierca, Eduardo; Rojo, Gerardo; Calabuig, Eva; Gutierrez, Belén; Norman, Francesca; Lopez-Velez, Rogelio

2016-02-01

The improvement in the prognosis of HIV infection, coupled with the increase in international travel and migration, has led to a rising number of HIV infected travelers. The objective of this study was to describe the epidemiological and clinical features of returning travelers, according to their HIV status. An observational prospective study was conducted including travelers and immigrants who traveled to visit friends and relatives (VFRs) registered in the +REDIVI collaborative network (January-2009; October-2014). +REDIVI is a national network that registers information regarding infections imported by travelers and immigrants at 21 different centers using a standardized protocol. A total of 3464 travellers were identified: 72 were HIV+ (2.1%) and 3.392 HIV- (98%). HIV+ vs. HIV- travelers were often older (40.5y vs. 34.2y P=.001), VFRs (79.1% vs. 44.4%; Ptravel advice (27% vs. 37%; P=.078). The main destinations for both groups were sub-Saharan Africa and Latin America. The most frequent reasons for consultation after travel were fever, request for a health examination, gastrointestinal complaints, and abnormal laboratory tests (mainly eosinophilia and anemia), which differed between groups. The most frequent diagnoses in HIV+ travelers were malaria (38.8%), newly diagnosed HIV infection (25%), and intestinal parasites (19.4%), while for HIV- travelers the main diagnoses were "healthy" (17.9%), malaria (14%), and intestinal parasites (17.3%). The typical profile of an HIV+ traveler in +REDIVI was that of a VFR traveler who did not seek pre-travel advice and made high-risk trips. This may increase the chance of acquiring travel-related infections which may pose a special risk for HIV-infected travelers. The post-travel visit was a good opportunity for HIV infection screening. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Absence of sodA Increases the Levels of Oxidation of Key Metabolic Determinants of Borrelia burgdorferi.

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Maria D Esteve-Gassent

Full Text Available Borrelia burgdorferi, the causative agent of Lyme disease, alters its gene expression in response to environmental signals unique to its tick vector or vertebrate hosts. B. burgdorferi carries one superoxide dismutase gene (sodA capable of controlling intracellular superoxide levels. Previously, sodA was shown to be essential for infection of B. burgdorferi in the C3H/HeN model of Lyme disease. We employed two-dimensional electrophoresis (2-DE and immunoblot analysis with antibodies specific to carbonylated proteins to identify targets that were differentially oxidized in the soluble fractions of the sodA mutant compared to its isogenic parental control strain following treatment with an endogenous superoxide generator, methyl viologen (MV, paraquat. HPLC-ESI-MS/MS analysis of oxidized proteins revealed that several proteins of the glycolytic pathway (BB0057, BB0020, BB0348 exhibited increased carbonylation in the sodA mutant treated with MV. Levels of ATP and NAD/NADH were reduced in the sodA mutant compared with the parental strain following treatment with MV and could be attributed to increased levels of oxidation of proteins of the glycolytic pathway. In addition, a chaperone, HtpG (BB0560, and outer surface protein A (OspA, BBA15 were also observed to be oxidized in the sodA mutant. Immunoblot analysis revealed reduced levels of Outer surface protein C (OspC, Decorin binding protein A (DbpA, fibronectin binding protein (BBK32, RpoS and BosR in the sodA mutant compared to the control strains. Viable sodA mutant spirochetes could not be recovered from both gp91/phox-⁄- and iNOS deficient mice while borrelial DNA was detected in multiple tissues samples from infected mice at significantly lower levels compared to the parental strain. Taken together, these observations indicate that the increased oxidation of select borrelial determinants and reduced levels of critical pathogenesis-associated lipoproteins contribute to the in vivo deficit of

Temporal transcriptomic analysis of Desulfovibrio vulgaris Hildenborough transition into stationary phase growth during electrondonor depletion

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Clark, M.E.; He, Q.; He, Z.; Huang, K.H.; Alm, E.J.; Wan, X.-F.; Hazen, T.C.; Arkin, A.P.; Wall, J.D.; Zhou, J.-Z.; Fields, M.W.

2006-08-01

Desulfovibrio vulgaris was cultivated in a defined medium, and biomass was sampled for approximately 70 h to characterize the shifts in gene expression as cells transitioned from the exponential to the stationary phase during electron donor depletion. In addition to temporal transcriptomics, total protein, carbohydrate, lactate, acetate, and sulfate levels were measured. The microarray data were examined for statistically significant expression changes, hierarchical cluster analysis, and promoter element prediction and were validated by quantitative PCR. As the cells transitioned from the exponential phase to the stationary phase, a majority of the down-expressed genes were involved in translation and transcription, and this trend continued at the remaining times. There were general increases in relative expression for intracellular trafficking and secretion, ion transport, and coenzyme metabolism as the cells entered the stationary phase. As expected, the DNA replication machinery was down-expressed, and the expression of genes involved in DNA repair increased during the stationary phase. Genes involved in amino acid acquisition, carbohydrate metabolism, energy production, and cell envelope biogenesis did not exhibit uniform transcriptional responses. Interestingly, most phage-related genes were up-expressed at the onset of the stationary phase. This result suggested that nutrient depletion may affect community dynamics and DNA transfer mechanisms of sulfate-reducing bacteria via the phage cycle. The putative feoAB system (in addition to other presumptive iron metabolism genes) was significantly up-expressed, and this suggested the possible importance of Fe{sup 2+} acquisition under metal-reducing conditions. The expression of a large subset of carbohydrate-related genes was altered, and the total cellular carbohydrate levels declined during the growth phase transition. Interestingly, the D. vulgaris genome does not contain a putative rpoS gene, a common attribute

Genetic selection of peptide aptamers that interact and inhibit both Small protein B and alternative ribosome-rescue factor A of Aeromonas veronii C4

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Peng Liu

2016-08-01

Full Text Available Aeromonas veronii is a pathogenic gram-negative bacterium, which infects a variety of animals and results in mass mortality. The stalled-ribosome rescues are reported to ensure viability and virulence under stress conditions, of which primarily include trans-translation and alternative ribosome-rescue factor A (ArfA in A. veronii. For identification of specific peptides that interact and inhibit the stalled-ribosome rescues, peptide aptamer library (pTRG-SN-peptides was constructed using pTRG as vector and Staphylococcus aureus nuclease (SN as scaffold protein, in which 16 random amino acids were introduced to form an exposed surface loop. In the meantime both Small Protein B (SmpB which acts as one of the key components in trans-translation, and alternative ribosome-rescue factor A (ArfA were inserted to pBT to constitute pBT-SmpB and pBT-ArfA, respectively. The peptide aptamer PA-2 was selected from pTRG-SN-peptides by bacterial two-hybrid system (B2H employing pBT-SmpB or pBT-ArfA as baits. The conserved sites G133K134 and D138K139R140 of C-terminal SmpB were identified by interacting with N-terminal SN, and concurrently the residue K62 of ArfA was recognized by interacting with the surface loop of the specific peptide aptamer PA-2. The expression plasmids pN-SN or pN-PA-2, which combined the duplication origin of pRE112 with the neokanamycin promoter expressing SN or PA-2, were created and transformed into A. veronii C4, separately. The engineered A. veronii C4 which endowing SN or PA-2 expression impaired growth capabilities under stress conditions including temperatures, sucrose, glucose, potassium chloride (KCl and antibiotics, and the stress-related genes rpoS and nhaP were down-regulated significantly by Quantitative Real-time PCR (qRT-PCR when treating in 2.0% KCl. Thus，the engineered A. veronii C4 conferring PA-2 expression might be potentially attenuated vaccine, and also the peptide aptamer PA-2 could develop as anti

Genetic Selection of Peptide Aptamers That Interact and Inhibit Both Small Protein B and Alternative Ribosome-Rescue Factor A of Aeromonas veronii C4.

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Liu, Peng; Chen, Yong; Wang, Dan; Tang, Yanqiong; Tang, Hongqian; Song, Haichao; Sun, Qun; Zhang, Yueling; Liu, Zhu

2016-01-01

Aeromonas veronii is a pathogenic gram-negative bacterium, which infects a variety of animals and results in mass mortality. The stalled-ribosome rescues are reported to ensure viability and virulence under stress conditions, of which primarily include trans-translation and alternative ribosome-rescue factor A (ArfA) in A. veronii. For identification of specific peptides that interact and inhibit the stalled-ribosome rescues, peptide aptamer library (pTRG-SN-peptides) was constructed using pTRG as vector and Staphylococcus aureus nuclease (SN) as scaffold protein, in which 16 random amino acids were introduced to form an exposed surface loop. In the meantime both Small Protein B (SmpB) which acts as one of the key components in trans-translation, and ArfA were inserted to pBT to constitute pBT-SmpB and pBT-ArfA, respectively. The peptide aptamer PA-2 was selected from pTRG-SN-peptides by bacterial two-hybrid system (B2H) employing pBT-SmpB or pBT-ArfA as baits. The conserved sites G133K134 and D138K139R140 of C-terminal SmpB were identified by interacting with N-terminal SN, and concurrently the residue K62 of ArfA was recognized by interacting with the surface loop of the specific peptide aptamer PA-2. The expression plasmids pN-SN or pN-PA-2, which combined the duplication origin of pRE112 with the neokanamycin promoter expressing SN or PA-2, were created and transformed into A. veronii C4, separately. The engineered A. veronii C4 which endowing SN or PA-2 expression impaired growth capabilities under stress conditions including temperatures, sucrose, glucose, potassium chloride (KCl) and antibiotics, and the stress-related genes rpoS and nhaP were down-regulated significantly by Quantitative Real-time PCR (qRT-PCR) when treating in 2.0% KCl. Thus, the engineered A. veronii C4 conferring PA-2 expression might be potentially attenuated vaccine, and also the peptide aptamer PA-2 could develop as anti-microbial drugs targeted to the ribosome rescued factors in A

The position of mefloquine as a 21st century malaria chemoprophylaxis

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Regep Loredana

2010-12-01

Full Text Available Abstract Background Malaria chemoprophylaxis prevents the occurrence of the symptoms of malaria. Travellers to high-risk Plasmodium falciparum endemic areas need an effective chemoprophylaxis. Methods A literature search to update the status of mefloquine as a malaria chemoprophylaxis. Results Except for clearly defined regions with multi-drug resistance, mefloquine is effective against the blood stages of all human malaria species, including the recently recognized fifth species, Plasmodium knowlesi. New data were found in the literature on the tolerability of mefloquine and the use of this medication by groups at high risk of malaria. Discussion Use of mefloquine for pregnant women in the second and third trimester is sanctioned by the WHO and some authorities (CDC allow the use of mefloquine even in the first trimester. Inadvertent pregnancy while using mefloquine is not considered grounds for pregnancy termination. Mefloquine chemoprophylaxis is allowed during breast-feeding. Studies show that mefloquine is a good option for other high-risk groups, such as long-term travellers, VFR travellers and families with small children. Despite a negative media perception, large pharmaco-epidemiological studies have shown that serious adverse events are rare. A recent US evaluation of serious events (hospitalization data found no association between mefloquine prescriptions and serious adverse events across a wide range of outcomes including mental disorders and diseases of the nervous system. As part of an in-depth analysis of mefloquine tolerability, a potential trend for increased propensity for neuropsychiatric adverse events in women was identified in a number of published clinical studies. This trend is corroborated by several cohort studies that identified female sex and low body weight as risk factors. Conclusion The choice of anti-malarial drug should be an evidence-based decision that considers the profile of the individual traveller and the

Phenotypic and Genotypic Features of a Salmonella Heidelberg Strain Isolated in Broilers in Brazil and Their Possible Association to Antibiotics and Short-Chain Organic Acids Resistance and Susceptibility.

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Santin, Elizabeth; Hayashi, Ricardo Mitsuo; Wammes, Jessica Caroline; Gonzalez-Esquerra, Ricardo; Carazzolle, Marcelo Falsarella; Freire, Caio César de Melo; Monzani, Paulo Sérgio; da Cunha, Anderson Ferreira

2017-01-01

Salmonella enterica serovar Heidelberg is a human pathogen also found in broilers. A strain (UFPR1) has been associated with field reports of resistance to short-chain organic acids (SCOA) in broilers in the South of Brazil, but was susceptible to a Bacillus subtilis -based probiotic added in feed in a related study. This work aimed to (i) report clinical symptoms caused by SH UFPR1 in broilers, (ii) study its susceptibility to some antibiotics in vitro , and (iii) SCOA in vivo ; and (iv) relate these phenotypic observations with its genome characteristics. Two in vivo trials used 1-day-old chicks housed for 21 days in 8 sterilized isolated negative pressure rooms with 4 battery cages of 12 birds each. Birds were challenged or not with 10 7  CFU/bird of SH UFPR1 orally and exposed or not to SCOA in a 2 × 2 factorial design. Zootechnical parameters were unaffected ( P  > 0.05), no clinical signs were observed, and few cecal and hepatic histologic and immune-related alterations were seen, in birds challenged with SH. Formic and propionic acids added together in drinking water, fumaric and benzoic acid in feed (Trial 1), and coated calcium butyrate in feed (Trial 2) did not reduce the SH isolation frequencies seen in cecum and liver in broilers after SH challenge ( P  > 0.05). SH UFPR1 was susceptible to amikacin, amoxicillin + clavulanate, ceftiofur, cephalexin, doxycycline and oxytetracycline; and mildly susceptible to ampicillin + sulbactam, cephalothin, ciprofloxacin, enrofloxacin, and gentamycin in an in vitro minimum inhibitory concentration model using Mueller-Hinton agar. The whole genome of SH UFPR1 was sequenced and consisted of a circular chromosome, spanning 4,760,321 bp with 52.18% of GC-content encoding 84 tRNA, 22 rRNA, and 4,427 protein-coding genes. The comparison between SH UFPR1 genome and a multidrug-resistant SL476 strain revealed 11 missing genomic fragments and 5 insertions related to bgt, bgr , and rpoS genes. The

Phenotypic and Genotypic Features of a Salmonella Heidelberg Strain Isolated in Broilers in Brazil and Their Possible Association to Antibiotics and Short-Chain Organic Acids Resistance and Susceptibility

Directory of Open Access Journals (Sweden)

Elizabeth Santin

2017-11-01

Full Text Available Salmonella enterica serovar Heidelberg is a human pathogen also found in broilers. A strain (UFPR1 has been associated with field reports of resistance to short-chain organic acids (SCOA in broilers in the South of Brazil, but was susceptible to a Bacillus subtilis-based probiotic added in feed in a related study. This work aimed to (i report clinical symptoms caused by SH UFPR1 in broilers, (ii study its susceptibility to some antibiotics in vitro, and (iii SCOA in vivo; and (iv relate these phenotypic observations with its genome characteristics. Two in vivo trials used 1-day-old chicks housed for 21 days in 8 sterilized isolated negative pressure rooms with 4 battery cages of 12 birds each. Birds were challenged or not with 107 CFU/bird of SH UFPR1 orally and exposed or not to SCOA in a 2 × 2 factorial design. Zootechnical parameters were unaffected (P > 0.05, no clinical signs were observed, and few cecal and hepatic histologic and immune-related alterations were seen, in birds challenged with SH. Formic and propionic acids added together in drinking water, fumaric and benzoic acid in feed (Trial 1, and coated calcium butyrate in feed (Trial 2 did not reduce the SH isolation frequencies seen in cecum and liver in broilers after SH challenge (P > 0.05. SH UFPR1 was susceptible to amikacin, amoxicillin + clavulanate, ceftiofur, cephalexin, doxycycline and oxytetracycline; and mildly susceptible to ampicillin + sulbactam, cephalothin, ciprofloxacin, enrofloxacin, and gentamycin in an in vitro minimum inhibitory concentration model using Mueller–Hinton agar. The whole genome of SH UFPR1 was sequenced and consisted of a circular chromosome, spanning 4,760,321 bp with 52.18% of GC-content encoding 84 tRNA, 22 rRNA, and 4,427 protein-coding genes. The comparison between SH UFPR1 genome and a multidrug-resistant SL476 strain revealed 11 missing genomic fragments and 5 insertions related to bgt, bgr, and rpoS genes. The

Regulatory network controlling extracellular proteins in Erwinia carotovora subsp. carotovora: FlhDC, the master regulator of flagellar genes, activates rsmB regulatory RNA production by affecting gacA and hexA (lrhA) expression.

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Cui, Yaya; Chatterjee, Asita; Yang, Hailian; Chatterjee, Arun K

2008-07-01

Erwinia carotovora subsp. carotovora produces an array of extracellular proteins (i.e., exoproteins), including plant cell wall-degrading enzymes and Harpin, an effector responsible for eliciting hypersensitive reaction. Exoprotein genes are coregulated by the quorum-sensing signal, N-acyl homoserine lactone, plant signals, an assortment of transcriptional factors/regulators (GacS/A, ExpR1, ExpR2, KdgR, RpoS, HexA, and RsmC) and posttranscriptional regulators (RsmA, rsmB RNA). rsmB RNA production is positively regulated by GacS/A, a two-component system, and negatively regulated by HexA (PecT in Erwinia chrysanthemi; LrhA [LysR homolog A] in Escherichia coli) and RsmC, a putative transcriptional adaptor. While free RsmA, an RNA-binding protein, promotes decay of mRNAs of exoprotein genes, binding of RsmA with rsmB RNA neutralizes the RsmA effect. In the course of studies of GacA regulation, we discovered that a locus bearing strong homology to the flhDC operon of E. coli also controls extracellular enzyme production. A transposon insertion FlhDC(-) mutant produces very low levels of pectate lyase, polygalacturonase, cellulase, protease, and E. carotovora subsp. carotovora Harpin (Harpin(Ecc)) and is severely attenuated in its plant virulence. The production of these exoproteins is restored in the mutant carrying an FlhDC(+) plasmid. Sequence analysis and transcript assays disclosed that the flhD operon of E. carotovora subsp. carotovora, like those of other enterobacteria, consists of flhD and flhC. Complementation analysis revealed that the regulatory effect requires functions of both flhD and flhC products. The data presented here show that FlhDC positively regulates gacA, rsmC, and fliA and negatively regulates hexA (lrhA). Evidence shows that FlhDC controls extracellular protein production through cumulative effects on hexA and gacA. Reduced levels of GacA and elevated levels of HexA in the FlhDC(-) mutant are responsible for the inhibition of rsmB RNA

Regulatory Network Controlling Extracellular Proteins in Erwinia carotovora subsp. carotovora: FlhDC, the Master Regulator of Flagellar Genes, Activates rsmB Regulatory RNA Production by Affecting gacA and hexA (lrhA) Expression▿

Science.gov (United States)

Cui, Yaya; Chatterjee, Asita; Yang, Hailian; Chatterjee, Arun K.

2008-01-01

Erwinia carotovora subsp. carotovora produces an array of extracellular proteins (i.e., exoproteins), including plant cell wall-degrading enzymes and Harpin, an effector responsible for eliciting hypersensitive reaction. Exoprotein genes are coregulated by the quorum-sensing signal, N-acyl homoserine lactone, plant signals, an assortment of transcriptional factors/regulators (GacS/A, ExpR1, ExpR2, KdgR, RpoS, HexA, and RsmC) and posttranscriptional regulators (RsmA, rsmB RNA). rsmB RNA production is positively regulated by GacS/A, a two-component system, and negatively regulated by HexA (PecT in Erwinia chrysanthemi; LrhA [LysR homolog A] in Escherichia coli) and RsmC, a putative transcriptional adaptor. While free RsmA, an RNA-binding protein, promotes decay of mRNAs of exoprotein genes, binding of RsmA with rsmB RNA neutralizes the RsmA effect. In the course of studies of GacA regulation, we discovered that a locus bearing strong homology to the flhDC operon of E. coli also controls extracellular enzyme production. A transposon insertion FlhDC− mutant produces very low levels of pectate lyase, polygalacturonase, cellulase, protease, and E. carotovora subsp. carotovora Harpin (HarpinEcc) and is severely attenuated in its plant virulence. The production of these exoproteins is restored in the mutant carrying an FlhDC+ plasmid. Sequence analysis and transcript assays disclosed that the flhD operon of E. carotovora subsp. carotovora, like those of other enterobacteria, consists of flhD and flhC. Complementation analysis revealed that the regulatory effect requires functions of both flhD and flhC products. The data presented here show that FlhDC positively regulates gacA, rsmC, and fliA and negatively regulates hexA (lrhA). Evidence shows that FlhDC controls extracellular protein production through cumulative effects on hexA and gacA. Reduced levels of GacA and elevated levels of HexA in the FlhDC− mutant are responsible for the inhibition of rsmB RNA production

Identification of Fitness Determinants during Energy-Limited Growth Arrest in Pseudomonas aeruginosa.

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Basta, David W; Bergkessel, Megan; Newman, Dianne K

2017-11-28

Microbial growth arrest can be triggered by diverse factors, one of which is energy limitation due to scarcity of electron donors or acceptors. Genes that govern fitness during energy-limited growth arrest and the extent to which they overlap between different types of energy limitation are poorly defined. In this study, we exploited the fact that Pseudomonas aeruginosa can remain viable over several weeks when limited for organic carbon (pyruvate) as an electron donor or oxygen as an electron acceptor. ATP values were reduced under both types of limitation, yet more severely in the absence of oxygen. Using transposon-insertion sequencing (Tn-seq), we identified fitness determinants in these two energy-limited states. Multiple genes encoding general functions like transcriptional regulation and energy generation were required for fitness during carbon or oxygen limitation, yet many specific genes, and thus specific activities, differed in their relevance between these states. For instance, the global regulator RpoS was required during both types of energy limitation, while other global regulators such as DksA and LasR were required only during carbon or oxygen limitation, respectively. Similarly, certain ribosomal and tRNA modifications were specifically required during oxygen limitation. We validated fitness defects during energy limitation using independently generated mutants of genes detected in our screen. Mutants in distinct functional categories exhibited different fitness dynamics: regulatory genes generally manifested a phenotype early, whereas genes involved in cell wall metabolism were required later. Together, these results provide a new window into how P. aeruginosa survives growth arrest. IMPORTANCE Growth-arrested bacteria are ubiquitous in nature and disease yet understudied at the molecular level. For example, growth-arrested cells constitute a major subpopulation of mature biofilms, serving as an antibiotic-tolerant reservoir in chronic

National infrastructure for detecting, controlling and monitoring radioactive materials

International Nuclear Information System (INIS)

Othman, I.

2001-01-01

Full text: The Atomic Energy Commission of Syria (AECS) has the direct responsibility to assure proper safety for handling, accounting for and controlling of nuclear materials and radioactive sources which based on a solid regulatory infrastructure , its elements contains the following items: preventing, responding, training, exchanging of information. Based on the National Law for AECS's Establishment no. 12/1976, a Ministerial Decree for Radiation Safety no. 6514 dated 8.12.1997, issued by the Prime Minister. This Decree authorizes the Syrian Atomic Energy Commission to regulate all kinds of radiation sources. It fulfills the basic requirements of radiation protection and enforce the rules and regulations. The Radiation and Nuclear Regulatory Office (RNRO) is responsible for preparing all the draft regulations. In 1999 the General Regulations for Radiation Protection was issued by the Director General of the AECS, under Decision no. 112/99 dated 3.2.1999. It is based on an IAEA publication, Safety Series no. 115 (1996), and adopted to meet the national requirements. Syria has nine Boarding Centers seeking to prevent unauthorized movement of nuclear material and radioactive sources in and out side the country. They are related to the Atomic Energy Commission (AECS), and are located at the main entrances of the country. Each is provided with the practical tools and equipment in order to assist Radiation Protection Officers (RPO) in fulfilling their commitments, by promoting greater transparency in legal transfers of radioactive materials and devices. They apply complete procedures for the safe import, export and transit of radioactive sources. The RPOs provide authorizations by issuing an entry approval document, after making sure that each concerned shipments has an authorized license from the Syrian Regulatory Body (RNRO) before permitting shipments to leave, arrive or transit across their territory, enabling law enforcement to track the legal movement of

Circuitry linking the global Csr and σE-dependent cell envelope stress response systems.

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Yakhnin, Helen; Aichele, Robert; Ades, Sarah E; Romeo, Tony; Babitzke, Paul

2017-09-18

CsrA of Escherichia coli is an RNA-binding protein that globally regulates a wide variety of cellular processes and behaviors including carbon metabolism, motility, biofilm formation, and the stringent response. CsrB and CsrC are sRNAs that sequester CsrA, thereby preventing CsrA-mRNA interaction. RpoE (σ E ) is the extracytoplasmic stress response sigma factor of E. coli Previous RNA-seq studies identified rpoE mRNA as a CsrA target. Here we explored the regulation of rpoE by CsrA and found that CsrA represses rpoE translation. Gel mobility shift, footprint and toeprint studies identified three CsrA binding sites in the rpoE leader transcript, one of which overlaps the rpoE Shine-Dalgarno (SD) sequence, while another overlaps the rpoE translation initiation codon. Coupled in vitro transcription-translation experiments showed that CsrA represses rpoE translation by binding to these sites. We further demonstrate that σ E indirectly activates transcription of csrB and csrC , leading to increased sequestration of CsrA such that repression of rpoE by CsrA is reduced. We propose that the Csr system fine-tunes the σ E -dependent cell envelope stress response. We also identified a 51 amino acid coding sequence whose stop codon overlaps the rpoE start codon, and demonstrate that rpoE is translationally coupled with this upstream open reading frame (ORF51). Loss of coupling reduces rpoE translation by more than 50%. Identification of a translationally coupled ORF upstream of rpoE suggests that this previously unannotated protein may participate in the cell envelope stress response. In keeping with existing nomenclature, we name ORF51 as rseD , resulting in an operon arrangement of rseD-rpoE-rseA-rseB-rseC IMPORTANCE CsrA posttranscriptionally represses genes required for bacterial stress responses, including the stringent response, catabolite repression, and the RpoS (σ S )-mediated general stress response. We show that CsrA represses translation of rpoE , encoding the

Conditional Function of Autoaggregative Protein Cah and Common cah Mutations in Shiga Toxin-Producing Escherichia coli.

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Carter, Michelle Qiu; Brandl, Maria T; Kudva, Indira T; Katani, Robab; Moreau, Matthew R; Kapur, Vivek

2018-01-01

autotransporter protein Cah confers on E. coli DH5α cells a strong autoaggregative phenotype that is inversely correlated with its ability to form biofilms and plays a strain-specific role in plant and animal colonization by STEC. Although cah is widespread in the STEC population, we detected a mutation rate of 31.3% in cah , which is similar to that reported for rpoS and fimH The formation of cell aggregates due to increased bacterium-to-bacterium interactions may be disadvantageous to bacterial populations under conditions that favor a planktonic state in STEC. Therefore, a loss-of-function mutation in cah is likely a selective trait in STEC when autoaggregative properties become detrimental to bacterial cells and may contribute to the adaptability of STEC to fluctuating environments. This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.

The importance of pretreatment tailoring on the performance of ultrafiltration membranes to treat two-phase olive mill wastewater

Directory of Open Access Journals (Sweden)

Ochando Pulido, J. M.

2015-03-01

Full Text Available In this work, the performance of an ultrafiltration (UF membrane in the treatment of the effluents by-produced by olive mills is addressed by applying different pretreatments on the raw effluents. By conducting a photo-catalytic process (UV/TiO2 PC after pH-temperature flocculation (pH-T F higher threshold flux values were observed for all feed stocks than by applying solely the pH-T F process, with an 18.8–34.2% increment. In addition, the performance of the UF membrane was also improved in terms of rejection efficiency, such that higher rejection values were yielded by the membrane for the organic pollutants (RCOD by 48.5 vs. 39.9% and 53.4 vs. 42.0%. The UF membrane performance was also improved in terms of the volume feed recovery factor (VFR, achieving up to 88.2 vs. 87.2% and 90.7 vs. 89.3%. Results in the same line were also observed when the highly polluted olives oil washing wastewater raw stream was previously mixed with the effluent stream coming from the washing of the olives. This permits the UF to permeate, achieving the standard limits to reuse the purified effluent for irrigation purposes (COD values below 1000 mg·L−1, which makes the treatment process cost-effective and results in making the olive oil production process environmentally friendly.En este estudio se aborda el rendimiento de una membrana de ultrafiltración (UF para el tratamiento de los efluentes generados por la industria oleícola, mediante la aplicación de distintos pretratamientos. Tras aplicar un proceso fotocatalítico (UV/TiO2 PC después de una floculación pH-temperatura (pH-T F se observaron flujos límite para todos los efluentes mayores que tras la aplicación únicamente del proceso pH-T F, con incrementos del 18.8–34.2 %. Además, el rendimiento de la membrana de UF mejoró en términos de eficiencia de rechazo, con mayores valores de rechazo respecto de los contaminantes orgánicos (RCOD, 48.5 vs. 39.9 % y 53.4 vs. 42.0 %. El rendimiento de

Malaria Surveillance - United States, 2014.

Science.gov (United States)

Mace, Kimberly E; Arguin, Paul M

2017-05-26

. Less than 1.0% of patients were infected with two species. The infecting species was unreported or undetermined in 11.7% of cases. CDC provided diagnostic assistance for 14.2% of confirmed cases and tested 12.0% of P. falciparum specimens for antimalarial resistance markers. Of patients who reported purpose of travel, 57.5% were visiting friends and relatives (VFR). Among U.S. residents for whom information on chemoprophylaxis use and travel region was known, 7.8% reported that they initiated and adhered to a chemoprophylaxis drug regimen recommended by CDC for the regions to which they had traveled. Thirty-two cases were among pregnant women, none of whom had adhered to chemoprophylaxis. Among all reported cases, 17.0% were classified as severe illness, and five persons with malaria died. CDC received 137 P. falciparum-positive samples for the detection of antimalarial resistance markers (although some loci for chloroquine and mefloquine were untestable for up to nine samples). Of the 137 samples tested, 131 (95.6%) had genetic polymorphisms associated with pyrimethamine drug resistance, 96 (70.0%) with sulfadoxine resistance, 77 (57.5%) with chloroquine resistance, three (2.3%) with mefloquine drug resistance, one (html). Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient's age and medical history, likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Recent molecular laboratory advances have enabled CDC to identify and conduct molecular surveillance of antimalarial drug resistance markers (https://www.cdc.gov/malaria/features/ars.html) and improve the ability of CDC to track, guide treatment, and manage drug resistance in malaria parasites both domestically and globally. For this effort to be successful, specimens should be submitted for all cases diagnosed in the United States. Clinicians should consult CDC Guidelines for Treatment of Malaria in the

Using Natural Products to Treat Resistant and Persistent Bacterial Infections

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Deering, Robert W.

-lactams, tetracyclines, aminoglycosides, and chloramphenicol. The efflux pump inhibitory mechanism was further proved through an accumulation assay with the Hoechst dye 33342. In chapter three, we report the discovery of a 1,2-benzisoxazole with new antibacterial activity against MDR A. baumannii, a pathogen with a critical need of new treatments. This compound was produced by bacterial fermentation and synthetic preparation and shows minimum inhibitory concentrations as low as 6.25 ?g/mL against a panel of four clinically relevant A. baumannii strains. Key structure activity relationships were demonstrated using synthetic analogs of the lead 1,2-benzisoxazole. We advocate for further studies to advance the development of this compound. The third study, describes an in vitro quiescent state of uropathogenic E. coli (UPEC) and bacteria-produced signals that can prevent this state. Quiescence was seen in the classic UPEC strain CFT073 only when grown on glucose M9 minimal medium agar plates seeded with ≤10 6 CFU. Interestingly, this quiescent state is seen in 80% of E. coli phylogenetic group B2 multilocus sequence type 73 strains, as well as 22.5% of randomly selected UPEC strains isolated from community acquired urinary tract infections in Denmark. Furthermore, it was determined that CFT073 forms a high persister cell fraction under these growth conditions. Both the persistent and quiescent states were inhibited significantly by a cocktail of lysine, tyrosine, and methionine at concentrations relevant to those in human urine. The use of CFT073 mini-Tn5 metabolic mutants ( gnd, gdhA, pykF, sdhA, and zwf) showed that both quiescence and persistence require a complete TCA cycle, but that the dormant states differ in that persistence requires a non-functional rpoS gene and quiescence does not. These results suggest that interference with these central metabolic pathways may be able to mitigate UPEC infections. In the fifth chapter, cranberry oligosaccharides and related compounds were