Immunogenicity and protective efficacy of a single-dose live non-pathogenic Escherichia coli oral vaccine against F4-positive enterotoxigenic Escherichia coli challenge in pigs.

Science.gov (United States)

Fairbrother, John Morris; Nadeau, Éric; Bélanger, Louise; Tremblay, Cindy-Love; Tremblay, Danielle; Brunelle, Mélanie; Wolf, Regina; Hellmann, Klaus; Hidalgo, Álvaro

2017-01-05

Enterotoxigenic Escherichia coli strains expressing F4 (K88) fimbriae (F4-ETEC) are one of the most important causes of post-weaning diarrhea (PWD) in pigs. F4, a major antigen, plays an important role in the early steps of the infection. Herein, the efficacy of a live oral vaccine consisting of a non-pathogenic E. coli strain expressing F4 for protection of pigs against PWD was evaluated. Three blinded, placebo-controlled, block design, parallel-group confirmatory experiments were conducted, using an F4-ETEC PWD challenge model, each with a different vaccination-challenge interval (3, 7, and 21days). The pigs were vaccinated via the drinking water with a single dose of the Coliprotec® F4 vaccine one day post-weaning. Efficacy was assessed by evaluating diarrhea, clinical observations, intestinal fluid accumulation, weight gain, intestinal colonization and fecal shedding of F4-ETEC. The immune response was evaluated by measuring serum and intestinal F4-specific antibodies. The administration of the vaccine resulted in a significant reduction of the incidence of moderate to severe diarrhea, ileal colonization by F4-ETEC, and fecal shedding of F4-ETEC after the heterologous challenge at 7 and 21days post-vaccination. The 7-day onset of protection was associated with an increase of serum anti-F4 IgM whereas the 21-day duration of protection was associated with an increase of both serum anti-F4 IgM and IgA. Significant correlations between levels of serum and intestinal secretory anti-F4 antibodies were detected. Maternally derived F4-specific serum antibodies did not interfere with the vaccine efficacy. The evaluation of protection following a challenge three days after vaccination showed a reduction of the severity and the duration of diarrhea and of fecal shedding of F4-ETEC. The 7-day onset and the 21-day duration of protection induced by Coliprotec® F4 vaccine administered once in drinking water to pigs of at least 18days of age were confirmed by protection

A Selected Lactobacillus rhamnosus Strain Promotes EGFR-Independent Akt Activation in an Enterotoxigenic Escherichia coli K88-Infected IPEC-J2 Cell Model.

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Wei Zhang

Full Text Available Enterotoxigenic Escherichia coli (ETEC are important intestinal pathogens that cause diarrhea in humans and animals. Although probiotic bacteria may protect against ETEC-induced enteric infections, the underlying mechanisms are unknown. In this study, porcine intestinal epithelial J2 cells (IPEC-J2 were pre-incubated with and without Lactobacillus rhamnosus ATCC 7469 and then exposed to F4+ ETEC. Increases in TLR4 and NOD2 mRNA expression were observed at 3 h after F4+ ETEC challenge, but these increases were attenuated by L. rhamnosus treatment. Expression of TLR2 and NOD1 mRNA was up-regulated in cells pre-treated with L. rhamnosus. Pre-treatment with L. rhamnosus counteracted F4+ ETEC-induced increases in TNF-α concentration. Increased PGE2. concentrations were observed in cells infected with F4+ ETEC and in cells treated with L. rhamnosus only. A decrease in phosphorylated epidermal growth factor receptor (EGFR was observed at 3 h after F4+ ETEC challenge in cells treated with L. rhamnosus. Pre-treatment with L. rhamnosus enhanced Akt phosphorylation and increased ZO-1 and occludin protein expression. Our findings suggest that L. rhamnosus protects intestinal epithelial cells from F4+ ETEC-induced damage, partly through the anti-inflammatory response involving synergism between TLR2 and NOD1. In addition, L. rhamnosus promotes EGFR-independent Akt activation, which may activate intestinal epithelial cells in response to bacterial infection, in turn increasing tight junction integrity and thus enhancing the barrier function and restricting pathogen invasion. Pre-incubation with L. rhamnosus was superior to co-incubation in reducing the adhesion of F4+ ETEC to IPEC-J2 cells and subsequently attenuating F4+ ETEC-induced mucin layer destruction and suppressing apoptosis. Our data indicate that a selected L. rhamnosus strain interacts with porcine intestinal epithelial cells to maintain the epithelial barrier and promote intestinal epithelial

A Selected Lactobacillus rhamnosus Strain Promotes EGFR-Independent Akt Activation in an Enterotoxigenic Escherichia coli K88-Infected IPEC-J2 Cell Model.

Science.gov (United States)

Zhang, Wei; Zhu, Yao-Hong; Yang, Jin-Cai; Yang, Gui-Yan; Zhou, Dong; Wang, Jiu-Feng

2015-01-01

Enterotoxigenic Escherichia coli (ETEC) are important intestinal pathogens that cause diarrhea in humans and animals. Although probiotic bacteria may protect against ETEC-induced enteric infections, the underlying mechanisms are unknown. In this study, porcine intestinal epithelial J2 cells (IPEC-J2) were pre-incubated with and without Lactobacillus rhamnosus ATCC 7469 and then exposed to F4+ ETEC. Increases in TLR4 and NOD2 mRNA expression were observed at 3 h after F4+ ETEC challenge, but these increases were attenuated by L. rhamnosus treatment. Expression of TLR2 and NOD1 mRNA was up-regulated in cells pre-treated with L. rhamnosus. Pre-treatment with L. rhamnosus counteracted F4+ ETEC-induced increases in TNF-α concentration. Increased PGE2. concentrations were observed in cells infected with F4+ ETEC and in cells treated with L. rhamnosus only. A decrease in phosphorylated epidermal growth factor receptor (EGFR) was observed at 3 h after F4+ ETEC challenge in cells treated with L. rhamnosus. Pre-treatment with L. rhamnosus enhanced Akt phosphorylation and increased ZO-1 and occludin protein expression. Our findings suggest that L. rhamnosus protects intestinal epithelial cells from F4+ ETEC-induced damage, partly through the anti-inflammatory response involving synergism between TLR2 and NOD1. In addition, L. rhamnosus promotes EGFR-independent Akt activation, which may activate intestinal epithelial cells in response to bacterial infection, in turn increasing tight junction integrity and thus enhancing the barrier function and restricting pathogen invasion. Pre-incubation with L. rhamnosus was superior to co-incubation in reducing the adhesion of F4+ ETEC to IPEC-J2 cells and subsequently attenuating F4+ ETEC-induced mucin layer destruction and suppressing apoptosis. Our data indicate that a selected L. rhamnosus strain interacts with porcine intestinal epithelial cells to maintain the epithelial barrier and promote intestinal epithelial cell activation in

Alkaline pH Is a signal for optimal production and secretion of the heat labile toxin, LT in enterotoxigenic Escherichia coli (ETEC.

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Lucia Gonzales

Full Text Available Enterotoxigenic Escherichia coli (ETEC cause secretory diarrhea in children and travelers to endemic areas. ETEC spreads through the fecal-oral route. After ingestion, ETEC passes through the stomach and duodenum before it colonizes the lower part of the small intestine, exposing bacteria to a wide range of pH and environmental conditions. This study aimed to determine the impact of external pH and activity of the Cyclic AMP receptor protein (CRP on the regulation of production and secretion of heat labile (LT enterotoxin. ETEC strain E2863wt and its isogenic mutant E2863ΔCRP were grown in LBK media buffered to pH 5, 7 and 9. GM1 ELISA, cDNA and cAMP analyses were carried out on bacterial pellet and supernatant samples derived from 3 and 5 hours growth and from overnight cultures. We confirm that CRP is a repressor of LT transcription and production as has been shown before but we show for the first time that CRP is a positive regulator of LT secretion both in vitro and in vivo. LT secretion increased at neutral to alkaline pH compared to acidic pH 5 where secretion was completely inhibited. At pH 9 secretion of LT was optimal resulting in 600 percent increase of secreted LT compared to unbuffered LBK media. This effect was not due to membrane leakage since the bacteria were viable at pH 9. The results indicate that the transition to the alkaline duodenum and/or exposure to high pH close to the epithelium as well as activation of the global transcription factor CRP are signals that induce secretion of the LT toxin in ETEC.

GLYCOSYLATED YGHJ POLYPEPTIDES FROM ENTEROTOXIGENIC ESCHERICHIA COLI (ETEC)

DEFF Research Database (Denmark)

2017-01-01

The present invention relates to glycosylated YghJ polypeptides from or derived from enterotoxigenic Escherichia coli (ETEC) that are immunogenic. In particular, the present invention relates to compositions or vaccines comprising the polypeptides and their application in immunization, vaccination...

The fecal presence of enterotoxin and F4 genes as an indicator of efficacy of treatment with colistin sulfate in pigs.

Science.gov (United States)

Rhouma, Mohamed; Fairbrother, John Morris; Thériault, William; Beaudry, Francis; Bergeron, Nadia; Laurent-Lewandowski, Sylvette; Letellier, Ann

2017-01-05

Enterotoxigenic Escherichia coli (ETEC) strains producing multiple enterotoxins are important causes of post-weaning diarrhea (PWD) in pigs. The aim of the present study was to investigate the fecal presence of ETEC enterotoxin as well as F4 and F18 genes as an indicator of colistin sulfate (CS) efficacy for treatment of PWD in pigs. Forty-eight piglets were weaned at the age of 21 days, and were divided into four groups: challenged treated, challenged untreated, unchallenged treated, and unchallenged untreated. Challenge was performed using 10 9  CFU of an ETEC: F4 strain, and treatment was conducted using oral CS at the dose of 50,000 IU/kg. The fecal presence of genes encoding for STa, STb, LT, F4 and F18 was detected using PCR. The PCR amplification of ETEC virulence genes showed that nearly 100% of pigs excreted genes encoding for STa and STb toxins in the feces before the challenge. These genes, in the absence of the gene encoding F4, were considered as a marker for F4-negative ETEC. One day after ETEC: F4 oral challenge pigs in the two challenged groups excreted the genes encoding LT and F4 in the feces. These genes were considered as a marker for F4-positive ETEC. However, the gene encoding F18 was not detected in any fecal samples of the 4 groups throughout the experiment. After only 3 days of successive oral treatment with CS, a significant reduction in both the F4-positive and negative ETEC populations was observed in the challenged treated group compared to the challenged untreated group (p F4-positive and F4-negative ETEC in pigs. However, CS clinical efficiency was correlated with non-detection of F4-positive ETEC in the feces. Furthermore the fecal presence of F4-negative ETEC was not associated with clinical symptoms of post-weaning diarrhea in pigs.

Efficacy of a single oral dose of a live bivalent E. coli vaccine against post-weaning diarrhea due to F4 and F18-positive enterotoxigenic E. coli.

Science.gov (United States)

Nadeau, É; Fairbrother, J M; Zentek, J; Bélanger, L; Tremblay, D; Tremblay, C-L; Röhe, I; Vahjen, W; Brunelle, M; Hellmann, K; Cvejić, D; Brunner, B; Schneider, C; Bauer, K; Wolf, R; Hidalgo, Á

2017-08-01

F4- and F18-positive enterotoxigenic E. coli strains (F4-ETEC and F18-ETEC) are important causes of post-weaning diarrhea (PWD) in pigs. F4 (antigenic variant ac) and F18 (ab and ac) fimbriae are major antigens that play an important role in the early stages of infection. Herein, the efficacy of a live oral vaccine consisting of two non-pathogenic E. coli strains, one F4ac- and one F18ac-positive, was evaluated using F4ac-ETEC and F18ab-ETEC challenge models. A randomized, masked, placebo-controlled, block design, parallel-group confirmatory study with two different vaccination-challenge intervals (7 and 21 days) was conducted for each challenge model. The vaccine was administered in one dose, to ≥18-day-old piglets via drinking water. Efficacy was assessed by evaluating diarrhea, clinical observations, weight gain and fecal shedding of F4-ETEC or F18-ETEC. Anti-F4 and anti-F18 immunoglobulins in blood were measured. The vaccination resulted in significant reductions in clinical PWD and fecal shedding of F4-ETEC and F18-ETEC after the 7- and 21-day-post-vaccination heterologous challenges, except for after the 21-day-post-vaccination F4-ETEC challenge, when the clinical PWD was too mild to demonstrate efficacy. A significant reduction of mortality and weight loss by vaccination were observed following the F18-ETEC challenge. The 7-day protection was associated with induction of anti-F4 and anti-F18 IgM, whereas the 21-day protection was mainly associated with anti-F4 and anti-F18 IgA. The 7-day onset and 21-day duration of protection induced by this vaccine administered once in drinking water to pigs of at least 18days of age were confirmed by protection against F4-ETEC and F18-ETEC, and induction of F4 and F18-specific immunity. Cross protection of the vaccine against F18ab-E. coli was demonstrated for both the 7- and 21-day F18-ETEC challenges. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Multiepitope fusion antigen induces broadly protective antibodies that prevent adherence of Escherichia coli strains expressing colonization factor antigen I (CFA/I), CFA/II, and CFA/IV.

Science.gov (United States)

Ruan, Xiaosai; Knudsen, David E; Wollenberg, Katie M; Sack, David A; Zhang, Weiping

2014-02-01

Diarrhea is the second leading cause of death in children younger than 5 years and continues to be a major threat to global health. Enterotoxigenic Escherichia coli (ETEC) strains are the most common bacteria causing diarrhea in developing countries. ETEC strains are able to attach to host small intestinal epithelial cells by using bacterial colonization factor antigen (CFA) adhesins. This attachment helps to initiate the diarrheal disease. Vaccines that induce antiadhesin immunity to block adherence of ETEC strains that express immunologically heterogeneous CFA adhesins are expected to protect against ETEC diarrhea. In this study, we created a CFA multiepitope fusion antigen (MEFA) carrying representative epitopes of CFA/I, CFA/II (CS1, CS2, and CS3), and CFA/IV (CS4, CS5, and CS6), examined its immunogenicity in mice, and assessed the potential of this MEFA as an antiadhesin vaccine against ETEC. Mice intraperitoneally immunized with this CFA MEFA exhibited no adverse effects and developed immune responses to CFA/I, CFA/II, and CFA/IV adhesins. Moreover, after incubation with serum of the immunized mice, ETEC or E. coli strains expressing CFA/I, CFA/II, or CFA/IV adhesins were significantly inhibited in adherence to Caco-2 cells. Our results indicated this CFA MEFA elicited antibodies that not only cross-reacted to CFA/I, CFA/II and CFA/IV adhesins but also broadly inhibited adherence of E. coli strains expressing these seven adhesins and suggested that this CFA MEFA could be a candidate to induce broad-spectrum antiadhesin protection against ETEC diarrhea. Additionally, this antigen construction approach (creating an MEFA) may be generally used in vaccine development against heterogenic pathogens.

An Evidenced-Based Scale of Disease Severity following Human Challenge with Enteroxigenic Escherichia coli.

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Chad K Porter

Full Text Available Experimental human challenge models have played a major role in enhancing our understanding of infectious diseases. Primary outcomes have typically utilized overly simplistic outcomes that fail to entirely account for complex illness syndromes. We sought to characterize clinical outcomes associated with experimental infection with enterotoxigenic Escherichia coli (ETEC and to develop a disease score.Data were obtained from prior controlled human ETEC infection studies. Correlation and univariate regression across sign and symptom severity was performed. A multiple correspondence analysis was conducted. A 3-parameter disease score with construct validity was developed in an iterative fashion, compared to standard outcome definitions and applied to prior vaccine challenge trials.Data on 264 subjects receiving seven ETEC strains at doses from 1x105 to 1x1010 cfu were used to construct a standardized dataset. The strongest observed correlation was between vomiting and nausea (r = 0.65; however, stool output was poorly correlated with subjective activity-impacting outcomes. Multiple correspondence analyses showed covariability in multiple signs and symptoms, with severity being the strongest factor corresponding across outcomes. The developed disease score performed well compared to standard outcome definitions and differentiated disease in vaccinated and unvaccinated subjects.Frequency and volumetric definitions of diarrhea severity poorly characterize ETEC disease. These data support a disease severity score accounting for stool output and other clinical signs and symptoms. Such a score could serve as the basis for better field trial outcomes and gives an additional outcome measure to help select future vaccines that warrant expanded testing in pivotal pre-licensure trials.

Possibilidades de atuação para o licenciado em Psicologia nas Etecs Posibilidades de actuación para el licenciado en Psicología en las Etecs Possibilities of acting for the licensee in Psychology in Etecs

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Angelina Pandita-Pereira

2012-01-01

Full Text Available Este artigo apresenta um levantamento do campo de atuação possível para o licenciado em Psicologia nas escolas técnicas estaduais de São Paulo (Etecs, buscando evidenciar a existência desse campo e provocar o debate sobre ele. Iniciamos o texto historicizando e contextualizando o ensino de Psicologia na educação profissional de nível médio. Posteriormente, apresentamos o processo de construção dos dados, que consistiu em levantamento e organização de informações disponíveis em sítios oficiais do Centro Paula Souza, identificando em quais disciplinas e cursos o licenciado em Psicologia pode ministrar aulas nas Etecs, bem como quão representativos são esses cursos na rede de ensino técnica pública estadual. Os resultados apontam um amplo campo possível de atuação para o licenciado em Psicologia, como em cursos técnicos de Administração, Marketing e Segurança do Trabalho, e sua ausência nos cursos técnicos de Enfermagem, e incitam ainda questões sobre os objetivos e as contribuições dos conhecimentos psicológicos abordados nas Etecs e sobre os fatores que determinam sua presença nesse contexto. Os resultados destacam também a necessidade de os profissionais da Psicologia fomentarem discussões quanto à licenciatura em Psicologia no sentido de avaliar as contribuições que o ensino da área pode trazer ao ensino médio profissional.Este artículo presenta un relevamiento del campo de actuación posible para el licenciado en Psicología en las escuelas técnicas estaduales de São Paulo (Etecs, buscando evidenciar la existencia de ese campo y provocar el debate sobre él. Iniciamos el texto historiando y contextualizando la enseñanza de Psicología en la educación profesional de nivel secundario. Posteriormente, presentamos el proceso de construcción de los datos, que consistió en el relevamiento y organización de informaciones disponibles en sitios oficiales del Centro Paula Souza, identificando en que

Lactobacillus plantarum BSGP201683 Isolated from Giant Panda Feces Attenuated Inflammation and Improved Gut Microflora in Mice Challenged with Enterotoxigenic Escherichia coli

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Qian Liu

2017-09-01

Full Text Available In this work, we searched for an effective probiotic that can help control intestinal infection, particularly enterotoxigenic Escherichia coli K88 (ETEC invasion, in giant panda (Ailuropoda melanoleuca. As a potential probiotic strain, Lactobacillus plantarum BSGP201683 (L. plantarum G83 was isolated from the feces of giant panda and proven beneficial in vitro. This study was aimed to evaluate the protective effect of L. plantarum G83 in mice challenged with ETEC. The mice were orally administered with 0.2 mL of PBS containing L. plantarum G83 at 0 colony-forming units (cfu mL−1 (control; negative control, ETEC group, 5.0 × 108 cfu mL−1 (LDLP, 5.0 × 109 cfu mL−1 (MDLP, and 5.0 × 1010 cfu mL−1 (HDLP for 14 consecutive days. At day 15, the mice (LDLP, MDLP, HDLP, and ETEC groups were challenged with ETEC and assessed at 0, 24, and 144 h. Animal health status; chemical and biological intestinal barriers; and body weight were measured. Results showed that L. plantarum G83 supplementation protected the mouse gut mainly by attenuating inflammation and improving the gut microflora. Most indices significantly changed at 24 h after challenge compared to those at 0 and 144 h. All treatment groups showed inhibited plasma diamine oxidase activity and D-lactate concentration. Tight-junction protein expression was down-regulated, and interleukin (IL-1β, IL-6, IL-8, TLR4, and MyD88 levels were up-regulated in the jejunum in the LDLP and MDLP groups. The number of the Enterobacteriaceae family and the heat-labile enterotoxin (LT gene decreased (P < 0.05 in the colons in the LDLP and MDLP groups. All data indicated that L. plantarum G83 could attenuate acute intestinal inflammation caused by ETEC infection, and the low and intermediate doses were superior to the high dose. These findings suggested that L. plantarum G83 may serve as a protective probiotic for intestinal disease and merits further investigation.

Lactobacillus plantarum BSGP201683 Isolated from Giant Panda Feces Attenuated Inflammation and Improved Gut Microflora in Mice Challenged with Enterotoxigenic Escherichia coli.

Science.gov (United States)

Liu, Qian; Ni, Xueqin; Wang, Qiang; Peng, Zhirong; Niu, Lili; Wang, Hengsong; Zhou, Yi; Sun, Hao; Pan, Kangcheng; Jing, Bo; Zeng, Dong

2017-01-01

In this work, we searched for an effective probiotic that can help control intestinal infection, particularly enterotoxigenic Escherichia coli K88 (ETEC) invasion, in giant panda ( Ailuropoda melanoleuca ). As a potential probiotic strain, Lactobacillus plantarum BSGP201683 ( L. plantarum G83) was isolated from the feces of giant panda and proven beneficial in vitro . This study was aimed to evaluate the protective effect of L. plantarum G83 in mice challenged with ETEC. The mice were orally administered with 0.2 mL of PBS containing L. plantarum G83 at 0 colony-forming units (cfu) mL -1 (control; negative control, ETEC group), 5.0 × 10 8 cfu mL -1 (LDLP), 5.0 × 10 9 cfu mL -1 (MDLP), and 5.0 × 10 10 cfu mL -1 (HDLP) for 14 consecutive days. At day 15, the mice (LDLP, MDLP, HDLP, and ETEC groups) were challenged with ETEC and assessed at 0, 24, and 144 h. Animal health status; chemical and biological intestinal barriers; and body weight were measured. Results showed that L. plantarum G83 supplementation protected the mouse gut mainly by attenuating inflammation and improving the gut microflora. Most indices significantly changed at 24 h after challenge compared to those at 0 and 144 h. All treatment groups showed inhibited plasma diamine oxidase activity and D -lactate concentration. Tight-junction protein expression was down-regulated, and interleukin (IL)-1β, IL-6, IL-8, TLR4, and MyD88 levels were up-regulated in the jejunum in the LDLP and MDLP groups. The number of the Enterobacteriaceae family and the heat-labile enterotoxin (LT) gene decreased ( P < 0.05) in the colons in the LDLP and MDLP groups. All data indicated that L. plantarum G83 could attenuate acute intestinal inflammation caused by ETEC infection, and the low and intermediate doses were superior to the high dose. These findings suggested that L. plantarum G83 may serve as a protective probiotic for intestinal disease and merits further investigation.

Determination of the optimum standardised ileal digestible sulphur amino acids to lysine ratio in weaned pigs challenged with enterotoxigenic Escherichia coli

DEFF Research Database (Denmark)

Capozzalo, M. M.; Resink, J. W.; Htoo, J. K.

2017-01-01

This experiment tested the hypothesis that pigs challenged with an enterotoxigenic strain of E. coli (ETEC) would require a higher sulphur amino acids (SAA) to Lys ratio (SAA:Lys). Pigs (n = 120) weighing 7.4 ± 0.52 kg (mean ± SD) and weaned at 27 d (Pietrain genotype, mixed sex) were stratified...

Receptor for the F4 fimbriae of enterotoxigenic Escherichia coli (ETEC).

Science.gov (United States)

Xia, Pengpeng; Zou, Yajie; Wang, Yiting; Song, Yujie; Liu, Wei; Francis, David H; Zhu, Guoqiang

2015-06-01

Infection with F4(+) enterotoxigenic Escherichia coli (ETEC) responsible for diarrhea in neonatal and post-weaned piglets leads to great economic losses in the swine industry. These pathogenic bacteria express either of three fimbrial variants F4ab, F4ac, and F4ad, which have long been known for their importance in host infection and initiating protective immune responses. The initial step in infection for the bacterium is to adhere to host enterocytes through fimbriae-mediated recognition of receptors on the host cell surface. A number of receptors for ETEC F4 have now been described and characterized, but their functions are still poorly understood. The current review summarizes the latest research addressing the characteristics of F4 fimbriae receptors and the interactions of F4 fimbriae and their receptors on host cells. These include observations that as follows: (1) FaeG mediates the binding activities of F4 and is an essential component of the F4 fimbriae, (2) the F4 fimbrial receptor gene is located in a region of chromosome 13, (3) the biochemical properties of F4 fimbrial receptors that form the binding site of the bacterium are now recognized, and (4) specific receptors confer susceptibility/resistance to ETEC F4 infection in pigs. Characterizing the host-pathogen interaction will be crucial to understand the pathogenicity of the bacteria, provide insights into receptor activation of the innate immune system, and develop therapeutic strategies to prevent this illness.

Development and preclinical evaluation of safety and immunogenicity of an oral ETEC vaccine containing inactivated E. coli bacteria overexpressing colonization factors CFA/I, CS3, CS5 and CS6 combined with a hybrid LT/CT B subunit antigen, administered alone and together with dmLT adjuvant.

Science.gov (United States)

Holmgren, J; Bourgeois, L; Carlin, N; Clements, J; Gustafsson, B; Lundgren, A; Nygren, E; Tobias, J; Walker, R; Svennerholm, A-M

2013-05-07

A first-generation oral inactivated whole-cell enterotoxigenic Escherichia coli (ETEC) vaccine, comprising formalin-killed ETEC bacteria expressing different colonization factor (CF) antigens combined with cholera toxin B subunit (CTB), when tested in phase III studies did not significantly reduce overall (generally mild) ETEC diarrhea in travelers or children although it reduced more severe ETEC diarrhea in travelers by almost 80%. We have now developed a novel more immunogenic ETEC vaccine based on recombinant non-toxigenic E. coli strains engineered to express increased amounts of CF antigens, including CS6 as well as an ETEC-based B subunit protein (LCTBA), and the optional combination with a nontoxic double-mutant heat-labile toxin (LT) molecule (dmLT) as an adjuvant. Two test vaccines were prepared under GMP: (1) A prototype E. coli CFA/I-only formalin-killed whole-cell+LCTBA vaccine, and (2) A "complete" inactivated multivalent ETEC-CF (CFA/I, CS3, CS5 and CS6 antigens) whole-cell+LCTBA vaccine. These vaccines, when given intragastrically alone or together with dmLT in mice, were well tolerated and induced strong intestinal-mucosal IgA antibody responses as well as serum IgG and IgA responses to each of the vaccine CF antigens as well as to LT B subunit (LTB). Both mucosal and serum responses were further enhanced (adjuvanted) when the vaccines were co-administered with dmLT. We conclude that the new multivalent oral ETEC vaccine, both alone and especially in combination with the dmLT adjuvant, shows great promise for further testing in humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cost-benefit of WC/rBS oral cholera vaccine for vaccination against ETEC-caused travelers' diarrhea.

Science.gov (United States)

Lundkvist, Jonas; Steffen, Robert; Jönsson, Bengt

2009-01-01

The most common infectious health problem encountered by travelers to countries in the developing region is travelers' diarrhea (TD), with enterotoxigenic Escherichia coli (ETEC) being the most common pathogen isolated. Although mild in most cases, the disease still leads to the loss of a significant part of a vacation or business trip. There is currently a lack of knowledge about the costs in relation to the benefits of vaccination against TD caused by ETEC, and the purposes of this study were to estimate and develop a cost-benefit analysis of vaccination using whole-cell/recombinant-B-subunit oral cholera vaccine. The consequences of the vaccination were identified and quantified in monetary terms. The cost-benefits for leisure and business travelers were assessed separately. The value of the travel was separated into the cost of the trip and of lost leisure time/business opportunities. A person with TD was in base case estimated to lose on average 3.5 days of a 7-day leisure trip and 2.5 days of a 4-day business trip. Results are presented for a Canadian traveler to endemic areas in year 2007 in US$. The average cost of a TD event was estimated at $1,460 and $1,996 for leisure and business travelers, respectively. The net value of the vaccination, however, varied with the risk of the disease. Through extensive literature searches, an updated ETEC map illustrating the proportion of ETEC-caused TD was created. The analysis indicated that vaccination would be considered cost-effective at incidence rates of ETEC-caused TD above about 13 and 9% for leisure and business travelers, respectively. It is, however, important to keep in mind that it is the value of the travel for the individual traveler that will decide if the vaccination provides good value for money.

Characterisation of five candidate genes within the ETEC F4ab/ac candidate region in pigs

DEFF Research Database (Denmark)

Jacobsen, Mette Juul; Cirera Salicio, Susanna; Joller, David

2011-01-01

by haplotype sharing to a 2.5 Mb region on pig chromosome 13, a region containing 18 annotated genes. FINDINGS: The coding regions of five candidate genes for susceptibility to ETEC F4ab/ac infection (TFRC, ACK1, MUC20, MUC4 and KIAA0226), all located in the 2.5 Mb region, were investigated for the presence...... polymorphism in exon 22 of KIAA0226. Transcriptional profiles of the five genes were investigated in a porcine tissue panel including various intestinal tissues. All five genes were expressed in intestinal tissues at different levels but none of the genes were found differentially expressed between ETEC F4ab/ac...... of the amino acids composition. However, we cannot exclude that the five tested genes are bona fide candidate genes for susceptibility to ETEC F4ab/ac infection since the identified polymorphism might affect the translational apparatus, alternative splice forms may exist and post translational mechanisms might...

Multiepitope Fusion Antigen Induces Broadly Protective Antibodies That Prevent Adherence of Escherichia coli Strains Expressing Colonization Factor Antigen I (CFA/I), CFA/II, and CFA/IV

OpenAIRE

Ruan, Xiaosai; Knudsen, David E.; Wollenberg, Katie M.; Sack, David A.; Zhang, Weiping

2014-01-01

Diarrhea is the second leading cause of death in children younger than 5 years and continues to be a major threat to global health. Enterotoxigenic Escherichia coli (ETEC) strains are the most common bacteria causing diarrhea in developing countries. ETEC strains are able to attach to host small intestinal epithelial cells by using bacterial colonization factor antigen (CFA) adhesins. This attachment helps to initiate the diarrheal disease. Vaccines that induce antiadhesin immunity to block a...

Bioactivity of tempe by inhibiting adhesion of ETEC to intestinal cells, as influenced by fermentation substrates and starter pure cultures

NARCIS (Netherlands)

Roubos-van den Hil, P.J.; Nout, M.J.R.; Meulen, van der J.; Gruppen, H.

2010-01-01

Soya bean tempe is known for its bioactivity in reducing the severity of diarrhoea in piglets. This bioactivity is caused by an inhibition of the adhesion of enterotoxigenic Escherichia coli (ETEC) to intestinal cells. In this paper, we assessed the bioactive effect of soya tempe on a range of ETEC

A Selected Lactobacillus rhamnosus Strain Promotes EGFR-Independent Akt Activation in an Enterotoxigenic Escherichia coli K88-Infected IPEC-J2 Cell Model

OpenAIRE

Zhang, Wei; Zhu, Yao-Hong; Yang, Jin-Cai; Yang, Gui-Yan; Zhou, Dong; Wang, Jiu-Feng

2015-01-01

Enterotoxigenic Escherichia coli (ETEC) are important intestinal pathogens that cause diarrhea in humans and animals. Although probiotic bacteria may protect against ETEC-induced enteric infections, the underlying mechanisms are unknown. In this study, porcine intestinal epithelial J2 cells (IPEC-J2) were pre-incubated with and without Lactobacillus rhamnosus ATCC 7469 and then exposed to F4+ ETEC. Increases in TLR4 and NOD2 mRNA expression were observed at 3 h after F4+ ETEC challenge, but t...

Five challenges in modelling interacting strain dynamics

Directory of Open Access Journals (Sweden)

Paul S. Wikramaratna

2015-03-01

Full Text Available Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity accumulates over multiple exposures.

Development and accuracy of quantitative real-time polymerase chain reaction assays for detection and quantification of enterotoxigenic Escherichia coli (ETEC) heat labile and heat stable toxin genes in travelers' diarrhea samples.

Science.gov (United States)

Youmans, Bonnie P; Ajami, Nadim J; Jiang, Zhi-Dong; Petrosino, Joseph F; DuPont, Herbert L; Highlander, Sarah K

2014-01-01

Enterotoxigenic Escherichia coli (ETEC), the leading bacterial pathogen of travelers' diarrhea, is routinely detected by an established DNA hybridization protocol that is neither sensitive nor quantitative. Quantitative real-time polymerase chain reaction (qPCR) assays that detect the ETEC toxin genes eltA, sta1, and sta2 in clinical stool samples were developed and tested using donor stool inoculated with known quantities of ETEC bacteria. The sensitivity of the qPCR assays is 89%, compared with 22% for the DNA hybridization assay, and the limits of detection are 10,000-fold lower than the DNA hybridization assays performed in parallel. Ninety-three clinical stool samples, previously characterized by DNA hybridization, were tested using the new ETEC qPCR assays. Discordant toxin profiles were observed for 22 samples, notably, four samples originally typed as ETEC negative were ETEC positive. The qPCR assays are unique in their sensitivity and ability to quantify the three toxin genes in clinical stool samples.

Dose-dependent effects of Lactobacillus rhamnosus on serum interleukin-17 production and intestinal T-cell responses in pigs challenged with Escherichia coli.

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Zhu, Yao-Hong; Li, Xiao-Qiong; Zhang, Wei; Zhou, Dong; Liu, Hao-Yu; Wang, Jiu-Feng

2014-03-01

The mechanism underlying the dose effect of probiotics on ameliorating diarrhea has not been fully elucidated. Here, low (1 × 10(9) CFU/ml) or high (1 × 10(11) CFU/ml) doses of Lactobacillus rhamnosus ATCC 7469 were administered orally to piglets for 1 week before F4 (K88)-positive enterotoxigenic Escherichia coli (F4(+) ETEC) challenge. Administration of a low, but not a high, dose of L. rhamnosus decreased the percentage of CD3(+) CD4(+) CD8(-) T cells in the peripheral blood. Notably, transiently increased serum concentrations of interleukin-17A (IL-17A) were observed after F4(+) ETEC challenge in pigs pretreated with a high dose of L. rhamnosus. Administration of L. rhamnosus increased the percentage of the small intestinal lamina propria CD3(+) CD4(+) CD8(-) cells and Peyer's patch CD3(+) CD4(-) CD8(-) and CD3(-) CD4(-) CD8(+) cells. The percentage of ileal intraepithelial CD3(+) CD4(-) CD8(+) cells increased only in the high-dose piglets. Administration of L. rhamnosus downregulated expression of ileal IL-17A after F4(+) ETEC challenge but had no effect on expression of gamma interferon (IFN-γ), IL-12, IL-4, and FOXP3 mRNA in the small intestine. Expression of jejunal IL-2, ileal transforming growth factor β1 (TGF-β1), and ileal IL-10 was upregulated in the low-dose piglets after F4(+) ETEC challenge. Our findings suggest that amelioration of infectious diarrhea in piglets by L. rhamnosus is associated with the generation of lamina propria CD3(+) CD4(+) CD8(-) T cells, the expansion of Peyer's patch CD3(+) CD4(-) CD8(-) and CD3(-) CD4(-) CD8(+) cells, and the attenuation of F4(+) ETEC-induced increase in CD3(+) CD4(+) CD8(+) T cells in the small intestine. However, consumption of high doses of L. rhamnosus may increase levels of serum IL-17A after F4(+) ETEC challenge, thus eliciting a strong proinflammatory response.

Five challenges in modelling interacting strain dynamics

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Wikramaratna, Paul S; Kurcharski, Adam; Gupta, Sunetra

2015-01-01

population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity...

Hydrolysable chestnut tannins for reduction of postweaning diarrhea: Efficacy on an experimental ETEC F4 model.

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Girard, Marion; Thanner, Sophie; Pradervand, Nicolas; Hu, Dou; Ollagnier, Catherine; Bee, Giuseppe

2018-01-01

An experimental model for postweaning diarrhea with enterotoxigenic Escherichia coli F4 (ETEC F4) was set up in piglets, and the efficacy of 1% chestnut-tannin extract in preventing diarrhea was subsequently assessed. In a first trial (infection model), 32 Swiss Large White piglets (age: 24 days; average BW: 7.8 ± 0.8 kg) were randomly assigned to two experimental groups (infected [INF], noninfected [NINF]). In a subsequent trial, 72 Swiss Large White piglets (age: 26 days; average BW: 7.4 ± 1.5 kg) were blocked by BW and assigned within block to four experimental groups: NINF-CO: not infected and fed a standard control starter diet (CO); INF-CO: infected and fed the CO diet; NINF-TA: not infected and fed the CO diet supplemented with 1% chestnut extract containing 54% of hydrolysable tannins (TA); and INF-TA: infected and fed the TA diet. Both diets (TA and CO) were formulated to be isocaloric and isoproteic and to meet or surpass the nutritional requirements. In both trials, four days after weaning, piglets assigned to the INF group received an oral suspension of ETEC F4. Fecal score, ETEC shedding in feces (only in trial 2), and growth performance traits were measured for the following 14 days post infection. In both trials, more than 50% of the INF piglets developed diarrhea within six days post infection. Tannins reduced (P < 0.05) the average fecal score, the percentage of piglets in diarrhea, and the duration of diarrhea, whereas feed intake and the average daily gain were unaffected.

Determination of the optimum standardised ileal digestible sulphur amino acids to lysine ratio in weaned pigs challenged with enterotoxigenic Escherichia coli

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Capozzalo, M. M.; Resink, J. W.; Htoo, J. K.

2017-01-01

This experiment tested the hypothesis that pigs challenged with an enterotoxigenic strain of E. coli (ETEC) would require a higher sulphur amino acids (SAA) to Lys ratio (SAA:Lys). Pigs (n = 120) weighing 7.4 ± 0.52 kg (mean ± SD) and weaned at 27 d (Pietrain genotype, mixed sex) were stratified...... into 1 of 6 treatments based on weaning weight, sex and genotype for the F4 fimbria receptor (n = 20). Five diets were formulated with increasing ratios of standardised ileal digestible (SID) sulphurSAA:Lys. Pigs were housed in pens of 4 during an adaptation period of 6 d after which time pigs were...... housed individually. Pigs fed different SID SAA:Lys levels were infected with ETEC (5 mL, 1.13 × 108 CFU/mL, serotype O149:K91:K88) on d 8, 9, and 10 after weaning. The sixth diet, which contained 0.55 SID SAA:Lys and corresponded to current NRC recommendations, was allocated to 2 groups of pigs either...

Pigs experimentally infected with an enterotoxigenic strain of Escherichia coli have improved feed efficiency and indicators of inflammation with dietary supplementation of tryptophan and methionine in the immediate post-weaning period

DEFF Research Database (Denmark)

Capozzalo, Meeka M; Kim, Jae Cheol; Htoo, J.K.

2017-01-01

This experiment tested the hypothesis that pigs challenged with an enterotoxigenic strain of E. coli (ETEC) will improve performance by dietary supplementation of sulfur amino acids (SAA) and tryptophan (Trp) above the current recommended levels in the immediate post-weaning period. Male pigs (n...... arrangement of treatments with two levels of SID SAA : Lys ratio (0.52 vs 0.60) and two levels of SID Trp : Lys ratio (0.16 vs 0.24). Diets did not contain any antimicrobial compounds. Pigs were individually housed and were fed diets for 14 days after weaning. Pigs were infected with ETEC (3.44 × 108 CFU....../mL, serotype O149 : K91 : K88) on Days 5, 6, and 7 after weaning. Pigs were bled on Days 5, 8 and 14 and subsequently analysed for plasma levels of acute-phase proteins, urea, cytokines (Days 5 and 8 only) and amino acids (Days 5 and 8 only). Increasing Trp (P = 0.036) and SAA (P = 0.028) improved feed...

Dose-Dependent Effects of Lactobacillus rhamnosus on Serum Interleukin-17 Production and Intestinal T-Cell Responses in Pigs Challenged with Escherichia coli

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Zhu, Yao-Hong; Li, Xiao-Qiong; Zhang, Wei; Zhou, Dong; Liu, Hao-Yu

2014-01-01

The mechanism underlying the dose effect of probiotics on ameliorating diarrhea has not been fully elucidated. Here, low (1 × 109 CFU/ml) or high (1 × 1011 CFU/ml) doses of Lactobacillus rhamnosus ATCC 7469 were administered orally to piglets for 1 week before F4 (K88)-positive enterotoxigenic Escherichia coli (F4+ ETEC) challenge. Administration of a low, but not a high, dose of L. rhamnosus decreased the percentage of CD3+ CD4+ CD8− T cells in the peripheral blood. Notably, transiently increased serum concentrations of interleukin-17A (IL-17A) were observed after F4+ ETEC challenge in pigs pretreated with a high dose of L. rhamnosus. Administration of L. rhamnosus increased the percentage of the small intestinal lamina propria CD3+ CD4+ CD8− cells and Peyer's patch CD3+ CD4− CD8− and CD3− CD4− CD8+ cells. The percentage of ileal intraepithelial CD3+ CD4− CD8+ cells increased only in the high-dose piglets. Administration of L. rhamnosus downregulated expression of ileal IL-17A after F4+ ETEC challenge but had no effect on expression of gamma interferon (IFN-γ), IL-12, IL-4, and FOXP3 mRNA in the small intestine. Expression of jejunal IL-2, ileal transforming growth factor β1 (TGF-β1), and ileal IL-10 was upregulated in the low-dose piglets after F4+ ETEC challenge. Our findings suggest that amelioration of infectious diarrhea in piglets by L. rhamnosus is associated with the generation of lamina propria CD3+ CD4+ CD8− T cells, the expansion of Peyer's patch CD3+ CD4− CD8− and CD3− CD4− CD8+ cells, and the attenuation of F4+ ETEC-induced increase in CD3+ CD4+ CD8+ T cells in the small intestine. However, consumption of high doses of L. rhamnosus may increase levels of serum IL-17A after F4+ ETEC challenge, thus eliciting a strong proinflammatory response. PMID:24389928

Prevalence of adhesin and toxin genes in E. coli strains isolated from diarrheic and non-diarrheic pigs from smallholder herds in northern and eastern Uganda.

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Ikwap, Kokas; Larsson, Jenny; Jacobson, Magdalena; Owiny, David Okello; Nasinyama, George William; Nabukenya, Immaculate; Mattsson, Sigbrit; Aspan, Anna; Erume, Joseph

2016-08-05

Enterotoxigenic E. coli (ETEC) significantly contribute to diarrhea in piglets and weaners. The smallholder pig producers in Uganda identified diarrhea as one of the major problems especially in piglets. The aim of this study was to; i) characterize the virulence factors of E. coli strains isolated from diarrheic and non-diarrheic suckling piglets and weaners from smallholder herds in northern and eastern Uganda and ii) identify and describe the post-mortem picture of ETEC infection in severely diarrheic piglets. Rectal swab samples were collected from 83 piglets and weaners in 20 herds and isolated E. coli were characterized by PCR, serotyping and hemolysis. The E. coli strains carried genes for the heat stable toxins STa, STb and EAST1 and adhesins F4 and AIDA-I. The genes for the heat labile toxin LT and adhesins F5, F6, F18 and F41 were not detected in any of the E. coli isolates. Where the serogroup could be identified, E. coli isolates from the same diarrheic pig belonged to the same serogroup. The prevalence of EAST1, STb, Stx2e, STa, AIDA-I, and F4 in the E. coli isolates from suckling piglets and weaners (diarrheic and non-diarrheic combined) was 29, 26.5, 2.4, 1.2, 16, and 8.4 %, respectively. However the prevalence of F4 and AIDA-I in E. coli from diarrheic suckling piglets alone was 22.2 and 20 %, respectively. There was no significant difference in the prevalence of the individual virulence factors in E. coli from the diarrheic and non-diarrheic pigs (p > 0.05). The main ETEC strains isolated from diarrheic and non-diarrheic pigs included F4/STb/EAST1 (7.2 %), F4/STb (1.2 %), AIDA/STb/EAST1 (8 %) and AIDA/STb (8 %). At post-mortem, two diarrheic suckling piglets carrying ETEC showed intact intestinal villi, enterocytes and brush border but with a layer of cells attached to the brush border, suggestive of ETEC infections. This study has shown that the F4 fimbriae is the most predominant in E. coli from diarrheic piglets in the study area and

Control of Virulence Gene Expression by the Master Regulator, CfaD, in the Prototypical Enterotoxigenic Escherichia coli Strain, H10407

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Carla Hodson

2017-08-01

Full Text Available Enterotoxigenic Escherichia coli (ETEC is the most common bacterial cause of diarrhea in children in developing countries, as well as in travelers to these countries. To cause disease, ETEC needs to produce a series of virulence proteins including enterotoxins, colonization factors and secretion pathways, which enable this pathogen to colonize the human small intestine and deliver enterotoxins to epithelial cells. Previously, a number of studies have demonstrated that CfaD, an AraC-like transcriptional regulator, plays a key role in virulence gene expression by ETEC. In this study, we carried out a transcriptomic analysis of ETEC strain, H10407, grown under different conditions, and determined the complete set of genes that are regulated by CfaD. In this way, we identified a number of new target genes, including rnr-1, rnr-2, etpBAC, agn43, flu, traM and ETEC_3214, whose expression is strongly activated by CfaD. Using promoter-lacZ reporters, primer extension and electrophoretic mobility shift assays, we characterized the CfaD-mediated activation of several selected target promoters. We also showed that the gut-associated environmental signal, sodium bicarbonate, stimulates CfaD-mediated upregulation of its virulence target operons. Finally, we screened a commercial small molecule library and identified a compound (CH-1 that specifically inhibited the regulatory function of CfaD, and by 2-D analoging, we identified a second inhibitor (CH-2 with greater potency.

Effects of Lactobacillus johnsonii and Lactobacillus reuteri on gut barrier function and heat shock proteins in intestinal porcine epithelial cells.

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Liu, Hao-Yu; Roos, Stefan; Jonsson, Hans; Ahl, David; Dicksved, Johan; Lindberg, Jan Erik; Lundh, Torbjörn

2015-04-01

Heat shock proteins (HSPs) are a set of highly conserved proteins that can serve as intestinal gate keepers in gut homeostasis. Here, effects of a probiotic, Lactobacillus rhamnosus GG (LGG), and two novel porcine isolates, Lactobacillus johnsonii strain P47-HY and Lactobacillus reuteri strain P43-HUV, on cytoprotective HSP expression and gut barrier function, were investigated in a porcine IPEC-J2 intestinal epithelial cell line model. The IPEC-J2 cells polarized on a permeable filter exhibited villus-like cell phenotype with development of apical microvilli. Western blot analysis detected HSP expression in IPEC-J2 and revealed that L. johnsonii and L. reuteri strains were able to significantly induce HSP27, despite high basal expression in IPEC-J2, whereas LGG did not. For HSP72, only the supernatant of L. reuteri induced the expression, which was comparable to the heat shock treatment, which indicated that HSP72 expression was more stimulus specific. The protective effect of lactobacilli was further studied in IPEC-J2 under an enterotoxigenic Escherichia coli (ETEC) challenge. ETEC caused intestinal barrier destruction, as reflected by loss of cell-cell contact, reduced IPEC-J2 cell viability and transepithelial electrical resistance, and disruption of tight junction protein zonula occludens-1. In contrast, the L. reuteri treatment substantially counteracted these detrimental effects and preserved the barrier function. L. johnsonii and LGG also achieved barrier protection, partly by directly inhibiting ETEC attachment. Together, the results indicate that specific strains of Lactobacillus can enhance gut barrier function through cytoprotective HSP induction and fortify the cell protection against ETEC challenge through tight junction protein modulation and direct interaction with pathogens. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

RESPONS ANTIBODI ANTI ETEC K99 PADA INDUK SAPI BUNTING SETELAH PEMBERIAN VAKSIN ESCHERICHIA COLI POLIVALEN

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Anita Esfandiari

2014-08-01

Full Text Available The objective of this experiment was to detect antibody (IgG against enterotoxigenic Escherichia coli (ETECK99 in the blood of cows vaccinated by Escherichia coli polyvalent vaccine. Eight dry cows were injectedsubcutaneously by polyvalent Escherichia coli twice prior to parturition. Before vaccinated, the cows were givenimmunomodulator orally for 3 days. Blood samples were drawn from coccigeal vein prior to the 1st vaccination,two week following the 1st vaccination and at 1, 2, and 4 weeks after the 2nd vaccination. Blood samples wereanalyzed for IgG and ETEC K99 using indirect Enzyme Linked Immunosorbent Assay (ELISA assay. Results of theexperiment indicated that absorbance values of all vaccinated cows before the first vaccination until third weekfollowing the 2nd vaccination were below cut off values. The absorbance values then increased and were above cutoff values at fourth week following the 2nd vaccination. In conclusion, antibody against ETEC K99, were detected inthe blood of cows, fourth week following the 2nd vaccination.

In Vitro Evaluation of Swine-Derived Lactobacillus reuteri: Probiotic Properties and Effects on Intestinal Porcine Epithelial Cells Challenged with Enterotoxigenic Escherichia coli K88.

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Wang, Zhilin; Wang, Li; Chen, Zhuang; Ma, Xianyong; Yang, Xuefen; Zhang, Jian; Jiang, Zongyong

2016-06-28

Probiotics are considered as the best effective alternatives to antibiotics. The aim of this study was to characterize the probiotic potential of lactobacilli for use in swine farming by using in vitro evaluation methods. A total of 106 lactic acid bacterial isolates, originating from porcine feces, were first screened for the capacity to survive stresses considered important for putative probiotic strains. Sixteen isolates showed notable acid and bile resistance, antibacterial activity, and adherence to intestinal porcine epithelial cells (IPEC-1). One isolate, LR1, identified as Lactobacillus reuteri, was selected for extensive study of its probiotic and functional properties in IPEC-1 cell models. L. reuteri LR1 exhibited good adhesion to IPEC-1 cells and could inhibit the adhesion of enterotoxigenic Escherichia coli (ETEC) to IPEC-1 cells. L. reuteri LR1 could also modulate transcript and protein expression of cytokines involved in inflammation in IPEC-1 cells; the Lactobacillus strain inhibited the ETEC-induced expression of proinflammatory transcripts (IL-6 and TNF-α) and protein (IL-6), and increased the level of anti-inflammatory cytokine (IL-10). Measurement of the permeation of FD-4 showed that L. reuteri LR1 could maintain barrier integrity in monolayer IPEC-1 cells exposed to ETEC. Immunolocalization experiments showed L. reuteri LR1 could also prevent ETEC-induced tight junction ZO-1 disruption. Together, these results indicate that L. reuteri LR1 exhibits desirable probiotic properties and could be a potential probiotic for use in swine production.

Administration of probiotics influences F4 (K88-positive enterotoxigenic Escherichia coli attachment and intestinal cytokine expression in weaned pigs

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Daudelin Jean-François

2011-05-01

Full Text Available Abstract This study evaluated the effect of the probiotics Pediococcus acidilactici and Saccharomyces cerevisiae boulardii on the intestinal colonization of O149 enterotoxigenic Escherichia coli harbouring the F4 (K88 fimbriae (ETEC F4 and on the expression of ileal cytokines in weaned pigs. At birth, different litters of pigs were randomly assigned to one of the following treatments: 1 control without antibiotics or probiotics (CTRL; 2 reference group in which chlortetracycline and tiamulin were added to weanling feed (ATB; 3 P. acidilactici; 4 S. cerevisiae boulardii; or 5 P. acidilactici + S. cerevisiae boulardii. Probiotics were administered daily (1 × 109 CFU per pig during the lactation period and after weaning (day 21. At 28 days of age, all pigs were orally challenged with an ETEC F4 strain, and a necropsy was performed 24 h later. Intestinal segments were collected to evaluate bacterial colonization in the small intestine and ileal cytokine expressions. Attachment of ETEC F4 to the intestinal mucosa was significantly reduced in pigs treated with P. acidilactici or S. cerevisiae boulardii in comparison with the ATB group (P = 0.01 and P = 0.03, respectively. In addition, proinflammatory cytokines, such as IL-6, were upregulated in ETEC F4 challenged pigs treated with P. acidilactici alone or in combination with S. cerevisiae boulardii compared with the CTRL group. In conclusion, the administration of P. acidilactici or S. cerevisiae boulardii was effective in reducing ETEC F4 attachment to the ileal mucosa, whereas the presence of P. acidilactici was required to modulate the expression of intestinal inflammatory cytokines in pigs challenged with ETEC F4.

Administration of probiotics influences F4 (K88)-positive enterotoxigenic Escherichia coli attachment and intestinal cytokine expression in weaned pigs.

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Daudelin, Jean-François; Lessard, Martin; Beaudoin, Frédéric; Nadeau, Eric; Bissonnette, Nathalie; Boutin, Yvan; Brousseau, Jean-Philippe; Lauzon, Karoline; Fairbrother, John Morris

2011-05-23

This study evaluated the effect of the probiotics Pediococcus acidilactici and Saccharomyces cerevisiae boulardii on the intestinal colonization of O149 enterotoxigenic Escherichia coli harbouring the F4 (K88) fimbriae (ETEC F4) and on the expression of ileal cytokines in weaned pigs. At birth, different litters of pigs were randomly assigned to one of the following treatments: 1) control without antibiotics or probiotics (CTRL); 2) reference group in which chlortetracycline and tiamulin were added to weanling feed (ATB); 3) P. acidilactici; 4) S. cerevisiae boulardii; or 5) P. acidilactici + S. cerevisiae boulardii. Probiotics were administered daily (1 × 10(9) CFU per pig) during the lactation period and after weaning (day 21). At 28 days of age, all pigs were orally challenged with an ETEC F4 strain, and a necropsy was performed 24 h later. Intestinal segments were collected to evaluate bacterial colonization in the small intestine and ileal cytokine expressions. Attachment of ETEC F4 to the intestinal mucosa was significantly reduced in pigs treated with P. acidilactici or S. cerevisiae boulardii in comparison with the ATB group (P = 0.01 and P = 0.03, respectively). In addition, proinflammatory cytokines, such as IL-6, were upregulated in ETEC F4 challenged pigs treated with P. acidilactici alone or in combination with S. cerevisiae boulardii compared with the CTRL group. In conclusion, the administration of P. acidilactici or S. cerevisiae boulardii was effective in reducing ETEC F4 attachment to the ileal mucosa, whereas the presence of P. acidilactici was required to modulate the expression of intestinal inflammatory cytokines in pigs challenged with ETEC F4.

Pigs experimentally infected with an enterotoxigenic strain of Escherichia coli have improved feed efficiency and indicators of inflammation with dietary supplementation of tryptophan and methionine in the immediate post-weaning period

DEFF Research Database (Denmark)

Capozzalo, Meeka M; Kim, Jae Cheol; Htoo, J.K.

2017-01-01

This experiment tested the hypothesis that pigs challenged with an enterotoxigenic strain of E. coli (ETEC) will improve performance by dietary supplementation of sulfur amino acids (SAA) and tryptophan (Trp) above the current recommended levels in the immediate post-weaning period. Male pigs (n ...... of inflammation and SAA supplementation decreased the pro-inflammatory interferon-gamma response and improved protein utilisation, as measured by PU, whereas supplementation with both Trp and SAA improved feed conversion ratio....... interferon-gamma regardless of dietary Trp or day of sampling (P = 0.043). Increasing dietary SAA decreased plasma urea (PU) levels on Days 5, 8 and 14 (P

Effect of chicken egg anti-F4 antibodies on performance and diarrhea incidences in enterotoxigenic Escherichia coli K88+-challenged piglets.

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Aluko, Kolawole; Velayudhan, Deepak E; Khafipour, Ehsan; Fang, Lin; Nyachoti, Martin

2017-12-01

The aim was to evaluate the effects of dietary supplementation of spay-dried whole egg containing anti-F4 antibodies (SDWE) against recombinantly produced F4 antigens in enterotoxigenic Escherichia coli K88 + (ETEC)-challenged piglets. Twenty-seven 21-d-old and individually housed piglets were randomly allotted to 3 treatments consisting of a wheat-soybean meal basal diet containing either 0 (control egg powder; CEP), 0.1% (SDWE1) or 0.4% (SDWE2) SDWE. After a 7-d adaptation period, blood samples were collected from all pigs, and pigs were weighed and orally challenged with an ETEC inoculum. Blood was sampled at 24 and 48 h post-challenge, and diarrhea incidences and scores were recorded. On d 14, all pigs were weighed and then euthanized to obtain intestinal tissue samples for histomorphology measurement. During the pre-challenge period, pigs fed the SDWE showed a linear improvement ( P  < 0.05) in average daily gain (ADG) and gain to feed ratio (G:F), but there were no differences among treatments in growth performance during the post-challenge period. Diarrhea incidences and scores, fecal shedding of ETEC, plasma urea nitrogen content and intestinal histomorphology were similar among treatments. The results show that 0.4% SDWE supported greater piglet performance before challenge although such benefits were not evident during the post-challenge period at either 0.1% or 0.4% supplementation.

Effect of pea and faba bean fractions on net fluid absorption in ETEC-infected small intestinal segements of weaned piglets

NARCIS (Netherlands)

Meulen, van der J.; Jansman, A.J.M.

2010-01-01

After weaning piglets frequently have diarrhoea associated with an enterotoxigenic Escherichia coli (ETEC) infection. Alternative plant protein sources such as peas, faba beans and lupins may contribute in preventing gastrointestinal problems. In the small intestinal segment perfusion model, the

Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part II: Vaccines for Shigella, Salmonella, enterotoxigenic E. coli (ETEC) enterohemorragic E. coli (EHEC) and Campylobacter jejuni

Science.gov (United States)

O’Ryan, Miguel; Vidal, Roberto; del Canto, Felipe; Carlos Salazar, Juan; Montero, David

2015-01-01

In Part II we discuss the following bacterial pathogens: Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic) and Campylobacter jejuni. In contrast to the enteric viruses and Vibrio cholerae discussed in Part I of this series, for the bacterial pathogens described here there is only one licensed vaccine, developed primarily for Vibrio cholerae and which provides moderate protection against enterotoxigenic E. coli (ETEC) (Dukoral®), as well as a few additional candidates in advanced stages of development for ETEC and one candidate for Shigella spp. Numerous vaccine candidates in earlier stages of development are discussed. PMID:25715096

Histomorphometric evaluation of intestinal cellular immune responses in pigs immunized with live oral F4ac+ non-enterotoxigenic E. coli vaccine against postweaning colibacillosis

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A. Kovšca Janjatovic

2010-02-01

Full Text Available Enterotoxigenic Escherichia coli (ETEC infection is the most common type of porcine postweaning colibacillosis (PWC. Among fimbriae of porcine ETEC strains the best studied family of fimbriae are the members of F4 adhesins, existing in at least three variants: ab, ac, ad. Active immunization against porcine PWC is difficult due to: i ETEC strains are only one of the essential predisposing factors, ii the success of vaccinal antigen uptake depends on the presence of enterocyte receptors for F4 adhesins, iii the intestinal immune system may react with tolerance or hypersensitivity to the same antigens depending on the dose and form of the vaccinal immunogen, and iv kinetics of the specific immune responses may be different in the case of F4 (earlier and the other ETEC adhesins, particularly F18 (later. The aim of this study was to test the effectiveness of a live attenuated F4ac+ non-ETEC vaccine against porcine PWC by analyzing quantitative differences in the small intestinal lymphoid and myeloid cell subsets of immunized (with or without levamisole given as an adjuvant vs control non-immunized pigs. Four week-old pigs were intragastrically immunized with a vaccine candidate F4ac+ non-ETEC strain 2407 at day 0, challenged 7 days later with a virulent F4ac+ strain ETEC 11-800/1/94, euthanatized at day 13 and sampled for immunohistology. Non-immunized pigs received saline at day 0 and were processed as the principals. Immuno-phenotypes of lymphoid and myeloid cell subsets were demonstrated within jejunal and ileal mucosa by immunohistochemical avidin-biotin complex method and corresponding morphometric data were analyzed using software program Lucia G for digital image analyses. Monoclonal antibodies reactive with surface molecules on porcine immune cells such as CD3, CD45RA, CD45RC, CD21 and SWC3 enabled clear insight into distribution patterns and amount of these cells within the gut-associated lymphoid tissues (GALT examined. The numbers of

Biofilm formation and binding specificities of CFA/I, CFA/II and CS2 adhesions of enterotoxigenic Escherichia coli and Cfae-R181A mutant.

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Liaqat, Iram; Sakellaris, Harry

2012-07-01

Enterotoxigenic Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. Adhesion is the first step in pathogenesis of ETEC infections and ETEC pili designated colonization factor antigens (CFAs) are believed to be important in the biofim formation, colonization and host cell adhesions. As a first step, we have determined the biofilm capability of ETEC expressing various types of pili (CFA/I, CfaE-R181A mutant/CfaE tip mutant, CFA/II and CS2). Further, enzyme-linked immunosorbent assay (ELISA) assay were developed to compare the binding specificity of CFA/I, CFA/II (CS1 - CS3) and CS2 of ETEC, using extracted pili and piliated bacteria. CFA/II strain (E24377a) as well as extracted pili exhibited significantly higher binding both in biofilm and ELISA assays compared to non piliated wild type E24377a, CFA/I and CS2 strains. This indicates that co-expression of two or more CS2 in same strain is more efficient in increasing adherence. Significant decrease in binding specificity of DH5αF'lacI (q)/∆cotD (CS2) strain and MC4100/pEU2124 (CfaE-R181A) mutant strain indicated the important contribution of tip proteins in adherence assays. However, CS2 tip mutant strain (DH5αF'lacI (q)/pEU5881) showed that this specific residue may not be important as adhesions in these strains. In summary, our data suggest that pili, their minor subunits are important for biofilm formation and adherence mechanisms. Overall, the functional reactivity of strains co expressing various antigens, particularly minor subunit antigen observed in this study suggest that fewer antibodies may be required to elicit immunity to ETEC expressing a wider array of related pili.

Enterococcus faecium NCIMB 10415 Modulates Epithelial Integrity, Heat Shock Protein, and Proinflammatory Cytokine Response in Intestinal Cells

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Shanti Klingspor

2015-01-01

Full Text Available Probiotics have shown positive effects on gastrointestinal diseases; they have barrier-modulating effects and change the inflammatory response towards pathogens in studies in vitro. The aim of this investigation has been to examine the response of intestinal epithelial cells to Enterococcus faecium NCIMB 10415 (E. faecium, a probiotic positively affecting diarrhea incidence in piglets, and two pathogenic Escherichia coli (E. coli strains, with specific focus on the probiotic modulation of the response to the pathogenic challenge. Porcine (IPEC-J2 and human (Caco-2 intestinal cells were incubated without bacteria (control, with E. faecium, with enteropathogenic (EPEC or enterotoxigenic E. coli (ETEC each alone or in combination with E. faecium. The ETEC strain decreased transepithelial resistance (TER and increased IL-8 mRNA and protein expression in both cell lines compared with control cells, an effect that could be prevented by pre- and coincubation with E. faecium. Similar effects were observed for the increased expression of heat shock protein 70 in Caco-2 cells. When the cells were challenged by the EPEC strain, no such pattern of changes could be observed. The reduced decrease in TER and the reduction of the proinflammatory and stress response of enterocytes following pathogenic challenge indicate the protective effect of the probiotic.

A Commensal Gone Bad: Complete Genome Sequence of the Prototypical Enterotoxigenic Escherichia coli Strain H10407

Science.gov (United States)

2010-11-01

and Escherichia ferguso- . TABLE 2. General characteristics of the plasm ids from ETEC strains H10407 and E1392/75 Value in E. c·oli: Characteristic...0352). consetved proteins with unknown func- tions (CDSs 0673 to 0678), a flavoprotein electron transfer system (CDSs 1730 to 1734), the colanic...mediating diarrhea are not chromosomally encoded. indicating that the essential virulence factors are encoded on the plasm ids (61 ). Potentia l

Single Chain Variable Fragments Produced in Escherichia coli against Heat-Labile and Heat-Stable Toxins from Enterotoxigenic E. coli.

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Christiane Y Ozaki

Full Text Available Diarrhea is a prevalent pathological condition frequently associated to the colonization of the small intestine by enterotoxigenic Escherichia coli (ETEC strains, known to be endemic in developing countries. These strains can produce two enterotoxins associated with the manifestation of clinical symptoms that can be used to detect these pathogens. Although several detection tests have been developed, minimally equipped laboratories are still in need of simple and cost-effective methods. With the aim to contribute to the development of such diagnostic approaches, we describe here two mouse hybridoma-derived single chain fragment variable (scFv that were produced in E. coli against enterotoxins of ETEC strains.Recombinant scFv were developed against ETEC heat-labile toxin (LT and heat-stable toxin (ST, from previously isolated hybridoma clones. This work reports their design, construction, molecular and functional characterization against LT and ST toxins. Both antibody fragments were able to recognize the cell-interacting toxins by immunofluorescence, the purified toxins by ELISA and also LT-, ST- and LT/ST-producing ETEC strains.The developed recombinant scFvs against LT and ST constitute promising starting point for simple and cost-effective ETEC diagnosis.

Expression of colonization factor CS5 of enterotoxigenic Escherichia coli (ETEC is enhanced in vivo and by the bile component Na glycocholate hydrate.

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Matilda Nicklasson

Full Text Available Enterotoxigenic Escherichia coli (ETEC is an important cause of acute watery diarrhoea in developing countries. Colonization factors (CFs on the bacterial surface mediate adhesion to the small intestinal epithelium. Two of the most common CFs worldwide are coli surface antigens 5 and 6 (CS5, CS6. In this study we investigated the expression of CS5 and CS6 in vivo, and the effects of bile and sodium bicarbonate, present in the human gut, on the expression of CS5. Five CS5+CS6 ETEC isolates from adult Bangladeshi patients with acute diarrhoea were studied. The level of transcription from the CS5 operon was approximately 100-fold higher than from the CS6 operon in ETEC bacteria recovered directly from diarrhoeal stool without sub-culturing (in vivo. The glyco-conjugated primary bile salt sodium glycocholate hydrate (NaGCH induced phenotypic expression of CS5 in a dose-dependent manner and caused a 100-fold up-regulation of CS5 mRNA levels; this is the first description of NaGCH as an enteropathogenic virulence inducer. The relative transcription levels from the CS5 and CS6 operons in the presence of bile or NaGCH in vitro were similar to those in vivo. Another bile salt, sodium deoxycholate (NaDC, previously reported to induce enteropathogenic virulence, also induced expression of CS5, whereas sodium bicarbonate did not.

An outbreak of enterotoxigenic Escherichia coli (ETEC) infection in Norway, 2012: a reminder to consider uncommon pathogens in outbreaks involving imported products.

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MacDonald, E; Møller, K E; Wester, A L; Dahle, U R; Hermansen, N O; Jenum, P A; Thoresen, L; Vold, L

2015-02-01

We investigated an outbreak of gastroenteritis following a Christmas buffet served on 4-9 December 2012 to ~1300 hotel guests. More than 300 people were reported ill in initial interviews with hotel guests. To identify possible sources of infection we conducted a cohort investigation through which we identified 214 probable cases. Illness was associated with consumption of scrambled eggs (odds ratio 9·07, 95% confidence interval 5·20-15·84). Imported chives added fresh to the scrambled eggs were the suspected source of the outbreak but were unavailable for testing. Enterotoxigenic Escherichia coli (ETEC) infection was eventually confirmed in 40 hotel guests. This outbreak reinforces that ETEC should be considered in non-endemic countries when the clinical picture is consistent and common gastrointestinal pathogens are not found. Following this outbreak, the Norwegian Food Safety Authority recommended that imported fresh herbs should be heat-treated before use in commercial kitchens.

Construction of a nontoxigenic Clostridium botulinum strain for food challenge studies.

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Bradshaw, Marite; Marshall, Kristin M; Heap, John T; Tepp, William H; Minton, Nigel P; Johnson, Eric A

2010-01-01

Clostridium botulinum produces the most poisonous natural toxin known and is a perennial concern to the food industry and to regulatory agencies due to the potential threat of food-borne botulism. To ensure the botulinal safety of foods, rigorous food challenge testing to validate food-processing conditions and food formulations has been routinely performed. Detection of the botulinum neurotoxin is performed by using a mouse bioassay and/or in vitro assays. There has been considerable interest by the food industry and regulatory agencies in minimizing or even replacing the use of animals in these challenge studies. In addition, due to stringent select-agent regulations, the testing of various foods using toxigenic C. botulinum strains requires facilities and personnel that are certified for work with this organism. For this purpose we propose to generate sets of nontoxigenic C. botulinum strains from proteolytic and nonproteolytic groups that differ from the wild-type strains only by their inability to produce botulinum neurotoxin. In this initial study we describe the generation of a nontoxigenic mutant of C. botulinum strain 62A using the ClosTron mutagenesis system by inserting a group II intron into the botulinum neurotoxin type A gene (bont/A). The mutant clones were nontoxigenic as determined by Western blots and mouse bioassays but showed physiological characteristics, including growth properties and sporulation, that were similar to those of the parent strain in laboratory media. Additional studies will be required to evaluate comparable characteristics in various food matrices. The availability of suitable nontoxigenic C. botulinum strains for food challenge studies will be beneficial for enhancing the botulinal safety of foods as well as increasing the biosafety of workers and may eliminate the use of laboratory animals.

Effect of Saccharomyces cerevisiae var. Boulardii and β-galactomannan oligosaccharide on porcine intestinal epithelial and dendritic cells challenged in vitro with Escherichia coli F4 (K88

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Badia Roger

2012-01-01

Full Text Available Abstract Probiotic and prebiotics, often called "immune-enhancing" feed additives, are believed to deal with pathogens, preventing the need of an immune response and reducing tissue damage. In this study, we investigated if a recently developed β-galactomannan (βGM had a similar protective role compared to Saccharomyces cerevisiae var. Boulardii (Scb, a proven probiotic, in the context of enterotoxigenic Escherichia coli (ETEC infection. ETEC causes inflammation, diarrhea and intestinal damage in piglets, resulting in large economic loses worldwide. We observed that Scb and βGM products inhibited in vitro adhesion of ETEC on cell surface of porcine intestinal IPI-2I cells. Our data showed that Scb and βGM decreased the mRNA ETEC-induced gene expression of pro-inflammatory cytokines TNF-α, IL-6, GM-CSF and chemokines CCL2, CCL20 and CXCL8 on intestinal IPI-2I. Furthermore, we investigated the putative immunomodulatory role of Scb and βGM on porcine monocyte-derived dendritic cells (DCs per se and under infection conditions. We observed a slight up-regulation of mRNA for TNF-α and CCR7 receptor after co-incubation of DC with Scb and βGM. However, no differences were found in DC activation upon ETEC infection and Scb or βGM co-culture. Therefore, our results indicate that, similar to probiotic Scb, prebiotic βGM may protect intestinal epithelial cells against intestinal pathogens. Finally, although these products may modulate DC activation, their effect under ETEC challenge conditions remains to be elucidated.

A Chimeric protein of CFA/I, CS6 subunits and LTB/STa toxoid protects immunized mice against enterotoxigenic Escherichia coli.

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Zeinalzadeh, Narges; Salmanian, Ali Hatef; Goujani, Goli; Amani, Jafar; Ahangari, Ghasem; Akhavian, Asal; Jafari, Mahyat

2017-07-01

Enterotoxigenic Escherichia Coli (ETEC) strains are the commonest bacteria causing diarrhea in children in developing countries and travelers to these areas. Colonization factors (CFs) and enterotoxins are the main virulence determinants in ETEC pathogenesis. Heterogeneity of CFs is commonly considered the bottleneck to developing an effective vaccine. It is believed that broad spectrum protection against ETEC would be achieved by induced anti-CF and anti-enterotoxin immunity simultaneously. Here, a fusion antigen strategy was used to construct a quadrivalent recombinant protein called 3CL and composed of CfaB, a structural subunit of CFA/I, and CS6 structural subunits, LTB and STa toxoid of ETEC. Its anti-CF and antitoxin immunogenicity was then assessed. To achieve high-level expression, the 3CL gene was synthesized using E. coli codon bias. Female BALB/C mice were immunized with purified recombinant 3CL. Immunized mice developed antibodies that were capable of detecting each recombinant subunit in addition to native CS6 protein and also protected the mice against ETEC challenge. Moreover, sera from immunized mice also neutralized STa toxin in a suckling mouse assay. These results indicate that 3CL can induce anti-CF and neutralizing antitoxin antibodies along with introducing CFA/I as a platform for epitope insertion. © 2017 The Societies and John Wiley & Sons Australia, Ltd.

Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

KAUST Repository

Joffré , Enrique; von Mentzer, Astrid; Abd El Ghany, Moataz; Oezguen, Numan; Savidge, Tor; Dougan, Gordon; Svennerholm, Ann-Mari; Sjö ling, Å sa

2015-01-01

Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1-enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally.

Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

KAUST Repository

Joffré, Enrique

2015-01-15

Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1-enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally.

Enterotoxigenic Escherichia coli Subclinical Infection in Pigs: Bacteriological and Genotypic Characterization and Antimicrobial Resistance Profiles.

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Moredo, Fabiana A; Piñeyro, Pablo E; Márquez, Gabriela C; Sanz, Marcelo; Colello, Rocío; Etcheverría, Analía; Padola, Nora L; Quiroga, María A; Perfumo, Carlos J; Galli, Lucía; Leotta, Gerardo A

2015-08-01

Enterotoxigenic Escherichia coli (ETEC) is the major pathogen responsible for neonatal diarrhea, postweaning diarrhea, and edema disease in pigs. Although it can be harmless, ETEC is also present in the intestines of other animal species and humans, causing occasional diarrhea outbreaks. The evaluation of this pathogen's presence in food sources is becoming an increasingly important issue in human health. In order to determine the prevalence of ETEC in nondiarrheic pigs, 990 animals from 11 pig farms were sampled. Using end-time polymerase chain reaction (PCR), eltA, estI genes, or both, were detected in 150 (15.2%) animals. From the positive samples, 40 (26.6%) ETEC strains were isolated, showing 19 antibiotic-resistance patterns; 52.5% of these strains had multiple antibiotic resistances, and 17.5% carried the intI2 gene. The most prevalent genotypes were rfb(O157)/estII/aidA (32.5%) and estI/estII (25.0%). The estII gene was identified most frequently (97.5%), followed by estI (37.5%), astA (20.0%), and eltA (12.5%). The genes coding the fimbriae F5, F6, and F18 were detected in three single isolates. The aidA gene was detected in 20 ETEC strains associated with the estII gene. Among the isolated ETEC strains, stx(2e)/estI, stx(2e)/estI/estII, and stx(2e)/estI/estII/intI2 genotypes were identified. The ETEC belonged to 12 different serogroups; 37.5% of them belonged to serotype O157:H19. Isolates were grouped by enterobacterial repetitive intergenic consensus-PCR into 5 clusters with 100.0% similarity. In this study, we demonstrated that numerous ETEC genotypes cohabit and circulate in swine populations without clinical manifestation of neonatal diarrhea, postweaning diarrhea, or edema disease in different production stages. The information generated is important not only for diagnostic and epidemiological purposes, but also for understanding the dynamics and ecology of ETEC in pigs in different production stages that can be potentially transmitted to humans

Dietary addition of Lactobacillus rhamnosus GG impairs the health of Escherichia coli F4-challenged piglets.

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Trevisi, P; Casini, L; Coloretti, F; Mazzoni, M; Merialdi, G; Bosi, P

2011-08-01

Lactobacillus rhamnosus GG (LGG) is a probiotic for humans and is normally not found in pigs; however, it has been shown to protect the human-derived intestinal Caco-2 cells against the damage induced by an important intestinal pathogen, enterotoxigenic Escherichia coli F4 (ETEC). An experiment was conducted to test whether the dietary addition of LGG improves the growth and health of weaned pigs when orally challenged by E. coli F4. Thirty-six pigs were weaned at 21 days and assigned to a standard weaning diet with or without 1010 CFU LGG (ATCC 53103) per day. The pigs, individually penned, were orally challenged with 1.5 ml of a 1010 CFU E. coli F4 suspension on day 7 and slaughtered on day 12 or 14. With the addition of LGG, the average daily gain and the average daily feed intake were reduced after the challenge with ETEC and for the entire trial (P F4-specific IgA activity was not affected by the diet at all the samplings. Our result shows that, the administration of LGG do not prevent or reduce the detrimental effect of the E. coli F4 infection on the growth performance and health status of weaned piglet.

New perspectives to the enterotoxigenic E. coli F4 porcine infection model: Susceptibility genotypes in relation to performance, diarrhoea and bacterial shedding.

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Roubos-van den Hil, Petra J; Litjens, Ralph; Oudshoorn, Anna-Katharina; Resink, Jan Willem; Smits, Coen H M

2017-04-01

Enterotoxigenic E. coli (ETEC), causing post-weaning diarrhoea, is a major problem in weaned piglets. Individual animal responses to ETEC infection show high variability in animal experiments. Two studies were designed to optimize the ETEC F4ac infection model in piglets by combining the genotype susceptibility with performance, diarrhoea incidence and bacterial shedding. The studies were performed with respectively 120 and 80 male piglets that were tested for susceptibility or resistance towards ETEC O149:F4ac by a DNA marker based test. Three different genotypes were observed; resistant (RR), susceptible heterozygote (RS) and susceptible homozygote (SS). Piglets, were orally infected with an inoculum suspension (containing 1.5E8 CFU/ml ETEC F4ac) at day 0, 1 and 2 of the study. Performance, diarrhoea incidence and bacterial shedding were followed for 21days. In the first week after challenge a difference in average daily gain was observed between resistant and susceptible piglets in both studies. For the complete study period no significant differences were observed. Diarrhoea incidence was significantly higher in susceptible pigs compared to the resistant pigs in the first week after challenge. Bacterial shedding was much higher in the susceptible pigs and ETEC excretion lasted longer. ETEC was hardly detected in the faecal material of the resistant pigs. In conclusion, susceptible pigs showed higher diarrhoea incidence and higher numbers of faecal ETEC shedding in the first week after challenge compared to resistant pigs. The DNA marker based test can be used to select pigs that are susceptible for ETEC for inclusion in ETEC infection model, resulting in less animals needed to perform infection studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Prevention of diarrhoea using pathogen specific monoclonal antibodies in an experimental enterotoxigenic E. coli infection in germfree piglets

NARCIS (Netherlands)

Geus, de B.; Harmsen, M.; Zijderveld, van F.

1998-01-01

In the present study we describe the effect of oral application of mAB specific for ETEC F4(ac) fimbriae in an experimental ETEC challenge model in neonatal germfree piglets. The results show that mAB, specific for different F4(ac) epitopes protect animals against ETEC specific pathology. Moreover,

Feed Fermentation with Reuteran- and Levan-Producing Lactobacillus reuteri Reduces Colonization of Weanling Pigs by Enterotoxigenic Escherichia coli.

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Yang, Yan; Galle, Sandra; Le, Minh Hong Anh; Zijlstra, Ruurd T; Gänzle, Michael G

2015-09-01

This study determined the effect of feed fermentation with Lactobacillus reuteri on growth performance and the abundance of enterotoxigenic Escherichia coli (ETEC) in weanling piglets. L. reuteri strains produce reuteran or levan, exopolysaccharides that inhibit ETEC adhesion to the mucosa, and feed fermentation was conducted under conditions supporting exopolysaccharide formation and under conditions not supporting exopolysaccharide formation. Diets were chosen to assess the impact of organic acids and the impact of viable L. reuteri bacteria. Fecal samples were taken throughout 3 weeks of feeding; at the end of the 21-day feeding period, animals were euthanized to sample the gut digesta. The feed intake was reduced in pigs fed diets containing exopolysaccharides; however, feed efficiencies did not differ among the diets. Quantification of L. reuteri by quantitative PCR (qPCR) detected the two strains used for feed fermentation throughout the intestinal tract. Quantification of E. coli and ETEC virulence factors by qPCR demonstrated that fermented diets containing reuteran significantly (P reuteri reduced the level of colonization of weaning piglets with ETEC, and feed fermentation supplied concentrations of reuteran that may specifically contribute to the effect on ETEC. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

The challenges of measuring in vivo knee collateral ligament strains using ultrasound.

Science.gov (United States)

Slane, Laura C; Slane, Josh A; D'hooge, Jan; Scheys, Lennart

2017-08-16

Ultrasound-based methods have shown promise in their ability to characterize non-uniform deformations in large energy-storing tendons such as the Achilles and patellar tendons, yet applications to other areas of the body have been largely unexplored. The noninvasive quantification of collateral ligament strain could provide an important clinical metric of knee frontal plane stability, which is relevant in ligament injury and for measuring outcomes following total knee arthroplasty. In this pilot cadaveric experiment, we investigated the possibility of measuring collateral ligament strain with our previously validated speckle-tracking approach, but encountered a number of challenges during both data acquisition and processing. Given the clinical interest in this type of tool, and the fact that this is a developing area of research, the goal of this article is to transparently describe this pilot study, both in terms of methods and results, while also identifying specific challenges to this work and areas for future study. Some challenges faced relate generally to speckle-tracking of soft tissues (e.g. the limitations of using a 2D imaging modality to characterize 3D motion), while others are specific to this application (e.g. the small size and complex anatomy of the collateral ligaments). This work illustrates a clear need for additional studies, particularly relating to the collection of ground-truth data and more thorough validation work. These steps will be critical prior to the translation of ultrasound-based measures of collateral ligament strains into the clinic. Copyright © 2017 Elsevier Ltd. All rights reserved.

Frequency of virulence genes of Escherichia coli among newborn piglets from an intensive pig farm in Argentina Frecuencia de genes de virulencia de Escherichia coli en lechones neonatos de un criadero intensivo de Argentina

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Fabrisio E Alustiza

2012-12-01

Full Text Available The enterotoxigenic and porcine enteropathogenic Escherichia coli (ETEC and PEPEC strains are agents associated with swine neonatal diarrhea, causing economic losses in swine production. The main goal of this study was to identify virulence genes of ETEC, verotoxigenic (VTEC and PEPEC in intestinal strains responsible for swine diseases, by molecular typing using PCR in newborn piglets from an intensive farm system. Two hundred and sixty seven rectal swabbings from 7-15 days- old Landrace x Large White crossbred piglets were taken, and 123 randomly selected samples, biochemically compatible with E. coli, were tested for E. coli virulence genes by PCR. A frequency (% compatible with: 68 ETEC, 24 VTEC, and 8 EPEc were found. Of all E. coli strains studied, 19.51 % carried at least one virulence gene. These data showed conclusively that, in spite of the application of strict sanitary measures in the intensive farm, genes encoding virulence factors of intestinal pathogens compatible with ETEC are still dETECted; therefore these strains will probably keep circulating among animals.El objetivo del trabajo fue identificar genes de virulencia de cepas intestinales de Escherichia coli de los grupos enterotoxigénico (ETEC, verotoxigénico (VTEC y enteropatogénico porcino (PEPEC, responsables de patologías en cerdos, mediante tipificación molecular por PCR. Para ello se trabajó en un criadero intensivo, donde se tomaron 267 hisopados rectales de lechones cruza Landrace por Large White de 7-15 días de edad. Del total de aislamientos obtenidos se seleccionaron al azar 123 de ellos, bioquímicamente compatibles con E. coli, los que fueron analizados por PCR. La frecuencia de genes compatibles con ETEC, VTEC y PEPEC fue de 68 %, 24 % y 8 %, respectivamente. De las cepas de E. coli seleccionadas, el 19,51 % portaban al menos un gen codificante de un factor de virulencia. Estos hallazgos muestran de manera concluyente que la aplicación de estrictas

Epithelial Cell Adherence Mediated by the Enterotoxigenic Escherichia coli Tia Protein

OpenAIRE

Mammarappallil, Joseph G.; Elsinghorst, Eric A.

2000-01-01

In vitro studies have shown that enterotoxigenic Escherichia coli (ETEC) strains are capable of invading cultured epithelial cells derived from the human ileum and colon. Two separate invasion loci (tia and tib) have previously been isolated from the classical ETEC strain H10407. The tia locus has been shown to direct the synthesis of Tia, a 25-kDa outer membrane protein. Tia is sufficient to confer the adherence and invasion phenotypes on laboratory stains of E. coli, suggesting that this pr...

Comparison of Growth Kinetics of Various Pathogenic E. coli on Fresh Perilla Leaf

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Juhui Kim

2013-08-01

Full Text Available Growth kinetics for Escherichia coli O157:H7 in perilla leaves were compared to those of pathogenic E. coli strains, including enteropathogenic (EPEC, enterotoxigenic (ETEC, enteroinvasive (EIEC and other enterohemorrhagic (EHEC at 13, 17, 24, 30 and 36 °C. Models for lag time (LT, specific growth rate (SGR and maximum population density (MPD as a function of temperature were developed. The performance of the models was quantified using the ratio method and an acceptable prediction zone method. Significant differences in SGR and LT among the strains were observed at all temperatures. Overall, the shortest LT was observed with E. coli O157:H7, followed by EPEC, other EHEC, EIEC and ETEC, while the fastest growth rates were noted in EPEC, followed by E. coli O157:H7, ETEC, other EHEC and EIEC. The models for E. coli O157:H7 in perilla leaves was suitable for use in making predictions for EPEC and other EHEC strains.

Lactobacillus zeae protects Caenorhabditis elegans from enterotoxigenic Escherichia coli-caused death by inhibiting enterotoxin gene expression of the pathogen.

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Mengzhou Zhou

Full Text Available BACKGROUND: The nematode Caenorhabditis elegans has become increasingly used for screening antimicrobials and probiotics for pathogen control. It also provides a useful tool for studying microbe-host interactions. This study has established a C. elegans life-span assay to preselect probiotic bacteria for controlling K88(+ enterotoxigenic Escherichia coli (ETEC, a pathogen causing pig diarrhea, and has determined a potential mechanism underlying the protection provided by Lactobacillus. METHODOLOGY/PRINCIPAL FINDINGS: Life-span of C. elegans was used to measure the response of worms to ETEC infection and protection provided by lactic acid-producing bacteria (LAB. Among 13 LAB isolates that varied in their ability to protect C. elegans from death induced by ETEC strain JG280, Lactobacillus zeae LB1 offered the highest level of protection (86%. The treatment with Lactobacillus did not reduce ETEC JG280 colonization in the nematode intestine. Feeding E. coli strain JFF4 (K88(+ but lacking enterotoxin genes of estA, estB, and elt did not cause death of worms. There was a significant increase in gene expression of estA, estB, and elt during ETEC JG280 infection, which was remarkably inhibited by isolate LB1. The clone with either estA or estB expressed in E. coli DH5α was as effective as ETEC JG280 in killing the nematode. However, the elt clone killed only approximately 40% of worms. The killing by the clones could also be prevented by isolate LB1. The same isolate only partially inhibited the gene expression of enterotoxins in both ETEC JG280 and E. coli DH5α in-vitro. CONCLUSIONS/SIGNIFICANCE: The established life-span assay can be used for studies of probiotics to control ETEC (for effective selection and mechanistic studies. Heat-stable enterotoxins appeared to be the main factors responsible for the death of C. elegans. Inhibition of ETEC enterotoxin production, rather than interference of its intestinal colonization, appears to be the

Effects of lng Mutations on LngA Expression, Processing, and CS21 Assembly in Enterotoxigenic Escherichia coli E9034A

Science.gov (United States)

Saldaña-Ahuactzi, Zeus; Rodea, Gerardo E.; Cruz-Córdova, Ariadnna; Rodríguez-Ramírez, Viridiana; Espinosa-Mazariego, Karina; González-Montalvo, Martín A.; Ochoa, Sara A.; González-Pedrajo, Bertha; Eslava-Campos, Carlos A.; López-Villegas, Edgar O.; Hernández-Castro, Rigoberto; Arellano-Galindo, José; Patiño-López, Genaro; Xicohtencatl-Cortes, Juan

2016-01-01

Enterotoxigenic Escherichia coli (ETEC) is a major cause of morbidity in children under 5 years of age in low- and middle-income countries and a leading cause of traveler's diarrhea worldwide. The ability of ETEC to colonize the intestinal epithelium is mediated by fimbrial adhesins, such as CS21 (Longus). This adhesin is a type IVb pilus involved in adherence to intestinal cells in vitro and bacterial self-aggregation. Fourteen open reading frames have been proposed to be involved in CS21 assembly, hitherto only the lngA and lngB genes, coding for the major (LngA) and minor (LngB) structural subunit, have been characterized. In this study, we investigated the role of the LngA, LngB, LngC, LngD, LngH, and LngP proteins in the assembly of CS21 in ETEC strain E9034A. The deletion of the lngA, lngB, lngC, lngD, lngH, or lngP genes, abolished CS21 assembly in ETEC strain E9034A and the adherence to HT-29 cells was reduced 90%, compared to wild-type strain. Subcellular localization prediction of CS21 proteins was similar to other well-known type IV pili homologs. We showed that LngP is the prepilin peptidase of LngA, and that ETEC strain E9034A has another peptidase capable of processing LngA, although with less efficiency. Additionally, we present immuno-electron microscopy images to show that the LngB protein could be localized at the tip of CS21. In conclusion, our results demonstrate that the LngA, LngB, LngC, LngD, LngH, and LngP proteins are essential for CS21 assembly, as well as for bacterial aggregation and adherence to HT-29 cells. PMID:27536289

Porcine aminopeptidase N binds to F4+ enterotoxigenic Escherichia coli fimbriae.

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Xia, Pengpeng; Wang, Yiting; Zhu, Congrui; Zou, Yajie; Yang, Ying; Liu, Wei; Hardwidge, Philip R; Zhu, Guoqiang

2016-02-09

F4(+) enterotoxigenic Escherichia coli (ETEC) strains cause diarrheal disease in neonatal and post-weaned piglets. Several different host receptors for F4 fimbriae have been described, with porcine aminopeptidase N (APN) reported most recently. The FaeG subunit is essential for the binding of the three F4 variants to host cells. Here we show in both yeast two-hybrid and pulldown assays that APN binds directly to FaeG, the major subunit of F4 fimbriae, from three serotypes of F4(+) ETEC. Modulating APN gene expression in IPEC-J2 cells affected ETEC adherence. Antibodies raised against APN or F4 fimbriae both reduced ETEC adherence. Thus, APN mediates the attachment of F4(+) E. coli to intestinal epithelial cells.

Protective effects of indigenous Escherichia coli against a pathogenic E. coli challenge strain in pigs.

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Vahjen, W; Cuisiniere, T; Zentek, J

2017-10-13

To investigate the inhibitory effect of indigenous enterobacteria on pathogenic Escherichia coli, a challenge trial with postweaning pigs was conducted. A pathogenic E. coli strain was administered to all animals and their health was closely monitored thereafter. Faecal samples were taken from three healthy and three diarrhoeic animals. Samples were cultivated on MacConkey agar and isolates were subcultured. A soft agar overlay assay was used to determine the inhibitory activity of the isolates. A total of 1,173 enterobacterial isolates were screened for their ability to inhibit the E. coli challenge strain. Colony forming units of enterobacteria on MacConkey agar were not different between healthy and diarrhoeic animals in the original samples. Furthermore, numbers of isolates per animal were also not significantly different between healthy (482 isolates) and diarrhoeic animals (691 isolates). A total of 43 isolates (3.7%) with inhibitory activity against the pathogenic E. coli challenge strain were detected. All inhibitory isolates were identified as E. coli via MALDI-TOF. The isolates belonged to the phylotypes A, C and E. Many isolates (67.4%) were commensal E. coli without relevant porcine pathogenic factors, but toxin- and fimbrial genes (stx2e, fae, estIb, elt1a, fas, fan) were detected in 14 inhibitory isolates. Healthy animals showed significantly (P=0.003) more inhibitory isolates (36 of 482 isolates; 7.5%) than diseased animals (7 of 691 isolates; 1.0%). There were no significant correlations regarding phylotype or pathogenic factors between healthy and diseased animals. This study has shown that a small proportion of indigenous E. coli is able to inhibit in vitro growth of a pathogenic E. coli strain in pigs. Furthermore, healthy animals possess significantly more inhibitory E. coli strains than diarrhoeic animals. The inhibition of pathogenic E. coli by specific indigenous E. coli strains may be an underlying principle for the containment of pathogenic

Construction and expression of immunogenic hybrid enterotoxigenic Escherichia coli CFA/I and CS2 colonization fimbriae for use in vaccines.

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Tobias, Joshua; Svennerholm, Ann-Mari; Holmgren, Jan; Lebens, Michael

2010-07-01

Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrheal morbidity in developing countries, especially in children and also of traveler's diarrhea. Colonization factors (CFs) of ETEC, like CFA/I and CS2 which are genetically and structurally related, play a substantial role in pathogenicity, and since intestinal-mucosal immune responses against CFs appear to be protective, much effort has focused on the development of a CF-based ETEC vaccine. We have constructed hybrid operons in which the major CS2 subunit-encoding cotA gene was inserted into the CFA/I operon, either replacing (hybrid I) or being added to the major CFA/I subunit-encoding cfaB gene (hybrid II). Using specific monoclonal antibodies against the major subunits of CFA/I and CS2, high levels of surface expression of both fimbrial subunits were shown in E. coli carrying the hybrid II operon. Oral immunization of mice with formalin-killed bacteria expressing hybrid II fimbriae induced strong CFA/I- and CS2-specific serum IgG + IgM and fecal IgA antibody responses, which were higher than those achieved by similar immunization with the reference strains. Bacteria expressing hybrid fimbriae are potential candidate strains in an oral-killed CF-ETEC vaccine, and the approach represents an attractive and novel means of producing a broad-spectrum ETEC vaccine.

Enterotoxigenic Escherichia coli Adhesin-Toxoid Multiepitope Fusion Antigen CFA/I/II/IV-3xSTaN12S-mnLTG192G/L211A-Derived Antibodies Inhibit Adherence of Seven Adhesins, Neutralize Enterotoxicity of LT and STa Toxins, and Protect Piglets against Diarrhea.

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Nandre, Rahul; Ruan, Xiaosai; Lu, Ti; Duan, Qiangde; Sack, David; Zhang, Weiping

2018-03-01

Enterotoxigenic Escherichia coli (ETEC) strains are a leading cause of children's diarrhea and travelers' diarrhea. Vaccines inducing antibodies to broadly inhibit bacterial adherence and to neutralize toxin enterotoxicity are expected to be effective against ETEC-associated diarrhea. 6×His-tagged adhesin-toxoid fusion proteins were shown to induce neutralizing antibodies to several adhesins and LT and STa toxins (X. Ruan, D. A. Sack, W. Zhang, PLoS One 10:e0121623, 2015, https://doi.org/10.1371/journal.pone.0121623). However, antibodies derived from His-tagged CFA/I/II/IV-2xSTa A14Q -dmLT or CFA/I/II/IV-2xSTa N12S -dmLT protein were less effective in neutralizing STa enterotoxicity and were not evaluated in vivo for efficacy against ETEC diarrhea. Additionally, His-tagged proteins are considered less desirable for human vaccines. In this study, we produced a tagless adhesin-toxoid MEFA (multiepitope fusion antigen) protein, enhanced anti-STa immunogenicity by including a third copy of STa toxoid STa N12S , and examined antigen immunogenicity in a murine model. Moreover, we immunized pregnant pigs with the tagless adhesin-toxoid MEFA protein and evaluated passive antibody protection against STa + or LT + ETEC infection in a pig challenge model. Results showed that tagless adhesin-toxoid MEFA CFA/I/II/IV-3xSTa N12S -mnLT R192G/L211A induced broad antiadhesin and antitoxin antibody responses in the intraperitoneally immunized mice and the intramuscularly immunized pigs. Mouse and pig serum antibodies significantly inhibited adherence of seven colonization factor antigen (CFA) adhesins (CFA/I and CS1 to CS6) and effectively neutralized both toxins. More importantly, suckling piglets born to the immunized mothers acquired antibodies and were protected against STa + ETEC and LT + ETEC diarrhea. These results indicated that tagless CFA/I/II/IV-3xSTa N12S -mnLT R192G/L211A induced broadly protective antiadhesin and antitoxin antibodies and demonstrate that this adhesin

Both flagella and F4 fimbriae from F4ac+ enterotoxigenic Escherichia coli contribute to attachment to IPEC-J2 cells in vitro.

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Zhou, Mingxu; Duan, Qiangde; Zhu, Xiaofang; Guo, Zhiyan; Li, Yinchau; Hardwidge, Philip R; Zhu, Guoqiang

2013-05-13

The role of flagella in the pathogenesis of F4ac+ Enterotoxigenic Escherichia coli (ETEC) mediated neonatal and post-weaning diarrhea (PWD) is not currently understood. We targeted the reference C83902 ETEC strain (O8:H19:F4ac+ LT+ STa+ STb+), to construct isogenic mutants in the fliC (encoding the major flagellin protein), motA (encoding the flagella motor), and faeG (encoding the major subunit of F4 fimbriae) genes. Both the ΔfliC and ΔfaeG mutants had a reduced ability to adhere to porcine intestinal epithelial IPEC-J2 cells. F4 fimbriae expression was significantly down-regulated after deleting fliC, which revealed that co-regulation exists between flagella and F4 fimbriae. However, there was no difference in adhesion between the ΔmotA mutant and its parent strain. These data demonstrate that both flagella and F4 fimbriae are required for efficient F4ac+ ETEC adhesion in vitro.

Effect of challenge of pigs previously immunised with inactivated vaccines containing homologous and heterologous Mycoplasma hyopneumoniae strains

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Villarreal Iris

2012-01-01

Full Text Available Abstract Background Mycoplasma hyopneumoniae is the primary cause of enzootic pneumonia in pigs. Although vaccination is an important control tool, the results observed under field conditions are variable. This may be due to antigenic differences between the strains circulating in pig herds and the vaccine strain. This study compared the protective efficacy of four bacterins against challenge infection with a highly virulent field strain of M. hyopneumoniae. Seventy eight, one-week old piglets were randomly assigned to five treatment groups (A, B, C, D, E, 14 piglets each, and a negative control group (F consisting of 8 piglets. All pigs were injected at 1 (D7 and 4 weeks of age (D28, with 2 ml of either a placebo or a bacterin based on selected M. hyopneumoniae strains, namely A (F7.2C, B (F20.1L, C (B2V1W20 1A-F, D (J strain, E (placebo; positive control, F (placebo; negative control. At D56, all pigs except those of group F were challenged intratracheally with 7 ml culture medium containing 107 CCU/ml of M. hyopneumoniae strain F7.2C. All pigs were euthanized and necropsied at D84. The severity of coughing and pneumonia lesions were the main parameters. Immunofluorescence (IF testing, nested PCR testing of bronchoalveolar lavage (BAL fluid and serology for M. hyopneumoniae were also performed. Results The different bacterins only slightly improved clinical symptoms (average 0.38 in vaccinated groups vs. 0.45 in group E and histopathological lung lesions (average 3.20 in vaccinated groups vs. 3.45 in group E, but did not improve macroscopic lung lesions (score 4.30 vs. 4.03 in group E. None of the vaccines was significantly and/or consistently better or worse than the other ones. All bacterins evoked a serological response in the vaccinated animals. All pigs, except those from group F, were positive with nPCR in BAL fluid at D84. Conclusion The bacterins did not induce a clear overall protection against challenge infection, and there were no

Effect of challenge of pigs previously immunised with inactivated vaccines containing homologous and heterologous Mycoplasma hyopneumoniae strains.

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Villarreal, Iris; Vranckx, Katleen; Calus, Dries; Pasmans, Frank; Haesebrouck, Freddy; Maes, Dominiek

2012-01-06

Mycoplasma hyopneumoniae is the primary cause of enzootic pneumonia in pigs. Although vaccination is an important control tool, the results observed under field conditions are variable. This may be due to antigenic differences between the strains circulating in pig herds and the vaccine strain. This study compared the protective efficacy of four bacterins against challenge infection with a highly virulent field strain of M. hyopneumoniae. Seventy eight, one-week old piglets were randomly assigned to five treatment groups (A, B, C, D, E), 14 piglets each, and a negative control group (F) consisting of 8 piglets. All pigs were injected at 1 (D7) and 4 weeks of age (D28), with 2 ml of either a placebo or a bacterin based on selected M. hyopneumoniae strains, namely A (F7.2C), B (F20.1L), C (B2V1W20 1A-F), D (J strain), E (placebo; positive control), F (placebo; negative control). At D56, all pigs except those of group F were challenged intratracheally with 7 ml culture medium containing 107 CCU/ml of M. hyopneumoniae strain F7.2C. All pigs were euthanized and necropsied at D84. The severity of coughing and pneumonia lesions were the main parameters. Immunofluorescence (IF) testing, nested PCR testing of bronchoalveolar lavage (BAL) fluid and serology for M. hyopneumoniae were also performed. The different bacterins only slightly improved clinical symptoms (average 0.38 in vaccinated groups vs. 0.45 in group E) and histopathological lung lesions (average 3.20 in vaccinated groups vs. 3.45 in group E), but did not improve macroscopic lung lesions (score 4.30 vs. 4.03 in group E). None of the vaccines was significantly and/or consistently better or worse than the other ones. All bacterins evoked a serological response in the vaccinated animals. All pigs, except those from group F, were positive with nPCR in BAL fluid at D84. The bacterins did not induce a clear overall protection against challenge infection, and there were no significant differences in protective

ISOLASI STREPTOMYCES SPP. PADA KAWASAN HUTAN PROVINSI BALI SERTA UJI DAYA HAMBATNYA TERHADAP LIMA STRAIN DIARRHEAGENIC ESCHERICHIA COLI

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I WAYAN EKA DHARMAWAN

2014-04-01

Full Text Available An exploration study of natural resources soil bacteria antibiotic-producer, Streptomyces spp. was done in two steps. The first step was isolation of Streptomyces and the second involved testing their inhibition activities against five strains diarrheagenic Escherichia coli. Soil samples were collected from ten forest areas in Bali. As many as 55 isolates were collected with various macroscopic dan microscopic characters. Most isolates (eight Streptomyces isolates were collected from forest area in Penulisan, Kintamani (RTK. 20. The diversities of isolates are influenced by environment condition. All Streptomyces isolated were tested against five strains diarrheagenic Escherichia coli to check antibiotic activity for inhibit growth of E. coli. Streptomycine was used as a control. The result showed that the largest inhibition zones of Streptomyces against E. coli strains EHEC, ETEC, EIEC, EPEC and DAEC were produced by Streptomyces PK5 (48,67 ± 0,58 mm, Streptomyces GAA4 (29,00 ± 2,00 mm, Streptomyces GBK3 (42,67 ± 2,08 mm, Streptomyces SkBB5 (29,00 ± 2,65 mm and Streptomyces GM3 (33,67 ± 3,21 mm respectively.

Complex adenovirus-vectored vaccine protects guinea pigs from three strains of Marburg virus challenges

International Nuclear Information System (INIS)

Wang Danher; Hevey, Michael; Juompan, Laure Y.; Trubey, Charles M.; Raja, Nicholas U.; Deitz, Stephen B.; Woraratanadharm, Jan; Luo Min; Yu Hong; Swain, Benjamin M.; Moore, Kevin M.; Dong, John Y.

2006-01-01

The Marburg virus (MARV), an African filovirus closely related to the Ebola virus, causes a deadly hemorrhagic fever in humans, with up to 90% mortality. Currently, treatment of disease is only supportive, and no vaccines are available to prevent spread of MARV infections. In order to address this need, we have developed and characterized a novel recombinant vaccine that utilizes a single complex adenovirus-vectored vaccine (cAdVax) to overexpress a MARV glycoprotein (GP) fusion protein derived from the Musoke and Ci67 strains of MARV. Vaccination with the cAdVaxM(fus) vaccine led to efficient production of MARV-specific antibodies in both mice and guinea pigs. Significantly, guinea pigs vaccinated with at least 5 x 10 7 pfu of cAdVaxM(fus) vaccine were 100% protected against lethal challenges by the Musoke, Ci67 and Ravn strains of MARV, making it a vaccine with trivalent protective efficacy. Therefore, the cAdVaxM(fus) vaccine serves as a promising vaccine candidate to prevent and contain multi-strain infections by MARV

An objective approach for Burkholderia pseudomallei strain selection as challenge material for medical countermeasures efficacy testing

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Kristopher E. Van Zandt

2012-09-01

Full Text Available Burkholderia pseudomallei is the causative agent of melioidosis, a rare disease of biodefense concern with high mortality and extreme difficulty in treatment. No human vaccines are available that protect against B. pseudomallei infection, and with the current limitations of antibiotic treatment, the development of new preventative and therapeutic interventions is crucial. Although clinical trials could be used to test the efficacy of new medical countermeasures (MCMs, the high mortality rates associated with melioidosis raises significant ethical issues concerning treating individuals with new compounds with unknown efficacies. The US Food and Drug Administration (FDA has formulated a set of guidelines for the licensure of new MCMs to treat diseases in which it would be unethical to test the efficacy of these drugs in humans. The FDA Animal Rule 21 CFR 314 calls for consistent, well-characterized B. pseudomallei strains to be used as challenge material in animal models. In order to facilitate the efficacy testing of new MCMs for melioidosis using animal models, we intend to develop a well-characterized panel of strains for use. This panel will comprise of strains that were isolated from human cases, have a low passage history, are virulent in animal models, and are well characterized phenotypically and genotypically. We have reviewed published and unpublished data on various B. pseudomallei strains to establish an objective method for selecting the strains to be included in the panel of B. pseudomallei strains with attention to five categories: animal infection models, genetic characterization, clinical and passage history, and availability of the strain to the research community. We identified 109 strains with data in at least one of the five categories, scored each strain based on the gathered data and identified 6 strains as candidate for a B. pseudomallei strain panel.

An objective approach for Burkholderia pseudomallei strain selection as challenge material for medical countermeasures efficacy testing.

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Van Zandt, Kristopher E; Tuanyok, Apichai; Keim, Paul S; Warren, Richard L; Gelhaus, H Carl

2012-01-01

Burkholderia pseudomallei is the causative agent of melioidosis, a rare disease of biodefense concern with high mortality and extreme difficulty in treatment. No human vaccines are available that protect against B. pseudomallei infection, and with the current limitations of antibiotic treatment, the development of new preventative and therapeutic interventions is crucial. Although clinical trials could be used to test the efficacy of new medical countermeasures (MCMs), the high mortality rates associated with melioidosis raises significant ethical issues concerning treating individuals with new compounds with unknown efficacies. The US Food and Drug Administration (FDA) has formulated a set of guidelines for the licensure of new MCMs to treat diseases in which it would be unethical to test the efficacy of these drugs in humans. The FDA "Animal Rule" 21 CFR 314 calls for consistent, well-characterized B. pseudomallei strains to be used as challenge material in animal models. In order to facilitate the efficacy testing of new MCMs for melioidosis using animal models, we intend to develop a well-characterized panel of strains for use. This panel will comprise of strains that were isolated from human cases, have a low passage history, are virulent in animal models, and are well-characterized phenotypically and genotypically. We have reviewed published and unpublished data on various B. pseudomallei strains to establish an objective method for selecting the strains to be included in the panel of B. pseudomallei strains with attention to five categories: animal infection models, genetic characterization, clinical and passage history, and availability of the strain to the research community. We identified 109 strains with data in at least one of the five categories, scored each strain based on the gathered data and identified six strains as candidate for a B. pseudomallei strain panel.

Reflexões sobre mediação pedagógica em programas de formação a distância (e-TEC Brasil)

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Queiroz, Magali Aparecida Mendes; IFTM- Instituto Federal de Educação Ciência e Tecnologia do Triângulo Mineiro

2012-01-01

Resumo: A educação a distância é hoje uma realidade, não só em cursos de nível superior, mas também em nível médio como é o caso do Programa Escola Técnica Aberta do Brasil (e-TEC Brasil), do Ministério da Educação. Este artigo faz uma análise sobre a mediação pedagógica nesta modalidade de ensino no tocante ao papel do professor frente a este novo paradigma e a sua abrangência social e educacional. As reflexões teóricas fundamentam-se em Lima (2007), Behrens (2000), Moran (2003), Lévy (2000)...

A large family of antivirulence regulators modulates the effects of transcriptional activators in Gram-negative pathogenic bacteria.

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Araceli E Santiago

2014-05-01

Full Text Available We have reported that transcription of a hypothetical small open reading frame (orf60 in enteroaggregative E. coli (EAEC strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44-100% similarity to at least fifty previously undescribed small (<10 kDa hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators for this family.

Characterization of Diarrheagenic Escherichia coli Isolated in Organic Waste Products (Cattle Fecal Matter, Manure and, Slurry) from Cattle's Markets in Ouagadougou, Burkina Faso.

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Bako, Evariste; Kagambèga, Assèta; Traore, Kuan Abdoulaye; Bagre, Touwendsida Serge; Ibrahim, Hadiza Bawa; Bouda, Soutongnooma Caroline; Bonkoungou, Isidore Juste Ouindgueta; Kaboré, Saidou; Zongo, Cheikna; Traore, Alfred Sababenejo; Barro, Nicolas

2017-09-22

Cattle farming can promote diarrheal disease transmission through waste, effluents or cattle fecal matter. The study aims to characterize the diarrheagenic Escherichia coli (DEC) isolated from cattle feces, manure in the composting process and slurry, collected from four cattle markets in Ouagadougou. A total of 585 samples (340 cattle feces, 200 slurries and 45 manures in the composting process) were collected from the four cattle markets between May 2015 and May 2016. A multiplex Polymerase Chain Reaction (PCR), namely 16-plex PCR, was used to screen simultaneously the virulence genes specific for shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC) and enteroaggregative E. coli (EAEC). DEC was detected in 10.76% of samples. ETEC was the most prevalent (9.91%). STEC and EAEC have been observed with the same rate (0.51%). ETEC were detected in 12.64% of cattle feces, in 6.66% of manure in the composting process and in 5% of slurry. STEC were detected in 0.58% of cattle feces and in 2.22% of manure in the composting process. EAEC was detected only in 1% of slurry and in 2.22% of manure in the composting process. ETEC strains were identified based on estIa gene and/or estIb gene and/or elt gene amplification. Of the 58 ETEC, 10.34% contained astA , 17.24% contained elt , 3.44% contained estIa and 79.31% contained estIb . The two positive EAEC strains contained only the aggR gene, and the third was positive only for the pic gene. The results show that effluent from cattle markets could contribute to the spreading of DEC in the environment in Burkina Faso.

Characterization of Diarrheagenic Escherichia coli Isolated in Organic Waste Products (Cattle Fecal Matter, Manure and, Slurry from Cattle’s Markets in Ouagadougou, Burkina Faso

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Evariste Bako

2017-09-01

Full Text Available Cattle farming can promote diarrheal disease transmission through waste, effluents or cattle fecal matter. The study aims to characterize the diarrheagenic Escherichia coli (DEC isolated from cattle feces, manure in the composting process and slurry, collected from four cattle markets in Ouagadougou. A total of 585 samples (340 cattle feces, 200 slurries and 45 manures in the composting process were collected from the four cattle markets between May 2015 and May 2016. A multiplex Polymerase Chain Reaction (PCR, namely 16-plex PCR, was used to screen simultaneously the virulence genes specific for shiga toxin-producing E. coli (STEC, enteropathogenic E. coli (EPEC, enterotoxigenic E. coli (ETEC, enteroinvasive E. coli (EIEC and enteroaggregative E. coli (EAEC. DEC was detected in 10.76% of samples. ETEC was the most prevalent (9.91%. STEC and EAEC have been observed with the same rate (0.51%. ETEC were detected in 12.64% of cattle feces, in 6.66% of manure in the composting process and in 5% of slurry. STEC were detected in 0.58% of cattle feces and in 2.22% of manure in the composting process. EAEC was detected only in 1% of slurry and in 2.22% of manure in the composting process. ETEC strains were identified based on estIa gene and/or estIb gene and/or elt gene amplification. Of the 58 ETEC, 10.34% contained astA, 17.24% contained elt, 3.44% contained estIa and 79.31% contained estIb. The two positive EAEC strains contained only the aggR gene, and the third was positive only for the pic gene. The results show that effluent from cattle markets could contribute to the spreading of DEC in the environment in Burkina Faso.

Emporiatric enteritis: lessons learned from U.S. students in Mexico.

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Dupont, H L; Ericsson, C D; Dupont, M W

1986-01-01

In the studies reported, evidence has been presented that U.S. students traveling to Mexico represent a model for the study of travelers' diarrhea. The incidence of illness acquisition approximates that published in other studies of travelers. Natural immunity was shown to develop as students remained in Mexico presumably through repeated exposure to prevalent agents, particularly ETEC. ETEC, shigella strains and no detectable agent represented the largest groups when etiologic assessment was made. Food probably served as the important source of diarrhea particularly that due to ETEC and shigella strains. The level of bacteria isolated from food suggested that organism replication occurred due to improper temperature storage rather than to heavy initial contamination. The location of food consumption was related to degree of risk: self preparation was the safest, eating in Mexican homes the least safe and consumption of food in public restaurants was intermediate in risk. Water probably played a role in the transmission of viral infection. The risk of water contamination appeared to be highest during the rainy seasons. Finally, the antimicrobial agents TMP/SMX and TMP alone were shown to effectively prevent and treat this form of travelers' diarrhea.

Methyltransferase-defective avian metapneumovirus vaccines provide complete protection against challenge with the homologous Colorado strain and the heterologous Minnesota strain.

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Sun, Jing; Wei, Yongwei; Rauf, Abdul; Zhang, Yu; Ma, Yuanmei; Zhang, Xiaodong; Shilo, Konstantin; Yu, Qingzhong; Saif, Y M; Lu, Xingmeng; Yu, Lian; Li, Jianrong

2014-11-01

Avian metapneumovirus (aMPV), also known as avian pneumovirus or turkey rhinotracheitis virus, is the causative agent of turkey rhinotracheitis and is associated with swollen head syndrome in chickens. Since its discovery in the 1970s, aMPV has been recognized as an economically important pathogen in the poultry industry worldwide. The conserved region VI (CR VI) of the large (L) polymerase proteins of paramyxoviruses catalyzes methyltransferase (MTase) activities that typically methylate viral mRNAs at guanine N-7 (G-N-7) and ribose 2'-O positions. In this study, we generated a panel of recombinant aMPV (raMPV) Colorado strains carrying mutations in the S-adenosyl methionine (SAM) binding site in the CR VI of L protein. These recombinant viruses were specifically defective in ribose 2'-O, but not G-N-7 methylation and were genetically stable and highly attenuated in cell culture and viral replication in the upper and lower respiratory tracts of specific-pathogen-free (SPF) young turkeys. Importantly, turkeys vaccinated with these MTase-defective raMPVs triggered a high level of neutralizing antibody and were completely protected from challenge with homologous aMPV Colorado strain and heterologous aMPV Minnesota strain. Collectively, our results indicate (i) that aMPV lacking 2'-O methylation is highly attenuated in vitro and in vivo and (ii) that inhibition of mRNA cap MTase can serve as a novel target to rationally design live attenuated vaccines for aMPV and perhaps other paramyxoviruses. Paramyxoviruses include many economically and agriculturally important viruses such as avian metapneumovirus (aMPV), and Newcastle disease virus (NDV), human pathogens such as human respiratory syncytial virus, human metapneumovirus, human parainfluenza virus type 3, and measles virus, and highly lethal emerging pathogens such as Nipah virus and Hendra virus. For many of them, there is no effective vaccine or antiviral drug. These viruses share common strategies for viral gene

Identification of Extended-Spectrum β-Lactamases Escherichia coli Strains Isolated from Market Garden Products and Irrigation Water in Benin

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Wassiyath Moussé

2015-01-01

Full Text Available The present study aimed at biochemical and molecular characterization of Escherichia coli strains isolated from horticultural products and irrigation water of Cotonou. The samples were collected from 12 market gardeners of 4 different sites. Rapid’ E. coli medium was used for identification of E. coli strains and the antimicrobial susceptibility was performed by the agar disk diffusion method. The β-lactamases production was sought by the liquid acidimetric method. The genes coding for β-lactamases and toxins were identified by PCR method. The results revealed that about 34.95% of the analyzed samples were contaminated by E. coli. Cabbages were the most contaminated by E. coli (28.26% in dry season. All isolated strains were resistant to amoxicillin. The penicillinase producing E. coli carried blaTEM (67.50%, blaSHV (10%, and blaCTX-M (22.50% genes. The study revealed that the resistance genes such as SLTI (35.71%, SLTII (35.71%, ETEC (7.15%, and VTEC (21.43% were carried. Openly to the found results and considering the importance of horticultural products in Beninese food habits, it is important to put several strategies aiming at a sanitary security by surveillance and sensitization of all the actors on the risks of some practices.

Identification of Extended-Spectrum β-Lactamases Escherichia coli Strains Isolated from Market Garden Products and Irrigation Water in Benin

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Moussé, Wassiyath; Sina, Haziz; Baba-Moussa, Farid; Noumavo, Pacôme A.; Agbodjato, Nadège A.; Adjanohoun, Adolphe; Baba-Moussa, Lamine

2015-01-01

The present study aimed at biochemical and molecular characterization of Escherichia coli strains isolated from horticultural products and irrigation water of Cotonou. The samples were collected from 12 market gardeners of 4 different sites. Rapid' E. coli medium was used for identification of E. coli strains and the antimicrobial susceptibility was performed by the agar disk diffusion method. The β-lactamases production was sought by the liquid acidimetric method. The genes coding for β-lactamases and toxins were identified by PCR method. The results revealed that about 34.95% of the analyzed samples were contaminated by E. coli. Cabbages were the most contaminated by E. coli (28.26%) in dry season. All isolated strains were resistant to amoxicillin. The penicillinase producing E. coli carried blaTEM (67.50%), blaSHV (10%), and blaCTX-M (22.50%) genes. The study revealed that the resistance genes such as SLTI (35.71%), SLTII (35.71%), ETEC (7.15%), and VTEC (21.43%) were carried. Openly to the found results and considering the importance of horticultural products in Beninese food habits, it is important to put several strategies aiming at a sanitary security by surveillance and sensitization of all the actors on the risks of some practices. PMID:26770972

Comparison of abortion and infection after experimental challenge of pregnant bison and cattle with Brucella abortus strain 2308

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A comparative study was conducted using data from naive bison (n=45) and cattle (n=46) from 8 and 6 studies, respectively, in which a standardized Brucella abortus strain 2308 experimental challenge was administered. The incidence of abortion, fetal infection, uterine or mammary infection, or infec...

Entericidin is required for a probiotic treatment (Enterobacter sp. strain C6-6) to protect trout from cold-water disease challenge.

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Schubiger, Carla B; Orfe, Lisa H; Sudheesh, Ponnerassery S; Cain, Kenneth D; Shah, Devendra H; Call, Douglas R

2015-01-01

Flavobacterium psychrophilum causes bacterial cold-water disease in multiple fish species, including salmonids. An autochthonous Enterobacter strain (C6-6) inhibits the in vitro growth of F. psychrophilum, and when ingested as a putative probiotic, it provides protection against injection challenge with F. psychrophilum in rainbow trout. In this study, low-molecular-mass (≤3 kDa) fractions from both Enterobacter C6-6 and Escherichia coli K-12 culture supernatants inhibited the growth of F. psychrophilum. The ≤3-kDa fraction from Enterobacter C6-6 was analyzed by SDS-PAGE, and subsequent tandem mass spectroscopy identified EcnB, which is a small membrane lipoprotein that is a putative pore-forming toxin. Agar plate diffusion assays demonstrated that ecnAB knockout strains of both Enterobacter C6-6 and E. coli K-12 no longer inhibited F. psychrophilum (P ) and the wild-type strain (C6-6) were added to the fish diet every day for 38 days. On day 11, the fish were challenged by injection with a virulent strain of F. psychrophilum (CSF 259-93). Fish that were fed C6-6 had significantly longer survival than fish fed the ecnAB knockout strain (P Enterobacter C6-6, and it may present new opportunities for therapeutic and prophylactic treatments against similarly susceptible pathogens. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Caracterización genotipica de aislamientos de Escherichia coli obtenidos de cerdos con diarrea posdestete y enfermedad de los edemas Genotypic characterization of toxigenic Escherichia coli isolated from pigs with postweaning diarrhea (PWD and edema disease (ED

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Fabiana A Moredo

2012-06-01

Full Text Available El objetivo del trabajo fue caracterizar mediante PCR 47 aislamientos de Escheríchia coli recuperados de 32 cerdos con diagnóstico clínico de diarrea posdestete (DPD y de 3 cerdos con enfermedad de los edemas (ED. Sobre 44 aislamientos provenientes de cerdos con DPD, 42 (95,5 % fueron caracterizados como E. coli enterotoxigénicos (ETEC y 2 (4,5 % como E. coli productores de toxina Shiga (STEC. Catorce aislamientos de ETEC (33,3 % fueron positivos para los genes estl/estlI/fedA. El genotipo más complejo fue eltA/estll/east1/faeG/aidA. Los aislamientos provenientes de cerdos con ED se clasificaron como STEC porcinos y fueron portadores de stxJaidA. Once aislamientos (25 % fueron portadores del gen que codifica la expresión de la adhesina AIDA-I. Sin embargo, en ningún aislamiento se detectaron los genes que codifican la expresión de las adhesinas F5, F6, F41, de intimina y de "Paa". La prevención de la DPD y de la ED podría realizarse mediante el desarrollo de vacunas que generen anticuerpos contra las adhesinas de las cepas de E. coli prevalentes en la Argentina.The purpose of this work was to characterize 47 Escherichia coli strains isolated from 32 pigs diagnosed with postweaning diarrhea and tree pigs with edema disease by PCR. Forty two (95.5 % of the strains isolated from diarrheic pigs were characterized as enterotoxigenic E. coli (ETEC and 2 (4.5 % as Shiga toxin-producing E. coli (STEC. Fourteen (33.3 % ETEC strains were positive for est/estll/fedA genes. The most complex genotype was eltA/estl/faeG/aidA. Strains isolated from pigs with ED were classified as porcine STEC and were stxjaidA carriers. Eleven (25 % strains carried the gene encoding adhesln protein AIDA-I. However, genes coding for F5, F6, F41, intimin and Paa were not detected. The development of vaccines generating antibodies against prevalent E. coli adhesins in Argentina could be useful for the prevention of PWD and ED.

Distribution of Escherichia coli F4 adhesion phenotypes in pigs of 15 Chinese and Western breeds and a White DurocxErhualian intercross.

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Yan, Xueming; Huang, Xiang; Ren, Jun; Zou, Zhengzhi; Yang, Shujin; Ouyang, Jing; Zeng, Weihong; Yang, Bin; Xiao, Shijun; Huang, Lusheng

2009-08-01

Diarrhoea in newborn and weaned piglets is mainly caused by enterotoxigenic Escherichia coli (ETEC) with fimbriae F4. To investigate the prevalence of resistance to three fimbrial strains, F4ab, F4ac and F4ad, among Chinese indigenous pigs and Western commercial pigs introduced into China, we determined the ETEC F4 adhesion phenotypes in 292 pure-bred piglets from three Western commercial breeds and 12 Chinese indigenous breeds, and a total of 1093 adult pigs in a White DurocxErhualian intercross, by an in vitro microscopic adhesion assay. All the Tibet and Lantang pigs and a majority of the Erhualian and Rongchang pigs were resistant (nonadherent) to ETEC F4 whereas all the Laiwu pigs and most of the Jiangquhai and Tongcheng pigs were susceptible (adhesive) to at least one of the F4 strains. Yushan Black pigs were uniformly resistant to F4ab, and Jinhua pigs were predominantly resistant to F4ac. Susceptible and resistant animals were observed in the other breeds, indicating that diarrhoea caused by ETEC F4 could be prevalent in these breeds. This study confirmed the existence of eight previously reported F4 adhesion patterns, and supported the assumption that the three F4 receptors are encoded by distinct loci. Expression of the weakly adherent phenotype was observed in six pure-bred piglets and 90 adult F(2)/F(3) animals, and the inheritance of this phenotype and its correlation with susceptibility to disease are still not known.

Recombinant M. bovis BCG expressing the PLD protein promotes survival in mice challenged with a C. pseudotuberculosis virulent strain.

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Leal, Karen Silva; de Oliveira Silva, Mara Thais; de Fátima Silva Rezende, Andréa; Bezerra, Francisco Silvestre Brilhante; Begnini, Karine; Seixas, Fabiana; Collares, Tiago; Dellagostin, Odir; Portela, Ricardo Wagner; de Carvalho Azevedo, Vasco Ariston; Borsuk, Sibele

2018-06-14

The aim of this study was to evaluate the survival of mice inoculated with M. bovis BCG Pasteur recombinant expressing the PLD protein and challenged with a C. pseudotuberculosis virulent strain. Four groups were immunized with a sterile 0.9% saline solution (G1), 10 6  CFU of M. bovis BCG Pasteur (G2), 10 6  CFU of M. bovis BCG/pld (G3) or 10 6  CFU of M. bovis BCG/pld with a booster with rPLD (G4) and challenged with 10 4 CFU of C. pseudotuberculosis MIC-6 strain. The highest survival rate of 88% was observed in G4, followed by 77% in G3 and 66% in G2. A significant statistical difference was observed in the levels of cytokines IFN-γ and IL-10 in vaccinated groups (G3 and G4) when compared with the control group (G1) (p < 0.05). The results seem promising as the recombinant vaccine elicited a cellular immune response and provided significant survival after a high virulent challenge. Copyright © 2018 Elsevier Ltd. All rights reserved.

Outbreaks of cholera-like diarrhoea caused by enterotoxigenic Escherichia coli in the Brazilian Amazon Rainforest.

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Vicente, Ana C P; Teixeira, Luiz F M; Iniguez-Rojas, L; Luna, M G; Silva, L; Andrade, J R C; Guth, B E C

2005-09-01

The relationship between enteropathogens and severe diarrhoea in the Brazilian Amazon is poorly understood. In 1998, outbreaks of acute diarrhoea clinically diagnosed as cholera occurred in two small villages localized far from the main cholera route in the Brazilian rainforest. PCR was performed on some enteropathogens and heat-labile (LT) and/or heat-stable (STh) toxin genes, the virulence determinants of enterotoxigenic Escherichia coli (ETEC), were detected. Further characterization of ETEC isolates revealed the presence of two clones, one from each outbreak. One presenting serotype O167:H5 harboured LT-I and STh toxin genes and expressed the CS5CS6 colonization factor. The other, a non-typeable serotype, was positive for the LT-I gene and expressed the CS7 colonization factor. The current study demonstrates the importance of molecular diagnosis in regions such as the Amazon basin, where the enormous distances and local support conditions make standard laboratory diagnosis difficult. Here we also show that the mis-identified cholera cases were in fact associated with ETEC strains. This is the first report of ETEC, molecularly characterized as the aetiological agent of severe diarrhoea in children and adults in the Brazilian Amazon Rainforest.

Vaccination against porcine parvovirus protects against disease, but does not prevent infection and virus shedding after challenge infection with a heterologous virus strain.

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Jóźwik, A; Manteufel, J; Selbitz, H-J; Truyen, U

2009-10-01

The demonstration of field isolates of porcine parvovirus (PPV) that differ genetically and antigenically from vaccine strains of PPV raises the question of whether the broadly used inactivated vaccines can still protect sows against the novel viruses. Ten specific-pathogen-free primiparous sows were assigned to three groups and were vaccinated with one of two vaccines based on the old vaccine strains, or served as non-vaccinated controls. After insemination, all sows were challenged with the prototype genotype 2 virus, PPV-27a, on gestation day 41; fetuses were delivered on gestation day 90 and examined for virus infection. The fetuses of the vaccinated sows were protected against disease, but both the vaccinated and the non-vaccinated sows showed a marked increase in antibody titres after challenge infection, indicating replication of the challenge virus. All sows (vaccinated and non-vaccinated) shed the challenge virus for at least 10 days after infection, with no difference in the pattern or duration of virus shedding.

Molecular Characterization of Enterotoxin-Producing Escherichia coli Collected in 2011-2012, Russia.

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Nikolay N Kartsev

Full Text Available Enterotoxin-producing Escherichia coli (ETEC are one of the main causative agents of diarrhea in children especially in developing countries and travel diarrhoea in adults. Pathogenic properties of ETEC associated with their ability to produce a heat-stable (ST and/or heat-labile (LT enterotoxins, as well as adhesins providing bacterial adhesion to intestinal epithelial cells. This study presents the molecular characterization of the ETEC isolates collected from the Central and Far-Eastern regions of Russia in 2011-2012. It was shown that all ETEC under study (n=18 had the heat-labile enterotoxin-coding operon elt, and had no the genes of the heat-stable enterotoxin operon est. DNA sequencing revealed two types of nucleotide exchanges in the eltB gene coding subunit B of LT in isolates collected from Cherepovets city (Central region, Russia and Vladivostok city (Far-East region, Russia. Only one ETEC strain carried genes cfaA, cfaB, cfaC and cfaD coding adhesion factor CFA/I. Expression of LT in four ETEC isolates in the agglutination reaction was detected using a latex test-system. The isolates were assigned to serogroups O142 (n = 6, О6 (n = 4, О25 (n = 5, О26 (n = 2, and O115 (n = 1. Genotyping showed that they belonged to an earlier described sequence-type ST4 (n = 3 as well as to 11 novel sequence-types ST1043, ST1312, ST3697, ST3707, ST3708, ST3709, ST3710, ST3755, ST3756, ST3757 and ST4509. The ETEC isolates displayed different levels of antimicrobial resistance. Eight isolates were resistant to only one drug, three isolates-to two drugs, one isolate-to three drugs, two isolates-to four antibacterials, and only one isolate to each of the five, six and ten antibacterials simultaneously. Genetic determinants of the resistance to beta-lactams and other classes of antibacterials on the ETEC genomes were identified. There are blaTEM (n = 10, blaCTX-M-15 (n = 1, class 1 integron (n = 3 carrying resistance cassettes to aminoglycosides and

Molecular Characterization of Enterotoxin-Producing Escherichia coli Collected in 2011-2012, Russia.

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Kartsev, Nikolay N; Fursova, Nadezhda K; Pachkunov, Dmitry M; Bannov, Vasiliy A; Eruslanov, Boris V; Svetoch, Edward A; Dyatlov, Ivan A

2015-01-01

Enterotoxin-producing Escherichia coli (ETEC) are one of the main causative agents of diarrhea in children especially in developing countries and travel diarrhoea in adults. Pathogenic properties of ETEC associated with their ability to produce a heat-stable (ST) and/or heat-labile (LT) enterotoxins, as well as adhesins providing bacterial adhesion to intestinal epithelial cells. This study presents the molecular characterization of the ETEC isolates collected from the Central and Far-Eastern regions of Russia in 2011-2012. It was shown that all ETEC under study (n=18) had the heat-labile enterotoxin-coding operon elt, and had no the genes of the heat-stable enterotoxin operon est. DNA sequencing revealed two types of nucleotide exchanges in the eltB gene coding subunit B of LT in isolates collected from Cherepovets city (Central region, Russia) and Vladivostok city (Far-East region, Russia). Only one ETEC strain carried genes cfaA, cfaB, cfaC and cfaD coding adhesion factor CFA/I. Expression of LT in four ETEC isolates in the agglutination reaction was detected using a latex test-system. The isolates were assigned to serogroups O142 (n = 6), О6 (n = 4), О25 (n = 5), О26 (n = 2), and O115 (n = 1). Genotyping showed that they belonged to an earlier described sequence-type ST4 (n = 3) as well as to 11 novel sequence-types ST1043, ST1312, ST3697, ST3707, ST3708, ST3709, ST3710, ST3755, ST3756, ST3757 and ST4509. The ETEC isolates displayed different levels of antimicrobial resistance. Eight isolates were resistant to only one drug, three isolates-to two drugs, one isolate-to three drugs, two isolates-to four antibacterials, and only one isolate to each of the five, six and ten antibacterials simultaneously. Genetic determinants of the resistance to beta-lactams and other classes of antibacterials on the ETEC genomes were identified. There are blaTEM (n = 10), blaCTX-M-15 (n = 1), class 1 integron (n = 3) carrying resistance cassettes to aminoglycosides and

Flagellin and F4 fimbriae have opposite effects on biofilm formation and quorum sensing in F4ac+ enterotoxigenic Escherichia coli.

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Zhou, Mingxu; Guo, Zhiyan; Yang, Yang; Duan, Qiangde; Zhang, Qi; Yao, Fenghua; Zhu, Jun; Zhang, Xinjun; Hardwidge, Philip R; Zhu, Guoqiang

2014-01-10

Bacteria that form biofilms are often highly resistant to antibiotics and are capable of evading the host immune system. To evaluate the role of flagellin and F4 fimbriae on biofilm formation by enterotoxigenic Escherichia coli (ETEC), we deleted the fliC (encoding the major flagellin protein) and/or the faeG (encoding the major subunit of F4 fimbriae) genes from ETEC C83902. Biofilm formation was reduced in the fliC mutant but increased in the faeG mutant, as compared with the wild-type strain. The expression of AI-2 quorum sensing associated genes was regulated in the fliC and faeG mutants, consistent with the biofilm formation of these strains. But, deleting fliC and/or faeG also inhibited AI-2 quorum sensing activity. Copyright © 2013 Elsevier B.V. All rights reserved.

New vaccine strategies against enterotoxigenic Escherichia coli: II: Enhanced systemic and secreted antibody responses against the CFA/I fimbriae by priming with DNA and boosting with a live recombinant Salmonella vaccine

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M.O. Lásaro

1999-02-01

Full Text Available The induction of systemic (IgG and mucosal (IgA antibody responses against the colonization factor I antigen (CFA/I of enterotoxigenic Escherichia coli (ETEC was evaluated in mice primed with an intramuscularly delivered CFA/I-encoding DNA vaccine followed by two oral immunizations with a live recombinant Salmonella typhimurium vaccine strain expressing the ETEC antigen. The booster effect induced by the oral immunization was detected two weeks and one year after the administration of the DNA vaccine. The DNA-primed/Salmonella-boosted vaccination regime showed a synergistic effect on the induced CFA/I-specific systemic and secreted antibody levels which could not be attained by either immunization strategy alone. These results suggest that the combined use of DNA vaccines and recombinant Salmonella vaccine strains can be a useful immunization strategy against enteric pathogens.

Immunogenicity of recombinant Lactobacillus casei-expressing F4 (K88) fimbrial adhesin FaeG in conjunction with a heat-labile enterotoxin A (LTAK63) and heat-labile enterotoxin B (LTB) of enterotoxigenic Escherichia coli as an oral adjuvant in mice.

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Yu, M; Qi, R; Chen, C; Yin, J; Ma, S; Shi, W; Wu, Y; Ge, J; Jiang, Y; Tang, L; Xu, Y; Li, Y

2017-02-01

The aims of this study were to develop an effective oral vaccine against enterotoxigenic Escherichia coli (ETEC) infection and to design new and more versatile mucosal adjuvants. Genetically engineered Lactobacillus casei strains expressing F4 (K88) fimbrial adhesin FaeG (rLpPG-2-FaeG) and either co-expressing heat-labile enterotoxin A (LTA) subunit with an amino acid mutation associated with reduced virulence (LTAK63) and a heat-labile enterotoxin B (LTB) subunit of E. coli (rLpPG-2-LTAK63-co-LTB) or fused-expressing LTAK63 and LTB (rLpPG-2-LTAK63-fu-LTB) were constructed. The immunogenicity of rLpPG-2-FaeG in conjunction with rLpPG-2-LTAK63-co-LTB or rLpPG-2-LTAK63-fu-LTB as an orally administered mucosal adjuvant in mice was evaluated. Results showed that the levels of FaeG-specific serum IgG and mucosal sIgA, as well as the proliferation of lymphocytes, were significantly higher in mice orally co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-fu-LTB compared with those administered rLpPG-2-FaeG alone, and were lower than those co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-co-LTB. Moreover, effective protection was observed after challenge with F4+ ETEC strain CVCC 230 in mice co-administered rLpPG-2-FaeG and rLpPG-2-LTAK63-co-LTB or rLpPG-2-FaeG and rLpPG-2-LTAK63-fu-LTB group compared with those that received rLpPG-2-FaeG alone. rLpPG-2-FaeG showed greater immunogenicity in combination with LTAK63 and LTB as molecular adjuvants. Recombinant Lactobacillus provides a promising platform for the development of vaccines against F4+ ETEC infection. © 2016 The Society for Applied Microbiology.

Adjuvant effect of Gantrez®AN nanoparticles during oral vaccination of piglets against F4+enterotoxigenic Escherichia coli.

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Vandamme, Katrien; Melkebeek, Vesna; Vesna, Melkebeek; Cox, Eric; Eric, Cox; Remon, Jean Paul; Paul, Remon Jean; Vervaet, Chris; Chris, Vervaet

2011-02-15

In this study, the adjuvanticity of methylvinylether-co-maleic anhydride (Gantrez(®)AN) nanoparticles (NP) was investigated in an oral immunisation experiment of pigs against F4+enterotoxigenic Escherichia coli (F4+ETEC). In addition, Wheat Germ Agglutinin (WGA)-coating of the nanoparticles was tested for enterocyte-targeting. Pigs were either vaccinated with F4 fimbriae, F4 encapsulated in Gantrez(®)AN NP, F4 encapsulated in Gantrez(®)AN NP coated with WGA or F4 fimbriae mixed with empty Gantrez(®)AN NP. Only vaccination with the combination of F4 mixed with empty Gantrez(®)AN NP improved protection against F4+ETEC infection. In addition, vaccination with this formulation also resulted in an F4-specific serum antibody response prior to F4+ETEC challenge. Encapsulation of F4 in Gantrez(®)AN NP only raised the serum antibody response after F4+ETEC challenge compared to soluble F4, but did not improve protection, whereas WGA-coating almost completely abolished the serum antibody response. These data indicate that nanoparticle effects after F4 encapsulation were of lesser importance for the adjuvant effect of Gantrez(®)AN NP, contrarily to the reactivity of the Gantrez(®)AN polymer used to prepare the nanoparticles. Copyright © 2010 Elsevier B.V. All rights reserved.

Intraspecies diversity of Lactobacillus sakei response to oxidative stress and variability of strain performance in mixed strains challenges.

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Guilbaud, Morgan; Zagorec, Monique; Chaillou, Stéphane; Champomier-Vergès, Marie-Christine

2012-04-01

Lactobacillus sakei is a meat-borne lactic acid bacterium species exhibiting a wide genomic diversity. We have investigated the diversity of response to various oxidative compounds, between L. sakei strains, among a collection representing the genomic diversity. We observed various responses to the different compounds as well as a diversity of response depending on the aeration conditions used for cell growth. A principal component analysis revealed two main phenotypic groups, partially correlating with previously described genomic clusters. We designed strains mixes composed of three different strains, in order to examine the behavior of each strain, when cultured alone or in the presence of other strains. The strains composing the mixtures were chosen as diverse as possible, i.e. exhibiting diverse responses to oxidative stress and belonging to different genomic clusters. Growth and survival rates of each strain were monitored under various aeration conditions, with or without heme supplementation. The results obtained suggest that some strains may act as "helper" or "burden" strains depending on the oxidative conditions encountered during incubation. This study confirms that resistance to oxidative stress is extremely variable within the L. sakei species and that this property should be considered when investigating starter performance in the complex meat bacterial ecosystems. Copyright © 2011 Elsevier Ltd. All rights reserved.

Development of an Aotus nancymaae Model for Shigella Vaccine Immunogenicity and Efficacy Studies

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Gregory, Michael; Lugo-Roman, Luis A.; Galvez Carrillo, Hugo; Tilley, Drake Hamilton; Baldeviano, Christian; Simons, Mark P.; Reynolds, Nathanael D.; Ranallo, Ryan T.; Suvarnapunya, Akamol E.; Venkatesan, Malabi M.; Oaks, Edwin V.

2014-01-01

Several animal models exist to evaluate the immunogenicity and protective efficacy of candidate Shigella vaccines. The two most widely used nonprimate models for vaccine development include a murine pulmonary challenge model and a guinea pig keratoconjunctivitis model. Nonhuman primate models exhibit clinical features and gross and microscopic colonic lesions that mimic those induced in human shigellosis. Challenge models for enterotoxigenic Escherichia coli (ETEC) and Campylobacter spp. have been successfully developed with Aotus nancymaae, and the addition of a Shigella-Aotus challenge model would facilitate the testing of combination vaccines. A series of experiments were designed to identify the dose of Shigella flexneri 2a strain 2457T that induces an attack rate of 75% in the Aotus monkey. After primary challenge, the dose required to induce an attack rate of 75% was calculated to be 1 × 1011 CFU. Shigella-specific immune responses were low after primary challenge and subsequently boosted upon rechallenge. However, preexisting immunity derived from the primary challenge was insufficient to protect against the homologous Shigella serotype. A successive study in A. nancymaae evaluated the ability of multiple oral immunizations with live-attenuated Shigella vaccine strain SC602 to protect against challenge. After three oral immunizations, animals were challenged with S. flexneri 2a 2457T. A 70% attack rate was demonstrated in control animals, whereas animals immunized with vaccine strain SC602 were protected from challenge (efficacy of 80%; P = 0.05). The overall study results indicate that the Shigella-Aotus nancymaae challenge model may be a valuable tool for evaluating vaccine efficacy and investigating immune correlates of protection. PMID:24595138

Risks Associated with High-Dose Lactobacillus rhamnosus in an Escherichia coli Model of Piglet Diarrhoea: Intestinal Microbiota and Immune Imbalances

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Yue, Yuan; Cai, Zheng-Xing; Lu, Qing-Ping; Zhang, Lu; Weng, Xiao-Gang; Zhang, Fan-Jian; Zhou, Dong; Yang, Jin-Cai; Wang, Jiu-Feng

2012-01-01

Probiotic could be a promising alternative to antibiotics for the prevention of enteric infections; however, further information on the dose effects is required. In this study, weanling piglets were orally administered low- or high-dose Lactobacillus rhamnosus ACTT 7469 (1010 CFU/d or 1012 CFU/d) for 1 week before F4 (K88)-positive Escherichia coli challenge. The compositions of faecal and gastrointestinal microbiota were recorded; gene expression in the intestines was assessed by real-time PCR; serum tumour necrosis factor-α (TNF-α) concentrations and intestinal Toll-like receptor 4 (TLR4) were detected by ELISA and immunohistochemistry, respectively. Unexpectedly, high-dose administration increased the incidence of diarrhoea before F4+ETEC challenge, despite the fact that both doses ameliorated F4+ETEC-induced diarrhoea with increased Lactobacillus and Bifidobacterium counts accompanied by reduced coliform shedding in faeces. Interestingly, L. rhamnosus administration reduced Lactobacillus and Bifidobacterium counts in the colonic contents, and the high-dose piglets also had lower Lactobacillius and Bacteroides counts in the ileal contents. An increase in the concentration of serum TNF-α induced by F4+ETEC was observed, but the increase was delayed by L. rhamnosus. In piglets exposed to F4+ETEC, jejunal TLR4 expression increased at the mRNA and protein levels, while jejunal interleukin (IL)-8 and ileal porcine β-defensins 2 (pBD2) mRNA expression increased; however, these increases were attenuated by administration of L. rhamnosus. Notably, expression of jejunal TLR2, ileal TLR9, Nod-like receptor NOD1 and TNF-α mRNA was upregulated in the low-dose piglets after F4+ETEC challenge, but not in the high-dose piglets. These findings indicate that pretreatment with a low dose of L. rhamnosus might be more effective than a high dose at ameliorating diarrhoea. There is a risk that high-dose L. rhamnosus pretreatment may negate the preventative effects, thus

Structural and functional insight into the carbohydrate receptor binding of F4 fimbriae-producing enterotoxigenic Escherichia coli.

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Moonens, Kristof; Van den Broeck, Imke; De Kerpel, Maia; Deboeck, Francine; Raymaekers, Hanne; Remaut, Han; De Greve, Henri

2015-03-27

Enterotoxigenic Escherichia coli (ETEC) strains are important causes of intestinal disease in humans and lead to severe production losses in animal farming. A range of fimbrial adhesins in ETEC strains determines host and tissue tropism. ETEC strains expressing F4 fimbriae are associated with neonatal and post-weaning diarrhea in piglets. Three naturally occurring variants of F4 fimbriae (F4ab, F4ac, and F4ad) exist that differ in the primary sequence of their major adhesive subunit FaeG, and each features a related yet distinct receptor binding profile. Here the x-ray structure of FaeGad bound to lactose provides the first structural insight into the receptor specificity and mode of binding by the poly-adhesive F4 fimbriae. A small D'-D″-α1-α2 subdomain grafted on the immunoglobulin-like core of FaeG hosts the carbohydrate binding site. Two short amino acid stretches Phe(150)-Glu(152) and Val(166)-Glu(170) of FaeGad bind the terminal galactose in the lactosyl unit and provide affinity and specificity to the interaction. A hemagglutination-based assay with E. coli expressing mutant F4ad fimbriae confirmed the elucidated co-complex structure. Interestingly, the crucial D'-α1 loop that borders the FaeGad binding site adopts a different conformation in the two other FaeG variants and hints at a heterogeneous binding pocket among the FaeG serotypes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

The increased severity in patients presenting to hospital with diarrhea in Dhaka, Bangladesh since the emergence of the hybrid strain of Vibrio cholerae O1 is not unique to cholera patients.

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Chowdhury, Fahima; Kuchta, Alison; Khan, Ashraful Islam; Faruque, A S G; Calderwood, Stephen B; Ryan, Edward T; Qadri, Firdausi

2015-11-01

A hybrid strain of Vibrio cholerae O1 El Tor that expresses a classical cholera toxin (CT) emerged in 2001. This hybrid variant rapidly replaced the previous El Tor strain around the world. The global emergence of this variant coincided with anecdotal reports that cholera patients were presenting with more severe dehydration and disease in many locations. A comparison was made of the severity of disease before and after the emergence of the hybrid strain in cholera patients attending an icddr,b hospital in Dhaka, Bangladesh. It was found that cholera patients presented with more severe dehydration and severe disease in the later period. However, this was also true for all non-cholera patients as well. In addition, in sub-analyses of patients who presented with rotavirus and enterotoxigenic Escherichia coli (ETEC), similar results were found. Comparing the two periods for differences in patient characteristics, nutritional status, vaccination status, and income, no plausible cause for patients presenting with more severe disease was identified in the later period. As a shift in severity for both cholera and non-cholera was observed, these results indicate that the altered El Tor strain cannot fully explain the difference in cholera severity before and after 2001. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Protection of pigs against challenge with virulent Streptococcus suis serotype 2 strains by a muramidase-released protein and extracellular factor vaccine

NARCIS (Netherlands)

Wisselink, H.J.; Vecht, U.; Stockhofe Zurwieden, N.; Smith, H.E.

2001-01-01

The efficacy of a muramidase-released protein (MRP) and extracellular factor (EF) vaccine in preventing infection and disease in pigs challenged either with a homologous or a heterologous Streptococcus suis serotype 2 strain (MRP EF ) was compared with the efficacy of a vaccine containing

Vaccination-challenge studies with a Port Chalmers/73 (H3N2)-based swine influenza virus vaccine: Reflections on vaccine strain updates and on the vaccine potency test.

Science.gov (United States)

De Vleeschauwer, Annebel; Qiu, Yu; Van Reeth, Kristien

2015-05-11

The human A/Port Chalmers/1/73 (H3N2) influenza virus strain, the supposed ancestor of European H3N2 swine influenza viruses (SIVs), was used in most commercial SIV vaccines in Europe until recently. If manufacturers want to update vaccine strains, they have to perform laborious intratracheal (IT) challenge experiments and demonstrate reduced virus titres in the lungs of vaccinated pigs. We aimed to examine (a) the ability of a Port Chalmers/73-based commercial vaccine to induce cross-protection against a contemporary European H3N2 SIV and serologic cross-reaction against H3N2 SIVs from Europe and North America and (b) the validity of intranasal (IN) challenge and virus titrations of nasal swabs as alternatives for IT challenge and titrations of lung tissue in vaccine potency tests. Pigs were vaccinated with Suvaxyn Flu(®) and challenged by the IT or IN route with sw/Gent/172/08. Post-vaccination sera were examined in haemagglutination-inhibition assays against vaccine and challenge strains and additional H3N2 SIVs from Europe and North America, including an H3N2 variant virus. Tissues of the respiratory tract and nasal swabs were collected 3 days post challenge (DPCh) and from 0-7 DPCh, respectively, and examined by virus titration. Two vaccinations consistently induced cross-reactive antibodies against European H3N2 SIVs from 1998-2012, but minimal or undetectable antibody titres against North American viruses. Challenge virus titres in the lungs, trachea and nasal mucosa of the vaccinated pigs were significantly reduced after both IT and IN challenge. Yet the reduction of virus titres and nasal shedding was greater after IT challenge. The Port Chalmers/73-based vaccine still offered protection against a European H3N2 SIV isolated 35 years later and with only 86.9% amino acid homology in its HA1, but it is unlikely to protect against H3N2 SIVs that are endemic in North America. We use our data to reflect on vaccine strain updates and on the vaccine potency test

Immunogenicity of nuclear-encoded LTB:ST fusion protein from Escherichia coli expressed in tobacco plants.

Science.gov (United States)

Rosales-Mendoza, Sergio; Soria-Guerra, Ruth E; Moreno-Fierros, Leticia; Govea-Alonso, Dania O; Herrera-Díaz, Areli; Korban, Schuyler S; Alpuche-Solís, Ángel G

2011-06-01

Enterotoxigenic Escherichia coli (ETEC) is one of the main causative agents of diarrhea in infants and for travelers. Inclusion of a heat-stable (ST) toxin into vaccine formulations is mandatory as most ETEC strains can produce both heat-labile (LT) and ST enterotoxins. In this study, a genetic fusion gene encoding for an LTB:ST protein has been constructed and transferred into tobacco via Agrobacterium tumefaciens-mediated transformation. Transgenic tobacco plants carrying the LTB:ST gene are then subjected to GM1-ELISA revealing that the LTB:ST has assembled into pentamers and displays antigenic determinants from both LTB and ST. Protein accumulation of up to 0.05% total soluble protein is detected. Subsequently, mucosal and systemic humoral responses are elicited in mice orally dosed with transgenic tobacco leaves. This has suggested that the plant-derived LTB:ST is immunogenic via the oral route. These findings are critical for the development of a plant-based vaccine capable of eliciting broader protection against ETEC and targeting both LTB and ST. Features of this platform in comparison to transplastomic approaches are discussed.

CfaE tip mutations in enterotoxigenic Escherichia coli CFA/I fimbriae define critical human intestinal binding sites.

Science.gov (United States)

Baker, K K; Levine, M M; Morison, J; Phillips, A; Barry, E M

2009-05-01

Enterotoxigenic Escherichia coli (ETEC) use colonization factors to attach to the human intestinal mucosa, followed by enterotoxin expression that induces net secretion and diarrhoeal illness. ETEC strain H10407 expresses CFA/I fimbriae, which are composed of multiple CfaB structural subunits and a CfaE tip subunit. Currently, the contribution of these individual fimbrial subunits in intestinal binding remains incompletely defined. To identify the role of CfaE in attachment in the native ETEC background, an R181A single-amino-acid substitution was introduced by recombination into the H10407 genome. The substitution of R181A eliminated haemagglutination and binding of intestinal mucosa biopsies in in vitro organ culture assays, without loss of CFA/I fimbriae expression. Wild-type in trans plasmid-expressed cfaE restored the binding phenotype. In contrast, in trans expression of cfaE containing amino acid 181 substitutions with similar amino acids, lysine, methionine and glutamine did not restore the binding phenotype, indicating that the loss of the binding phenotype was due to localized areas of epitope disruption. R181 appears to have an irreplaceable role in the formation of a receptor-binding feature on CFA/I fimbriae. The results specifically indicate that the CfaE tip protein is a required binding factor in CFA/I-mediated ETEC colonization, making it a potentially important vaccine antigen. © 2009 Blackwell Publishing Ltd.

Mutations in the Histone-like Nucleoid Structuring Regulatory Gene (hns) Decrease the Adherence of Shiga Toxin-producing Escherichia coli 091:H21 Strain B2F1 to Human Colonic Epithelial Cells and Increase the Production of Hemolysin

Science.gov (United States)

1999-10-19

osmoregulation of outer membrane proteins and virulence determinants in Vibrio cholerae requires toxR. J. Bacteriol. 170:2575-2583. Mobley, H. L., D. M. Green...produced by ETEC organisms is homologous to the toxin encoded by Y: cholerae . These toxins are the primary cause of the watery diarrhea associated with ETEC...Escherichia coli as a cause ofdiarrhea among children in Mexico . J. Clin. Microbiol. 25:1913-1919. Maurelli, A. T., and P. J. Sansonetti. 1988

Risks associated with high-dose Lactobacillus rhamnosus in an Escherichia coli model of piglet diarrhoea: intestinal microbiota and immune imbalances.

Directory of Open Access Journals (Sweden)

Xiao-Qiong Li

Full Text Available Probiotic could be a promising alternative to antibiotics for the prevention of enteric infections; however, further information on the dose effects is required. In this study, weanling piglets were orally administered low- or high-dose Lactobacillus rhamnosus ACTT 7469 (10(10 CFU/d or 10(12 CFU/d for 1 week before F4 (K88-positive Escherichia coli challenge. The compositions of faecal and gastrointestinal microbiota were recorded; gene expression in the intestines was assessed by real-time PCR; serum tumour necrosis factor-α (TNF-α concentrations and intestinal Toll-like receptor 4 (TLR4 were detected by ELISA and immunohistochemistry, respectively. Unexpectedly, high-dose administration increased the incidence of diarrhoea before F4(+ETEC challenge, despite the fact that both doses ameliorated F4(+ETEC-induced diarrhoea with increased Lactobacillus and Bifidobacterium counts accompanied by reduced coliform shedding in faeces. Interestingly, L. rhamnosus administration reduced Lactobacillus and Bifidobacterium counts in the colonic contents, and the high-dose piglets also had lower Lactobacillius and Bacteroides counts in the ileal contents. An increase in the concentration of serum TNF-α induced by F4(+ETEC was observed, but the increase was delayed by L. rhamnosus. In piglets exposed to F4(+ETEC, jejunal TLR4 expression increased at the mRNA and protein levels, while jejunal interleukin (IL-8 and ileal porcine β-defensins 2 (pBD2 mRNA expression increased; however, these increases were attenuated by administration of L. rhamnosus. Notably, expression of jejunal TLR2, ileal TLR9, Nod-like receptor NOD1 and TNF-α mRNA was upregulated in the low-dose piglets after F4(+ETEC challenge, but not in the high-dose piglets. These findings indicate that pretreatment with a low dose of L. rhamnosus might be more effective than a high dose at ameliorating diarrhoea. There is a risk that high-dose L. rhamnosus pretreatment may negate the preventative

Injury and mechanism of recombinant E. coli expressing STa on piglets colon.

Science.gov (United States)

Lv, Yang; Li, Xueni; Zhang, Lin; Shi, Yutao; DU, Linxiao; Ding, Binying; Hou, Yongqing; Gong, Joshua; Wu, Tao

2018-02-09

Enterotoxigenic Escherichia coli (ETEC) is primary pathogenic bacteria of piglet diarrhea, over two thirds of piglets diarrhea caused by ETEC are resulted from STa-producing ETEC strains. This experiment was conducted to construct the recombinant E. coli expressing STa and study the injury and mechanism of recombinant E. coli expressing STa on 7 days old piglets colon. Twenty-four 7 days old piglets were allotted to four treatments: control group, STa group (2 × 10 9 CFU E. coli LMG194-STa), LMG194 group (2 × 10 9 CFU E. coli LMG194) and K88 group (2 × 10 9 CFU E. coli K88). The result showed that E. coli infection significantly increased diarrhea rates; changed DAO activity in plasma and colon; damaged colonic mucosal morphology including crypt depth, number of globet cells, density of lymphocytes and lamina propria cell density; substantially reduced antioxidant capacity by altering activities of GSH-Px, SOD, and TNOS and productions of MDA and H 2 O 2 ; obviously decreased AQP3, AQP4 and KCNJ13 protein expression levels; substantially altered the gene expression levels of inflammatory cytokines. Conclusively, STa group had the biggest effect on these indices in four treatment groups. These results suggested that the recombinant strain expressed STa can induce piglets diarrhea and colonic morphological and funtional damage by altering expression of proteins connect to transportation function and genes associated with intestinal injury and inflammatory cytokines.

Clostridium difficile chimeric toxin receptor binding domain vaccine induced protection against different strains in active and passive challenge models.

Science.gov (United States)

Tian, Jing-Hui; Glenn, Gregory; Flyer, David; Zhou, Bin; Liu, Ye; Sullivan, Eddie; Wu, Hua; Cummings, James F; Elllingsworth, Larry; Smith, Gale

2017-07-24

Clostridium difficile is the number one cause of nosocomial antibiotic-associated diarrhea in developed countries. Historically, pathogenesis was attributed two homologous glucosylating toxins, toxin-A (TcdA) and toxin-B (TcdB). Over the past decade, however, highly virulent epidemic strains of C. difficile (B1/NAP1/027) have emerged and are linked to an increase in morbidity and mortality. Increased virulence is attributed to multiple factors including: increased production of A- and B-toxins; production of binary toxin (CDT); and the emergence of more toxic TcdB variants (TcdB (027) ). TcdB (027) is more cytotoxicity to cells; causes greater tissue damage and toxicity in animals; and is antigenically distinct from historical TcdB (TcdB (003) ). Broadly protective vaccines and therapeutic antibody strategies, therefore, may target TcdA, TcdB variants and CDT. To facilitate the generation of multivalent toxin-based C. difficile vaccines and therapeutic antibodies, we have generated fusion proteins constructed from the receptor binding domains (RBD) of TcdA, TcdB (003) , TcdB (027) and CDT. Herein, we describe the development of a trivalent toxin (T-toxin) vaccine (CDTb/TcdB (003) /TcdA) and quadravalent toxin (Q-toxin) vaccine (CDTb/TcB (003) /TcdA/TcdB (027) ) fusion proteins that retain the protective toxin neutralizing epitopes. Active immunization of mice or hamsters with T-toxin or Q-toxin fusion protein vaccines elicited the generation of toxin neutralizing antibodies to each of the toxins. Hamsters immunized with the Q-toxin vaccine were broadly protected against spore challenge with historical C. difficile 630 (toxinotype 0/ribotype 003) and epidemic NAP1 (toxinotype III/ribotype 027) strains. Fully human polyclonal antitoxin IgG was produced by immunization of transgenic bovine with these fusion proteins. In passive transfer studies, mice were protected against lethal toxin challenge. Hamsters treated with human antitoxin IgG were completely protected when

Strain-based fracture assessment of pipelines

Energy Technology Data Exchange (ETDEWEB)

Olsoe, Erlend; Oestby, Erling; Nyhus, Baard [SINTEF, Trondheim (Norway); Skallerud, Bjoern; Holthe, Kjell [Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Berg, Espen [LINKftr AS, Trondheim (Norway)

2009-12-19

The oil and gas industry moves into harsher regions and faces challenges with i.e. deep water, arctic conditions and seismic regions. Consequently, ensuring the integrity of pipelines becomes more challenging, and potential large deformation scenarios that can be attributed to the above mentioned areas have lead to a current strong focus on strain-based fracture assessment methods for pipelines. However, no widely established methods exist today. In this paper specific challenges related to development of such methods are discussed. Keywords are biaxial loading, crack driving force relations, ductile tearing resistance, and definition of strain capacity. The effect of the different features will be illustrated with both experimental and numerical simulation results. Experimental results presented will cover both large- and small-scale testing. A highly efficient and accurate line-spring based numerical fracture assessment method will be presented. A simplified scheme for a strain-based fracture assessment method will also be briefly outlined, and the extension of this method to also include partial safety factors is discussed. (author)

Prospective study of pathogens in asymptomatic travellers and those with diarrhoea: aetiological agents revisited.

Science.gov (United States)

Lääveri, T; Antikainen, J; Pakkanen, S H; Kirveskari, J; Kantele, A

2016-06-01

Travellers' diarrhoea (TD) remains the most frequent health problem encountered by visitors to the (sub)tropics. Traditional stool culture identifies the pathogen in only 15% of cases. Exploiting PCR-based methods, we investigated TD pathogens with a focus on asymptomatic travellers and severity of symptoms. Pre- and post-travel stools of 382 travellers with no history of antibiotic use during travel were analysed with a multiplex quantitative PCR for Salmonella, Yersinia, Campylobacter, Shigella, Vibrio cholerae and five diarrhoeagenic Escherichia coli: enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC) and enteroinvasive (EIEC). The participants were categorized by presence/absence of TD during travel and on return, and by severity of symptoms. A pathogen was indentified in 61% of the asymptomatic travellers, 83% of those with resolved TD, and 83% of those with ongoing TD; 25%, 43% and 53% had multiple pathogens, respectively. EPEC, EAEC, ETEC and Campylobacter associated especially with ongoing TD symptoms. EAEC and EPEC proved more common than ETEC. To conclude, modern methodology challenges our perception of stool pathogens: all pathogens were common both in asymptomatic and symptomatic travellers. TD has a multibacterial nature, but diarrhoeal symptoms mostly associate with EAEC, EPEC, ETEC and Campylobacter. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Influence of Host Interleukin-10 Polymorphisms on Development of Traveler's Diarrhea Due to Heat-Labile Enterotoxin-Producing Escherichia coli in Travelers from the United States Who Are Visiting Mexico▿

Science.gov (United States)

Flores, Jose; DuPont, Herbert L.; Lee, Stephanie A.; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A.; Armitige, Lisa Y.; Guo, Dong-Chuan; Okhuysen, Pablo C.

2008-01-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position −1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position −819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position −592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD. PMID:18579697

Influence of host interleukin-10 polymorphisms on development of traveler's diarrhea due to heat-labile enterotoxin-producing Escherichia coli in travelers from the United States who are visiting Mexico.

Science.gov (United States)

Flores, Jose; DuPont, Herbert L; Lee, Stephanie A; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A; Armitige, Lisa Y; Guo, Dong-Chuan; Okhuysen, Pablo C

2008-08-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position -1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position -819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position -592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD.

Detection of virulence genes and the phylogenetic groups of Escherichia coli isolated from dogs in Brazil

Directory of Open Access Journals (Sweden)

Fernanda Morcatti Coura

2018-02-01

Full Text Available ABSTRACT: This study identified the virulence genes, pathovars, and phylogenetic groups of Escherichia coli strains obtained from the feces of dogs with and without diarrhea. Virulence genes and phylogenetic group identification were studied using polymerase chain reaction. Thirty-seven E. coli isolates were positive for at least one virulence factor gene. Twenty-one (57.8% of the positive isolates were isolated from diarrheal feces and sixteen (43.2% were from the feces of non-diarrheic dogs. Enteropathogenic E. coli (EPEC were the most frequently (62.2% detected pathovar in dog feces and were mainly from phylogroup B1 and E. Necrotoxigenic E. coli were detected in 16.2% of the virulence-positive isolates and these contained the cytotoxic necrotizing factor 1 (cnf1 gene and were classified into phylogroups B2 and D. All E. coli strains were negative for the presence of enterotoxigenic E. coli (ETEC enterotoxin genes, but four strains were positive for ETEC-related fimbriae 987P and F18. Two isolates were Shiga toxin-producing E. coli strains and contained the toxin genesStx2 or Stx2e, both from phylogroup B1. Our data showed that EPEC was the most frequent pathovar and B1 and E were the most common phylogroups detected in E. coli isolated from the feces of diarrheic and non-diarrheic dogs.

Performance of rats orogastrically dosed with faecal strains of ...

African Journals Online (AJOL)

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strains of Lactobacillus acidophilus and challenged ... Albino rats (Rattus norvegicus) were orogastrically dosed with faecal strains of Lactobacillus .... Chang et al. (2001) reported a similar observation in piglets fed probiotic strain, Lactobacillus reuteri BSA 131. Francisco et al. (1995) had earlier reported that selected ...

Genotypic and Phenotypic Characterization of Enterotoxigenic Escherichia coli Strains Isolated from Peruvian Children

Science.gov (United States)

2010-09-01

adhesion, ETEC elabo- rates one or both of two enterotoxins: heat-labile toxin (LT), a protein multimer which shares many features with cholera toxin...pathogens (Shigella, Salmonella. Vibrio , Campylo/Jacter, Gi- ardia Iamblia, Cryptosporidium, and rotavirus) by conventional methods. Five lactose...studies performed in developing coun- tries: 38% in children ɚ years of age in Nicaragua (19), 33% in children ə year of age in Mexico (6), and 18% in

Rice evapotranspiration at the field and canopy scales under water-saving irrigation

Science.gov (United States)

Liu, Xiaoyin; Xu, Junzeng; Yang, Shihong; Zhang, Jiangang

2018-04-01

Evapotranspiration (ET) is an important process of land surface water and thermal cycling, with large temporal and spatial variability. To reveal the effect of water-saving irrigation (WSI) on rice ET at different spatial scales and understand the cross spatial scale difference, rice ET under WSI condition at canopy (ETCML) and field scale (ETEC) were measured simultaneously by mini-lysimeter and eddy covariance (EC) in the rice season of 2014. To overcome the shortage of energy balance deficit by EC system, and evaluate the influence of energy balance closure degree on ETEC, ETEC was corrected as {ET}_{EC}^{*} by energy balance closure correction according to the evaporative fraction. Seasonal average daily ETEC, {ET}_{EC}^{*} and ETCML of rice under WSI practice were estimated as 3.12, 4.03 and 4.35 mm day-1, smaller than the values reported in flooded paddy fields. Daily ETEC, {ET}_{EC}^{*} and ETCML varied in a similar trends and reached the maximum in late tillering, then decreased along with the crop growth in late season. The value of ETEC was much lower than ETCML, and was frequently 1-2 h lagged behind ETCML. It indicated that the energy balance deficit resulted in underestimation of crop ET by EC system. The corrected value of {ET}_{EC}^{*} matched ETCML much better than ETEC, with a smaller RMSE (0.086 mm h-1) and higher R 2 (0.843) and IOA (0.961). The time lapse between {ET}_{EC}^{*} and ETCML was mostly shortened to less than 0.5 h. The multiple stepwise regression analysis indicated that net radiation ( R n) is the dominant factor for rice ET, and soil moisture ( θ) is another significant factor ( p rice fields. The difference between ETCML and {ET}_{EC}^{*} ({ET}_{CML} - {ET}_{EC}^{*}) were significantly ( p rice ET in WSI fields, and for its cross scale conversion.

Heat strain in protective clothing - challenges and intervention strategies

NARCIS (Netherlands)

McLellan, T.M.; Daanen, H.A.M.; Kiekens, P.; Jayaraman, S.

2012-01-01

Humans rely on sweat evaporation during exercise in the heat to promote cooling and to maintain thermal homeostasis. In protective clothing, however, sweat evaporation is severely hampered and this may lead to uncompensable heat strain, where core body temperature continues to rise leading to

A small animal peripheral challenge model of yellow fever using interferon-receptor deficient mice and the 17D-204 vaccine strain.

Science.gov (United States)

Thibodeaux, Brett A; Garbino, Nina C; Liss, Nathan M; Piper, Joseph; Blair, Carol D; Roehrig, John T

2012-05-02

Yellow fever virus (YFV), a member of the genus Flavivirus, is a mosquito-borne pathogen that requires wild-type (wt), virulent strains to be handled at biosafety level (BSL) 3, with HEPA-filtration of room air exhaust (BSL3+). YFV is found in tropical regions of Africa and South America and causes severe hepatic disease and death in humans. Despite the availability of effective vaccines (17D-204 or 17DD), YFV is still responsible for an estimated 200,000 cases of illness and 30,000 deaths annually. Besides vaccination, there are no other prophylactic or therapeutic strategies approved for use in human YF. Current small animal models of YF require either intra-cranial inoculation of YF vaccine to establish infection, or use of wt strains (e.g., Asibi) in order to achieve pathology. We have developed and characterized a BSL2, adult mouse peripheral challenge model for YFV infection in mice lacking receptors for interferons α, β, and γ (strain AG129). Intraperitoneal challenge of AG129 mice with 17D-204 is a uniformly lethal in a dose-dependent manner, and 17D-204-infected AG129 mice exhibit high viral titers in both brain and liver suggesting this infection is both neurotropic and viscerotropic. Furthermore the use of a mouse model permitted the construction of a 59-biomarker multi-analyte profile (MAP) using samples of brain, liver, and serum taken at multiple time points over the course of infection. This MAP serves as a baseline for evaluating novel therapeutics and their effect on disease progression. Changes (4-fold or greater) in serum and tissue levels of pro- and anti-inflammatory mediators as well as other factors associated with tissue damage were noted in AG129 mice infected with 17D-204 as compared to mock-infected control animals. Published by Elsevier Ltd.

FREQUENCY AND DISTRIBUTION OF DIARRHOEAGENIC ESCHERICHIA COLI STRAINS ISOLATED FROM PEDIATRIC PATIENTS WITH DIARRHOEA IN BOSNIA AND HERZEGOVINA

OpenAIRE

Dedeić-Ljubović, AmeLa; Hukić, Mirsada; Bekić, DaRia; Zvizdić, AmrA

2009-01-01

Diarrhoeal disease is a major cause of illness and death among infants and young children worldwide. Among the Escherichia coli (E. coli) causing intestinal diseases, there are six well-described categories: enteroaggregative E. coli (EAEC), diffusely adherent E. coli (DAEC), enteroinvasive E. coli (EIEC), entero-pathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC) and enterotoxigenic E. coli (ETEC).

Survival study of enterotoxigenic Escherichia colistrain in seawater and wastewater microcosms.

Science.gov (United States)

Boukef Ben Omrane, I; El Bour, M; Mejri, S; Mraouna, R; Got, P; Troussellier, M; Boudabous, A

2011-01-01

In order to survey osmotic and oligotrophic stress consequence on pathogenic enterobacteria discharged in marine areas, we examined enterotoxigenic Escherichia coli (ETEC) and a reference (Ecoli O126:B16) strains during their survival (47 days) in wastewater microcosms, submerged in natural seawater and maintained in laboratory conditions. The results revealed that the survival time for the two strains was prolonged when bacterial cells were previously incubated in wastewater, with less cellular membrane damage. In addition, the wild clinical E. coli strain showed a better survival capacity than the reference E. coli strain one. For both, we noted some modifications in biochemical profiles relatively to the initial state, notably when they were previously incubated in wastewater microcosm.

Strain- and Dose-Dependent Reduction of Toxoplasma gondii Burden in Pigs Is Associated with Interferon-Gamma Production by CD8+ Lymphocytes in a Heterologous Challenge Model

Directory of Open Access Journals (Sweden)

Malgorzata Jennes

2017-06-01

Full Text Available Toxoplasma gondii is a worldwide prevalent parasite of humans and animals. The global infection burden exceeds yearly one million disability-adjusted life years (DALY's in infected individuals. Therefore, effective preventive measures should be taken to decrease the risk of infection in humans. Although human toxoplasmosis is predominantly foodborne by ingestion of tissue cysts in meat from domestic animals such as pigs, the incidence risk is difficult to estimate due to the lack of screening of animals for infection and insights in location and persistence of the parasite in the tissues. Hence, experimental infections in pigs can provide more information on the risk for zoonosis based on the parasite burden in meat products intended for human consumption and on the immune responses induced by infection. In the present study, homo- and heterologous infection experiments with two distinct T. gondii strains (IPB-LR and IPB-Gangji were performed. The humoral and cellular immune responses, the presence of viable parasites and the parasite load in edible meat samples were evaluated. In homologous infection experiments the parasite persistence was clearly strain-dependent and inversely correlated with the infection dose. The results strongly indicate a change in the amount of parasite DNA and viable cysts in porcine tissues over time. Heterologous challenge infections demonstrated that IPB-G strain could considerably reduce the parasite burden in the subsequent IPB-LR infection. A strong, however, not protective humoral response was observed against GRA7 and TLA antigens upon inoculation with both strains. The in vitro IFN-γ production by TLA-stimulated PBMCs was correlated with the infection dose and predominantly brought about by CD3+CD4−CD8αbright T-lymphocytes. The described adaptive cellular and humoral immune responses in pigs are in line with the induced or natural infections in mice and humans. Previous studies underscored the

Prevalence and behavior of multidrug-resistant shiga toxin-producing Escherichia coli, enteropathogenic E. coli and enterotoxigenic E. coli on coriander.

Science.gov (United States)

Gómez-Aldapa, Carlos A; Segovia-Cruz, Jesús A; Cerna-Cortes, Jorge F; Rangel-Vargas, Esmeralda; Salas-Rangel, Laura P; Gutiérrez-Alcántara, Eduardo J; Castro-Rosas, Javier

2016-10-01

The prevalence and behavior of multidrug-resistant diarrheagenic Escherichia coli pathotypes on coriander was determined. One hundred coriander samples were collected from markets. Generic E. coli were determined using the most probable number procedure. Diarrheagenic E. coli pathotypes (DEPs) were identified using two multiplex polymerase chain reaction procedures. Susceptibility to sixteen antibiotics was tested for the isolated DEPs strains by standard test. The behavior of multidrug-resistant DEPs isolated from coriander was determined on coriander leaves and chopped coriander at 25°± 2 °C and 3°± 2 °C. Generic E. coli and DEPs were identified, respectively, in 43 and 7% of samples. Nine DEPs strains were isolated from positive coriander samples. The identified DEPs included Shiga toxin-producing E. coli (STEC, 4%) enterotoxigenic E. coli (ETEC, 2%) and enteropathogenic E. coli (EPEC, 1%). All isolated DEPs strains exhibited multi-resistance to antibiotics. On inoculated coriander leaves stored at 25°± 2 °C or 3°± 2 °C, no growth was observed for multidrug-resistant DEPs strains. However, multidrug-resistant DEPs strains grew in chopped coriander: after 24 h at 25° ± 2 °C, DEPs strains had grown to approximately 3 log CFU/g. However, at 3°± 2 °C the bacterial growth was inhibited. To the best of our knowledge, this is the first report of the presence and behavior of multidrug-resistant STEC, ETEC and EPEC on coriander and chopped coriander. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of antimicrobial resistance in E. coli isolated from rectal and floor samples in pens with diarrhoeic nursery pigs in Denmark

DEFF Research Database (Denmark)

Weber, Nicolai Rosager; Nielsen, Jens Peter; Jorsal, Sven Erik Lind

2017-01-01

and classified as ETEC when genes for adhesin factors and enterotoxins were detected. Minimum inhibitory concentrations of 13 antimicrobial agents were determined by the broth micro dilution method. Isolates were classified as resistant based on clinical breakpoints. Results. Based on logistic regression models......%: 2.87-18.10). The odds of an isolate being resistant were significantly higher in ETEC isolates compared to Non-ETEC isolates for ampicillin (p trimethoprim (p..., sulphamethoxazole, tetracycline and trimethoprim. Conclusions. We found that ETEC isolates were more resistant than Non-ETEC isolates. Furthermore, this study indicates that resistance testing of ETEC isolates from pen floor samples can be used as a convenient sampling method for resistance testing...

Ultrasensitive, Stretchable Strain Sensors Based on Fragmented Carbon Nanotube Papers

KAUST Repository

Zhou, Jian; Yu, Hu; Xu, Xuezhu; Han, Fei; Lubineau, Gilles

2017-01-01

The development of strain sensors featuring both ultra high sensitivity and high stretchability is still a challenge. We demonstrate that strain sensors based on fragmented single-walled carbon nanotube (SWCNT) paper embedded in poly

Clinical trial to evaluate safety and immunogenicity of an oral inactivated enterotoxigenic Escherichia coli prototype vaccine containing CFA/I overexpressing bacteria and recombinantly produced LTB/CTB hybrid protein.

Science.gov (United States)

Lundgren, A; Leach, S; Tobias, J; Carlin, N; Gustafsson, B; Jertborn, M; Bourgeois, L; Walker, R; Holmgren, J; Svennerholm, A-M

2013-02-06

We have developed a new oral vaccine against enterotoxigenic Escherichia coli (ETEC) diarrhea containing killed recombinant E. coli bacteria expressing increased levels of ETEC colonization factors (CFs) and a recombinant protein (LCTBA), i.e. a hybrid between the binding subunits of E. coli heat labile toxin (LTB) and cholera toxin (CTB). We describe a randomized, comparator controlled, double-blind phase I trial in 60 adult Swedish volunteers of a prototype of this vaccine. The safety and immunogenicity of the prototype vaccine, containing LCTBA and an E. coli strain overexpressing the colonization factor CFA/I, was compared to a previously developed oral ETEC vaccine, consisting of CTB and inactivated wild type ETEC bacteria expressing CFA/I (reference vaccine). Groups of volunteers were given two oral doses of either the prototype or the reference vaccine; the prototype vaccine was administered at the same or a fourfold higher dosage than the reference vaccine. The prototype vaccine was found to be safe and equally well-tolerated as the reference vaccine at either dosage tested. The prototype vaccine induced mucosal IgA (fecal secretory IgA and intestine-derived IgA antibody secreting cell) responses to both LTB and CFA/I, as well as serum IgA and IgG antibody responses to LTB. Immunization with LCTBA resulted in about twofold higher mucosal and systemic IgA responses against LTB than a comparable dose of CTB. The higher dose of the prototype vaccine induced significantly higher fecal and systemic IgA responses to LTB and fecal IgA responses to CFA/I than the reference vaccine. These results demonstrate that CF over-expression and inclusion of the LCTBA hybrid protein in an oral inactivated ETEC vaccine does not change the safety profile when compared to a previous generation of such a vaccine and that the prototype vaccine induces significant dose dependent mucosal immune responses against CFA/I and LTB. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of an Aotus nancymaae Model for Shigella Vaccine Immunogenicity and Efficacy Studies

OpenAIRE

Gregory, Michael; Kaminski, Robert W.; Lugo-Roman, Luis A.; Galvez Carrillo, Hugo; Tilley, Drake Hamilton; Baldeviano, Christian; Simons, Mark P.; Reynolds, Nathanael D.; Ranallo, Ryan T.; Suvarnapunya, Akamol E.; Venkatesan, Malabi M.; Oaks, Edwin V.

2014-01-01

Several animal models exist to evaluate the immunogenicity and protective efficacy of candidate Shigella vaccines. The two most widely used nonprimate models for vaccine development include a murine pulmonary challenge model and a guinea pig keratoconjunctivitis model. Nonhuman primate models exhibit clinical features and gross and microscopic colonic lesions that mimic those induced in human shigellosis. Challenge models for enterotoxigenic Escherichia coli (ETEC) and Campylobacter spp. have...

Prior Inoculation with Type B Strains of Francisella tularensis Provides Partial Protection against Virulent Type A Strains in Cottontail Rabbits.

Directory of Open Access Journals (Sweden)

Vienna R Brown

Full Text Available Francisella tularensis is a highly virulent bacterium that is capable of causing severe disease (tularemia in a wide range of species. This organism is characterized into two distinct subspecies: tularensis (type A and holarctica (type B which vary in several crucial ways, with some type A strains having been found to be considerably more virulent in humans and laboratory animals. Cottontail rabbits have been widely implicated as a reservoir species for this subspecies; however, experimental inoculation in our laboratory revealed type A organisms to be highly virulent, resulting in 100% mortality following challenge with 50-100 organisms. Inoculation of cottontail rabbits with the same number of organisms from type B strains of bacteria was found to be rarely lethal and to result in a robust humoral immune response. The objective of this study was to characterize the protection afforded by a prior challenge with type B strains against a later inoculation with a type A strain in North American cottontail rabbits (Sylvilagus spp. Previous infection with a type B strain of organism was found to lengthen survival time and in some cases prevent death following inoculation with a type A2 strain of F. tularensis. In contrast, inoculation of a type A1b strain was uniformly lethal in cottontail rabbits irrespective of a prior type B inoculation. These findings provide important insight about the role cottontail rabbits may play in environmental maintenance and transmission of this organism.

Strain expansion-reduction approach

Science.gov (United States)

Baqersad, Javad; Bharadwaj, Kedar

2018-02-01

Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

Gamma-irradiated scrub typhus immunogens: broad-spectrum immunity with combinations of rickettsial strains

International Nuclear Information System (INIS)

Eisenberg, G.H. Jr.; Osterman, J.V.

1979-01-01

Scrub typhus immunogens were prepared from Rickettsia tsutsugamushi strains Karp, Kato, Gilliam, Kostival, and Buie by exposing frozen infected yolk sac suspensions to 300 krad of gamma radiation. Mouse protection tests showed that each of the irradiated immunogens protected C3H/HeDub mice against high challenge levels of Karp and Gilliam, but that none of these single-strain immunogens were capable of protecting against all five of the challenge strains. Broad-spectrum protection was achieved by using combinations of three strains of irradiated rickettsiae in a vaccination regimen of three injections at 5-day intervals

Comparative analysis of antimicrobial resistance in enterotoxigenic Escherichia coli isolates from two paediatric cohort studies in Lima, Peru.

Science.gov (United States)

Medina, Anicia M; Rivera, Fulton P; Pons, Maria J; Riveros, Maribel; Gomes, Cláudia; Bernal, María; Meza, Rina; Maves, Ryan C; Huicho, Luis; Chea-Woo, Elsa; Lanata, Claudio F; Gil, Ana I; Ochoa, Theresa J; Ruiz, Joaquim

2015-08-01

Antibiotic resistance is increasing worldwide, being of special concern in low- and middle-income countries. The aim of this study was to determine the antimicrobial susceptibility and mechanisms of resistance in 205 enterotoxigenic Escherichia coli (ETEC) isolates from two cohort studies in children Peru. ETEC were identified by an in-house multiplex real-time PCR. Susceptibility to 13 antimicrobial agents was tested by disk diffusion; mechanisms of resistance were evaluated by PCR. ETEC isolates were resistant to ampicillin (64%), cotrimoxazole (52%), tetracycline (37%); 39% of the isolates were multidrug-resistant. Heat-stable toxin producing (ETEC-st) (48%) and heat-labile toxin producing ETEC (ETEC-lt) (40%) had higher rates of multidrug resistance than isolates producing both toxins (ETEC-lt-st) (21%), pPeru. However, further development of resistance should be closely monitored. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Heat strain in personal protective clothing: Challenges and intervention strategies

NARCIS (Netherlands)

McLellan, T.M.; Daanen, H.A.M.

2012-01-01

Humans rely on sweat evaporation during exercise in the heat to promote cooling and to maintain thermal homeostasis. In protective clothing, however, sweat evaporation is severely hampered and this may lead to uncompensable heat strain, where core body temperature continues to rise leading to

Susceptibility of multidrug resistant enterotoxigenic escherichia coli to saponin extract from phyllanthus niruri

International Nuclear Information System (INIS)

Ajibade, V.A.; Famurewa, O.

2013-01-01

Escherichia coli were isolated from 140 samples of blood, urine, stool and water made up of 15.7%, 42.9% and 30.0% and 25.7% respectively. From the samples, 71.9% enterotoxigenic E. coli (ETEC), 14.3% enteropathogenic E. coli (EPEC), 7.1% enterohemorrhagic E. coil (EHEC) and 7.1% enteroinvasive E. coli (EIEC) occurred as diarrheagenic E. coli. Of the ETEC (240) isolates tested for susceptibility to eight conventional antibiotics. 110 (46.0%) showed resistance to all the tested antimicrobial agents. However, of the resistant strains; 24 (22.0%) were multidrug resistant. These were tested against 3.0 mg/mL of saponin extract from phyllanthus niruri and 13 (55.0%) of these were susceptible to the saponin. The antimicrobial activities of saponin from P. niruri are of interest since the crude extract was effective at concentration of 3.0 mg/ml to multiple resistant isolates of EEC. (author)

Yersinia pestis biovar Microtus strain 201, an avirulent strain to humans, provides protection against bubonic plague in rhesus macaques.

Science.gov (United States)

Zhang, Qingwen; Wang, Qiong; Tian, Guang; Qi, Zhizhen; Zhang, Xuecan; Wu, Xiaohong; Qiu, Yefeng; Bi, Yujing; Yang, Xiaoyan; Xin, Youquan; He, Jian; Zhou, Jiyuan; Zeng, Lin; Yang, Ruifu; Wang, Xiaoyi

2014-01-01

Yersinia pestis biovar Microtus is considered to be a virulent to larger mammals, including guinea pigs, rabbits and humans. It may be used as live attenuated plague vaccine candidates in terms of its low virulence. However, the Microtus strain's protection against plague has yet to be demonstrated in larger mammals. In this study, we evaluated the protective efficacy of the Microtus strain 201 as a live attenuated plague vaccine candidate. Our results show that this strain is highly attenuated by subcutaneous route, elicits an F1-specific antibody titer similar to the EV and provides a protective efficacy similar to the EV against bubonic plague in Chinese-origin rhesus macaques. The Microtus strain 201 could induce elevated secretion of both Th1-associated cytokines (IFN-γ, IL-2 and TNF-α) and Th2-associated cytokines (IL-4, IL-5, and IL-6), as well as chemokines MCP-1 and IL-8. However, the protected animals developed skin ulcer at challenge site with different severity in most of the immunized and some of the EV-immunized monkeys. Generally, the Microtus strain 201 represented a good plague vaccine candidate based on its ability to generate strong humoral and cell-mediated immune responses as well as its good protection against high dose of subcutaneous virulent Y. pestis challenge.

Immunization by intrabronchial administration to 1-week-old foals of an unmarked double gene disruption strain of Rhodococcus equi strain 103+.

Science.gov (United States)

Pei, Yanlong; Nicholson, Vivian; Woods, Katharine; Prescott, John F

2007-11-15

Rhodococcus equi causes fatal granulomatous pneumonia in foals and immunocompromised animals and humans. However, there is no effective vaccine against this infection. In this study, the chromosomal genes isocitrate lyase (icl) and cholesterol oxidase (choE) were chosen as targets for mutation and assessment of the double mutant as an intrabronchial vaccine in 1-week-old foals. Using a modification of a suicide plasmid previously developed in this laboratory, we developed a choE-icl unmarked deletion mutant of R. equi strain 103+. Five 1-week-old foals were infected intrabronchially with the mutant and challenged intrabronchially with the parent, virulent, strain 2 weeks later. Three of the foals were protected against pneumonia caused by the virulent strain, but the other two foals developed pneumonia caused by the mutant strain during the post-challenge period. Since infection of 3-week-old foals by an icl mutant in an earlier study had shown complete attenuation of the strain, we conclude that a proportion of foals in the 1st week or so of life are predisposed to developing R. equi pneumonia because of an inability to mount an effective immune response. This has been suspected previously but this is the first time that this has been demonstrated experimentally.

Fermented soya bean (tempe) extracts reduce adhesion of enterotoxigenic Escherichia coli to intestinal epithelial cells.

Science.gov (United States)

Roubos-van den Hil, P J; Nout, M J R; Beumer, R R; van der Meulen, J; Zwietering, M H

2009-03-01

This study aimed to investigate the effect of processed soya bean, during the successive stages of tempe fermentation and different fermentation times, on adhesion of enterotoxigenic Escherichia coli (ETEC) K88 to intestinal brush border cells as well as Caco-2 intestinal epithelial cells; and to clarify the mechanism of action. Tempe was prepared at controlled laboratory scale using Rhizopus microsporus var. microsporus as the inoculum. Extracts of raw, soaked and cooked soya beans reduced ETEC adhesion to brush border cells by 40%. Tempe extracts reduced adhesion by 80% or more. ETEC adhesion to Caco-2 cells reduced by 50% in the presence of tempe extracts. ETEC K88 bacteria were found to interact with soya bean extracts, and this may contribute to the observed decrease of ETEC adhesion to intestinal epithelial cells. Fermented soya beans (tempe) reduce the adhesion of ETEC to intestinal epithelial cells of pig and human origin. This reduced adhesion is caused by an interaction between ETEC K88 bacteria and soya bean compounds. The results strengthen previous observations on the anti-diarrhoeal effect of tempe. This effect indicates that soya-derived compounds may reduce adhesion of ETEC to intestinal cells in pigs as well as in humans and prevent against diarrhoeal diseases.

Reflection of serum immunoglobulin isotypes in the egg yolk of laying hens immunized with enterotoxigenic Escherichia coli

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Nagendra Nath Barman

2014-09-01

Full Text Available Aim: The aim was to study the seroconversion and development of egg yolk immunoglobulins in adult laying White Leghorn hens immunized against an isolate of enterotoxigenic Escherichia coli (ETEC bearing K91 and K88ac antigens, obtained from diarrheic piglet. Materials and Methods: Adult laying White Leghorn hens were immunized with inactivated enterotoxic E. coli strain isolated originally from a case of piglet diarrhea following recommended schedule. The development of whole antibodies and isotype-specific antibodies in serum and egg yolk were measured using indirect enzyme-linked immunosorbent assay (ELISA. Piglets suffering from diarrhea with fecal samples positive for ETEC were fed with egg yolk and compared with diarrheic control group. Results: The serum and egg yolk ELISA antibody titer against E. coli strain used in the present study was as high as 2666.66±307.92 and 933.33±203.67 respectively on 50 day-post-vaccination (DPV. The immunoglobulin Y (IgY was the predominant isotype in serum and egg yolk, which reached the peak titer of 2200±519.61 in serum on 40 DPV and 800±244.94 in egg yolk on 50 DPV. IgM titer in serum and egg yolk was found to be meager, and no IgA could be detected. Diarrheic piglets fed with the egg yolk suspension from immunized hens showed a promising result in controlling diarrhea. Conclusion: Egg yolk antibodies are considered a suitable immunotherapeutic alternative to conventional antibiotic therapy. High titer of egg yolk antibodies raised in the immunized hen against an isolate of ETEC holds the potential to be used for passive protection of diarrheic piglets during their most susceptible period of infection.

Immunity to infection with porcine parvovirus in pigs inoculated with the attenuated HT- strain.

Science.gov (United States)

Fujisaki, Y; Murakami, Y

1982-01-01

Swine were inoculated once with the attenuated HT- strain of porcine parvovirus. Several months later they were challenged by oral inoculation with a field strain of the virus to examine an ability to prevent infection. After challenge inoculation unimmunized control swine exhibited an increase in antibody titer, viremia, and virus discharge. The virus was recovered from many organs. The swine preinoculated with the attenuated HT- strain, however, manifested none of these symptoms and were negative for virus recovery from any organ.

Host Response in Rabbits to Infection with Pasteurella multocida Serogroup F Strains Originating from Fowl Cholera

Science.gov (United States)

The ability of two avian Pasteurella multocida serogroup F strains to induce disease in rabbits was investigated in this study. Two groups of 18 Pasteurella-free rabbits each were intranasally challenged with strains isolated from chicken and turkey, respectively. Half the animals in each challenge ...

Need Satisfaction at Work, Job Strain, and Performance: A Diary Study.

Science.gov (United States)

De Gieter, Sara; Hofmans, Joeri; Bakker, Arnold B

2017-08-24

We performed a daily diary study to examine the mediating role of autonomy need satisfaction and competence need satisfaction in the relationships between job characteristics (i.e., job resources, challenge and hindrance demands) and strain and performance. For 10 consecutive working days, 194 employees reported on their daily job resources, challenge and hindrance demands, task performance, strain level, and satisfaction of the needs for competence and autonomy. Multilevel path modeling demonstrated that the within-person relationships between job resources, challenge and hindrance demands, and strain are mediated by autonomy need satisfaction, but not by competence need satisfaction. However, the relationships between job resources and hindrance demands, and performance are mediated by both competence and autonomy need satisfaction. Our findings show that organizations may benefit from designing jobs that provide employees with the opportunity to satisfy their basic needs for competence and autonomy. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Comparative Genomic Characterization of the Highly Persistent and Potentially Virulent Cronobacter sakazakii ST83, CC65 Strain H322 and Other ST83 Strains

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Hannah R. Chase

2017-06-01

Full Text Available Cronobacter (C. sakazakii is an opportunistic pathogen and has been associated with serious infections with high mortality rates predominantly in pre-term, low-birth weight and/or immune compromised neonates and infants. Infections have been epidemiologically linked to consumption of intrinsically and extrinsically contaminated lots of reconstituted powdered infant formula (PIF, thus contamination of such products is a challenging task for the PIF producing industry. We present the draft genome of C. sakazakii H322, a highly persistent sequence type (ST 83, clonal complex (CC 65, serotype O:7 strain obtained from a batch of non-released contaminated PIF product. The presence of this strain in the production environment was traced back more than 4 years. Whole genome sequencing (WGS of this strain together with four more ST83 strains (PIF production environment-associated confirmed a high degree of sequence homology among four of the five strains. Phylogenetic analysis using microarray (MA and WGS data showed that the ST83 strains were highly phylogenetically related and MA showed that between 5 and 38 genes differed from one another in these strains. All strains possessed the pESA3-like virulence plasmid and one strain possessed a pESA2-like plasmid. In addition, a pCS1-like plasmid was also found. In order to assess the potential in vivo pathogenicity of the ST83 strains, each strain was subjected to infection studies using the recently developed zebrafish embryo model. Our results showed a high (90–100% zebrafish mortality rate for all of these strains, suggesting a high risk for infections and illness in neonates potentially exposed to PIF contaminated with ST83 C. sakazakii strains. In summary, virulent ST83, CC65, serotype CsakO:7 strains, though rarely found intrinsically in PIF, can persist within a PIF manufacturing facility for years and potentially pose significant quality assurance challenges to the PIF manufacturing industry.

Effect of Lactobacillus salivarius on growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs challenged with F4+ enterotoxigenic Escherichia coli.

Science.gov (United States)

Sayan, Harutai; Assavacheep, Pornchalit; Angkanaporn, Kris; Assavacheep, Anongnart

2018-04-12

Gut health improvements were monitored with respect to growth performance, diarrhea incidence, fecal bacterial population and intestinal morphology of suckling pigs orally supplemented with live Lactobacillus salivarius oral suspensions and challenged with F4+ enterotoxigenic Escherichia coli (ETEC). Two groups of newborn pigs from 18 multiparous sows were randomly designated as non-supplemented (control: n=114 piglets) and L. salivarius supplemented groups (treatment: n=87 piglets). Treatment pigs were orally administered with 2 ml of 109 CFU/ml L. salivarius on days 1 - 3, then they were orally administered with 5 ml of 109 CFU/ml L. salivarius on days 4 - 10, while those in control group received an equal amount of phosphate buffered saline solution (PBS). On day 24 (2 weeks post supplementation), one pig per replicate of both groups was orally administered with 108 CFU/ml F4+ ETEC, then they were euthanized on day 29 of experiment. Results revealed that pigs in treatment group had statistically significant in average daily gain (ADG), body weight and weight gain, and tended to lower diarrhea throughout the study. Numbers of Lactobacillus population in feces of treatment pigs were higher than control pigs, especially on day 10 of study. Numbers of total bacteria in intestinal contents of control pigs were also increased, but not Coliform and Lactobacillus populations. Histological examination revealed statistically significant improvement of villous height and villous/crypt ratio of duodenum, proximal jejunum and distal jejunum parts of treatment pigs better than control. Duodenal pH of treatment group was significantly decreased. Oral supplementation of live L. salivarius during the first 10 days of suckling pig promoted growth performance and guts health, reduced diarrhea incidence, and increased fecal Lactobacillus populations, and improved intestinal morphology.

Randomised, double-blind, safety and efficacy of a killed oral vaccine for enterotoxigenic E. Coli diarrhoea of travellers to Guatemala and Mexico.

Science.gov (United States)

Sack, David A; Shimko, Janet; Torres, Olga; Bourgeois, August L; Francia, Domingo Sanchez; Gustafsson, Björn; Kärnell, Anders; Nyquist, Iréne; Svennerholm, Ann-Mari

2007-05-30

We tested the efficacy of a killed oral vaccine for enterotoxigenic Escherichia coli (ETEC) diarrhoea to determine if two doses of vaccine with colonization factor antigens (CF) and cholera B subunit would protect against ETEC diarrhoea of travellers. Six hundred seventy-two healthy travellers going to Mexico or Guatemala were studied in a prospective, randomised, placebo-controlled trial. The primary outcome was a vaccine preventable outcome (VPO), defined as an episode of ETEC diarrhoea with an ETEC organism producing heat labile toxin (LT) or CF homologous with the vaccine, without other known causes. The vaccine was safe and stimulated anti-heat labile toxin antibodies. There was a significant decrease in more severe VPO episodes (PE=77%, p=0.039) as defined by symptoms that interfered with daily activities or more than five loose stools in a day, although the total number of VPO events did not differ significantly in the vaccine and placebo groups. We conclude that the new oral ETEC vaccine reduces the rate of more severe episodes of traveller's diarrhoea (TD) due to VPO-ETEC, but it did not reduce the overall rate of ETEC diarrhoea or of travellers' diarrhoea due to other causes.

Leak rate analysis of the Westinghouse Reactor Coolant Pump

International Nuclear Information System (INIS)

Boardman, T.; Jeanmougin, N.; Lofaro, R.; Prevost, J.

1985-07-01

An independent analysis was performed by ETEC to determine what the seal leakage rates would be for the Westinghouse Reactor Coolant Pump (RCP) during a postulated station blackout resulting from loss of ac electric power. The object of the study was to determine leakage rates for the following conditions: Case 1: All three seals function. Case 2: No. 1 seal fails open while Nos. 2 and 3 seals function. Case 3: All three seals fail open. The ETEC analysis confirmed Westinghouse calculations on RCP seal performance for the conditions investigated. The leak rates predicted by ETEC were slightly lower than those predicted by Westinghouse for each of the three cases as summarized below. Case 1: ETEC predicted 19.6 gpm, Westinghouse predicted 21.1 gpm. Case 2: ETEC predicted 64.7 gpm, Westinghouse predicted 75.6 gpm. Case 3: ETEC predicted 422 gpm, Westinghouse predicted 480 gpm. 3 refs., 22 figs., 6 tabs

Differentiation of strains of yellow fever virus in γ-irradiated mice

International Nuclear Information System (INIS)

Fitzgeorge, R.; Bradish, C.J.

1980-01-01

The mouse sensitized by optimal, sub-lethal γ-irradiation has been used for the differentiation of strains of yellow fever virus and for the resolution of their immunogenicity and pathogenicity as distinct characteristics. For different strains of yellow fever virus, the patterns of antibody-synthesis, regulatory immunity (pre-challenge) and protective immunity (post-challenge) are differentially sensitive to γ-irradiation. These critical differentiations of strains of yellow fever virus in γ-irradiated mice have been compared with those shown in normal athymic and immature mice in order to elucidate the range of quantifiable in vivo characteristics and the course of the virus-host interaction. This is discussed as a basis for the comparisons of the responses of model and principal hosts to vaccines and pathogens. (author)

F4+ enterotoxigenic Escherichia coli (ETEC) adhesion mediated by the major fimbrial subunit FaeG.

Science.gov (United States)

Xia, Pengpeng; Song, Yujie; Zou, Yajie; Yang, Ying; Zhu, Guoqiang

2015-09-01

The FaeG subunit is the major constituent of F4(+) fimbriae, associated with glycoprotein and/or glycolipid receptor recognition and majorly contributes to the pathogen attachment to the host cells. To investigate the key factor involved in the fimbrial binding of F4(+) Escherichia coli, both the recombinant E. coli SE5000 strains carrying the fae operon gene clusters that express the different types of fimbriae in vitro, named as rF4ab, rF4ac, and rF4ad, respectively, corresponding to the fimbrial types F4ab, F4ac, and F4ad, and the three isogenic in-frame faeG gene deletion mutants were constructed. The adhesion assays and adhesion inhibition assays showed that ΔfaeG mutants had a significant reduction in the binding to porcine brush border as well as the intestinal epithelial cell lines, while the complemented strain ΔfaeG/pfaeG restored the adhesion function. The recombinant bacterial strains rF4ab, rF4ac, and rF4ad have the same binding property as wild-type F4(+) E. coli strains do and improvement in terms of binding to porcine brush border and the intestinal epithelial cells, and the adherence was blocked by the monoclonal antibody anti-F4 fimbriae. These data demonstrate that the fimbrial binding of F4(+) E. coli is directly mediated by the major FaeG subunit. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic Characterization of Bacillus anthracis 17 JB strain.

Science.gov (United States)

Seyed-Mohamadi, Sakineh; Moradi Bidhendi, Soheila; Tadayon, Keyvan; Ghaderi, Rainak

2015-06-01

Bacillus anthracis is one of the most homogenous bacteria ever described. Some level of diversity. Bacillus anthracis 17JB is a laboratory strain It is broadly used as a challenge strain in guinea pigs for potency test of anthrax vaccine. This work describes genetic characterization of B. anthracis 17 JB strain using the SNPs and MLVA genotyping. In SNPs typing, the originally French 17JB strain represented the A.Br. 008/009 subgroup. In Levy's genotyping method, 843, 451 and 864 bp long fragments were identified at AA03, AJ03 and AA07 loci, respectively. In the vaccine manufacturer perspective these findings are much valuable on their own account, but similar research is required to extend molecular knowledge of B. anthracis epidemiology in Persia.

Distinct virulence of Rift Valley fever phlebovirus strains from different genetic lineages in a mouse model.

Directory of Open Access Journals (Sweden)

Tetsuro Ikegami

Full Text Available Rift Valley fever phlebovirus (RVFV causes high rates of abortions and fetal malformations in ruminants, and hemorrhagic fever, encephalitis, or blindness in humans. Viral transmission occurs via mosquito vectors in endemic areas, which necessitates regular vaccination of susceptible livestock animals to prevent the RVF outbreaks. Although ZH501 strain has been used as a challenge strain for past vaccine efficacy studies, further characterization of other RVFV strains is important to optimize ruminant and nonhuman primate RVFV challenge models. This study aimed to characterize the virulence of wild-type RVFV strains belonging to different genetic lineages in outbred CD1 mice. Mice were intraperitoneally infected with 1x103 PFU of wild-type ZH501, Kenya 9800523, Kenya 90058, Saudi Arabia 200010911, OS1, OS7, SA75, Entebbe, or SA51 strains. Among them, mice infected with SA51, Entebbe, or OS7 strain showed rapid dissemination of virus in livers and peracute necrotic hepatitis at 2-3 dpi. Recombinant SA51 (rSA51 and Zinga (rZinga strains were recovered by reverse genetics, and their virulence was also tested in CD1 mice. The rSA51 strain reproduced peracute RVF disease in mice, whereas the rZinga strain showed a similar virulence with that of rZH501 strain. This study showed that RVFV strains in different genetic lineages display distinct virulence in outbred mice. Importantly, since wild-type RVFV strains contain defective-interfering RNA or various genetic subpopulations during passage from original viral isolations, recombinant RVFV strains generated by reverse genetics will be better suitable for reproducible challenge studies for vaccine development as well as pathological studies.

Strain-controlled electrocatalysis on multimetallic nanomaterials

Science.gov (United States)

Luo, Mingchuan; Guo, Shaojun

2017-11-01

Electrocatalysis is crucial for the development of clean and renewable energy technologies, which may reduce our reliance on fossil fuels. Multimetallic nanomaterials serve as state-of-the-art electrocatalysts as a consequence of their unique physico-chemical properties. One method of enhancing the electrocatalytic performance of multimetallic nanomaterials is to tune or control the surface strain of the nanomaterials, and tremendous progress has been made in this area in the past decade. In this Review, we summarize advances in the introduction, tuning and quantification of strain in multimetallic nanocrystals to achieve more efficient energy conversion by electrocatalysis. First, we introduce the concept of strain and its correlation with other key physico-chemical properties. Then, using the electrocatalytic reduction of oxygen as a model reaction, we discuss the underlying mechanisms behind the strain-adsorption-reactivity relationship based on combined classical theories and models. We describe how this knowledge can be harnessed to design multimetallic nanocrystals with optimized strain to increase the efficiency of oxygen reduction. In particular, we highlight the unexpectedly beneficial (and previously overlooked) role of tensile strain from multimetallic nanocrystals in improving electrocatalysis. We conclude by outlining the challenges and offering our perspectives on the research directions in this burgeoning field.

Challenge Pools of Hepatitis C Virus Genotypes 1–6 Prototype Strains: Replication Fitness and Pathogenicity in Chimpanzees and Human Liver–Chimeric Mouse Models

Science.gov (United States)

Bukh, Jens; Meuleman, Philip; Tellier, Raymond; Engle, Ronald E.; Feinstone, Stephen M.; Eder, Gerald; Satterfield, William C.; Govindarajan, Sugantha; Krawczynski, Krzysztof; Miller, Roger H.; Leroux-Roels, Geert; Purcell, Robert H.

2010-01-01

Chimpanzees represent the only animal model for studies of the natural history of hepatitis C virus (HCV). To generate virus stocks of important HCV variants, we infected chimpanzees with HCV strains of genotypes 1–6 and determined the infectivity titer of acute-phase plasma pools in additional animals. The courses of first- and second-passage infections were similar, with early appearance of viremia, HCV RNA titers of >104.7 IU/mL, and development of acute hepatitis; the chronicity rate was 56%. The challenge pools had titers of 103–105 chimpanzee infectious doses/mL. Human liver–chimeric mice developed high-titer infections after inoculation with the challenge viruses of genotypes 1–6. Inoculation studies with different doses of the genotype 1b pool suggested that a relatively high virus dose is required to consistently infect chimeric mice. The challenge pools represent a unique resource for studies of HCV molecular virology and for studies of pathogenesis, protective immunity, and vaccine efficacy in vivo. PMID:20353362

Complete Genome Sequence of Enterotoxigenic Escherichia coli Siphophage Seurat.

Science.gov (United States)

Doan, Dung P; Lessor, Lauren E; Hernandez, Adriana C; Kuty Everett, Gabriel F

2015-02-26

Enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of diarrhea in developing countries. Bacteriophage therapy has the potential to aid in the prevention and treatment of ETEC-related illness. To that end, we present here the complete genome of ETEC siphophage Seurat and describe its major features. Copyright © 2015 Doan et al.

Large area strain analysis using scanning transmission electron microscopy across multiple images

International Nuclear Information System (INIS)

Oni, A. A.; Sang, X.; LeBeau, J. M.; Raju, S. V.; Saxena, S.; Dumpala, S.; Broderick, S.; Rajan, K.; Kumar, A.; Sinnott, S.

2015-01-01

Here, we apply revolving scanning transmission electron microscopy to measure lattice strain across a sample using a single reference area. To do so, we remove image distortion introduced by sample drift, which usually restricts strain analysis to a single image. Overcoming this challenge, we show that it is possible to use strain reference areas elsewhere in the sample, thereby enabling reliable strain mapping across large areas. As a prototypical example, we determine the strain present within the microstructure of a Ni-based superalloy directly from atom column positions as well as geometric phase analysis. While maintaining atomic resolution, we quantify strain within nanoscale regions and demonstrate that large, unit-cell level strain fluctuations are present within the intermetallic phase

Potential probiotic Lactobacillus strains from fermented sausages: Further investigations on their probiotic properties

NARCIS (Netherlands)

Pennacchia, C.; Vaughan, E.E.; Villani, F.

2006-01-01

A rational selection of probiotic microorganisms is an important challenge and requires the definition of fundamental information about the physiology and genetics of candidate strains. In this study, selected Lactobacillus (Lact.) strains already characterized in a previous study for their

Humoral immune response of C57Bl/6j and BALB/c mice immunized with irradiated tachyzoites of Toxoplasma gondii RH strain and oral challenge with ME-49 strain

Energy Technology Data Exchange (ETDEWEB)

Jimenez Galisteo Junior, Andres [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil). Centro de Biotecnologia; Instituto de Medicina Tropical de Sao Paulo, Sao Paulo, SP (Brazil). Lab. de Protozoologia; E-mail: galisteo@usp.br; Zorgi, Nahiara Esteves; Andrade Junior, Heitor Franco de [Instituto de Medicina Tropical de Sao Paulo, Sao Paulo, SP (Brazil). Lab. de Protozoologia; Alves, Janaina Baptista; Nascimento, Nanci do [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil). Centro de Biotecnologia; Hiramoto, Roberto Mitsuyoshi [instituto Adolfo Lutz, Sao Paulo, SP (Brazil)

2007-07-01

Toxoplasmosis, a prevalent widespread infection in man and animals, is mainly transmitted by oral route, through ingestion of oocysts from water and food contaminated with cat feces or infected animal tissue cysts in undercooked meat. Vaccine development implies in effective intestinal immunity, the first site of parasite entry. Radiation (255 Gy/{sup 60}Co) sterilized T. gondii RH strain tachyzoites (RST) induced significant protection when parentally administered, similar to chronically infected and acute disease protected animal. We study the humoral immune response in C57Bl/6j and BALB/c mice immunized with 10{sup 7} RST, by oral (with aluminium hydroxide 3%) or parenteral 3 biweekly administrations. T. gondii antigens specific ELISA for IgG, IgA, IgG1, IgG2a and IgG2b detection was performed in weekly blood samples during immunization. Also we evaluate of the intestinal epithelial of immunized mice the integrity of the radiated parasites by electronic microscopy. After 2 weeks, immunized and control animals were challenged with 10 cysts of ME-49 strain p.o. Protection was determined at the 30th day by brain cyst counting. As it was possible to observe in the intestinal mucosal, the aluminium hydroxide seems to maintain unchanged the parasite morphology and its mechanisms of invasion, probably due to keeping it safe from extreme pH condition of stomach. All immunized groups presented significant protection when challenged with ME-49; however, BALB/c mice showed better protection levels, with only one positive animal on brain microscopic analysis. IgG production in the serum of the animals was higher in groups immunized by i.p route, however, IgA and IgG1 levels were higher in BALB/c mice immunized by oral route. This higher protection found in BALB/c group could probably also be related to the Th2 response, demonstrated by higher IgG1 levels. All these data provide insights in oral immunization schedules for toxoplasmosis prevention, suggesting that oral

Humoral immune response of C57Bl/6j and BALB/c mice immunized with irradiated tachyzoites of Toxoplasma gondii RH strain and oral challenge with ME-49 strain

International Nuclear Information System (INIS)

Jimenez Galisteo Junior, Andres

2007-01-01

Toxoplasmosis, a prevalent widespread infection in man and animals, is mainly transmitted by oral route, through ingestion of oocysts from water and food contaminated with cat feces or infected animal tissue cysts in undercooked meat. Vaccine development implies in effective intestinal immunity, the first site of parasite entry. Radiation (255 Gy/ 60 Co) sterilized T. gondii RH strain tachyzoites (RST) induced significant protection when parentally administered, similar to chronically infected and acute disease protected animal. We study the humoral immune response in C57Bl/6j and BALB/c mice immunized with 10 7 RST, by oral (with aluminium hydroxide 3%) or parenteral 3 biweekly administrations. T. gondii antigens specific ELISA for IgG, IgA, IgG1, IgG2a and IgG2b detection was performed in weekly blood samples during immunization. Also we evaluate of the intestinal epithelial of immunized mice the integrity of the radiated parasites by electronic microscopy. After 2 weeks, immunized and control animals were challenged with 10 cysts of ME-49 strain p.o. Protection was determined at the 30th day by brain cyst counting. As it was possible to observe in the intestinal mucosal, the aluminium hydroxide seems to maintain unchanged the parasite morphology and its mechanisms of invasion, probably due to keeping it safe from extreme pH condition of stomach. All immunized groups presented significant protection when challenged with ME-49; however, BALB/c mice showed better protection levels, with only one positive animal on brain microscopic analysis. IgG production in the serum of the animals was higher in groups immunized by i.p route, however, IgA and IgG1 levels were higher in BALB/c mice immunized by oral route. This higher protection found in BALB/c group could probably also be related to the Th2 response, demonstrated by higher IgG1 levels. All these data provide insights in oral immunization schedules for toxoplasmosis prevention, suggesting that oral vaccines could

Stimulation of mucosal immune response following oral administration of enterotoxigenic Escherichia coli fimbriae (CFA/I) entrapped in liposomes in conjunction with inactivated whole-cell Vibrio cholerae vaccine.

Science.gov (United States)

Dima, V F; Ionescu, M D; Palade, R; Balotescu, C; Becheanu, G; Dima, S V

2001-01-01

In this study, we have searched for an effective mucosal vaccine. An oral enterotoxigenic E. coli vaccine containing colonization factor antigen (CFA/I) associated with inactivated whole-cell V. cholerae vaccine (WCV) has been tested for safety and immunogenicity in animals. Five groups of animals were used. The results showed the following: (a) vaccine containing CFA/I antigen entrapped in liposomes and associated with WCV (batch C) had increased titers of specific antibodies to CFA/I antigen in 15 to 18 (83.3%) animals; (b) specific Peyer's patches (PP), lymph nodes (LN) and spleen (SPL) lymphocytes proliferation was detected following in vitro restimulation with CFA/I antigen or WCV. This response gradually increased to the highest value by the 35th postimmunization day. Moreover, lower PP, LN and spleen (SPL) proliferation was observed in rabbits receiving soluble CFA/I antigen (S-CFA/I) or free liposomes (F-L) alone; (c) adhesion of E. coli H10407 strain labelled with 3H-leucine in immunized and control animals revealed the following local effects: (i) protection of rabbit intestinal mucosa against virulent E. coli cells; (ii) inhibition of adhesion of ETEC bacteria to intestinal mucosa and (iii) significantly faster release of E. coli H 10407 strain labelled with 3H-leucine from the intestinal tract of immunized animals. The histopathological and electron microscope findings confirmed the above results. The experimental results point out an efficient protection against infection with E. coli strains (ETEC), after mucosal vaccination with CFA/I antigen entrapped in liposomes associated with inactivated whole-cell Vibrio cholerae as immunological adjuvant.

A live, attenuated pseudorabies virus strain JS-2012 deleted for gE/gI protects against both classical and emerging strains.

Science.gov (United States)

Tong, Wu; Li, Guoxin; Liang, Chao; Liu, Fei; Tian, Qing; Cao, Yanyun; Li, Lin; Zheng, Xuchen; Zheng, Hao; Tong, Guangzhi

2016-06-01

Emerging pseudorabies virus (PRV) variant have led to pseudorabies outbreaks in Chinese pig farms. The commercially available PRV vaccine provides poor protection against the PRV variant. In this study, a gE/gI deleted PRV strain JS-2012-△gE/gI was generated from a PRV variant strain using homologous DNA recombination. Compared to the parental strain JS-2012, JS-2012-△gE/gI grew slowly and showed small plaque morphology on Vero cells. The safety and immunological efficacy of JS-2012-△gE/gI was evaluated as a vaccine candidate. JS-2012-△gE/gI was avirulent to suckling piglets, but was able to provide full protection for young piglets against challenge with both the classical virulent PRV and the emerging PRV variant. After sows were vaccinated with the gE/gI-deleted strain, their suckling offspring were resistant to an otherwise lethal challenge with the classical and the variant PRVs. Piglets inoculated with JS-2012-△gE/gI did not develop PRV-specific gE-ELISA antibodies. Thus, JS-2012-△gE/gI appears to be a promising marker vaccine candidate to control PRV variant circulating in pig farms in China. Copyright © 2016 Elsevier B.V. All rights reserved.

Differential protection by cell wall components of Lactobacillus amylovorus DSM 16698Tagainst alterations of membrane barrier and NF-kB activation induced by enterotoxigenic F4+ Escherichia coli on intestinal cells.

Science.gov (United States)

Roselli, Marianna; Finamore, Alberto; Hynönen, Ulla; Palva, Airi; Mengheri, Elena

2016-09-29

The role of Lactobacillus cell wall components in the protection against pathogen infection in the gut is still largely unexplored. We have previously shown that L. amylovorus DSM 16698 T is able to reduce the enterotoxigenic F4 + Escherichia coli (ETEC) adhesion and prevent the pathogen-induced membrane barrier disruption through the regulation of IL-10 and IL-8 expression in intestinal cells. We have also demonstrated that L. amylovorus DSM 16698 T protects host cells through the inhibition of NF-kB signaling. In the present study, we investigated the role of L. amylovorus DSM 16698 T cell wall components in the protection against F4 + ETEC infection using the intestinal Caco-2 cell line. Purified cell wall fragments (CWF) from L. amylovorus DSM 16698 T were used either as such (uncoated, U-CWF) or coated with S-layer proteins (S-CWF). Differentiated Caco-2/TC7 cells on Transwell filters were infected with F4 + ETEC, treated with S-CWF or U-CWF, co-treated with S-CWF or U-CWF and F4 + ETEC for 2.5 h, or pre-treated with S-CWF or U-CWF for 1 h before F4 + ETEC addition. Tight junction (TJ) and adherens junction (AJ) proteins were analyzed by immunofluorescence and Western blot. Membrane permeability was determined by phenol red passage. Phosphorylated p65-NF-kB was measured by Western blot. We showed that both the pre-treatment with S-CWF and the co- treatment of S-CWF with the pathogen protected the cells from F4 + ETEC induced TJ and AJ injury, increased membrane permeability and activation of NF-kB expression. Moreover, the U-CWF pre-treatment, but not the co-treatment with F4 + ETEC, inhibited membrane damage and prevented NF-kB activation. The results indicate that the various components of L. amylovorus DSM 16698 T cell wall may counteract the damage caused by F4 + ETEC through different mechanisms. S-layer proteins are essential for maintaining membrane barrier function and for mounting an anti-inflammatory response against F4 + ETEC infection. U-CWF are

Ultrasensitive, Stretchable Strain Sensors Based on Fragmented Carbon Nanotube Papers

KAUST Repository

Zhou, Jian

2017-01-17

The development of strain sensors featuring both ultra high sensitivity and high stretchability is still a challenge. We demonstrate that strain sensors based on fragmented single-walled carbon nanotube (SWCNT) paper embedded in poly(dimethylsiloxane) (PDMS) can sustain their sensitivity even at very high strain levels (with a gauge factor of over 10(7) at 50% strain). This record sensitivity is ascribed to the low initial electrical resistance (5-28 Omega) of the SWCNT paper and the wide change in resistance (up to 10(6) Omega) governed by the percolated network of SWCNT in the cracked region. The sensor response remains nearly unchanged after 10 000 strain cycles at 20% proving the robustness of this technology. This fragmentation based sensing system brings opportunities to engineer highly sensitive stretchable sensors.

Parallel Microcracks-based Ultrasensitive and Highly Stretchable Strain Sensors.

Science.gov (United States)

Amjadi, Morteza; Turan, Mehmet; Clementson, Cameron P; Sitti, Metin

2016-03-02

There is an increasing demand for flexible, skin-attachable, and wearable strain sensors due to their various potential applications. However, achieving strain sensors with both high sensitivity and high stretchability is still a grand challenge. Here, we propose highly sensitive and stretchable strain sensors based on the reversible microcrack formation in composite thin films. Controllable parallel microcracks are generated in graphite thin films coated on elastomer films. Sensors made of graphite thin films with short microcracks possess high gauge factors (maximum value of 522.6) and stretchability (ε ≥ 50%), whereas sensors with long microcracks show ultrahigh sensitivity (maximum value of 11,344) with limited stretchability (ε ≤ 50%). We demonstrate the high performance strain sensing of our sensors in both small and large strain sensing applications such as human physiological activity recognition, human body large motion capturing, vibration detection, pressure sensing, and soft robotics.

Enhancement of bile resistance in Lactobacillus plantarum strains by soy lecithin.

Science.gov (United States)

Hu, B; Tian, F; Wang, G; Zhang, Q; Zhao, J; Zhang, H; Chen, W

2015-07-01

This study evaluated the effect of soy lecithin on the bile resistance of Lactobacillus plantarum. Six strains were cultured in MRS broth supplemented with soy lecithin at different concentrations. The strains incubated in MRS broth with 1·0% soy lecithin showed no inhibitory effect on cell growth. After culturing in MRS broth with 0·2-1·0% soy lecithin, the survival rate of harvested cells increased significantly (P bile challenge compared with the no added soy lecithin group. The cells incubated with 0·6% soy lecithin were able to grow in an MRS broth with a higher bile salt content. The surface hydrophobicity and cell leakage in the bile challenge were assessed to reveal the physical changes caused by the addition of soy lecithin. The cell surface hydrophobicity was enhanced and the membrane integrity in the bile challenge increased after culturing with soy lecithin. A shift in the fatty acid composition was also observed, illustrating the cell membrane change in the soy lecithin culture. In this study, we report for the first time the beneficial effect of adding soy lecithin to an MRS broth on subsequent bile tolerance of Lactobacillus plantarum. Soy lecithin had no inhibitory effect on strain viability but significantly enhanced bile resistance. Surface hydrophobicity and cell integrity increased in strains cultured with soy lecithin. The observed shift in the cell fatty acid composition indicated changes to the cell membrane. As soy lecithin is safe for use in the food industry, its protective effects can be harnessed for the development of bile-sensitive strains with health-benefit functions for use in probiotic products. © 2015 The Society for Applied Microbiology.

Preparation for emergence of an Eastern European porcine reproductive and respiratory syndrome virus (PRRSV) strain in Western Europe: Immunization with modified live virus vaccines or a field strain confers partial protection.

Science.gov (United States)

Renson, P; Fablet, C; Le Dimna, M; Mahé, S; Touzain, F; Blanchard, Y; Paboeuf, F; Rose, N; Bourry, O

2017-05-01

The porcine reproductive and respiratory syndrome virus (PRRSV) causes huge economic losses for the swine industry worldwide. In the past several years, highly pathogenic strains that lead to even greater losses have emerged. For the Western European swine industry, one threat is the possible introduction of Eastern European PRRSV strains (example Lena genotype 1.3) which were shown to be more virulent than common Western resident strains under experimental conditions. To prepare for the possible emergence of this strain in Western Europe, we immunized piglets with a Western European PRRSV field strain (Finistere: Fini, genotype 1.1), a new genotype 1 commercial modified live virus (MLV) vaccine (MLV1) or a genotype 2 commercial MLV vaccine (MLV2) to evaluate and compare the level of protection that these strains conferred upon challenge with the Lena strain 4 weeks later. Results show that immunization with Fini, MLV1 or MLV2 strains shortened the Lena-induced hyperthermia. In the Fini group, a positive effect was also demonstrated in growth performance. The level of Lena viremia was reduced for all immunized groups (significantly so for Fini and MLV2). This reduction in Lena viremia was correlated with the level of Lena-specific IFNγ-secreting cells. In conclusion, we showed that a commercial MLV vaccine of genotype 1 or 2, as well as a field strain of genotype 1.1 may provide partial clinical and virological protection upon challenge with the Lena strain. The cross-protection induced by these immunizing strains was not related with the level of genetic similarity to the Lena strain. The slightly higher level of protection established with the field strain is attributed to a better cell-mediated immune response. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevention of Clostridium difficile infection in hamsters using a non-toxigenic strain

Directory of Open Access Journals (Sweden)

Carlos Augusto de Oliveira Júnior

2016-05-01

Full Text Available ABSTRACT: The present study aimed to evaluate five non-toxigenic strains of Clostridium difficile (NTCD in vitro and to select one strain to prevent C. difficile (CDI infection in hamsters ( Mesocricetus auratus . The NTCD strains were evaluated for spore production in vitro, antimicrobial susceptibility and presence of antimicrobial resistance genes. Approximately 107 spores of the selected strain (Z31 were administered by esophageal gavage in hamsters pretreated with 30mg kg-1 of clindamycin. The challenge with a toxigenic strain of C. difficile was conducted at 36 and 72h, and the animals were observed for 28 days. The NTCD strain of C. difficile (Z31 was able to prevent CDI in all animals that received it.

Psychological strains and youth suicide in rural China.

Science.gov (United States)

Zhang, Jie; Wieczorek, William F; Conwell, Yeates; Tu, Xin Ming

2011-06-01

The strain theory of suicide postulates that suicide is usually preceded by psychological strains. A strain can be a consequence of any of four conflicts: differential values, aspiration and reality, relative deprivation, and lack of coping skills for a crisis. This study, with a blend of psychiatric and social predictors of suicide, identified correlates of suicide that are relevant to Chinese culture and tested the strain theory of suicide with Chinese data. We sampled 392 suicides and 416 living controls (both aged 15-34 years) from 16 rural counties in China in 2008 and interviewed two informants for each suicide and each control. We found that marriage and religion/religiosity did not distinguish the suicides from the living controls among Chinese rural young women. Religion/religiosity tended to be stronger for suicides than for controls. Psychological strains in the forms of relative deprivation, unrealized aspiration, and lack of coping skills were significantly associated with suicide, even after accounting for the role of mental illness. The strain theory of suicide forms a challenge to the psychiatric model popular in the West, at least in explaining the Chinese suicide. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of bacterial culture and qPCR testing of rectal and pen floor samples as diagnostic approaches to detect enterotoxic Escherichia coli in nursery pigs

DEFF Research Database (Denmark)

Weber, N. R.; Nielsen, J. P.; Hjulsager, Charlotte Kristiane

2017-01-01

Enterotoxigenic E. coli (ETEC) are a major cause of diarrhoea in weaned pigs. The objective of this study was to evaluate the agreement at pen level among three different diagnostic approaches for the detection of ETEC in groups of nursery pigs with diarrhoea. The diagnostic approaches used were...... to determine the quantity of F18 and F4 genes. The study was carried out in three Danish pig herds and included 31 pens with a pen-level diarrhoea prevalence of > 25%, as well as samples from 93 diarrhoeic nursery pigs from these pens. All E. coli isolates were analysed by PCR and classified as ETEC when genes...... was observed between the detection of ETEC by bacterial culture and qPCR in the same pen floor sample in 26 (83.9%, Kappa = 0.679) pens. Conclusion: We observed an acceptable agreement for the detection of ETEC-positive diarrhoeic nursery pigs in pen samples for both bacterial culture of pen floor samples...

Bandgap-customizable germanium using lithographically determined biaxial tensile strain for silicon-compatible optoelectronics.

Science.gov (United States)

Sukhdeo, David S; Nam, Donguk; Kang, Ju-Hyung; Brongersma, Mark L; Saraswat, Krishna C

2015-06-29

Strain engineering has proven to be vital for germanium-based photonics, in particular light emission. However, applying a large permanent biaxial tensile strain to germanium has been a challenge. We present a simple, CMOS-compatible technique to conveniently induce a large, spatially homogenous strain in circular structures patterned within germanium nanomembranes. Our technique works by concentrating and amplifying a pre-existing small strain into a circular region. Biaxial tensile strains as large as 1.11% are observed by Raman spectroscopy and are further confirmed by photoluminescence measurements, which show enhanced and redshifted light emission from the strained germanium. Our technique allows the amount of biaxial strain to be customized lithographically, allowing the bandgaps of different germanium structures to be independently customized in a single mask process.

Bacillus subtilis strain specificity affects performance improvement in broilers.

Science.gov (United States)

Rhayat, L; Jacquier, V; Brinch, K S; Nielsen, P; Nelson, A; Geraert, P-A; Devillard, E

2017-07-01

The study reports the effects on broiler performance of a newly isolated Bacillus subtilis strain, which is phylogenetically not closely related to already well-described strains of B. subtilis. In the first experiment, birds were reared in battery cages and exposed to C. perfringens. An increase in growth performance was observed with the strain when compared to the challenged animals. Three additional growth trials were conducted to 35 d of age, in different rearing conditions (genetic breeds, corn-soybean meal-based diet with or without animal proteins, in presence or absence of phytase, on fresh or used litter) to investigate the efficacy and the specificity of this new B. subtilis strain on the improvement of BWG and FCR of broilers in comparison with a B. subtilis-based DFM already used in the field. Whatever the rearing conditions tested, the new B. subtilis strain led to an average 3.2% improvement in feed conversion ratio or bodyweight. Comparatively, the commercial Bacillus strain significantly improved broiler performance in only one trial out of 3 with an average improvement reaching 2%. All these results indicate that this new B. subtilis strain consistently improves broiler performances. © 2017 Poultry Science Association Inc.

Experimental reinfection of BALB/c mice with different recombinant type I/III strains of Toxoplasma gondii: involvement of IFN-³ and IL-10

OpenAIRE

Brandão,Geane Peroni; Melo,Maria Norma; Gazzinelli,Ricardo Tostes; Caetano,Braulia Costa; Ferreira,Adriana Melo; Silva,Letícia Azevedo; Vitor,Ricardo Wagner Almeida

2009-01-01

To assess reinfection of BALB/c mice with different Toxoplasma gondii strains, the animals were prime infected with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction and PCR-RFLP analysis to distinguish the different T. gondii strains present in possible co-infections. Anti-Toxoplasma immune responses were evaluated ...

Comparison of the protective resistance induced by 60Co-irradiated cercariae and schistosomula of the WFFS and NMRI strains of Schistosoma mansoni

International Nuclear Information System (INIS)

James, E.R.; Dobinson, A.R.

1985-01-01

Mice, CBA/HT6T6 and C57BL/10, were vaccinated with 1 x 350 or 1 x 500 Schistosoma mansoni cercariae or schistosomula attenuated with 20 or 56 krad 60 Co irradiation and challenged with 200 cercariae. Protective resistance against homologous strain challenge was compared using the Winches Farm Field Station (WFFS) and Naval Medical Research Institute (NMRI) strains of S. mansoni. Maximal resistance to challenge was obtained in both strains of mice with cercariae or schistosomula of either WFFS or NMRI strain attenuated with 20 krad. Protection using organisms attenuated with 56 krad was significantly lower. Since previous studies with the two parasite strains have shown that the biological effects of irradiation are similar, the difference in the immunogenicity of the 56 krad-irradiated NMRI strain in this study from earlier studies must be due either to different local conditions for irradiation or to adaptation of the NMRI strain to a new laboratory environment. This finding may have important implications for vaccination studies and investigations of the mechanisms of immunity where radiation-attenuated parasites are used. (author)

Engineering and preclinical evaluation of attenuated nontyphoidal Salmonella strains serving as live oral vaccines and as reagent strains.

Science.gov (United States)

Tennant, Sharon M; Wang, Jin-Yuan; Galen, James E; Simon, Raphael; Pasetti, Marcela F; Gat, Orit; Levine, Myron M

2011-10-01

While nontyphoidal Salmonella (NTS) has long been recognized as a cause of self-limited gastroenteritis, it is becoming increasingly evident that multiple-antibiotic-resistant strains are also emerging as important causes of invasive bacteremia and focal infections, resulting in hospitalizations and deaths. We have constructed attenuated Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis strains that can serve as live oral vaccines and as "reagent strains" for subunit vaccine production in a safe and economical manner. Prototype attenuated vaccine strains CVD 1921 and CVD 1941, derived from the invasive wild-type strains S. Typhimurium I77 and S. Enteritidis R11, respectively, were constructed by deleting guaBA, encoding guanine biosynthesis, and clpP, encoding a master protease regulator. The clpP mutation resulted in a hyperflagellation phenotype. An additional deletion in fliD yielded reagent strains CVD 1923 and CVD 1943, respectively, which export flagellin monomers. Oral 50% lethal dose (LD₅₀) analyses showed that the NTS vaccine strains were all highly attenuated in mice. Oral immunization with CVD 1921 or CVD 1923 protected mice against lethal challenge with wild-type S. Typhimurium I77. Immunization with CVD 1941 but not CVD 1943 protected mice against lethal infection with S. Enteritidis R11. Immune responses induced by these strains included high levels of serum IgG anti-lipopolysaccharide (LPS) and anti-flagellum antibodies, with titers increasing progressively during the immunization schedule. Since S. Typhimurium and S. Enteritidis are the most common NTS serovars associated with invasive disease, these findings can pave the way for development of a highly effective, broad-spectrum vaccine against invasive NTS.

Comparison of the immune responses associated with experimental bovine mastitis caused by different strains of Escherichia coli.

Science.gov (United States)

Blum, Shlomo E; Heller, Elimelech D; Jacoby, Shamay; Krifucks, Oleg; Leitner, Gabriel

2017-05-01

We studied the mammary immune response to different mammary pathogenic Escherichia coli (MPEC) strains in cows, hypothesising that the dynamics of response would differ. E. coli is a major aetiologic agent of acute clinical bovine mastitis of various degrees of severity with specific strains being associated with persistent infections. We compared challenge with three distinct pathogenic MPEC strains (VL2874, VL2732 and P4), isolated from different forms of mastitis (per-acute, persistent and acute, respectively). A secondary objective was to verify the lack of mammary pathogenicity of an environmental isolate (K71) that is used for comparison against MPEC in genomic and phenotypic studies. Twelve cows were challenged by intra-mammary infusion with one of the strains. Cellular and chemokine responses and bacterial culture follow-up were performed for 35 d. All cows challenged by any of the MPEC strains developed clinical mastitis. Differences were found in the intensity and duration of response, in somatic cell count, secreted cytokines (TNF-α, IL-6 and IL-17) and levels of milk leucocyte membrane Toll-like receptor 4 (TLR4). A sharp decrease of TLR4 on leucocytes was observed concomitantly to peak bacterial counts in milk. Intra-mammary infusion of strain K71 did not elicit inflammation and bacteria were not recovered from milk. Results suggest some differences in the mammary immune response to distinct MPEC strains that could be correlated to their previously observed pathogenic traits. This is also the first report of an E. coli strain that is non-pathogenic to the bovine mammary gland.

Saccharomyces cerevisiae strains for second-generation ethanol production: from academic exploration to industrial implementation

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Jansen, Mickel L. A.; Bracher, Jasmine M.; Papapetridis, Ioannis; Verhoeven, Maarten D.; de Bruijn, Hans; de Waal, Paul P.; van Maris, Antonius J. A.; Klaassen, Paul

2017-01-01

Abstract The recent start-up of several full-scale ‘second generation’ ethanol plants marks a major milestone in the development of Saccharomyces cerevisiae strains for fermentation of lignocellulosic hydrolysates of agricultural residues and energy crops. After a discussion of the challenges that these novel industrial contexts impose on yeast strains, this minireview describes key metabolic engineering strategies that have been developed to address these challenges. Additionally, it outlines how proof-of-concept studies, often developed in academic settings, can be used for the development of robust strain platforms that meet the requirements for industrial application. Fermentation performance of current engineered industrial S. cerevisiae strains is no longer a bottleneck in efforts to achieve the projected outputs of the first large-scale second-generation ethanol plants. Academic and industrial yeast research will continue to strengthen the economic value position of second-generation ethanol production by further improving fermentation kinetics, product yield and cellular robustness under process conditions. PMID:28899031

Aqueous synthesis of ZnTe/dendrimer nanocomposites and their antimicrobial activity: implications in therapeutics

Science.gov (United States)

Ghosh, S.; Ghosh, D.; Bag, P. K.; Bhattacharya, S. C.; Saha, A.

2011-03-01

The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they have a good degree of crystallinity with a hexagonal crystal phase. The antibacterial activities of the ZnTe/dendrimer nanocomposites (ZnTe DNCs) as well other semiconductor nanocomposites were evaluated against enteropathogenic bacteria including multi-drug resistant Vibrio cholerae serogroup O1 and enterotoxigenic Escherichia coli (ETEC). ZnTe DNCs had significant antibacterial activity against strains of V. cholerae and ETEC with minimum inhibitory concentrations ranging from 64 to 512 μg ml-1 and minimum bactericidal concentrations ranging from 128 to 1000 μg ml-1. Thus, the observed results suggest that these water-soluble active nanocomposites have potential for the treatment of enteric diseases like diarrhoea and cholera.The present strategy proposes a simple and single step aqueous route for synthesizing stable, fluorescent ZnTe/dendrimer nanocomposites with varying dendrimer terminal groups. In these hybrid materials, the fluorescence of the semiconductor combines with the biomimetic properties of the dendrimer making them suitable for various biomedical applications. The ZnTe nanocomposites thus obtained demonstrate bactericidal activity against enteropathogenic bacteria without having toxic effects on the human erythrocytes. The average size of the ZnTe nanoparticles within the dendrimer matrix was in the range of 2.9-6.0 nm, and they

Local host response following an intramammary challenge with Staphylococcus fleurettii and different strains of Staphylococcus chromogenes in dairy heifers.

Science.gov (United States)

Piccart, Kristine; Verbeke, Joren; De Visscher, Anneleen; Piepers, Sofie; Haesebrouck, Freddy; De Vliegher, Sarne

2016-05-12

Coagulase-negative staphylococci (CNS) are a common cause of subclinical mastitis in dairy cattle. The CNS inhabit various ecological habitats, ranging between the environment and the host. In order to obtain a better insight into the host response, an experimental infection was carried out in eight healthy heifers in mid-lactation with three different CNS strains: a Staphylococcus fleurettii strain originating from sawdust bedding, an intramammary Staphylococcus chromogenes strain originating from a persistent intramammary infection (S. chromogenes IM) and a S. chromogenes strain isolated from a heifer's teat apex (S. chromogenes TA). Each heifer was inoculated in the mammary gland with 1.0 × 10(6) colony forming units of each bacterial strain (one strain per udder quarter), whereas the remaining quarter was infused with phosphate-buffered saline. Overall, the CNS evoked a mild local host response. The somatic cell count increased in all S. fleurettii-inoculated quarters, although the strain was eliminated within 12 h. The two S. chromogenes strains were shed in larger numbers for a longer period. Bacterial and somatic cell counts, as well as neutrophil responses, were higher after inoculation with S. chromogenes IM than with S. chromogenes TA. In conclusion, these results suggest that S. chromogenes might be better adapted to the mammary gland than S. fleurettii. Furthermore, not all S. chromogenes strains induce the same local host response.

Brote causado por Escherichia coli en Chalco, México Outbreak caused by Escherichia coli in Chalco, México

Directory of Open Access Journals (Sweden)

Iliana Alejandra Cortés-Ortiz

2002-07-01

swab samples from diarrhea cases, to test for E. coli strains. Statistical analysis was performed to find a difference of proportions between cases and non-cases (chi-squared test. ETEC, EIEC, EPEC and EHEC pathogenic E. coli groups were hybridized by colony blot. Results. Strains isolated were ETEC (62.2%, EIEC (0.84%, EPEC (0.84%, and EHEC non-O157:H7 (0.08%; there was no hybridization in 36.02% of E. coli strains. Other isolated microorganisms were Salmonella spp (0.45% and Shigella spp (0.06%. Conclusions. Enterotoxigenic E. coli was the most likely etiologic agent. Sanitary control strategies should be targeted to preventing outbreaks caused by this pathogenic agent.

Management of digital eye strain.

Science.gov (United States)

Coles-Brennan, Chantal; Sulley, Anna; Young, Graeme

2018-05-23

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5 Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer

Experience of social role strain in Korean women with type 2 diabetes.

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Park, Hyunjeong; Wenzel, Jennifer A

2013-06-01

To expand our understanding of the experience of social role strain in the context of diabetes care among middle-aged married Korean women with type 2 diabetes. Diabetes remains an international concern. There are special challenges experienced by middle-aged married women who may not prioritize self-care and disease management. These challenges may be heightened in certain cultures due to traditional female and family roles along with other social norms and values. Descriptive qualitative study. This qualitative descriptive study involves in-depth interviews conducted between January-February 2007 with ten middle-aged married Korean women purposively selected to represent both higher and lower levels of role strain as measured by the measure of role gratification and strain instrument from the companion study, which was conducted simultaneously. Korean women in this study reported 'resentment regarding previous role strain'. This psychosocial burden was heightened by a noted pattern of 'sacrificing self in favour of others', which complicated both their personal lives and their ability to take care of themselves physically. Added to this were feelings of guilt related to their diabetes and the requirements of day-to-day management expressed as, 'my diabetes makes me a liability'. The women's role-strain experience related to their diabetes was intertwined with their past and current daily life. Further explication and interventions to address and manage role strain could potentially improve women's disease management and overall quality of life. © 2012 Blackwell Publishing Ltd.

Pilot study of whole-blood gamma interferon response to the Vibrio cholerae toxin B subunit and resistance to enterotoxigenic Escherichia coli-associated diarrhea.

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Flores, Jose; DuPont, Herbert L; Paredes-Paredes, Mercedes; Aguirre-Garcia, M Magdalena; Rojas, Araceli; Gonzalez, Alexei; Okhuysen, Pablo C

2010-05-01

Enterotoxigenic Escherichia coli (ETEC), which produces heat-labile toxin (LT), is a common cause of travelers' diarrhea (TD). The B subunit of ETEC LT is immunologically related to the B subunit of Vibrio cholerae toxin (CT). In this pilot study we evaluated the whole-blood gamma interferon response to CT B in 17 U.S. adults traveling to Mexico. Only one of nine subjects who demonstrated a cellular immune response as determined by whole-blood gamma interferon production to CT B on arrival to Mexico developed diarrhea, whereas five of eight without a cellular response developed diarrhea. Markers of the cellular immune response to ETEC LT could help in identifying individuals immune to ETEC LT, and these markers deserve additional study.

[Active etiological surveillance for foodborne diseases in Guangdong province, 2013-2014].

Science.gov (United States)

Ke, B X; He, D M; Tan, H L; Zeng, H H; Yang, T; Li, B S; Liang, Y H; Lu, L L; Liang, J H; Huang, Q; Ke, C W

2016-10-10

Objective: To study the infection status, serotypes, drug resistance and molecular characteristics of Salmonella, Shigella, Vibrio parahemolyticus , enterotoxigenic Escherichia ( E. ) coli (ETEC), pathogenic E. coli (EPEC), Shiga Toxin producing E. coli (STEC) and Enteroinvasive E. coli (EIEC) collected from diarrhea patients in Guangdong. Methods: The strains of Salmonella, Shigella, V. parahemolyticus and 4 kinds of E. coli isolated from foodborne diseases surveillance during 2013-2014 were collected to conduct serotyping, drug resistance test and pulsed-field gel electrophoresis (PFGE). Results: A total of 3 372 stains of pathogens were isolated from 57 834 stool samples during 2013-2014, the overall positive rate was 5.83 % and the positive rate of Salmonella was highest, followed by that of V. parahemolyticus , 4 kinds of E. coli and Shigella . And 3 213 strains of Salmonella were divided into 143 serotypes. The most prevalent serotypes were Salmonella typhimurium , 4, 5, 12: i:-, Enteritidis , Stanley and Derby . Salmonella was sensitive to cephalosporin and fluoroquinolones, and showed significant differences in drug resistance rate among different serotypes. In top 10 common serotypes, S. enteritidis and S. derby were most resistant to cephalosporin and ciprofloxacin respectively. PFGE was performed for 2 289 strains of Salmonella , showing distribution diversity and significant fingerprint polymorphisms. The 85 strains of V. parahemolyticus were divided into 10 serotypes, O3∶K6 (61.18 % ) was the most common serotype, followed by O4∶K8. The results showed that the carrying rate of virulence genes tdh (81.18 % ) was high, while the carrying rate of trh was low (7.06 % ), and there were 10 strains carrying no the two kinds of virulence genes. The sensitive rate of V. parahemolyticus to imipenem, nalidixic acid, SMZ-TMP, chloramphenicol and tetracycline were more than 95 % . Thirteen strains of Shigella were detected, including 9 strains of Shigella

Anaplasma marginale major surface protein 1a: a marker of strain diversity with implications for control of bovine anaplasmosis.

Science.gov (United States)

Cabezas-Cruz, Alejandro; de la Fuente, José

2015-04-01

Classification of bacteria is challenging due to the lack of a theory-based framework. In addition, the adaptation of bacteria to ecological niches often results in selection of strains with diverse virulence, pathogenicity and transmission characteristics. Bacterial strain diversity presents challenges for taxonomic classification, which in turn impacts the ability to develop accurate diagnostics and effective vaccines. Over the past decade, the worldwide diversity of Anaplasma marginale, an economically important tick-borne pathogen of cattle, has become apparent. The extent of A. marginale strain diversity, formerly underappreciated, has contributed to the challenges of classification which, in turn, likely impacts the design and development of improved vaccines. Notably, the A. marginale surface protein 1a (MSP1a) is a model molecule for these studies because it serves as a marker for strain identity, is both an adhesin necessary for infection of cells and an immuno-reactive protein and is also an indicator of the evolution of strain diversity. Herein, we discuss a molecular taxonomic approach for classification of A. marginale strain diversity. Taxonomic analysis of this important molecule provides the opportunity to understand A. marginale strain diversity as it relates geographic and ecological factors and to the development of effective vaccines for control of bovine anaplasmosis worldwide. Copyright © 2015 Elsevier GmbH. All rights reserved.

Risk factors for fecal colonization with multiple distinct strains of Escherichia coli among long-term care facility residents.

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Lautenbach, Ebbing; Tolomeo, Pam; Black, Nicole; Maslow, Joel N

2009-05-01

Of 49 long-term care facility residents, 21 (43%) were colonized with 2 or more distinct strains of Escherichia coli. There were no significant risk factors for colonization with multiple strains of E. coli. These results suggest that future efforts to efficiently identify the diversity of colonizing strains will be challenging.

Vaccine efficacy in senescent mice challenged with recombinant SARS-CoV bearing epidemic and zoonotic spike variants.

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Damon Deming

2006-12-01

Full Text Available In 2003, severe acute respiratory syndrome coronavirus (SARS-CoV was identified as the etiological agent of severe acute respiratory syndrome, a disease characterized by severe pneumonia that sometimes results in death. SARS-CoV is a zoonotic virus that crossed the species barrier, most likely originating from bats or from other species including civets, raccoon dogs, domestic cats, swine, and rodents. A SARS-CoV vaccine should confer long-term protection, especially in vulnerable senescent populations, against both the 2003 epidemic strains and zoonotic strains that may yet emerge from animal reservoirs. We report the comprehensive investigation of SARS vaccine efficacy in young and senescent mice following homologous and heterologous challenge.Using Venezuelan equine encephalitis virus replicon particles (VRP expressing the 2003 epidemic Urbani SARS-CoV strain spike (S glycoprotein (VRP-S or the nucleocapsid (N protein from the same strain (VRP-N, we demonstrate that VRP-S, but not VRP-N vaccines provide complete short- and long-term protection against homologous strain challenge in young and senescent mice. To test VRP vaccine efficacy against a heterologous SARS-CoV, we used phylogenetic analyses, synthetic biology, and reverse genetics to construct a chimeric virus (icGDO3-S encoding a synthetic S glycoprotein gene of the most genetically divergent human strain, GDO3, which clusters among the zoonotic SARS-CoV. icGD03-S replicated efficiently in human airway epithelial cells and in the lungs of young and senescent mice, and was highly resistant to neutralization with antisera directed against the Urbani strain. Although VRP-S vaccines provided complete short-term protection against heterologous icGD03-S challenge in young mice, only limited protection was seen in vaccinated senescent animals. VRP-N vaccines not only failed to protect from homologous or heterologous challenge, but resulted in enhanced immunopathology with eosinophilic

Rehabilitation and return to sport after hamstring strain injury

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Lauren N. Erickson

2017-09-01

Full Text Available Hamstring strain injuries are common among sports that involve sprinting, kicking, and high-speed skilled movements or extensive muscle lengthening-type maneuvers with hip flexion and knee extension. These injuries present the challenge of significant recovery time and a lengthy period of increased susceptibility for recurrent injury. Nearly one third of hamstring strains recur within the first year following return to sport with subsequent injuries often being more severe than the original. This high re-injury rate suggests that athletes may be returning to sport prematurely due to inadequate return to sport criteria. In this review article, we describe the epidemiology, risk factors, differential diagnosis, and prognosis of an acute hamstring strain. Based on the current available evidence, we then propose a clinical guide for the rehabilitation of acute hamstring strains and an algorithm to assist clinicians in the decision-making process when assessing readiness of an athlete to return to sport.

The Ambivalence of Challenge Stressors: Time Pressure Associated with Both Negative and Positive Well-Being

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Widmer, Pascale S.; Semmer, Norbert K.; Kalin, Wolfgang; Jacobshagen, Nicola; Meier, Laurenz L.

2012-01-01

According to the challenge-hindrance model, challenge stressors contain both stressful and challenging aspects, hindrance stressors only stressful aspects. Typically, negative outcomes of challenge stressors refer to well-being (strain), positive outcomes to so-called work outcomes (e.g., productivity, intention to quit). As both effects occur…

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

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Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

2017-04-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

International Nuclear Information System (INIS)

Aksoy, B; Alaca, B E; Rehman, A; Bayraktar, H

2017-01-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µ m are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

The role of the phoPQ operon in the pathogenesis of the fully virulent CO92 strain of Yersinia pestis and the IP32953 strain of Yersinia pseudotuberculosis.

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Bozue, Joel; Mou, Sherry; Moody, Krishna L; Cote, Christopher K; Trevino, Sylvia; Fritz, David; Worsham, Patricia

2011-06-01

At the genomic level, Yersinia pestis and Yersinia pseudotuberculosis are nearly identical but cause very different diseases. Y. pestis is the etiologic agent of plague; whereas Y. pseudotuberculosis causes a gastrointestinal infection primarily after the consumption of contaminated food. In many gram-negative pathogenic bacteria, PhoP is part of a two-component global regulatory system in which PhoQ serves as the sensor kinase, and PhoP is the response regulator. PhoP is known to activate a number of genes in many bacteria related to virulence. To determine the role of the PhoPQ proteins in Yersinia infections, primarily using aerosol challenge models, the phoP gene was deleted from the chromosome of the CO92 strain of Y. pestis and the IP32953 strain of Y. pseudotuberculosis, leading to a polar mutation of the phoPQ operon. We demonstrated that loss of phoPQ from both strains leads to a defect in intracellular growth and/or survival within macrophages. These in vitro data would suggest that the phoPQ mutants would be attenuated in vivo. However, the LD(50) for the Y. pestis mutant did not differ from the calculated LD(50) for the wild-type CO92 strain for either the bubonic or pneumonic murine models of infection. In contrast, mice challenged by aerosol with the Y. pseudotuberculosis mutant had a LD(50) value 40× higher than the wild-type strain. These results demonstrate that phoPQ are necessary for full virulence by aerosol infection with the IP32953 strain of Y. pseudotuberculosis. However, the PhoPQ proteins do not play a significant role in infection with a fully virulent strain of Y. pestis. Published by Elsevier India Pvt Ltd.

Changes in diffusion properties of biological tissues associated with mechanical strain

International Nuclear Information System (INIS)

Tanaka, Kenichiro; Imae, T.; Mima, Kazuo; Sekino, Masaki; Ohsaki, Hiroyuki; Ueno, Shogo

2007-01-01

Mechanical strain in biological tissues causes a change in the diffusion properties of water molecules. This paper proposes a method of estimating mechanical strain in biological tissues using diffusion magnetic resonance imaging (MRI). Measurements were carried out on uncompressed and compressed chicken skeletal muscles. A theoretical model of the diffusion of water molecules in muscle fibers was derived based on Tanner's equation. Diameter of the muscle fibers was estimated by fitting the model equation to the measured signals. Changes in the mean diffusivity (MD), the fractional anisotropy (FA), and diameter of the muscle fiber did not have any statistical significance. The intracellular diffusion coefficient (D int ) was changed by mechanical strain (p<.05). This method has potential applications in the quantitative evaluation of strain in biological tissues, a though it poses several technical challenges. (author)

Performance of rats orogastrically dosed with faecal strains of ...

African Journals Online (AJOL)

Albino rats (Rattus norvegicus) were orogastrically dosed with faecal strains of Lactobacillus acidophilus and simultaneously infected with Escherichia coli, while the control was challenged with E. coli alone. The treatment was repeated the second day and post ingestion period of 18 days follow. It was observed that rats ...

Evaluation of preservative efficacy in pharmaceutical products: the use of psychrotolerant, low-nutrient preferring microbes in challenge tests.

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Charnock, C; Otterholt, E

2012-10-01

Preservative efficacy in medicines is typically investigated using challenge tests. In such tests, the product is artificially contaminated with a high concentration of standard bacterial and fungal test strains such as Pseudomonas aeruginosa and Candida albicans. The rate and extent of reductions in inoculum viability over a specified period forms the basis for acceptance/rejection of preservative efficacy. None of the strains named for inclusion in the challenge test outlined in the European Pharmacopoeia are associated with the contamination of high-quality water used in pharmaceutical production. Alpha- and Betaproteobacteria are easily the most common microbes in waters intended for pharmaceutical production. In addition, none of the standard test strain panel prefer low-nutrient, dilute conditions or grow at or around refrigeration temperatures. This is important because the water activity and nutrient content of medicines can vary greatly and medicines are often stored cold. We investigate the relevance of these factors when testing preservative efficacy by including other strains in challenge tests. Psychrotolerant, low-nutrient preferring strains (Beta- and Alphaproteobacteria and a yeast) were isolated from pristine waters. These were compared in challenge tests with C. albicans and P. aeruginosa using different storage temperatures. Pharmaceutical products differing widely in water-content, pH and preservative systems were included in the study. Regardless of the type of medicine tested C. albicans always showed superior survival characteristics to the yeast isolate (Cryptococcus terricola). One of the three screened bacterial strains (a Sphingomonas sp.) survived significantly better than P. aeruginosa in all but one product tested. However, the results for all products taken together cannot easily be explained by reference to this strain's psychrotolerancy or its preference for dilute, low-nutrient environments. This study supports previous work

An inactivated gE-deleted pseudorabies vaccine provides complete clinical protection and reduces virus shedding against challenge by a Chinese pseudorabies variant.

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Wang, Jichun; Guo, Rongli; Qiao, Yongfeng; Xu, Mengwei; Wang, Zhisheng; Liu, Yamei; Gu, Yiqi; Liu, Chang; Hou, Jibo

2016-12-07

Since the end of 2011 an outbreak of pseudorabies affected Chinese pig herds that had been vaccinated with the commercial vaccine made of Bartha K61 strain. It is now clear that the outbreak was caused by an emergent PRV variant. Even though vaccines made of PRV Bartha K61 strain can confer certain cross protection against PRV variants based on experimental data, less than optimal clinical protection and virus shedding reduction were observed, making the control or eradication of this disease difficult. An infectious clone of PRV AH02LA strain was constructed to generate a gE deletion mutant PRV(LA-A B ) strain. PRV(LA-A B ) strain can reach a titer of 10 8.43 TCID 50 /mL (50% tissue culture infectious dose) on BHK-21 cells. To evaluate the efficiency of the inactivated vaccine made of PRV(LA-A B ) strain, thirty 3-week-old PRV-negative piglets were divided randomly into six groups for vaccination and challenge test. All five piglets in the challenge control showed typical clinical symptoms of pseudorabies post challenge. Sneezing and nasal discharge were observed in four and three piglets in groups C(vaccinated with inactivated PRV Bartha K61 strain vaccine) and D(vaccinated with live PRV Bartha K61 strain vaccine) respectively. In contrast, piglets in both groups A(vaccinated with inactivated PRV LA-AB strain vaccine) and B(vaccinated with inactivated PRV LA-A B strain vaccine with adjuvant) presented mild or no clinical symptoms. Moreover, viral titers detected via nasal swabs were approximately 100 times lower in group B than in the challenge control, and the duration of virus shedding (3-4 days) was shorter than in either the challenge control (5-10 days) or groups C and D (5-6 days). The infectious clone constructed in this study harbors the whole genome of the PRV variant AH02LA strain. The gE deletion mutant PRV(LA-A B )strain generated from PRV AH02LA strain can reach a high titer on BHK-21 cells. An inactivated vaccine of PRV LA-A B provides clinical

Protective effect of oral administration of transgenic tobacco seeds against verocytotoxic Escherichia coli strain in piglets.

Science.gov (United States)

Rossi, Luciana; Dell'Orto, Vittorio; Vagni, Simona; Sala, Vittorio; Reggi, Serena; Baldi, Antonella

2014-03-01

The use of transgenic plants as delivery system for antigenic proteins is attractive for its simplicity and increases likelihood for local immune response at sites of infection. The aim of this study was to evaluate the protective effect of oral administration of tobacco seeds, expressing the FedA, the major protein of the F18 adhesive fimbriae, and B subunit of verocytotoxin, against verocytotoxin-producing E. coli (VTEC) strain in piglets. Forty-three early weaned piglets, were randomly divided into 4 experimental groups: 3 test groups and a control. Treatment groups orally received a bolus, with different dose of tobacco seeds on 0, 1, 2, 14 days post primary administration. After challenge, with 1*10(10) CFU of O138 Escherichia coli strain, piglets showed clinical scores significantly higher in the control group compared to orally immunized groups (P administration of recombinant tobacco seeds expressing antigenic proteins against VTEC strains can induce a protective effect against challenger strain in piglets.

Differences in susceptibility among mouse strains to infection with Plasmodium berghei (ANKA clone) sporozoites and its relationship to protection by gamma-irradiated sporozoites

International Nuclear Information System (INIS)

Jaffe, R.I.; Lowell, G.H.; Gordon, D.M.

1990-01-01

Three inbred mouse strains, C57BL/6 (H-2b), A/J (H-2a), and BALB/c (H-2d), and 1 outbred strain, CD-1, demonstrated differences in susceptibility to iv challenge with the ANKA clone of Plasmodium berghei. Mice were challenged with 100, 1,000, or 10,000 sporozoites, then evaluated daily beginning on day 4 for patency. CD-1 mice were further evaluated at challenge doses of 12,500, 25,000, and 50,000 sporozoites. C57BL/6 mice were the easiest to infect, with 90% becoming infected with 100 sporozoites. The outbred strain CD-1 was the most difficult to infect, requiring a challenge dose of 25,000 sporozoites/mouse in order to achieve a 100% infection rate. Mouse strains also demonstrated differences in their ability to be protected by intravenous immunization with gamma-irradiated sporozoites. A/J mice needed a minimum of 3 doses of irradiated sporozoites for protection against a challenge with 10,000 sporozoites. In contrast, BALB/c mice immunized with a single dose of 1,000 irradiated sporozoites are protected against a 10,000 sporozoite challenge. These data suggest that both infectivity and protection are genetically restricted and that susceptibility to infection may be inversely related to protection

Recombinant Gallid herpesvirus 2 with interrupted meq genes confers safe and efficacious protection against virulent field strains.

Science.gov (United States)

Zhang, Yanping; Liu, Changjun; Yan, Fuhai; Liu, Ailing; Cheng, Yun; Li, Zhijie; Sun, Guorong; Lv, Hongchao; Wang, Xiaomei

2017-08-24

Gallid herpesvirus 2 (GaHV-2) continuously evolves, which reduces the effectiveness of existing vaccines. To construct new GaHV-2 candidate vaccines, LMS, which is a virulent GaHV-2 field strain isolated from diseased chicken flocks in Southwest China in 2007, was modified such that both copies of its meq oncogene were partially deleted. The resulting virus, i.e., rMSΔmeq, was characterized using PCR and sequencing. To evaluate the safety and protective efficacy of rMSΔmeq, specific pathogen-free (SPF) chickens were inoculated with 2000 plaque forming units (pfu) and 20,000pfu of rMSΔmeq immediately after hatching. All birds grew well during the experimental period, and none of the challenged chickens developed Marek's disease-associated lymphoma. In addition, the rMSΔmeq- and CVI988/Rispens-vaccinated SPF chickens were challenged with 1000 pfu and 5000 pfu of the representative virulent GaHV-2 Md5 strain and 1000 pfu of the variant GaHV-2 strains LCC or LTS. The results showed that the rMSΔmeq strain provided complete protection, which was similar to that provided by the CVI988/Rispens vaccine (protective index (PI) of 95.5) when challenged with a conventional dose of the Md5 strain. However, rMSΔmeq provided a PI of 90.9 when challenged with 5000 pfu of the Md5 strain, which was significantly higher than that provided by the CVI988/Rispens vaccine (54.5). rMSΔmeq provided a PI of 86.4 against LCC, which was equal to that provided by the CVI988/Rispens vaccine (81.8). In addition, rMSΔmeq provided a PI of 100 against LTS, which was significantly higher than that provided by the CVI988/Rispens vaccine (68.2). Altogether, the rMSΔmeq virus provided efficient protection against representative and variant GaHV-2 strains. In conclusion, the rMSΔmeq virus is a safe and effective vaccine candidate for the prevention of Marek's disease and is effective against the Chinese variant GaHV-2 strains. Copyright © 2017. Published by Elsevier Ltd.

Flexible and Transparent Strain Sensors with Embedded Multiwalled Carbon Nanotubes Meshes.

Science.gov (United States)

Nie, Bangbang; Li, Xiangming; Shao, Jinyou; Li, Xin; Tian, Hongmiao; Wang, Duorui; Zhang, Qiang; Lu, Bingheng

2017-11-22

Strain sensors combining high sensitivity with good transparency and flexibility would be of great usefulness in smart wearable/flexible electronics. However, the fabrication of such strain sensors is still challenging. In this study, new strain sensors with embedded multiwalled carbon nanotubes (MWCNTs) meshes in polydimethylsiloxane (PDMS) films were designed and tested. The strain sensors showed elevated optical transparency of up to 87% and high sensitivity with a gauge factor of 1140 at a small strain of 8.75%. The gauge factors of the sensors were also found relatively stable since they did not obviously change after 2000 stretching/releasing cycles. The sensors were tested to detect motion in the human body, such as wrist bending, eye blinking, mouth phonation, and pulse, and the results were shown to be satisfactory. Furthermore, the fabrication of the strain sensor consisting of mechanically blading MWCNTs aqueous dispersions into microtrenches of prestructured PDMS films was straightforward, was low cost, and resulted in high yield. All these features testify to the great potential of these sensors in future real applications.

ANIMAL ENTEROTOXIGENIC ESCHERICHIA COLI

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Dubreuil, J. Daniel; Isaacson, Richard E.; Schifferli, Dieter M.

2016-01-01

Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors; adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17 and F18 fimbriae. Once established in the animal small intestine, ETEC produces enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes; heat-labile toxin that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This chapter describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics and the identification of potential new targets identified by genomics are presented in the context of animal ETEC. PMID:27735786

A patented strain of Bacillus coagulans increased immune response to viral challenge.

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Baron, Mira

2009-03-01

Viral respiratory tract infection is the most common illness among humans. Probiotics have been known to enhance the immune system and, therefore, may represent a significant therapeutic advancement for treating viral respiratory tract infections. A controlled study was conducted to evaluate the effects of the patented GanedenBC30 probiotic (Bacillus coagulans GBI-30, 6086, marketed as Sustenex [Ganeden Biotech, Inc., Mayfield Heights, OH]) on the immune system when exposed to adenovirus and influenza in otherwise healthy adults. Ten healthy men and women (average age, 44 years) were instructed to consume 1 capsule of GanedenBC30 with water once a day for 30 days. At baseline and after completion of the 30-day treatment, blood levels of cytokines were measured in vitro after T-cell exposure to adenovirus and influenza A. Each participant served as his/her own control with baseline blood draw. The use of GanedenBC30 significantly increased T-cell production of TNF-alpha in response to adenovirus exposure (P = 0.027) and influenza A (H3N2 Texas strain) exposure (P = 0.004), but it did not have a significant effect on the response to other strains of influenza. No serious adverse events were reported throughout the study. The patented GanedenBC30 probiotic may be a safe and effective therapeutic option for enhancing T-cell response to certain viral respiratory tract infections.

Identification and Characterization of T5-Like Bacteriophages Representing Two Novel Subgroups from Food Products

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Domonkos Sváb

2018-02-01

Full Text Available During recent years, interest in the use of bacteriophages as biocontrol agents against foodborne pathogens has increased, particularly for members of the family Enterobacteriaceae, with pathogenic Escherichia coli, Shigella, and Salmonella strains among them. Here, we report the isolation and characterisation of 12 novel T5-like bacteriophages from confiscated food samples. All bacterophages effectively lysed E. coli K-12 strains and were able to infect pathogenic E. coli strains representing enterohaemorrhagic (EHEC, enteropathogenic (EPEC, enterotoxigenic (ETEC, and enteroinvasive (EIEC pathotypes, Shigella dysenteriae, S. sonnei strains, as well as multidrug-resistant (MDR E. coli and multiple strains representing different Salmonella enterica serovars. All the bacteriophages exhibited Siphoviridae morphology. Whole genome sequencing of the novel T5-like bacteriophages showed that they represent two distinct groups, with the genome-based grouping correlating to the different host spectra. As these bacteriophages are of food origin, their stability and lack of any virulence genes, as well as their broad and mutually complementary host spectrum makes these new T5-like bacteriophages valuable candidates for use as biocontrol agents against foodborne pathogenic enterobacteria.

Bifidobacterium breve MCC-117 Induces Tolerance in Porcine Intestinal Epithelial Cells: Study of the Mechanisms Involved in the Immunoregulatory Effect

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MURATA, Kozue; TOMOSADA, Yohsuke; VILLENA, Julio; CHIBA, Eriko; SHIMAZU, Tomoyuki; ASO, Hisashi; IWABUCHI, Noriyuki; XIAO, Jin-zhong; SAITO, Tadao; KITAZAWA, Haruki

2014-01-01

Bifidobacterium breve MCC-117 is able to significantly reduce the expression of inflammatory cytokines in porcine intestinal epithelial (PIE) cells and to improve IL-10 levels in CD4+CD25high Foxp3+ lymphocytes in response to heat-stable enterotoxigenic Escherichia coli (ETEC) pathogen-associated molecular patterns (PAMPs), while the immunoregulatory effect of B. adolescentis ATCC15705 was significantly lower than that observed for the MCC-117 strain. Considering the different capacities of the two bifidobacterium strains to activate toll-like receptor (TLR)-2 and their differential immunoregulatory activities in PIE and immune cells, we hypothesized that comparative studies with both strains could provide important information regarding the molecular mechanism(s) involved in the anti-inflammatory activity of bifidobacteria. In this work, we demonstrated that the anti-inflammatory effect of B. breve MCC-117 was achieved by a complex interaction of multiple negative regulators of TLRs as well as inhibition of multiple signaling pathways. We showed that B. breve MCC-117 reduced heat-stable ETEC PAMP-induced NF-κB, p38 MAPK and PI3 K activation and expression of pro-inflammatory cytokines in PIE cells. In addition, we demonstrated that B. breve MCC-117 may activate TLR2 synergistically and cooperatively with one or more other pattern recognition receptors (PRRs), and that interactions may result in a coordinated sum of signals that induce the upregulation of A20, Bcl-3, Tollip and SIGIRR. Upregulation of these negative regulators could have an important physiological impact on maintaining or reestablishing homeostatic TLR signals in PIE cells. Therefore, in the present study, we gained insight into the molecular mechanisms involved in the immunoregulatory effect of B. breve MCC-117. PMID:24936377

Intestinal Pathogenic Escherichia coli: Insights for Vaccine Development

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Maricarmen Rojas-Lopez

2018-03-01

Full Text Available Diarrheal diseases are one of the major causes of mortality among children under five years old and intestinal pathogenic Escherichia coli (InPEC plays a role as one of the large causative groups of these infections worldwide. InPECs contribute significantly to the burden of intestinal diseases, which are a critical issue in low- and middle-income countries (Asia, Africa and Latin America. Intestinal pathotypes such as enteropathogenic E. coli (EPEC and enterotoxigenic E. coli (ETEC are mainly endemic in developing countries, while ETEC strains are the major cause of diarrhea in travelers to these countries. On the other hand, enterohemorrhagic E. coli (EHEC are the cause of large outbreaks around the world, mainly affecting developed countries and responsible for not only diarrheal disease but also severe clinical complications like hemorrhagic colitis and hemolytic uremic syndrome (HUS. Overall, the emergence of antibiotic resistant strains, the annual cost increase in the health care system, the high incidence of traveler diarrhea and the increased number of HUS episodes have raised the need for effective preventive treatments. Although the use of antibiotics is still important in treating such infections, non-antibiotic strategies are either a crucial option to limit the increase in antibiotic resistant strains or absolutely necessary for diseases such as those caused by EHEC infections, for which antibiotic therapies are not recommended. Among non-antibiotic therapies, vaccine development is a strategy of choice but, to date, there is no effective licensed vaccine against InPEC infections. For several years, there has been a sustained effort to identify efficacious vaccine candidates able to reduce the burden of diarrheal disease. The aim of this review is to summarize recent milestones and insights in vaccine development against InPECs.

Microbial compositional changes in broiler chicken cecal contents from birds challenged with different Salmonella vaccine candidate strains.

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Park, Si Hong; Kim, Sun Ae; Rubinelli, Peter M; Roto, Stephanie M; Ricke, Steven C

2017-05-31

Previously, we constructed and characterized the vaccine efficacy of Salmonella Typhimurium mutant strains in poultry with either inducible mviN expression (P BAD -mviN) or methionine auxotrophy (ΔΔmetRmetD). The aim of the present study was to assess potential impact of these Salmonella vaccine strains on the cecal microbiota using a next generation sequencing (NGS). The cecal microbial community obtained from unvaccinated (group 1) and vaccinated chickens (group 2, vaccinated with P BAD -mviN; group 3, vaccinated with wild type; group 4, vaccinated with ΔΔmetRmetD) were subjected to microbiome sequencing analysis with an Illumina MiSeq platform. The NGS microbiome analysis of chicken ceca revealed considerable changes in microbial composition in the presence of the different vaccine strains and exhibited detectable patterns of distinctive clustering among the respective groups (the R value of unweighted PCoA plot was 0.68). The present study indicates that different S. Typhimurium vaccine strains can differentially influence the microbiota of the ceca in terms of presence but not in the relative abundance of microbiota. Copyright © 2017 Elsevier Ltd. All rights reserved.

Vaccination of adult and newborn mice of a resistant strain (C57BL/6J) against challenge with leukemias induced by Moloney murine leukemia virus

International Nuclear Information System (INIS)

Reif, A.E.

1985-01-01

Adult or newborn C57BL/6J mice were immunized with isogenic Moloney strain MuLV-induced leukemia cells irradiated with 10,000 rads or treated with low concentrations of formalin. Groups of immunized and control mice were challenged with a range of doses of viable leukemia cells, and tumor deaths were recorded for 90 days after challenge. Then, the doses of challenge cells which produced 50% tumor deaths were calculated for immunized and control mice. The logarithm of their ratio quantified the degree of protection provided by immunization. For adult C57BL/6J mice, a single immunization with MuLV-induced leukemia cells was not effective; either cells plus Bacillus Calmette-Guerin or Corynebacterium parvum, or else two immunizations with irradiated leukemia cells were needed to produce statistically significant increases in the values of the doses of challenge cells which produced 50% tumor deaths. Cross-protection was obtained by immunization with other isogenic MuLV-induced leukemias, but not by immunization with isogenic carcinogen-induced tumors or with an isogenic spontaneous leukemia. For newborn mice, a single injection of irradiated leukemia cells provided 1.3 to 1.5 logs of protection, and admixture of B. Calmette-Guerin or C. parvum increased this protection to 2.4 to 2.7 logs. Since irradiated and frozen-thawed MuLV-induced leukemia cells contained viable MuLV, leukemia cells treated with 0.5 or 1.0% formalin were tested as an alternative. A single injection of formalin-treated isogenic leukemia cells admixed with C. parvum provided between 1.7 and 2.8 logs of protection. These results demonstrate that a single vaccination of newborn animals against a highly antigenic virally induced leukemia produces strong protection against a subsequent challenge with viable leukemia cells

Strain-tuned optoelectronic properties of hollow gallium sulphide microspheres

Science.gov (United States)

Zhang, Yin; Chen, Chen; Liang, C. Y.; Liu, Z. W.; Li, Y. S.; Che, Renchao

2015-10-01

Sulfide semiconductors have attracted considerable attention. The main challenge is to prepare materials with a designable morphology, a controllable band structure and optoelectronic properties. Herein, we report a facile chemical transportation reaction for the synthesis of Ga2S3 microspheres with novel hollow morphologies and partially filled volumes. Even without any extrinsic dopant, photoluminescence (PL) emission wavelength could be facilely tuned from 635 to 665 nm, depending on its intrinsic inhomogeneous strain distribution. Geometric phase analysis (GPA) based on high-resolution transmission electron microscopy (HRTEM) imaging reveals that the strain distribution and the associated PL properties can be accurately controlled by changing the growth temperature gradient, which depends on the distance between the boats used for raw material evaporation and microsphere deposition. The stacking-fault density, lattice distortion degree and strain distribution at the shell interfacial region of the Ga2S3 microspheres could be readily adjusted. Ab initio first-principles calculations confirm that the lowest conductive band (LCB) is dominated by S-3s and Ga-4p states, which shift to the low-energy band as a result of the introduction of tensile strain, well in accordance with the observed PL evolution. Therefore, based on our strain driving strategy, novel guidelines toward the reasonable design of sulfide semiconductors with tunable photoluminescence properties are proposed.Sulfide semiconductors have attracted considerable attention. The main challenge is to prepare materials with a designable morphology, a controllable band structure and optoelectronic properties. Herein, we report a facile chemical transportation reaction for the synthesis of Ga2S3 microspheres with novel hollow morphologies and partially filled volumes. Even without any extrinsic dopant, photoluminescence (PL) emission wavelength could be facilely tuned from 635 to 665 nm, depending on its

A strain-mediated corrosion model for bioabsorbable metallic stents.

Science.gov (United States)

Galvin, E; O'Brien, D; Cummins, C; Mac Donald, B J; Lally, C

2017-06-01

This paper presents a strain-mediated phenomenological corrosion model, based on the discrete finite element modelling method which was developed for use with the ANSYS Implicit finite element code. The corrosion model was calibrated from experimental data and used to simulate the corrosion performance of a WE43 magnesium alloy stent. The model was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile. The non-linear plastic strain model, extrapolated from the experimental data, was also found to adequately capture the corrosion-induced reduction in the radial stiffness of the stent over time. The model developed will help direct future design efforts towards the minimisation of plastic strain during device manufacture, deployment and in-service, in order to reduce corrosion rates and prolong the mechanical integrity of magnesium devices. The need for corrosion models that explore the interaction of strain with corrosion damage has been recognised as one of the current challenges in degradable material modelling (Gastaldi et al., 2011). A finite element based plastic strain-mediated phenomenological corrosion model was developed in this work and was calibrated based on the results of the corrosion experiments. It was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile and the corrosion-induced reduction in the radial stiffness of the stent over time. To the author's knowledge, the results presented here represent the first experimental calibration of a plastic strain-mediated corrosion model of a corroding magnesium stent. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

ACUTE ENTERIC INFECTIONS POLYMERASE CHAIN REACTION ASSAY IN PEDIATRIC PRACTICE: OPPORTUNITIES AND CHALLENGES

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E. D. Sokolova

2016-01-01

Full Text Available The aim of the study is estimate the opportunities of local multi-prime PCR reagents kits in children enteric infections etiological diagnostics amongst the patients with diarrhoea vs traditional bacteriological methods. We used 4 kits of reagents that provide multiple pathogens simultaneous indication in one sample: 1 Rotavirus, Norovirus, Astrovirus; 2 Shigella spp./EIEC, Salmonella spp., Campylobacter spp.; 3 Yersinia enterocolitica and Yersinia pseudotuberculosis; 4 E. coli: EIEC (enteroinvasive, EPEC (enteropathogenic, ETEC (enterotoxigenic, EHEC (enterohaemorrhagic, EAgEC (enteroaggregative. It has been shown that the viral intestinal infections is increased by 14%, bacterial — in 2,5 times. PCR diagnostics identified in 62% of patients the viral gastroenteritis: Rotavirus (52%, Norovirus (9%, Astrovirus (1%. Detected bacterial pathogens PCR markers number proved up to 2.5 times high than according to bacteriological examination. The spectrum of bacterial agents increased due to E. coli and Y. enterocolitica. PCR diagnostics increased detection of Campylobacter up to 2 times. Detected E. coli DNA prevalence: EPEC — 66%, EAgEC, ETEC and EHEC were 31%, 9% and 4%, respectively. DNA Campylobacter spp. and E. coli constituted 2/3 of all findings: Campylobacter spp. (41%, E. coli (24%, Salmonella spp. (19%, Yersinia spp. (11%, Shigella spp./EIEC (5%. The positive results of bacteriological and serological methods duplicate the positive results of PCR diagnostics. In general, the positive results of PCR diagnosis of bacterial pathogens were detected in 46.35% of the examined patients. In 48.4% of patients identified PCR markers viral — bacterial infection, in 5.25% — of bacterial associations, in 11% of them were found the DNA 2–3 bacterial pathogens. The study was shown in children in St. Petersburg in 2012–2014 dominated rotavirus infection, campylobacteriosis and escherichiosis. The prevalence of viral-bacterial confections is more

Cell Factory Stability and Genetic Circuits for Improved Strain Development

DEFF Research Database (Denmark)

Rugbjerg, Peter

. However, all synthetic gene systems -­ including the target metabolic pathways themselves -­ represent a possible fitness burden to the cell and thus constitute a threat to strain stability. In this thesis, several studies served to develop genetic systems for optimizing cell factory development...... systems can challenge the stability of strain designs. A metabolite-­producing Escherichia coli strain was long-­term cultured to study production stability and the dynamic effects of mutations within the cell population. A genetic error landscape of pathway disruptions was identified including particular......Development of new chemical-­‐producing microbial cell factories is an iterative trial-­and-­error process, and to screen candidate cells at high throughput, genetic biosensor systems are appealing. Each biosensor has distinct biological parameters, making modular tuning networks attractive...

Strain-Dependent Edge Structures in MoS2 Layers.

Science.gov (United States)

Tinoco, Miguel; Maduro, Luigi; Masaki, Mukai; Okunishi, Eiji; Conesa-Boj, Sonia

2017-11-08

Edge structures are low-dimensional defects unavoidable in layered materials of the transition metal dichalcogenides (TMD) family. Among the various types of such structures, the armchair (AC) and zigzag (ZZ) edge types are the most common. It has been predicted that the presence of intrinsic strain localized along these edges structures can have direct implications for the customization of their electronic properties. However, pinning down the relation between local structure and electronic properties at these edges is challenging. Here, we quantify the local strain field that arises at the edges of MoS 2 flakes by combining aberration-corrected transmission electron microscopy (TEM) with the geometrical-phase analysis (GPA) method. We also provide further insight on the possible effects of such edge strain on the resulting electronic behavior by means of electron energy loss spectroscopy (EELS) measurements. Our results reveal that the two-dominant edge structures, ZZ and AC, induce the formation of different amounts of localized strain fields. We also show that by varying the free edge curvature from concave to convex, compressive strain turns into tensile strain. These results pave the way toward the customization of edge structures in MoS 2 , which can be used to engineer the properties of layered materials and thus contribute to the optimization of the next generation of atomic-scale electronic devices built upon them.

Study on the efficacy and safety of different antigens and oil formulations of infectious coryza vaccines containing an NAD-independent strain of Avibacterium paragallinarum

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B. Dungu

2009-09-01

Full Text Available The present study was designed to assess and compare three different formulations of the new Onderstepoort infectious coryza (IC quadrivalent vaccine, which contain an NAD-independent strain of Avibacterium paragallinarum (previously known as Haemophilus paragallinarum, and a commercial IC vaccine, not containing an NAD-independent strain, for their safety and ability to protect chickens of varying ages against virulent challenges with four different serovars of A. paragallinarum, including the NAD-independent strain of the C-3 serovar. Four groups of 140 chickens each were vaccinated at the age of 17 weeks and revaccinated at the age of 19 weeks with each of the four vaccine formulations. A similar sized group of non-vaccinated chickens was used as control. Two rounds of challenge were conducted: a group of chicken in each vaccination group was challenged between 31 and 35 weeks of age, while another group was challenged between 51 and 55 weeks of age. The ''in-contact'' challenge model was used in this experiment. For each vaccination group, the four challenge strains representing four local serovars were used in each challenge round. The efficacy of the vaccines was compared based on overall protection levels obtained and the duration of protection. The safety of the different vaccines was determined by the severity of post-vaccination reactions. The need for the incorporation of the NAD-independent strain in the vaccine was evidenced by the low protection level against NAD-independent challenge recorded in the group of birds vaccinated with the commercial vaccine. The results obtained confirmed not only the variation in virulence of different South African serovars, with serovar C-3 being the most virulent and serovar B having almost no virulence but also the age related increase in susceptibility. The importance of a suitable formulation of the vaccine is discussed.

A Facile and General Approach to Recoverable High-Strain Multishape Shape Memory Polymers.

Science.gov (United States)

Li, Xingjian; Pan, Yi; Zheng, Zhaohui; Ding, Xiaobin

2018-03-01

Fabricating a single polymer network with no need to design complex structures to achieve an ideal combination of tunable high-strain multiple-shape memory effects and highly recoverable shape memory property is a great challenge for the real applications of advanced shape memory devices. Here, a facile and general approach to recoverable high-strain multishape shape memory polymers is presented via a random copolymerization of acrylate monomers and a chain-extended multiblock copolymer crosslinker. As-prepared shape memory networks show a large width at the half-peak height of the glass transition, far wider than current classical multishape shape memory polymers. A combination of tunable high-strain multishape memory effect and as high as 1000% recoverable strain in a single chemical-crosslinking network can be obtained. To the best of our knowledge, this is the first thermosetting material with a combination of highly recoverable strain and tunable high-strain multiple-shape memory effects. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design of homo-organic acid producing strains using multi-objective optimization

DEFF Research Database (Denmark)

Kim, Tae Yong; Park, Jong Myoung; Kim, Hyun Uk

2015-01-01

Production of homo-organic acids without byproducts is an important challenge in bioprocess engineering to minimize operation cost for separation processes. In this study, we used multi-objective optimization to design Escherichia coli strains with the goals of maximally producing target organic ...

Improvement of industrially important microbial strains by genome shuffling: Current status and future prospects.

Science.gov (United States)

Magocha, Tinashe Archbold; Zabed, H; Yang, Miaomiao; Yun, Junhua; Zhang, Huanhuan; Qi, Xianghui

2018-06-01

The growing demand for biotechnological products against limited metabolic capacity of industrially used microorganisms has led to an increased interest on strain-improvement over the last several decades, which aimed to enhance metabolite yield, substrate uptake and tolerance of the strains. Among a few techniques of strain-improvement, genome shuffling is the most recent and promising approach used for rapid strain-improvement that can yield a new strain by combining whole genomes of multi-parental microorganisms using the principles of protoplast fusion. Genome shuffling has brought a major breakthrough in the strain-improvement concept as it is found to be effective and reliable for expressing complex phenotypes. This review will discuss the technical aspects and applications of genome shuffling for various industrial strains to present its current status and recent progress. In the concluding remarks, a summary will be presented focusing on the major challenges and future outlooks of this technology. Copyright © 2018 Elsevier Ltd. All rights reserved.

Maillard neoglycans as inhibitors for in vitro adhesion of F4+ enterotoxigenic Escherichia coli to piglet intestinal cells.

Science.gov (United States)

Sarabia-Sainz, Héctor Manuel; Mata Haro, Verónica; Sarabia Sainz, José Andre-I; Vázquez-Moreno, Luz; Montfort, Gabriela Ramos-Clamont

2017-01-01

Adhesion of enterotoxigenic (ETEC) E. coli to host intestinal cells is mediated by lectin-like fimbriae that bind to specific glycan moieties on the surfaces of enterocytes. To prevent in vitro binding of E. coli F4 fimbriae (F4 ETEC + ) to piglet enterocytes, neoglycans were synthesized by the Maillard reaction conjugating lactose (Lac), galacto-oligosaccharides (GOS) or chitin oligosaccharides (Ochit) to porcine serum albumin (PSA). Neoglycans were characterized by SDS-PAGE, intrinsic tryptophan fluorescence and recognition by plant lectins, as well as by F4 ETEC variants. Electrophoretic patterns suggested the binding to PSA of 63, 13 and 2 molecules of Lac, GOS and Ochit, respectively. All neoglycans displayed quenching of tryptophan fluorescence consistent with the degree of glycation estimated by SDS-PAGE. Plant lectins recognized the neoglycans according to their specificity, whereas antigenic variants of F4 ETEC (ab, ac and ad) recognized PSA-Ochit and PSA-Lac with higher affinity than that for GOS. Neoglycans partially hindered the in vitro binding of F4 + ETEC to piglet enterocytes in a dose-dependent manner. The most effective blocking was observed with PSA-Lac that partially inhibited the adhesion of bacteria to enterocytes in a dose dependent manner, as quantified by flow cytometry. Increased production of the cytokines IL-6 and TNF-α was observed in response to F4 + ETEC infection of enterocytes and production was reduced in the presence of PSA-Ochit and PSA-GOS. These results suggest that neoglycans synthesized by the Maillard reaction could be useful in the prophylaxis of diarrhea in piglets.

A Francisella tularensis live vaccine strain that improves stimulation of antigen-presenting cells does not enhance vaccine efficacy.

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Deanna M Schmitt

Full Text Available Vaccination is a proven strategy to mitigate morbidity and mortality of infectious diseases. The methodology of identifying and testing new vaccine candidates could be improved with rational design and in vitro testing prior to animal experimentation. The tularemia vaccine, Francisella tularensis live vaccine strain (LVS, does not elicit complete protection against lethal challenge with a virulent type A Francisella strain. One factor that may contribute to this poor performance is limited stimulation of antigen-presenting cells. In this study, we examined whether the interaction of genetically modified LVS strains with human antigen-presenting cells correlated with effectiveness as tularemia vaccine candidates. Human dendritic cells infected with wild-type LVS secrete low levels of proinflammatory cytokines, fail to upregulate costimulatory molecules, and activate human T cells poorly in vitro. One LVS mutant, strain 13B47, stimulated higher levels of proinflammatory cytokines from dendritic cells and macrophages and increased costimulatory molecule expression on dendritic cells compared to wild type. Additionally, 13B47-infected dendritic cells activated T cells more efficiently than LVS-infected cells. A deletion allele of the same gene in LVS displayed similar in vitro characteristics, but vaccination with this strain did not improve survival after challenge with a virulent Francisella strain. In vivo, this mutant was attenuated for growth and did not stimulate T cell responses in the lung comparable to wild type. Therefore, stimulation of antigen-presenting cells in vitro was improved by genetic modification of LVS, but did not correlate with efficacy against challenge in vivo within this model system.

Recombinant infectious bronchitis virus (IBV) H120 vaccine strain expressing the hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) protects chickens against IBV and NDV challenge.

Science.gov (United States)

Yang, Xin; Zhou, Yingshun; Li, Jianan; Fu, Li; Ji, Gaosheng; Zeng, Fanya; Zhou, Long; Gao, Wenqian; Wang, Hongning

2016-05-01

Infectious bronchitis (IB) and Newcastle disease (ND) are common viral diseases of chickens, which are caused by infectious bronchitis virus (IBV) and Newcastle disease virus (NDV), respectively. Vaccination with live attenuated strains of IBV-H120 and NDV-LaSota are important for the control of IB and ND. However, conventional live attenuated vaccines are expensive and result in the inability to differentiate between infected and vaccinated chickens. Therefore, there is an urgent need to develop new efficacious vaccines. In this study, using a previously established reverse genetics system, we generated a recombinant IBV virus based on the IBV H120 vaccine strain expressing the haemagglutinin-neuraminidase (HN) protein of NDV. The recombinant virus, R-H120-HN/5a, exhibited growth dynamics, pathogenicity and viral titers that were similar to those of the parental IBV H120, but it had acquired hemagglutination activity from NDV. Vaccination of SPF chickens with the R-H120-HN/5a virus induced a humoral response at a level comparable to that of the LaSota/H120 commercial bivalent vaccine and provided significant protection against challenge with virulent IBV and NDV. In summary, the results of this study indicate that the IBV H120 strain could serve as an effective tool for designing vaccines against IB and other infectious diseases, and the generation of IBV R-H120-HN/5a provides a solid foundation for the development of an effective bivalent vaccine against IBV and NDV.

A monoallelic deletion of the TcCRT gene increases the attenuation of a cultured Trypanosoma cruzi strain, protecting against an in vivo virulent challenge.

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Fernando J Sánchez-Valdéz

2014-02-01

Full Text Available Trypanosoma cruzi calreticulin (TcCRT is a virulence factor that binds complement C1, thus inhibiting the activation of the classical complement pathway and generating pro-phagocytic signals that increase parasite infectivity. In a previous work, we characterized a clonal cell line lacking one TcCRT allele (TcCRT+/- and another overexpressing it (TcCRT+, both derived from the attenuated TCC T. cruzi strain. The TcCRT+/- mutant was highly susceptible to killing by the complement machinery and presented a remarkable reduced propagation and differentiation rate both in vitro and in vivo. In this report, we have extended these studies to assess, in a mouse model of disease, the virulence, immunogenicity and safety of the mutant as an experimental vaccine. Balb/c mice were inoculated with TcCRT+/- parasites and followed-up during a 6-month period. Mutant parasites were not detected by sensitive techniques, even after mice immune suppression. Total anti-T. cruzi IgG levels were undetectable in TcCRT+/- inoculated mice and the genetic alteration was stable after long-term infection and it did not revert back to wild type form. Most importantly, immunization with TcCRT+/- parasites induces a highly protective response after challenge with a virulent T. cruzi strain, as evidenced by lower parasite density, mortality, spleen index and tissue inflammatory response. TcCRT+/- clones are restricted in two important properties conferred by TcCRT and indirectly by C1q: their ability to evade the host immune response and their virulence. Therefore, deletion of one copy of the TcCRT gene in the attenuated TCC strain generated a safe and irreversibly gene-deleted live attenuated parasite with high immunoprotective properties. Our results also contribute to endorse the important role of TcCRT as a T. cruzi virulence factor.

A Yersinia pestis tat mutant is attenuated in bubonic and small-aerosol pneumonic challenge models of infection but not as attenuated by intranasal challenge.

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Joel Bozue

Full Text Available Bacterial proteins destined for the Tat pathway are folded before crossing the inner membrane and are typically identified by an N-terminal signal peptide containing a twin arginine motif. Translocation by the Tat pathway is dependent on the products of genes which encode proteins possessing the binding site of the signal peptide and mediating the actual translocation event. In the fully virulent CO92 strain of Yersinia pestis, the tatA gene was deleted. The mutant was assayed for loss of virulence through various in vitro and in vivo assays. Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type. Cell morphology of the mutant bacteria was altered and demonstrated a more elongated form. In addition, while cultures of the mutant strain were able to produce a biofilm, we observed a loss of adhesion of the mutant biofilm structure compared to the biofilm produced by the wild-type strain. Immuno-electron microscopy revealed a partial disruption of the F1 antigen on the surface of the mutant. The virulence of the ΔtatA mutant was assessed in various murine models of plague. The mutant was severely attenuated in the bubonic model with full virulence restored by complementation with the native gene. After small-particle aerosol challenge in a pneumonic model of infection, the mutant was also shown to be attenuated. In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains. However, an increased time-to-death and delay in bacterial dissemination was observed in mice infected with the ΔtatA mutant as compared to the parent strain. Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.

Comparative genomics and transcriptomics of Escherichia coli isolates carrying virulence factors of both enteropathogenic and enterotoxigenic E. coli.

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Hazen, Tracy H; Michalski, Jane; Luo, Qingwei; Shetty, Amol C; Daugherty, Sean C; Fleckenstein, James M; Rasko, David A

2017-06-14

Escherichia coli that are capable of causing human disease are often classified into pathogenic variants (pathovars) based on their virulence gene content. However, disease-associated hybrid E. coli, containing unique combinations of multiple canonical virulence factors have also been described. Such was the case of the E. coli O104:H4 outbreak in 2011, which caused significant morbidity and mortality. Among the pathovars of diarrheagenic E. coli that cause significant human disease are the enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). In the current study we use comparative genomics, transcriptomics, and functional studies to characterize isolates that contain virulence factors of both EPEC and ETEC. Based on phylogenomic analysis, these hybrid isolates are more genomically-related to EPEC, but appear to have acquired ETEC virulence genes. Global transcriptional analysis using RNA sequencing, demonstrated that the EPEC and ETEC virulence genes of these hybrid isolates were differentially-expressed under virulence-inducing laboratory conditions, similar to reference isolates. Immunoblot assays further verified that the virulence gene products were produced and that the T3SS effector EspB of EPEC, and heat-labile toxin of ETEC were secreted. These findings document the existence and virulence potential of an E. coli pathovar hybrid that blurs the distinction between E. coli pathovars.

Interference with the quorum sensing systems in a Vibrio harveyi strain alters the growth rate of gnotobiotically cultured rotifer Brachionus plicatilis.

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Tinh, N T N; Linh, N D; Wood, T K; Dierckens, K; Sorgeloos, P; Bossier, P

2007-07-01

To evaluate the effect of Vibrio harveyi strains on the growth rate of the gnotobiotically cultured rotifer Brachionus plicatilis, and to establish whether quorum sensing is involved in the observed phenomena. Gnotobiotic B. plicatilis sensu strictu, obtained by hatching glutaraldehyde-treated amictic eggs, were used as test organisms. Challenge tests were performed with 11 V. harveyi strains and different quorum sensing mutants derived from the V. harveyi BB120 strain. Brominated furanone [(5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone] as a quorum sensing inhibitor was tested in Brachionus challenge tests. Some V. harveyi strains, such as strain BB120, had a significantly negative effect on the Brachionus growth rate. In the challenge test with MM77, an isogenic strain of BB120 in which the two autoinducers (HAI-1 and AI-2) are both inactivated, no negative effect was observed. The effect of single mutants was the same as that observed in the BB120 strain. This indicates that both systems are responsible for the growth-retarding (GR) effect of the BB120 strain towards Brachionus. Moreover, the addition of an exogenous source of HAI-1 or AI-2 could restore the GR effect in the HAI-1 and AI-2 nonproducing mutant MM77. The addition of brominated furanone at a concentration of 2.5 mg l(-1) could neutralize the GR effect of some strains such as BB120 and VH-014. Two quorum sensing systems in V. harveyi strain BB120 (namely HAI-1 and AI-2-mediated) are necessary for its GR effect on B. plicatilis. With some other V. harveyi strains, however, growth inhibition towards Brachionus does not seem to be related to quorum sensing. Interference with the quorum sensing system might help to counteract the GR effect of some V. harveyi strains on Brachionus. However, further studies are needed to demonstrate the positive effect of halogenated furanone in nongnotobiotic Brachionus cultures and eventually, in other segments of the aquaculture industry.

Analysis of adrenocortical secretory responses during acute an prolonged immune stimulation in inflammation-susceptible and -resistant rat strains.

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Andersson, I M; Lorentzen, J C; Ericsson-Dahlstrand, A

2000-11-01

Endogenous corticosterone secreted during immune challenge restricts the inflammatory process and genetic variations in this neuroendocrine-immune dialogue have been suggested to influence an individuals sensitivity to develop chronic inflammatory disorders. We have tested inflammation-susceptible Dark Agouti (DA) rats and resistant, MHC-identical, PVG.1AV1 rats for their abilities to secrete corticosterone in response to acute challenge with bacterial lipopolysaccharide (LPS) or a prolonged activation of the nonspecific immune system with arthritogenic yeast beta-glucan. Intravenous injection of LPS triggered equipotent secretion of corticosterone in both rat strains. Interestingly, peak concentrations of corticosterone did not differ significantly between the strains. Intradermal injection of beta-glucan caused severe, monophasic, polyarthritis in DA rats while PVG.1AV1 responded with significantly milder joint inflammation. Importantly, serial sampling of plasma from glucan-injected DA and PVG.1AV1 rats did not reveal elevated concentrations of plasma corticosterone at any time from days 1-30 postinjection compared to preinjection values, in spite of the ongoing inflammatory process. Interestingly, adrenalectomized, beta-glucan-challenged DA rats responded with an aggravated arthritic process, indicating an anti-inflammatory role for the basal levels of corticosterone that were detected in intact DA rats challenged with beta-glucan. Moreover, substitution with subcutaneous corticosterone-secreting pellets, yielding moderate stress-levels, significantly attenuated the arthritic response. In contrast, adrenalectomized and glucan-challenged PVG.1AV1 rats did not respond with an elevated arthritic response, suggesting that these rats contain the arthritic process via corticosterone-independent mechanisms. In conclusion, the hypothalamic-pituitary-adrenal axis in both rat strains exhibited strong activation after challenge with LPS. This contrasted to the basal

On modeling micro-structural evolution using a higher order strain gradient continuum theory

DEFF Research Database (Denmark)

El-Naaman, S. A.; Nielsen, K. L.; Niordson, C. F.

2016-01-01

is to improve the micro-structural response predicted using strain gradient crystal plasticity within a continuum mechanics framework. One approach to modeling the dislocation structures observed is through a back stress formulation, which can be related directly to the strain gradient energy. The present work...... the experimentally observed micro-structural behavior, within a framework based on continuous field quantities, poses obvious challenges, since the evolution of dislocation structures is inherently a discrete and discontinuous process. This challenge, in particular, motivates the present study, and the aim...... offers an investigation of constitutive equations for the back stress based on both considerations of the gradient energy, but also includes results obtained from a purely phenomenological starting point. The influence of model parameters is brought out in a parametric study, and it is demonstrated how...

Experimental infection with Escherichia coli 0149 : F4ac in weaned piglets

DEFF Research Database (Denmark)

Jensen, Gerda M.; Frydendahl, Kai; Svendsen, Ove

2006-01-01

adhesion test made after slaughter of piglets. However, in an experimental infection study with the purpose to obtain diarrhoeic piglets, it would be an advantage to test for susceptibility prior to experimentation. The Mucin 4 gene on porcine chromosome 13 has been proposed as a candidate gene...... for the production of the specific ETEC F4ab/ac receptor, and a DNA marker-based test has been developed to allow genotyping for ETEC F4ab/ac resistance/susceptibility [Jorgensen, C.B., Cirera, S., Archibald, A.L., Anderson, L., Fredholm, M., Edfors-Lilja, I., 2004. Porcine polymorphisms and methods for detecting...... them. International application published under the patent cooperation treaty (PCT). PCT/DK2003/000807 or WO2004/048606-A2]. The aim of this study was to test an experimental model for ETEC O149:F4ac-induced diarrhoea in piglets, selected for susceptibility towards ETEC O149:F4ac adhesion prior...

Material-Point Analysis of Large-Strain Problems

DEFF Research Database (Denmark)

Andersen, Søren

The aim of this thesis is to apply and improve the material-point method for modelling of geotechnical problems. One of the geotechnical phenomena that is a subject of active research is the study of landslides. A large amount of research is focused on determining when slopes become unstable. Hence......, it is possible to predict if a certain slope is stable using commercial finite element or finite difference software such as PLAXIS, ABAQUS or FLAC. However, the dynamics during a landslide are less explored. The material-point method (MPM) is a novel numerical method aimed at analysing problems involving...... materials subjected to large strains in a dynamical time–space domain. This thesis explores the material-point method with the specific aim of improving the performance for geotechnical problems. Large-strain geotechnical problems such as landslides pose a major challenge to model numerically. Employing...

Epidemiology of bacterial pathogens associated with infectious diarrhea in Djibouti.

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Mikhail, I A; Fox, E; Haberberger, R L; Ahmed, M H; Abbatte, E A

1990-01-01

During a survey examining the causes of diarrhea in the East African country of Djibouti, 140 bacterial pathogens were recovered from 209 diarrheal and 100 control stools. The following pathogens were isolated at comparable frequencies from both diarrheal and control stools: enteroadherent Escherichia coli (EAEC) (10.6 versus 13%), enterotoxigenic E. coli (ETEC) (11 versus 10%), enteropathogenic E. coli (EPEC) (7.7 versus 12%), Salmonella spp. (2.9 versus 3%), and Campylobacter jejuni-C. coli (3.3 versus 5%). Surprisingly, the EAEC strains isolated did not correspond to well-recognized EPEC serogroups. No Yersinia spp., enteroinvasive E. coli, or enterohemorrhagic E. coli were isolated during the course of this study. Only the following two genera were recovered from diarrheal stools exclusively: Shigella spp. (7.7%) and Aeromonas hydrophila group organisms (3.3%). Shigella flexneri was the most common Shigella species isolated. Patients with Shigella species were of a higher average age than were controls (27 versus 13 years), while subjects with Campylobacter or Salmonella species belonged to younger age groups (2.6 and 1.6 years, respectively). Salmonella cases were more often in females. Shigella diarrhea was associated with fecal blood or mucus and leukocytes. ETEC was not associated with nausea or vomiting. Anorexia, weight loss, and fever were associated with the isolation of Salmonella and Aeromonas species. EAEC, ETEC, EPEC, and Shigella species were resistant to most drugs used for treating diarrhea in Africa, while the antibiotic most active against all bacteria tested was norfloxacin. We conclude that in Djibouti in 1989, Shigella and Aeromonas species must be considered as potential pathogens whenever they are isolated from diarrheal stools and that norfloxacin should be considered the drug of choice in adults for treating severe shigellosis and for diarrhea prophylaxis in travelers. PMID:2351738

An attenuated Shigella mutant lacking the RNA-binding protein Hfq provides cross-protection against Shigella strains of broad serotype.

Science.gov (United States)

Mitobe, Jiro; Sinha, Ritam; Mitra, Soma; Nag, Dhrubajyoti; Saito, Noriko; Shimuta, Ken; Koizumi, Nobuo; Koley, Hemanta

2017-07-01

Few live attenuated vaccines protect against multiple serotypes of bacterial pathogen because host serotype-specific immune responses are limited to the serotype present in the vaccine strain. Here, immunization with a mutant of Shigella flexneri 2a protected guinea pigs against subsequent infection by S. dysenteriae type 1 and S. sonnei strains. This deletion mutant lacked the RNA-binding protein Hfq leading to increased expression of the type III secretion system via loss of regulation, resulting in attenuation of cell viability through repression of stress response sigma factors. Such increased antigen production and simultaneous attenuation were expected to elicit protective immunity against Shigella strains of heterologous serotypes. Thus, the vaccine potential of this mutant was tested in two guinea pig models of shigellosis. Animals vaccinated in the left eye showed fewer symptoms upon subsequent challenge via the right eye, and even survived subsequent intestinal challenge. In addition, oral vaccination effectively induced production of immunoglobulins without severe side effects, again protecting all animals against subsequent intestinal challenge with S. dysenteriae type 1 or S. sonnei strains. Antibodies against common virulence proteins and the O-antigen of S. flexneri 2a were detected by immunofluorescence microscopy. Reaction of antibodies with various strains, including enteroinvasive Escherichia coli, suggested that common virulence proteins induced protective immunity against a range of serotypes. Therefore, vaccination is expected to cover not only the most prevalent serotypes of S. sonnei and S. flexneri 2a, but also various Shigella strains, including S. dysenteriae type 1, which produces Shiga toxin.

An attenuated Shigella mutant lacking the RNA-binding protein Hfq provides cross-protection against Shigella strains of broad serotype.

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Jiro Mitobe

2017-07-01

Full Text Available Few live attenuated vaccines protect against multiple serotypes of bacterial pathogen because host serotype-specific immune responses are limited to the serotype present in the vaccine strain. Here, immunization with a mutant of Shigella flexneri 2a protected guinea pigs against subsequent infection by S. dysenteriae type 1 and S. sonnei strains. This deletion mutant lacked the RNA-binding protein Hfq leading to increased expression of the type III secretion system via loss of regulation, resulting in attenuation of cell viability through repression of stress response sigma factors. Such increased antigen production and simultaneous attenuation were expected to elicit protective immunity against Shigella strains of heterologous serotypes. Thus, the vaccine potential of this mutant was tested in two guinea pig models of shigellosis. Animals vaccinated in the left eye showed fewer symptoms upon subsequent challenge via the right eye, and even survived subsequent intestinal challenge. In addition, oral vaccination effectively induced production of immunoglobulins without severe side effects, again protecting all animals against subsequent intestinal challenge with S. dysenteriae type 1 or S. sonnei strains. Antibodies against common virulence proteins and the O-antigen of S. flexneri 2a were detected by immunofluorescence microscopy. Reaction of antibodies with various strains, including enteroinvasive Escherichia coli, suggested that common virulence proteins induced protective immunity against a range of serotypes. Therefore, vaccination is expected to cover not only the most prevalent serotypes of S. sonnei and S. flexneri 2a, but also various Shigella strains, including S. dysenteriae type 1, which produces Shiga toxin.

Stochastic precision analysis of 2D cardiac strain estimation in vivo

International Nuclear Information System (INIS)

Bunting, E A; Provost, J; Konofagou, E E

2014-01-01

Ultrasonic strain imaging has been applied to echocardiography and carries great potential to be used as a tool in the clinical setting. Two-dimensional (2D) strain estimation may be useful when studying the heart due to the complex, 3D deformation of the cardiac tissue. Increasing the framerate used for motion estimation, i.e. motion estimation rate (MER), has been shown to improve the precision of the strain estimation, although maintaining the spatial resolution necessary to view the entire heart structure in a single heartbeat remains challenging at high MERs. Two previously developed methods, the temporally unequispaced acquisition sequence (TUAS) and the diverging beam sequence (DBS), have been used in the past to successfully estimate in vivo axial strain at high MERs without compromising spatial resolution. In this study, a stochastic assessment of 2D strain estimation precision is performed in vivo for both sequences at varying MERs (65, 272, 544, 815 Hz for TUAS; 250, 500, 1000, 2000 Hz for DBS). 2D incremental strains were estimated during left ventricular contraction in five healthy volunteers using a normalized cross-correlation function and a least-squares strain estimator. Both sequences were shown capable of estimating 2D incremental strains in vivo. The conditional expected value of the elastographic signal-to-noise ratio (E(SNRe|ε)) was used to compare strain estimation precision of both sequences at multiple MERs over a wide range of clinical strain values. The results here indicate that axial strain estimation precision is much more dependent on MER than lateral strain estimation, while lateral estimation is more affected by strain magnitude. MER should be increased at least above 544 Hz to avoid suboptimal axial strain estimation. Radial and circumferential strain estimations were influenced by the axial and lateral strain in different ways. Furthermore, the TUAS and DBS were found to be of comparable precision at similar MERs. (paper)

Isolation of an attenuated myxoma virus field strain that can confer protection against myxomatosis on contacts of vaccinates.

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Bárcena, J; Pagès-Manté, A; March, R; Morales, M; Ramírez, M A; Sánchez-Vizcaíno, J M; Torres, J M

2000-01-01

Twenty MV strains obtained from a survey of field strains currently circulating throughout Spain were analyzed for their virulence and horizontal spreading among rabbits by contact transmission. A virus strain with suitable characteristics to be used as a potential vaccine against myxomatosis in wild rabbit populations was selected. Following inoculation, the selected MV strain elicited high levels of MV specific antibodies and induced protection of rabbits against a virulent MV challenge. Furthermore, the attenuated MV was transmitted to 9 out of 16 uninoculated rabbits by contact, inducing protection against myxomatosis.

Micro-Structural Evolution and Size-Effects in Plastically Deformed Single Crystals: Strain Gradient Continuum Modeling

DEFF Research Database (Denmark)

El-Naaman, Salim Abdallah

the macroscopic effects related to strain gradients, most predict smooth micro-structures. The evolution of dislocation micro-structures, during plastic straining of ductile crystalline materials, is highly complex and nonuniform. Published experimental measurements on deformed metal crystals show distinct......An extensive amount of research has been devoted to the development of micro-mechanics based gradient plasticity continuum theories, which are necessary for modeling micron-scale plasticity when large spatial gradients of plastic strain appear. While many models have proven successful in capturing...... strain. It is clear that many challenges are associated with modeling dislocation structures, within a framework based on continuum fields, however, since the strain gradient effects are attributed to the dislocation micro-structure, it is a natural step, in the further development of gradient theories...

Antigenic variants of influenza A virus, PR8 strain. I. Their development during serial passage in the lungs of partially immune mice.

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GERBER, P; LOOSLI, C G; HAMBRE, D

1955-06-01

Antigenically different strains of mouse-adapted PR8 influenza A virus have been produced by 17 serial passages of the virus in the lungs of mice immunized with the homologous agent. Comparative serological tests show that the variant strains share antigenic components with the parent strain but the dominant antigen is different. By means of antibody absorption it was shown that the "new" antigenic component of the variant was already present in minor amounts up to the eighth passage and thereafter gained prominence with continued passage in vaccinated mice. Groups of mice vaccinated with either the PR8-S or T(21) virus and having comparable antibody titers showed no growth of virus in the lungs following aid-borne challenge with homologous strains. On the other hand, following heterologous air-borne challenge no deaths occurred, but virus grew in the lungs of both groups of vaccinated mice. Almost unrestricted virus multiplication took place in the lungs of mice vaccinated with the parent strain and challenged with the PR8-T(21) virus which resulted in extensive consolidation. Less virus grew in the lungs of the mice vaccinated with the variant strains and challenged with the PR8-S virus. In these animals only microscopic evidence of changes due to virus growth in the lungs was observed. The successful serial passage of PR8 influenza A virus in immunized animals was dependent on the initial selection of mice with uniformly low H.I. antibody titers as determined on tail blood, and the intranasal instillation of sufficient virus to favor the survival of those virus particles least related to the antibodies present. The epidemiological implications of these observations are discussed briefly.

Metabolic Modeling of Common Escherichia coli Strains in Human Gut Microbiome

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Yue-Dong Gao

2014-01-01

Full Text Available The recent high-throughput sequencing has enabled the composition of Escherichia coli strains in the human microbial community to be profiled en masse. However, there are two challenges to address: (1 exploring the genetic differences between E. coli strains in human gut and (2 dynamic responses of E. coli to diverse stress conditions. As a result, we investigated the E. coli strains in human gut microbiome using deep sequencing data and reconstructed genome-wide metabolic networks for the three most common E. coli strains, including E. coli HS, UTI89, and CFT073. The metabolic models show obvious strain-specific characteristics, both in network contents and in behaviors. We predicted optimal biomass production for three models on four different carbon sources (acetate, ethanol, glucose, and succinate and found that these stress-associated genes were involved in host-microbial interactions and increased in human obesity. Besides, it shows that the growth rates are similar among the models, but the flux distributions are different, even in E. coli core reactions. The correlations between human diabetes-associated metabolic reactions in the E. coli models were also predicted. The study provides a systems perspective on E. coli strains in human gut microbiome and will be helpful in integrating diverse data sources in the following study.

Strain detection in crystalline heterostructures using bidimensional blocking patterns of channelled particles

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Redondo-Cubero, A.; David-Bosne, E.; Wahl, U.; Miranda, P.; da Silva, M. R.; Correia, J. G.; Lorenz, K.

2018-03-01

Strain is a critical parameter affecting the growth and the performance of many semiconductor systems but, at the same time, the accurate determination of strain profiles in heterostructures can be challenging, especially at the nanoscale. Ion channelling/blocking is a powerful technique for the detection of the strain state of thin films, normally carried out through angular scans with conventional particle detectors. Here we report the novel application of position sensitive detectors for the evaluation of the strain in a series of AlInN/GaN heterostructures with different compositions and thicknesses. The tetragonal strain is varied from compressive to tensile and analysed through bidimensional blocking patterns. The results demonstrate that strain can be correctly quantified when compared to Monte Carlo channelling simulations, which are essential because of the presence of ion steering effects at the interface between the layer and the substrate. Despite this physical limitation caused by ion steering, our results show that full bidimensional patterns can be applied to detect fingerprints and enhance the accuracy for most critical cases, in which the angular shift associated to the lattice distortion is below the critical angle for channelling.

Characterization of Brucella abortus mutant strain Δ22915, a potential vaccine candidate.

Science.gov (United States)

Bao, Yanqing; Tian, Mingxing; Li, Peng; Liu, Jiameng; Ding, Chan; Yu, Shengqing

2017-04-04

Brucellosis, caused by Brucella spp., is an important zoonosis worldwide. Vaccination is an effective strategy for protection against Brucella infection in livestock in developing countries and in wildlife in developed countries. However, current vaccine strains including S19 and RB51 are pathogenic to humans and pregnant animals, limiting their use. In this study, we constructed the Brucella abortus (B. abortus) S2308 mutant strain Δ22915, in which the putative lytic transglycosylase gene BAB_RS22915 was deleted. The biological properties of mutant strain Δ22915 were characterized and protection of mice against virulent S2308 challenge was evaluated. The mutant strain Δ22915 showed reduced survival within RAW264.7 cells and survival in vivo in mice. In addition, the mutant strain Δ22915 failed to escape fusion with lysosomes within host cells, and caused no observable pathological damage. RNA-seq analysis indicated that four genes associated with amino acid/nucleotide transport and metabolism were significantly upregulated in mutant strain Δ22915. Furthermore, inoculation of ∆22915 at 10 5 colony forming units induced effective host immune responses and long-term protection of BALB/c mice. Therefore, mutant strain ∆22915 could be used as a novel vaccine candidate in the future to protect animals against B. abortus infection.

Inverse methods for the mechanical characterization of materials at high strain rates

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Casas-Rodriguez J.P.

2012-08-01

Full Text Available Mechanical material characterization represents a research challenge. Furthermore, special attention is directed to material characterization at high strain rates as the mechanical properties of some materials are influenced by the rate of loading. Diverse experimental techniques at high strain rates are available, such as the drop-test, the Taylor impact test or the Split Hopkinson pressure bar among others. However, the determination of the material parameters associated to a given mathematical constitutive model from the experimental data is a complex and indirect problem. This paper presents a material characterization methodology to determine the material parameters of a given material constitutive model from a given high strain rate experiment. The characterization methodology is based on an inverse technique in which an inverse problem is formulated and solved as an optimization procedure. The input of the optimization procedure is the characteristic signal from the high strain rate experiment. The output of the procedure is the optimum set of material parameters determined by fitting a numerical simulation to the high strain rate experimental signal.

Toward a Better Understanding of the Effects of Hindrance and Challenge Stressors on Work Behavior

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Webster, Jennica R.; Beehr, Terry A.; Christiansen, Neil D.

2010-01-01

This study investigated the processes whereby hindrance and challenge stressors may affect work behavior. Three mechanisms were examined to explain the differential effects these stressors have demonstrated: job satisfaction, strains, and work self-efficacy. A model is proposed in which both types of stressors will result in increases in strains,…

Xylose Fermentation by Saccharomyces cerevisiae: Challenges and Prospects

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Danuza Nogueira Moysés

2016-02-01

Full Text Available Many years have passed since the first genetically modified Saccharomyces cerevisiae strains capable of fermenting xylose were obtained with the promise of an environmentally sustainable solution for the conversion of the abundant lignocellulosic biomass to ethanol. Several challenges emerged from these first experiences, most of them related to solving redox imbalances, discovering new pathways for xylose utilization, modulation of the expression of genes of the non-oxidative pentose phosphate pathway, and reduction of xylitol formation. Strategies on evolutionary engineering were used to improve fermentation kinetics, but the resulting strains were still far from industrial application. Lignocellulosic hydrolysates proved to have different inhibitors derived from lignin and sugar degradation, along with significant amounts of acetic acid, intrinsically related with biomass deconstruction. This, associated with pH, temperature, high ethanol, and other stress fluctuations presented on large scale fermentations led the search for yeasts with more robust backgrounds, like industrial strains, as engineering targets. Some promising yeasts were obtained both from studies of stress tolerance genes and adaptation on hydrolysates. Since fermentation times on mixed-substrate hydrolysates were still not cost-effective, the more selective search for new or engineered sugar transporters for xylose are still the focus of many recent studies. These challenges, as well as under-appreciated process strategies, will be discussed in this review.

Electrochemical magneto immunosensor based on endogenous β-galactosidase enzyme to determine enterotoxicogenic Escherichia coli F4 (K88) in swine feces using square wave voltammetry.

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Viviana Tarditto, Lorena; Alicia Zon, María; García Ovando, Hugo; Roberto Vettorazzi, Nelio; Javier Arévalo, Fernando; Fernández, Héctor

2017-11-01

Diseases caused by enterotoxicogenic Escherichia coli F4 (K88) (ETEC F4) are a problem in swine production establishments. Due to the high rate of mortality and morbidity of E. coli infections, a rapid and accurate diagnosis is important in order to choose an appropriate treatment to reduce the economic impact. Therefore, an electrochemical magneto-immunosensor (EMI) was developed to detect and quantify ETEC F4 in swine feces samples through a direct non-competitive immunoassay. ETEC F4 was selectively captured by immunomagnetic separation. The detection principle was based on the activity of β-galactosidase endogenous enzyme (β-gal), which hydrolyses the p-aminophenyl-β-D-galactopyranoside (p-APG) producing p-aminophenol (p-AP), which was oxidized on a carbon screen printed electrode (CSPE) using square wave voltammetry (SWV). All parameters related to construction and electrochemical responses were optimized. The total analysis time to quantify ETEC F4 using the EMI was less than 2h and the limit of detection (LOD) was 33CFUmL -1 . The perceptual relative error (%E r ) was 20%. The magneto-immunosensor was validated versus conventional method of culture and plate count, obtaining a very good agreement. The EMI is simple, fast and economical to detect and quantify ETEC F4 in swine feces samples, being thus a valuable tool in swine production. Copyright © 2017 Elsevier B.V. All rights reserved.

The Role of Educational Technology Professionals as Perceived by Building Administrators

Science.gov (United States)

Murphy, Cheryl A.; Allred, Jonathan B.; Brescia, William F.

2018-01-01

Educational Technology (ETEC) professionals in the United States (US) fill multiple roles in public school systems. While these roles can be classified into broad categories, what remains unclear are the expectations and priorities for the completion of these roles and the tasks associated within each role category. In order for ETEC professionals…

Analysis of strain error sources in micro-beam Laue diffraction

International Nuclear Information System (INIS)

Hofmann, Felix; Eve, Sophie; Belnoue, Jonathan; Micha, Jean-Sébastien; Korsunsky, Alexander M.

2011-01-01

Micro-beam Laue diffraction is an experimental method that allows the measurement of local lattice orientation and elastic strain within individual grains of engineering alloys, ceramics, and other polycrystalline materials. Unlike other analytical techniques, e.g. based on electron microscopy, it is not limited to surface characterisation or thin sections, but rather allows non-destructive measurements in the material bulk. This is of particular importance for in situ loading experiments where the mechanical response of a material volume (rather than just surface) is studied and it is vital that no perturbation/disturbance is introduced by the measurement technique. Whilst the technique allows lattice orientation to be determined to a high level of precision, accurate measurement of elastic strains and estimating the errors involved is a significant challenge. We propose a simulation-based approach to assess the elastic strain errors that arise from geometrical perturbations of the experimental setup. Using an empirical combination rule, the contributions of different geometrical uncertainties to the overall experimental strain error are estimated. This approach was applied to the micro-beam Laue diffraction setup at beamline BM32 at the European Synchrotron Radiation Facility (ESRF). Using a highly perfect germanium single crystal, the mechanical stability of the instrument was determined and hence the expected strain errors predicted. Comparison with the actual strain errors found in a silicon four-point beam bending test showed good agreement. The simulation-based error analysis approach makes it possible to understand the origins of the experimental strain errors and thus allows a directed improvement of the experimental geometry to maximise the benefit in terms of strain accuracy.

Control of biaxial strain in single-layer molybdenite using local thermal expansion of the substrate

Science.gov (United States)

Plechinger, Gerd; Castellanos-Gomez, Andres; Buscema, Michele; van der Zant, Herre S. J.; Steele, Gary A.; Kuc, Agnieszka; Heine, Thomas; Schüller, Christian; Korn, Tobias

2015-03-01

Single-layer MoS2 is a direct-gap semiconductor whose electronic band structure strongly depends on the strain applied to its crystal lattice. While uniaxial strain can be easily applied in a controlled way, e.g., by bending of a flexible substrate with the atomically thin MoS2 layer on top, experimental realization of biaxial strain is more challenging. Here, we exploit the large mismatch between the thermal expansion coefficients of MoS2 and a silicone-based substrate to apply a controllable biaxial tensile strain by heating the substrate with a focused laser. The effect of this biaxial strain is directly observable in optical spectroscopy as a redshift of the MoS2 photoluminescence. We also demonstrate the potential of this method to engineer more complex strain patterns by employing highly absorptive features on the substrate to achieve non-uniform heat profiles. By comparison of the observed redshift to strain-dependent band structure calculations, we estimate the biaxial strain applied by the silicone-based substrate to be up to 0.2%, corresponding to a band gap modulation of 105 meV per percentage of biaxial tensile strain.

Bridge condition assessment based on long-term strain monitoring

Science.gov (United States)

Sun, LiMin; Sun, Shouwang

2011-04-01

In consideration of the important role that bridges play as transportation infrastructures, their safety, durability and serviceability have always been deeply concerned. Structural Health Monitoring Systems (SHMS) have been installed to many long-span bridges to provide bridge engineers with the information needed in making rational decisions for maintenance. However, SHMS also confronted bridge engineers with the challenge of efficient use of monitoring data. Thus, methodologies which are robust to random disturbance and sensitive to damage become a subject on which many researches in structural condition assessment concentrate. In this study, an innovative probabilistic approach for condition assessment of bridge structures was proposed on the basis of long-term strain monitoring on steel girder of a cable-stayed bridge. First, the methodology of damage detection in the vicinity of monitoring point using strain-based indices was investigated. Then, the composition of strain response of bridge under operational loads was analyzed. Thirdly, the influence of temperature and wind on strains was eliminated and thus strain fluctuation under vehicle loads is obtained. Finally, damage evolution assessment was carried out based on the statistical characteristics of rain-flow cycles derived from the strain fluctuation under vehicle loads. The research conducted indicates that the methodology proposed is qualified for structural condition assessment so far as the following respects are concerned: (a) capability of revealing structural deterioration; (b) immunity to the influence of environmental variation; (c) adaptability to the random characteristic exhibited by long-term monitoring data. Further examination of the applicability of the proposed methodology in aging bridge may provide a more convincing validation.

Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

Energy Technology Data Exchange (ETDEWEB)

Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

2014-06-01

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s^-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

A comparison of time-history elastic plastic piping analysis with measurement

International Nuclear Information System (INIS)

Scavuzzo, R.J.; Sansalone, K.H.

1992-01-01

The GE/ETEC Green piping system was subjected to high seismic inputs from hydraulic sleds at each pipe foundation. These inputs were high enough to force bending stresses into the plastic regime. Strain gages recorded the pipe response at various positions within the system. The ABAQUS finite element code was used to model this piping system and the dynamic input. Problems associated with the dynamic input are discussed. Various types of finite elements were evaluated for accurancy. Both an elastic time-history analysis and an elastic-plastic time-history analysis of the system were conducted. Results of these analyses are compared to each other and the experimental data. These comparisons indicated that elastic analysis of dynamic strains are conservative at all points of comparison and that there is good agreement between the nonlinear elastic-plastic analysis and experimental data. (orig.)

Toxicity and immunogenicity of Enterotoxigenic Escherichia coli heat-labile and heat-stable toxoid fusion 3xSTa(A14Q-LT(S63K/R192G/L211A in a murine model.

Directory of Open Access Journals (Sweden)

Chengxian Zhang

Full Text Available Diarrhea is the second leading cause of death to young children. Enterotoxigenic Escherichia coli (ETEC are the most common bacteria causing diarrhea. Adhesins and enterotoxins are the virulence determinants in ETEC diarrhea. Adhesins mediate bacterial attachment and colonization, and enterotoxins including heat-labile (LT and heat-stable type Ib toxin (STa disrupt fluid homeostasis in host cells that leads to fluid hyper-secretion and diarrhea. Thus, adhesins and enterotoxins have been primarily targeted in ETEC vaccine development. A recent study reported toxoid fusions with STa toxoid (STa(P13F fused at the N- or C-terminus, or inside the A subunit of LT(R192G elicited neutralizing antitoxin antibodies, and suggested application of toxoid fusions in ETEC vaccine development (Liu et al., Infect. Immun. 79:4002-4009, 2011. In this study, we generated a different STa toxoid (STa(A14Q and a triple-mutant LT toxoid (LT(S63K/R192G/L211A, tmLT, constructed a toxoid fusion (3xSTa(A14Q-tmLT that carried 3 copies of STa(A14Q for further facilitation of anti-STa immunogenicity, and assessed antigen safety and immunogenicity in a murine model to explore its potential for ETEC vaccine development. Mice immunized with this fusion antigen showed no adverse effects, and developed antitoxin antibodies particularly through the IP route. Anti-LT antibodies were detected and were shown neutralizing against CT in vitro. Anti-STa antibodies were also detected in the immunized mice, and serum from the IP immunized mice neutralized STa toxin in vitro. Data from this study indicated that toxoid fusion 3xSTa(A14Q-tmLT is safe and can induce neutralizing antitoxin antibodies, and provided helpful information for vaccine development against ETEC diarrhea.

Improving Phylogeny Reconstruction at the Strain Level Using Peptidome Datasets.

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Aitor Blanco-Míguez

2016-12-01

Full Text Available Typical bacterial strain differentiation methods are often challenged by high genetic similarity between strains. To address this problem, we introduce a novel in silico peptide fingerprinting method based on conventional wet-lab protocols that enables the identification of potential strain-specific peptides. These can be further investigated using in vitro approaches, laying a foundation for the development of biomarker detection and application-specific methods. This novel method aims at reducing large amounts of comparative peptide data to binary matrices while maintaining a high phylogenetic resolution. The underlying case study concerns the Bacillus cereus group, namely the differentiation of Bacillus thuringiensis, Bacillus anthracis and Bacillus cereus strains. Results show that trees based on cytoplasmic and extracellular peptidomes are only marginally in conflict with those based on whole proteomes, as inferred by the established Genome-BLAST Distance Phylogeny (GBDP method. Hence, these results indicate that the two approaches can most likely be used complementarily even in other organismal groups. The obtained results confirm previous reports about the misclassification of many strains within the B. cereus group. Moreover, our method was able to separate the B. anthracis strains with high resolution, similarly to the GBDP results as benchmarked via Bayesian inference and both Maximum Likelihood and Maximum Parsimony. In addition to the presented phylogenomic applications, whole-peptide fingerprinting might also become a valuable complementary technique to digital DNA-DNA hybridization, notably for bacterial classification at the species and subspecies level in the future.

Improving Phylogeny Reconstruction at the Strain Level Using Peptidome Datasets.

Science.gov (United States)

Blanco-Míguez, Aitor; Meier-Kolthoff, Jan P; Gutiérrez-Jácome, Alberto; Göker, Markus; Fdez-Riverola, Florentino; Sánchez, Borja; Lourenço, Anália

2016-12-01

Typical bacterial strain differentiation methods are often challenged by high genetic similarity between strains. To address this problem, we introduce a novel in silico peptide fingerprinting method based on conventional wet-lab protocols that enables the identification of potential strain-specific peptides. These can be further investigated using in vitro approaches, laying a foundation for the development of biomarker detection and application-specific methods. This novel method aims at reducing large amounts of comparative peptide data to binary matrices while maintaining a high phylogenetic resolution. The underlying case study concerns the Bacillus cereus group, namely the differentiation of Bacillus thuringiensis, Bacillus anthracis and Bacillus cereus strains. Results show that trees based on cytoplasmic and extracellular peptidomes are only marginally in conflict with those based on whole proteomes, as inferred by the established Genome-BLAST Distance Phylogeny (GBDP) method. Hence, these results indicate that the two approaches can most likely be used complementarily even in other organismal groups. The obtained results confirm previous reports about the misclassification of many strains within the B. cereus group. Moreover, our method was able to separate the B. anthracis strains with high resolution, similarly to the GBDP results as benchmarked via Bayesian inference and both Maximum Likelihood and Maximum Parsimony. In addition to the presented phylogenomic applications, whole-peptide fingerprinting might also become a valuable complementary technique to digital DNA-DNA hybridization, notably for bacterial classification at the species and subspecies level in the future.

Abortive Intestinal Infection With an Escherichia coli-Shigella flexneri Hybrid Strain

Science.gov (United States)

Formal, Samuel B.; LaBrec, E. H.; Kent, T. H.; Falkow, S.

1965-01-01

Formal, Samuel B., (Walter Reed Army Institute of Research, Washington, D.C.), E. H. LaBrec, T. H. Kent, and S. Falkow. Abortive intestinal infection with an Escherichia coli-Shigella flexneri hybrid strain. J. Bacteriol. 89:1374–1382. 1965.—The mechanism of the apparent loss of virulence of an Escherichia coli-Shigella flexneri hybrid strain was studied. The parent Shigella strain caused a fatal enteric infection when fed to starved guinea pigs, and signs of dysentery followed its oral administration to monkeys. The hybrid strain failed to produce any apparent symptoms when fed to either of these species. The parent strain was shown to invade the intestinal mucosa of starved guinea pigs. This caused a severe inflammatory reaction in the lamina propria, which progressed to ulceration of the intestinal epithelium and resulted in death of the animal. The hybrid strain also invaded the intestinal mucosa and produced an inflammatory reaction. In this case, the inflammatory reaction subsided, the intestine returned to normal within 4 days after challenge, and the animal survived. Both fluorescent-antibody techniques and in vivo growth studies have shown that the hybrid strain can not maintain itself in the intestinal mucosa. Preliminary studies have indicated that a similar situation also exists in the monkey. It is concluded that the virulence of dysentery bacilli rests not only in the capacity to reach the lamina propria, but also in the ability to multiply in this region. Images PMID:14293011

Campylobacter jejuni strains of human and chicken origin are invasive in chickens after oral challenge

DEFF Research Database (Denmark)

Knudsen, Katrine Nørrelund; Bang, Dang Duong; Andresen, Lars Ole

2006-01-01

to be associated with the Guillain Barre Syndrome (GBS) in humans. The minimum dose for establishing colonization in the clay-old chickens was approximately 2 cfu, whereas two- to threefold higher doses were required for establishing colonization in the 14-day-old chickens. Two of the C jejuni strains were shown...

Field Demonstration of Real-Time Wind Turbine Foundation Strain Monitoring.

Science.gov (United States)

Rubert, Tim; Perry, Marcus; Fusiek, Grzegorz; McAlorum, Jack; Niewczas, Pawel; Brotherston, Amanda; McCallum, David

2017-12-31

Onshore wind turbine foundations are generally over-engineered as their internal stress states are challenging to directly monitor during operation. While there are industry drivers to shift towards more economical foundation designs, making this transition safely will require new monitoring techniques, so that the uncertainties around structural health can be reduced. This paper presents the initial results of a real-time strain monitoring campaign for an operating wind turbine foundation. Selected reinforcement bars were instrumented with metal packaged optical fibre strain sensors prior to concrete casting. In this paper, we outline the sensors' design, characterisation and installation, and present 67 days of operational data. During this time, measured foundation strains did not exceed 95 μ ϵ , and showed a strong correlation with both measured tower displacements and the results of a foundation finite element model. The work demonstrates that real-time foundation monitoring is not only achievable, but that it has the potential to help operators and policymakers quantify the conservatism of their existing design codes.

Experimental reinfection of BALB/c mice with different recombinant type I/III strains of Toxoplasma gondii: involvement of IFN-gamma and IL-10.

Science.gov (United States)

Brandão, Geane Peroni; Melo, Maria Norma; Gazzinelli, Ricardo Tostes; Caetano, Braulia Costa; Ferreira, Adriana Melo; Silva, Letícia Azevedo; Vitor, Ricardo Wagner Almeida

2009-03-01

To assess reinfection of BALB/c mice with different Toxoplasma gondii strains, the animals were prime infected with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction and PCR-RFLP analysis to distinguish the different T. gondii strains present in possible co-infections. Anti-Toxoplasma immune responses were evaluated in D8-primed BALB/c mice by detecting IFN-gamma and IL-10 produced by T cells and measuring immunoglobulin levels in serum samples. PCR-RFLP demonstrated that BALB/c mice were reinfected with the EGS strain at 45 days post prime infection (dpi) and with the EGS and CH3 strains at 180 dpi. High levels of IFN-gamma were detected after D8 infection, with no significant difference between 45 and 180-day intervals. However, higher IL-10 levels and higher plasmatic IgG1 and IgA were detected from samples obtained 180 days after infection. BALB/c mice were susceptible to reinfection with different recombinant T. gondii strains and this susceptibility correlated with enhancement of IL-10 production.

Harnessing functional food strategies for the health challenges of space travel—Fermented soy for astronaut nutrition

Science.gov (United States)

Buckley, Nicole D.; Champagne, Claude P.; Masotti, Adriana I.; Wagar, Lisa E.; Tompkins, Thomas A.; Green-Johnson, Julia M.

2011-04-01

Astronauts face numerous health challenges during long-duration space missions, including diminished immunity, bone loss and increased risk of radiation-induced carcinogenesis. Changes in the intestinal flora of astronauts may contribute to these problems. Soy-based fermented food products could provide a nutritional strategy to help alleviate these challenges by incorporating beneficial lactic acid bacteria, while reaping the benefits of soy isoflavones. We carried out strain selection for the development of soy ferments, selecting strains of lactic acid bacteria showing the most effective growth and fermentation ability in soy milk ( Streptococcus thermophilus ST5, Bifidobacterium longum R0175 and Lactobacillus helveticus R0052). Immunomodulatory bioactivity of selected ferments was assessed using an in vitro challenge system with human intestinal epithelial and macrophage cell lines, and selected ferments show the ability to down-regulate production of the pro-inflammatory cytokine interleukin-8 following challenge with tumour necrosis factor-alpha. The impact of fermentation on vitamin B1 and B6 levels and on isoflavone biotransformation to agluconic forms was also assessed, with strain variation-dependent biotransformation ability detected. Overall this suggests that probiotic bacteria can be successfully utilized to develop soy-based fermented products targeted against health problems associated with long-term space travel.

High carriage of adherent invasive E. coli in wildlife and healthy individuals.

Science.gov (United States)

Rahmouni, Oumaïra; Vignal, Cécile; Titécat, Marie; Foligné, Benoît; Pariente, Benjamin; Dubuquoy, Laurent; Desreumaux, Pierre; Neut, Christel

2018-01-01

Adherent invasive Escherichia coli (AIEC) are suspected to be involved in the pathogenesis of inflammatory bowel diseases. Since AIEC was first described in 1999, despite important progress on its genomic and immune characterizations, some crucial questions remain unanswered, such as whether there exists a natural reservoir, or whether there is asymptomatic carriage. The ECOR collection, including E. coli strains isolated mainly from the gut of healthy humans and animals, constitutes an ideal tool to investigate AIEC prevalence in healthy condition. A total of 61 E. coli strains were examined for characteristics of AIEC. The adhesion, invasion and intramacrophage replication capabilities (AIEC phenotype) of 61 intestinal E. coli strains were determined. The absence of virulence-associated diarrheagenic E. coli pathotypes (EPEC, ETEC, EIEC, EHEC, DAEC, EAEC), and uropathogenic E. coli was checked. Out of 61 intestinal strains, 13 (21%) exhibit the AIEC phenotype, 7 are from human origin and 6 are from animal origin. Prevalence of AIEC strains is about 24 and 19% in healthy humans and animals respectively. These strains are highly genetically diverse as they are distributed among the main described phylogroups. Among E. coli strains from the ECOR collection, we also detected strains able to detach I-407 cells. Our study described for the first time AIEC strains isolated from the feces of healthy humans and animals.

Comparison of three methods of calculating strain in the mouse ulna in exogenous loading studies.

Science.gov (United States)

Norman, Stephanie C; Wagner, David W; Beaupre, Gary S; Castillo, Alesha B

2015-01-02

Axial compression of mouse limbs is commonly used to induce bone formation in a controlled, non-invasive manner. Determination of peak strains caused by loading is central to interpreting results. Load-strain calibration is typically performed using uniaxial strain gauges attached to the diaphyseal, periosteal surface of a small number of sacrificed animals. Strain is measured as the limb is loaded to a range of physiological loads known to be anabolic to bone. The load-strain relationship determined by this subgroup is then extrapolated to a larger group of experimental mice. This method of strain calculation requires the challenging process of strain gauging very small bones which is subject to variability in placement of the strain gauge. We previously developed a method to estimate animal-specific periosteal strain during axial ulnar loading using an image-based computational approach that does not require strain gauges. The purpose of this study was to compare the relationship between load-induced bone formation rates and periosteal strain at ulnar midshaft using three different methods to estimate strain: (A) Nominal strain values based solely on load-strain calibration; (B) Strains calculated from load-strain calibration, but scaled for differences in mid-shaft cross-sectional geometry among animals; and (C) An alternative image-based computational method for calculating strains based on beam theory and animal-specific bone geometry. Our results show that the alternative method (C) provides comparable correlation between strain and bone formation rates in the mouse ulna relative to the strain gauge-dependent methods (A and B), while avoiding the need to use strain gauges. Published by Elsevier Ltd.

Measurement of in-plane strain with dual beam spatial phase-shift digital shearography

International Nuclear Information System (INIS)

Xie, Xin; Chen, Xu; Li, Junrui; Yang, Lianxiang; Wang, Yonghong

2015-01-01

Full-field in-plane strain measurement under dynamic loading by digital shearography remains a big challenge in practice. A phase measurement for in-plane strain information within one time frame has to be achieved to solve this problem. This paper presents a dual beam spatial phase-shift digital shearography system with the capacity to measure phase distribution corresponding to in-plane strain information within a single time frame. Two laser beams with different wavelengths are symmetrically arranged to illuminate the object under test, and two cameras with corresponding filters, which enable simultaneous recording of two shearograms, are utilized for data acquisition. The phase information from the recorded shearograms, which corresponds to the in-plane strain, is evaluated by the spatial phase-shift method. The spatial phase-shift shearography system realizes a measurement of the in-plane strain through the introduction of the spatial phase-shift technique, using one frame after the loading and one frame before loading. This paper presents the theory of the spatial phase-shift digital shearography for in-plane strain measurement and its derivation, experimental results, and the technique’s potential. (paper)

Effect of mouse strain in a model of chemical-induced respiratory allergy.

Science.gov (United States)

Nishino, Risako; Fukuyama, Tomoki; Watanabe, Yuko; Kurosawa, Yoshimi; Ueda, Hideo; Kosaka, Tadashi

2014-01-01

The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical-related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical-related respiratory allergens by using a long-term sensitization-challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences in respiratory allergic reactions to the well-known chemical respiratory allergen glutaraldehyde (GA). According to our protocol, BALB/c, NC/Nga, C3H/HeN, C57BL/6N, and CBA/J mice were sensitized dermally with GA for 3 weeks and then challenged with intratracheal or inhaled GA at 2 weeks after the last sensitization. The day after the final challenge, all mice were euthanized, and total serum IgE levels were assayed. In addition, immunocyte counts, cytokine production, and chemokine levels in the hilar lymph nodes (LNs) and bronchoalveolar lavage fluids (BALF) were also assessed. In conclusion, BALB/c and NC/Nga mice demonstrated markedly increased IgE reactions. Inflammatory cell counts in BALF were increased in the treated groups of all strains, especially BALB/c, NC/Nga, and CBA/J strains. Cytokine levels in LNs were increased in all treated groups except for C3H/HeN and were particularly high in BALB/c and NC/Nga mice. According to our results, we suggest that BALB/c and NC/Nga are highly susceptible to respiratory allergic responses and therefore are good candidates for use in our model for detecting environmental chemical respiratory allergens.

Marker-assisted selection on E. coli F4ab/ac resistance and the effect on neonatal survival in piglets

DEFF Research Database (Denmark)

Jørgensen, Claus Bøttcher; Anderson, Susan I.; Cirera, Susanna

Enterotoxigenic Escherichia coli (ETEC) that express the F4ab or F4ac fimbriae (formerly known as K88ab/ac) are major causes of diarrhea and death in neonatal and young pigs. A locus controlling susceptibility towards ETEC F4ab/ac has previously been mapped to pig chromosome 13q41. A number...

Channeling techniques to study strains and defects in heterostructures and multi quantum wells

Science.gov (United States)

Pathak, A. P.; Dhamodaran, S.; Sathish, N.

2005-08-01

The importance and advantages of heterostructures and Quantum Wells (QWs) in device technology has made research challenging due to lack of direct techniques for their characterization. Particularly the characterization of strain and defects at the interfaces has become important due to their dominance in the electrical and optical properties of materials and devices. RBSiC has been used to study variety of defects in single crystalline materials, for nearly four decades now. Channeling based experiments play a crucial role in giving depth information of strain and defects. Ion beams are used for both material characterizations as well as for modifications. Hence it is also possible to monitor the modifications online, which are discussed in detail. In the present work, Swift Heavy Ion (SHI) modification of III-V semiconductor heterostnictures and MQWs and the results of subsequent strain measurements by RBSiC in initially strained as well as lattice matched systems are discussed. We find that the compressive strain decreases due to SHI irradiation and a tensile strain is induced in an initially lattice matched system. The incident ion fluence dependence of strain modifications in the heterostructures will also be discussed. The use of high energy channeling for better sensitivity of strain measurements in low mismatch materials will be discussed in detail. Wherever possible, a comparison of results with those obtained by other techniques like HRXRD is given.

CRISPR–Cas system enables fast and simple genome editing of industrial Saccharomyces cerevisiae strains

DEFF Research Database (Denmark)

Stovicek, Vratislav; Borodina, Irina; Förster, Jochen

2015-01-01

, their genetic manipulation is challenging, as they are usually diploid or polyploid. Therefore, there is a need to develop more efficient genetic engineering tools. We applied a CRISPR–Cas9 system for genome editing of different industrial strains, and show simultaneous disruption of two alleles of a gene...... in several unrelated strains with the efficiency ranging between 65% and 78%. We also achieved simultaneous disruption and knock-in of a reporter gene, and demonstrate the applicability of the method by designing lactic acid-producing strains in a single transformation event, where insertion...... of a heterologous gene and disruption of two endogenous genes occurred simultaneously. Our study provides a foundation for efficient engineering of industrial yeast cell factories....

Draft genome sequences of the oomycete Pythium insidiosum strain CBS 573.85 from a horse with pythiosis and strain CR02 from the environment

Directory of Open Access Journals (Sweden)

Preecha Patumcharoenpol

2018-02-01

Full Text Available Pythium insidiosum is an aquatic oomycete microorganism that causes the fatal infectious disease, pythiosis, in humans and animals. The organism has been successfully isolated from the environment worldwide. Diagnosis and treatment of pythiosis is difficult and challenging. Genome sequences of P. insidiosum, isolated from humans, are available and accessible in public databases. To further facilitate biology-, pathogenicity-, and evolution-related genomic and genetic studies of P. insidiosum, we report two additional draft genome sequences of the P. insidiosum strain CBS 573.85 (35.6 Mb in size; accession number, BCFO00000000.1 isolated from a horse with pythiosis, and strain CR02 (37.7 Mb in size; accession number, BCFR00000000.1 isolated from the environment. Keywords: Pythium insidiosum, Pythiosis, Draft genome sequence

Systems biology solutions for biochemical production challenges

DEFF Research Database (Denmark)

Hansen, Anne Sofie Lærke; Lennen, Rebecca M; Sonnenschein, Nikolaus

2017-01-01

There is an urgent need to significantly accelerate the development of microbial cell factories to produce fuels and chemicals from renewable feedstocks in order to facilitate the transition to a biobased society. Methods commonly used within the field of systems biology including omics...... characterization, genome-scale metabolic modeling, and adaptive laboratory evolution can be readily deployed in metabolic engineering projects. However, high performance strains usually carry tens of genetic modifications and need to operate in challenging environmental conditions. This additional complexity...... compared to basic science research requires pushing systems biology strategies to their limits and often spurs innovative developments that benefit fields outside metabolic engineering. Here we survey recent advanced applications of systems biology methods in engineering microbial production strains...

Strain-controlled magnetic domain wall propagation in hybrid piezoelectric/ferromagnetic structures.

Science.gov (United States)

Lei, Na; Devolder, Thibaut; Agnus, Guillaume; Aubert, Pascal; Daniel, Laurent; Kim, Joo-Von; Zhao, Weisheng; Trypiniotis, Theodossis; Cowburn, Russell P; Chappert, Claude; Ravelosona, Dafiné; Lecoeur, Philippe

2013-01-01

The control of magnetic order in nanoscale devices underpins many proposals for integrating spintronics concepts into conventional electronics. A key challenge lies in finding an energy-efficient means of control, as power dissipation remains an important factor limiting future miniaturization of integrated circuits. One promising approach involves magnetoelectric coupling in magnetostrictive/piezoelectric systems, where induced strains can bear directly on the magnetic anisotropy. While such processes have been demonstrated in several multiferroic heterostructures, the incorporation of such complex materials into practical geometries has been lacking. Here we demonstrate the possibility of generating sizeable anisotropy changes, through induced strains driven by applied electric fields, in hybrid piezoelectric/spin-valve nanowires. By combining magneto-optical Kerr effect and magnetoresistance measurements, we show that domain wall propagation fields can be doubled under locally applied strains. These results highlight the prospect of constructing low-power domain wall gates for magnetic logic devices.

Discrimination of Temperature and Strain in Brillouin Optical Time Domain Analysis Using a Multicore Optical Fiber.

Science.gov (United States)

Zaghloul, Mohamed A S; Wang, Mohan; Milione, Giovanni; Li, Ming-Jun; Li, Shenping; Huang, Yue-Kai; Wang, Ting; Chen, Kevin P

2018-04-12

Brillouin optical time domain analysis is the sensing of temperature and strain changes along an optical fiber by measuring the frequency shift changes of Brillouin backscattering. Because frequency shift changes are a linear combination of temperature and strain changes, their discrimination is a challenge. Here, a multicore optical fiber that has two cores is fabricated. The differences between the cores' temperature and strain coefficients are such that temperature (strain) changes can be discriminated with error amplification factors of 4.57 °C/MHz (69.11 μ ϵ /MHz), which is 2.63 (3.67) times lower than previously demonstrated. As proof of principle, using the multicore optical fiber and a commercial Brillouin optical time domain analyzer, the temperature (strain) changes of a thermally expanding metal cylinder are discriminated with an error of 0.24% (3.7%).

Discrimination of Temperature and Strain in Brillouin Optical Time Domain Analysis Using a Multicore Optical Fiber

Directory of Open Access Journals (Sweden)

Mohamed A. S. Zaghloul

2018-04-01

Full Text Available Brillouin optical time domain analysis is the sensing of temperature and strain changes along an optical fiber by measuring the frequency shift changes of Brillouin backscattering. Because frequency shift changes are a linear combination of temperature and strain changes, their discrimination is a challenge. Here, a multicore optical fiber that has two cores is fabricated. The differences between the cores’ temperature and strain coefficients are such that temperature (strain changes can be discriminated with error amplification factors of 4.57 °C/MHz (69.11 μ ϵ /MHz, which is 2.63 (3.67 times lower than previously demonstrated. As proof of principle, using the multicore optical fiber and a commercial Brillouin optical time domain analyzer, the temperature (strain changes of a thermally expanding metal cylinder are discriminated with an error of 0.24% (3.7%.

Synthetic Biology of Cyanobacteria: Unique Challenges and Opportunities

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Bertram M Berla

2013-08-01

Full Text Available Photosynthetic organisms, and especially cyanobacteria, hold great promise as sources of renewably-produced fuels, bulk and specialty chemicals, and nutritional products. Synthetic biology tools can help unlock cyanobacteria’s potential for these functions, but unfortunately tool development for these organisms has lagged behind that for S. cerevisiae and E. coli. While these organisms may in many cases be more difficult to work with as ‘chassis’ strains for synthetic biology than certain heterotrophs, the unique advantages of autotrophs in biotechnology applications as well as the scientific importance of improved understanding of photosynthesis warrant the development of these systems into something akin to a ‘green E. coli’. In this review, we highlight unique challenges and opportunities for development of synthetic biology approaches in cyanobacteria. We review classical and recently developed methods for constructing targeted mutants in various cyanobacterial strains, and offer perspective on what genetic tools might most greatly expand the ability to engineer new functions in such strains. Similarly, we review what genetic parts are most needed for the development of cyanobacterial synthetic biology. Finally, we highlight recent methods to construct genome-scale models of cyanobacterial metabolism and to use those models to measure properties of autotrophic metabolism. Throughout this paper, we discuss some of the unique challenges of a diurnal, autotrophic lifestyle along with how the development of synthetic biology and biotechnology in cyanobacteria must fit within those constraints.

Environmental Burkholderia cenocepacia Strain Enhances Fitness by Serial Passages during Long-Term Chronic Airways Infection in Mice

Directory of Open Access Journals (Sweden)

Alessandra Bragonzi

2017-11-01

Full Text Available Burkholderia cenocepacia is an important opportunistic pathogen in cystic fibrosis (CF patients, and has also been isolated from natural environments. In previous work, we explored the virulence and pathogenic potential of environmental B. cenocepacia strains and demonstrated that they do not differ from clinical strains in some pathogenic traits. Here, we investigated the ability of the environmental B. cenocepacia Mex1 strain, isolated from the maize rhizosphere, to persist and increase its virulence after serial passages in a mouse model of chronic infection. B. cenocepacia Mex1 strain, belonging to the recA lineage IIIA, was embedded in agar beads and challenged into the lung of C57Bl/6 mice. The mice were sacrificed after 28 days from infection and their lungs were tested for bacterial loads. Agar beads containing the pool of B. cenocepacia colonies from the four sequential passages were used to infect the mice. The environmental B. cenocepacia strain showed a low incidence of chronic infection after the first passage; after the second, third and fourth passages in mice, its ability to establish chronic infection increased significantly and progressively up to 100%. Colonial morphology analysis and genetic profiling of the Mex1-derived clones recovered after the fourth passage from infected mice revealed that they were indistinguishable from the challenged strain both at phenotypic and genetic level. By testing the virulence of single clones in the Galleria mellonella infection model, we found that two Mex1-derived clones significantly increased their pathogenicity compared to the parental Mex1 strain and behaved similarly to the clinical and epidemic B. cenocepacia LMG16656T. Our findings suggest that serial passages of the environmental B. cenocepacia Mex1 strain in mice resulted in an increased ability to determine chronic lung infection and the appearance of clonal variants with increased virulence in non-vertebrate hosts.

Attenuation of the goose parvovirus strain B. Laboratory and field trials of the attenuated mutant for vaccination against Derzsy's disease.

Science.gov (United States)

Kisary, J; Derzsy, D; Meszaros, J

1978-07-01

Serial transfer of the goose parvovirus strain B, causal agent of Derzsy's gosling disease, in cultured goose-embryo fibroblast (GEF) resulted in a mutant (designated as Bav) apathogenic for both goose embryos and susceptible goslings. Goose embryos inoculated with the 38th or higher passages of strain B survived the infection, although the virus replicated in their organs. Susceptible goslings survived challenge with the Bav strain without showing symptoms, and developed normally. Only 4.2% of gosling progeny of parents vaccinated twice with strain Bav died after challenge with the virulent strain B goose parvovirus compared with 95% of gosling progeny of unvaccinated parents. Progeny of vaccinated and unvaccinated geese were placed on a farm on which Derzsy's disease was present. During the first month of life mortality was 7.7% in the progeny of vaccinated geese compared with 59.8% in the progeny of the unvaccinated geese. At 8 weeks of age the mean weight of the vaccinated goslings was 20% greater than for the unvaccinated goslings. These results indicate that the attenuated apathogenic Bav mutant is suitable for the immunisation of layers to protect their progeny by passive immunisation against Derzsy's disease.

Persistent Transmissible Gastroenteritis Virus Infection Enhances Enterotoxigenic Escherichia coli K88 Adhesion by Promoting Epithelial-Mesenchymal Transition in Intestinal Epithelial Cells.

Science.gov (United States)

Xia, Lu; Dai, Lei; Yu, Qinghua; Yang, Qian

2017-11-01

Transmissible gastroenteritis virus (TGEV) is a coronavirus characterized by diarrhea and high morbidity rates, and the mortality rate is 100% in piglets less than 2 weeks old. Pigs infected with TGEV often suffer secondary infection by other pathogens, which aggravates the severity of diarrhea, but the mechanisms remain unknown. Here, we hypothesized that persistent TGEV infection stimulates the epithelial-mesenchymal transition (EMT), and thus enterotoxigenic Escherichia coli (ETEC) can more easily adhere to generating cells. Intestinal epithelial cells are the primary targets of TGEV and ETEC infections. We found that TGEV can persistently infect porcine intestinal columnar epithelial cells (IPEC-J2) and cause EMT, consistent with multiple changes in key cell characteristics. Infected cells display fibroblast-like shapes; exhibit increases in levels of mesenchymal markers with a corresponding loss of epithelial markers; have enhanced expression levels of interleukin-1β (IL-1β), IL-6, IL-8, transforming growth factor β (TGF-β), and tumor necrosis factor alpha (TNF-α) mRNAs; and demonstrate increases in migratory and invasive behaviors. Additional experiments showed that the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) signaling pathways via TGF-β is critical for the TGEV-mediated EMT process. Cellular uptake is also modified in cells that have undergone EMT. TGEV-infected cells have higher levels of integrin α5 and fibronectin and exhibit enhanced ETEC K88 adhesion. Reversal of EMT reduces ETEC K88 adhesion and inhibits the expression of integrin α5 and fibronectin. Overall, these results suggest that TGEV infection induces EMT in IPEC-J2 cells, increasing the adhesion of ETEC K88 in the intestine and facilitating dual infection. IMPORTANCE Transmissible gastroenteritis virus (TGEV) causes pig diarrhea and is often followed by secondary infection by other pathogens. In this study, we showed

Split-Hopkinson Pressure Bar: an experimental technique for high strain rate tests

International Nuclear Information System (INIS)

Sharma, S.; Chavan, V.M.; Agrawal, R.G.; Patel, R.J.; Kapoor, R.; Chakravartty, J.K.

2011-06-01

Mechanical properties of materials are, in general, strain rate dependent, i.e. they respond differently at quasi-static and higher strain rate condition. The Split-Hopkinson Pressure Bar (SHPB), also referred to as Kolsky bar is a commonly used setup for high strain rate testing. SHPB is suitable for high strain rate test in strain rate range of 10 2 to 10 4 s -1 . These high strain rate data are required for safety and structural integrity assessment of structures subjected to dynamic loading. As high strain rate data are not easily available in open literature need was felt for setting up such high strain rate testing machine. SHPB at BARC was designed and set-up inhouse jointly by Refuelling Technology Division and Mechanical Metallurgy Division, at Hall no. 3, BARC. A number of conceptual designs for SHPB were thought of and the optimized design was worked out. The challenges of precision tolerance, straightness in bars and design and proper functioning of pneumatic gun were met. This setup has been used extensively to study the high strain rate material behavior. This report introduces the SHPB in general and the setup at BARC in particular. The history of development of SHPB, the basic formulations of one dimensional wave propagation, the relations between the wave velocity, particle velocity and elastic strain in a one dimensional bar, and the equations used to obtain the final stress vs. strain curves are described. The calibration of the present setup, the pre-test calculations and the posttest analysis of data are described. Finally some of the experimental results on different materials such as Cu, SS305, SA516 and Zr, at room temperature and elevated temperatures are presented. (author)

Local host response following an intramammary challenge with Staphylococcus fleurettii and different strains of Staphylococcus chromogenes in dairy heifers

OpenAIRE

Piccart , Kristine; Verbeke , Joren; De Visscher , Anneleen; Piepers , Sofie; Haesebrouck , Freddy; De Vliegher , Sarne

2016-01-01

International audience; AbstractCoagulase-negative staphylococci (CNS) are a common cause of subclinical mastitis in dairy cattle. The CNS inhabit various ecological habitats, ranging between the environment and the host. In order to obtain a better insight into the host response, an experimental infection was carried out in eight healthy heifers in mid-lactation with three different CNS strains: a Staphylococcus fleurettii strain originating from sawdust bedding, an intramammary Staphylococc...

Respiratory and oral vaccination improves protection conferred by the live vaccine strain against pneumonic tularemia in the rabbit model.

Science.gov (United States)

Stinson, Elizabeth; Smith, Le'Kneitah P; Cole, Kelly Stefano; Barry, Eileen M; Reed, Douglas S

2016-10-01

Tularemia is a severe, zoonotic disease caused by a gram-negative bacterium, Francisella tularensis We have previously shown that rabbits are a good model of human pneumonic tularemia when exposed to aerosols containing a virulent, type A strain, SCHU S4. We further demonstrated that the live vaccine strain (LVS), an attenuated type B strain, extended time to death when given by scarification. Oral or aerosol vaccination has been previously shown in humans to offer superior protection to parenteral vaccination against respiratory tularemia challenge. Both oral and aerosol vaccination with LVS were well tolerated in the rabbit with only minimal fever and no weight loss after inoculation. Plasma antibody titers against F. tularensis were higher in rabbits that were vaccinated by either oral or aerosol routes compared to scarification. Thirty days after vaccination, all rabbits were challenged with aerosolized SCHU S4. LVS given by scarification extended time to death compared to mock-vaccinated controls. One orally vaccinated rabbit did survive aerosol challenge, however, only aerosol vaccination extended time to death significantly compared to scarification. These results further demonstrate the utility of the rabbit model of pneumonic tularemia in replicating what has been reported in humans and macaques as well as demonstrating the utility of vaccination by oral and respiratory routes against an aerosol tularemia challenge. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dilemas da docência na educação a distância: um estudo sobre o desenvolvimento profissional na perspectiva dos tutores da Rede e-Tec Brasil

Directory of Open Access Journals (Sweden)

Luciane Penteado Chaquime

Full Text Available Resumo: A docência configura-se como profissão por possuir um corpo de conhecimentos específicos para seu exercício, além de ser aprendida continuamente. Ao longo da trajetória profissional, o docente reinterpreta e amplia saberes da formação inicial e constrói novos por meio da prática e das interações com os alunos. Assim, pode-se pensar a tutoria virtual como uma atividade que contribui para o desenvolvimento profissional docente ao favorecer a construção de saberes pela experiência. O artigo traz resultados de um estudo em que um dos objetivos foi analisar como a atuação na tutoria virtual de cursos de educação a distância (EaD mediados por tecnologias digitais de informação e comunicação pode contribuir para o desenvolvimento profissional docente. A triangulação metodológica foi empregada para a investigação que ocorreu em etapas: levantamento e estudo de bibliografia; coleta de dados utilizando questionário, entrevista individual, sessões de entrevistas coletivas e análise de documentação oficial; sistematização e análise dos dados; e divulgação dos resultados. Os sujeitos foram os tutores virtuais de cursos EaD oferecidos pelo Instituto Federal de Educação, Ciência e Tecnologia de São Paulo (IFSP, por meio da Rede e-Tec Brasil. Dentre os principais resultados, observou-se que a experiência na tutoria virtual pode ser considerada um elemento que contribui para o desenvolvimento profissional docente, embora gere alguns dilemas.

Assessment of strain and strain rate by two-dimensional speckle tracking in mice: comparison with tissue Doppler echocardiography and conductance catheter measurements.

Science.gov (United States)

Ferferieva, V; Van den Bergh, A; Claus, P; Jasaityte, R; La Gerche, A; Rademakers, F; Herijgers, P; D'hooge, J

2013-08-01

This study was designed in order to compare the strain and strain rate deformation parameters assessed by speckle tracking imaging (STI) with those of tissue Doppler imaging (TDI) and conductance catheter measurements in chronic murine models of left ventricular (LV) dysfunction. Twenty-four male C57BL/6J mice were assigned to wild-type (n = 8), myocardial infarction (n = 8) and transaortic constriction (n = 8) groups. Echocardiographic and conductance measurements were simultaneously performed at rest and during dobutamine infusion (5 µg/kg/min) in all animals 10 weeks post-surgery. The LV circumferential strain (Scirc) and the strain rate (SRcirc) were derived from grey scale and tissue Doppler data at frame rates of 224 and 375 Hz, respectively. Scirc and SRcirc by TDI/STI correlated well with the preload recruitable stroke work (PRSW) (r = -0.64 and -0.71 for TDI; r = -0.46 and -0.50 for STI, P < 0.05). Both modalities showed a good agreement with respect to Scirc and SRcirc (r = 0.60 and r = 0.63, P < 0.05). During stress, however, TDI-estimated Scirc and SRcirc values were predominantly higher than those measured by STI (P < 0.05). The similarity of Scirc and SRcirc measurements with respect to the STI/TDI data was examined by the Bland-Altman analysis. In mice, the STI- and TDI-derived strain and strain rate deformation parameters relate closely to intrinsic myocardial function. At low heart rate-to-frame rate ratios (HR/FR), both STI and TDI are equally acceptable for assessing the LV function non-invasively in these animals. At HR/FR (e.g. dobutamine challenge), however, these methods cannot be used interchangeably as STI underestimates S and SR at high values.

Development of fowl cholera vaccine: I. Protection of Pasteurella multocida local isolate vaccine against challenge of homologous and heterologous strains.

Directory of Open Access Journals (Sweden)

Supar

2001-03-01

Full Text Available Pasteurella multocida locally isolated from chicken and ducks (BCC 299, BCC 2331, DY1, DY2, 12TG, 15TG andimported strains (BCC 1359, 1362; HEDDLESTON group 1 and 6 respectively had been tested for its pathogenicity in theprevious study. The aims of this experiment were to study the preparation of local isolate pasteurellosis vaccines and to determine the protective effect of that vaccines in chicken against the highly pathogenic local isolates of P. multocida. Killed monovalent, bivalent and polyvalent pasteurellosis vaccines were prepared and each was adjunvanted with aluminum hydroxide gel at a final concentration of 1.5% and the cell concentration was equal to the No 10 of MacFarland tube standard. Each of the vaccine prepared was used to vaccinated on a group of six week old of layer chicken (8 per group. Each chicken was subcutaneously injected with 0.2 ml of vaccine, four weeks later each was boostered with similar vaccine with the same dose. Two weeks after giving the boostered vaccine each group of chicken were challenged, half with life bacterium of P. Multocida BCC 2331 and other with DY2. Any chick which survive after challenge was designated as protected by vaccination. Before vaccination 1 ml of blood was drawn from each of chicken and then two weeks apart up to challenge. Serum from each sample was separated and kept in deep freeze until tested by enzyme-linked immunosorbent assay (ELISA. Chicken vaccinated with killed whole cell P. multocida vaccines of monovalent (BCC 2331 or DY2 and bivalent (BCC 2331 + DY2 were protected against challenge with live bacterium of either BCC 2331 or DY2 at rate 67-100%. There was no protection in chicken vaccinated with either BCC 299, DY1, 12TG, 15TG, BCC 1359, or 1362 killed vaccine. Similarly no protection of chicken vaccinated with either DY1 + BCC299, 12TG + 15TG or BCC 1359 + BCC 1362 bivalent vaccines. The protection rate of the polyvalent local isolate vaccine was at average 50-75%. All

A strain gauge

DEFF Research Database (Denmark)

2016-01-01

The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

Science.gov (United States)

Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

2017-03-01

Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Saccharomyces cerevisiae strains tor second-generation ethanol production : from academie exploration to industrial implementation

NARCIS (Netherlands)

Jansen, Mickel L.A.; Bracher, J.M.; Papapetridis, I.; Verhoeven, M.D.; de Bruijn, J.A.; de Waal, P.; van Maris, A.J.A.; Klaassen, P; Pronk, J.T.

2017-01-01

The recent start-up of several full-scale ‘second generation’ ethanol plants marks a major milestone in the development of Saccharomyces cerevisiae strains for fermentation of lignocellulosic hydrolysates of agricultural residues and energy crops. After a discussion of the challenges that these

Incorporating comparative genomics into the design-test-learn cycle of microbial strain engineering.

Science.gov (United States)

Sardi, Maria; Gasch, Audrey P

2017-08-01

Engineering microbes with new properties is an important goal in industrial engineering, to establish biological factories for production of biofuels, commodity chemicals and pharmaceutics. But engineering microbes to produce new compounds with high yield remains a major challenge toward economically viable production. Incorporating several modern approaches, including synthetic and systems biology, metabolic modeling and regulatory rewiring, has proven to significantly advance industrial strain engineering. This review highlights how comparative genomics can also facilitate strain engineering, by identifying novel genes and pathways, regulatory mechanisms and genetic background effects for engineering. We discuss how incorporating comparative genomics into the design-test-learn cycle of strain engineering can provide novel information that complements other engineering strategies. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Time-course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12-week-old free-range chickens

DEFF Research Database (Denmark)

Mbuthia, P.G.; Njagi, L.W.; Nyaga, P.N.

2011-01-01

Twelve-week-old indigenous chickens, either immune-suppressed using dexamethasone (IS) or non-immune-suppressed (NIS), were challenged with a low virulent strain, Pasteurella multocida strain NCTC 10322(T), and developed clinical signs and pathological lesions typical of chronic fowl cholera. NIS...

Experimental reinfection of BALB/c mice with different recombinant type I/III strains of Toxoplasma gondii: involvement of IFN-³ and IL-10

Directory of Open Access Journals (Sweden)

Geane Peroni Brandão

2009-03-01

Full Text Available To assess reinfection of BALB/c mice with different Toxoplasma gondii strains, the animals were prime infected with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction and PCR-RFLP analysis to distinguish the different T. gondii strains present in possible co-infections. Anti-Toxoplasma immune responses were evaluated in D8-primed BALB/c mice by detecting IFN-³ and IL-10 produced by T cells and measuring immunoglobulin levels in serum samples. PCR-RFLP demonstrated that BALB/c mice were reinfected with the EGS strain at 45 days post prime infection (dpi and with the EGS and CH3 strains at 180 dpi. High levels of IFN-³ were detected after D8 infection, with no significant difference between 45 and 180-day intervals. However, higher IL-10 levels and higher plasmatic IgG1 and IgA were detected from samples obtained 180 days after infection. BALB/c mice were susceptible to reinfection with different recombinant T. gondii strains and this susceptibility correlated with enhancement of IL-10 production.

Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis

Directory of Open Access Journals (Sweden)

Lynne V. McFarland

2018-05-01

Full Text Available BackgroundAs the use and diversity of probiotic products expands, the choice of an appropriate type of probiotic is challenging for both medical care professionals and the public alike. Two vital factors in choosing the appropriate probiotic are often ignored, namely, the probiotic strain-specificity and disease-specificity for efficacy. Reviews and meta-analyses often pool together different types of probiotics, resulting in misleading conclusions of efficacy.MethodsA systematic review of the literature (1970–2017 assessing strain-specific and disease-specific probiotic efficacy was conducted. Trials were included for probiotics with an identifiable strain (either single strain or mixtures of strains that had at least two randomized, controlled trials for each type of disease indication. The goal was to determine if probiotic strains have strain and/or disease-specific efficacy.ResultsWe included 228 trials and found evidence for both strain specificity and disease specificity for the efficacy of specific probiotic strains. Significant efficacy evidence was found for 7 (70% of probiotic strain(s among four preventive indications and 11 (65% probiotic strain(s among five treatment indications. Strain-specific efficacy for preventing adult antibiotic-associated diarrhea was clearly demonstrated within the Lactobacillus species [e.g., by the mixture of Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R, and Lactobacillus rhamnosus CLR2 (Bio-K+®, by L. casei DN114001 (Actimel® and by Lactobacillus reuteri 55730], while other Lactobacillus strains did not show efficacy. Significant disease-specific variations in efficacy was demonstrated by L. rhamnosus GG and Saccharomyces boulardii CNCM I-745, as well as other probiotic strains.ConclusionStrong evidence was found supporting the hypothesis that the efficacy of probiotics is both strain-specific and disease-specific. Clinical guidelines and meta-analyses need to recognize the

Comparison of biological and genomic characteristics between a newly isolated mink enteritis parvovirus MEV-LHV and an attenuated strain MEV-L.

Science.gov (United States)

Mao, Yaping; Wang, Jigui; Hou, Qiang; Xi, Ji; Zhang, Xiaomei; Bian, Dawei; Yu, Yongle; Wang, Xi; Liu, Weiquan

2016-06-01

A virus isolated from mink showing clinical signs of enteritis was identified as a high virulent mink enteritis parvovirus (MEV) based on its biological characteristics in vivo and in vitro. Mink, challenged with this strain named MEV-LHV, exhibited severe pathological lesions as compared to those challenged with attenuated strain MEV-L. MEV-LHV also showed higher infection and replication efficiencies in vitro than MEV-L. Sequence of the complete genome of MEV-LHV was determined and analyzed in comparison with those in GenBank, which revealed that MEV-LHV shared high homology with virulent strain MEV SD12/01, whereas MEV-L was closely related to Abashiri and vaccine strain MEVB, and belonged to a different branch of the phylogenetic tree. The genomes of the two strains differed by insertions and deletions in their palindromic termini and specific unique mutations (especially VP2 300) in coding sequences which may be involved in viral replication and pathogenicity. The results of this study provide a better understanding of the biological and genomic characteristics of MEV and identify certain regions and sites that may be involved in viral replication and pathogenicity.

Microscale and nanoscale strain mapping techniques applied to creep of rocks

Science.gov (United States)

Quintanilla-Terminel, Alejandra; Zimmerman, Mark E.; Evans, Brian; Kohlstedt, David L.

2017-07-01

Usually several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total strain is necessary to bridge the gaps from observations of microstructures, to geomechanical descriptions, to extrapolating from laboratory data to field observations. Here, we describe the experimental and computational techniques involved in microscale strain mapping (MSSM), which allows strain produced during high-pressure, high-temperature deformation experiments to be tracked with high resolution. MSSM relies on the analysis of the relative displacement of initially regularly spaced markers after deformation. We present two lithography techniques used to pattern rock substrates at different scales: photolithography and electron-beam lithography. Further, we discuss the challenges of applying the MSSM technique to samples used in high-temperature and high-pressure experiments. We applied the MSSM technique to a study of strain partitioning during creep of Carrara marble and grain boundary sliding in San Carlos olivine, synthetic forsterite, and Solnhofen limestone at a confining pressure, Pc, of 300 MPa and homologous temperatures, T/Tm, of 0.3 to 0.6. The MSSM technique works very well up to temperatures of 700 °C. The experimental developments described here show promising results for higher-temperature applications.

Cooperative photoinduced metastable phase control in strained manganite films

Science.gov (United States)

Zhang, Jingdi; Tan, Xuelian; Liu, Mengkun; Teitelbaum, S. W.; Post, K. W.; Jin, Feng; Nelson, K. A.; Basov, D. N.; Wu, Wenbin; Averitt, R. D.

2016-09-01

A major challenge in condensed-matter physics is active control of quantum phases. Dynamic control with pulsed electromagnetic fields can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. Here we demonstrate strain-engineered tuning of La2/3Ca1/3MnO3 into an emergent charge-ordered insulating phase with extreme photo-susceptibility, where even a single optical pulse can initiate a transition to a long-lived metastable hidden metallic phase. Comprehensive single-shot pulsed excitation measurements demonstrate that the transition is cooperative and ultrafast, requiring a critical absorbed photon density to activate local charge excitations that mediate magnetic-lattice coupling that, in turn, stabilize the metallic phase. These results reveal that strain engineering can tune emergent functionality towards proximal macroscopic states to enable dynamic ultrafast optical phase switching and control.

Strain coupling between nitrogen vacancy centers and the mechanical motion of a diamond optomechanical crystal resonator

Science.gov (United States)

Cady, J. V.; Lee, K. W.; Ovartchaiyapong, P.; Bleszynski Jayich, A. C.

Several experiments have recently demonstrated coupling between nitrogen vacancy (NV) centers in diamond and mechanical resonators via crystal strain. In the strong coupling regime, such devices could realize applications critical to emerging quantum technologies, including phonon-mediated spin-spin interactions and mechanical cooling with the NV center1. An outstanding challenge for these devices is generating higher strain coupling in high frequency devices while maintaining the excellent coherence properties of the NV center and high mechanical quality factors. As a step toward these objectives, we demonstrate single-crystal diamond optomechanical crystal resonators with embedded NV centers. These devices host highly-confined GHz-scale mechanical modes that are isolated from mechanical clamping losses and generate strain profiles that allow for large strain coupling to NV centers far from noise-inducing surfaces.

Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

Energy Technology Data Exchange (ETDEWEB)

Bintu, Alexandra [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Vincze, Gabriela, E-mail: gvincze@ua.pt [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Picu, Catalin R. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lopes, Augusto B. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Grácio, Jose J. [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Barlat, Frederic [Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

2015-04-01

TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS.

Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

International Nuclear Information System (INIS)

Bintu, Alexandra; Vincze, Gabriela; Picu, Catalin R.; Lopes, Augusto B.; Grácio, Jose J.; Barlat, Frederic

2015-01-01

TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS

Tiger Team Assessment, Energy Technology Engineering Center

International Nuclear Information System (INIS)

1991-04-01

The Office Special Projects within the Office of Environment, Safety, and Health (EH) has the responsibility to conduct Tiger Team Assessments for the Secretary of Energy. This report presents the assessment of the buildings, facilities, and activities under the DOE/Rockwell Contract No. DE-AM03-76SF00700 for the Energy Technology Engineering Center (ETEC) and of other DOE-owned buildings and facilities at the Santa Susana Field Laboratory (SSFL) site in southeastern Ventura County, California, not covered under Contract No. DE-AM03-76SF00700, but constructed over the years under various other contracts between DOE and Rockwell International. ETEC is an engineering development complex operated for DOE by the Rocketdyne Division of Rockwell International Corporation. ETEC is located within SSFL on land owned by Rockwell. The balance of the SSFL complex is owned and operated by Rocketdyne, with the exception of a 42-acre parcel owned by the National Aeronautics and Space Administration (NASA). The primary mission of ETEC is to provide engineering, testing, and development of components related to liquid metals technology and to conduct applied engineering development of emerging energy technologies

Tiger Team Assessment, Energy Technology Engineering Center

Energy Technology Data Exchange (ETDEWEB)

1991-04-01

The Office Special Projects within the Office of Environment, Safety, and Health (EH) has the responsibility to conduct Tiger Team Assessments for the Secretary of Energy. This report presents the assessment of the buildings, facilities, and activities under the DOE/Rockwell Contract No. DE-AM03-76SF00700 for the Energy Technology Engineering Center (ETEC) and of other DOE-owned buildings and facilities at the Santa Susana Field Laboratory (SSFL) site in southeastern Ventura County, California, not covered under Contract No. DE-AM03-76SF00700, but constructed over the years under various other contracts between DOE and Rockwell International. ETEC is an engineering development complex operated for DOE by the Rocketdyne Division of Rockwell International Corporation. ETEC is located within SSFL on land owned by Rockwell. The balance of the SSFL complex is owned and operated by Rocketdyne, with the exception of a 42-acre parcel owned by the National Aeronautics and Space Administration (NASA). The primary mission of ETEC is to provide engineering, testing, and development of components related to liquid metals technology and to conduct applied engineering development of emerging energy technologies.

Kinetics of Leptospira interrogans infection in hamsters after intradermal and subcutaneous challenge.

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Mariana L Coutinho

2014-11-01

Full Text Available Leptospirosis is a zoonosis caused by highly motile, helically shaped bacteria that penetrate the skin and mucous membranes through lesions or abrasions, and rapidly disseminate throughout the body. Although the intraperitoneal route of infection is widely used to experimentally inoculate hamsters, this challenge route does not represent a natural route of infection.Here we describe the kinetics of disease and infection in hamster model of leptospirosis after subcutaneous and intradermal inoculation of Leptospira interrogans serovar Copenhageni, strain Fiocruz L1-130. Histopathologic changes in and around the kidney, including glomerular and tubular damage and interstitial inflammatory changes, began on day 5, and preceded deterioration in renal function as measured by serum creatinine. Weight loss, hemoconcentration, increased absolute neutrophil counts (ANC in the blood and hepatic dysfunction were first noted on day 6. Vascular endothelial growth factor, a serum marker of sepsis severity, became elevated during the later stages of infection. The burden of infection, as measured by quantitative PCR, was highest in the kidney and peaked on day 5 after intradermal challenge and on day 6 after subcutaneous challenge. Compared to subcutaneous challenge, intradermal challenge resulted in a lower burden of infection in both the kidney and liver on day 6, lower ANC and less weight loss on day 7.The intradermal and subcutaneous challenge routes result in significant differences in the kinetics of dissemination and disease after challenge with L. interrogans serovar Copenhageni strain Fiocruz L1-130 at an experimental dose of 2×106 leptospires. These results provide new information regarding infection kinetics in the hamster model of leptospirosis.

Improving industrial yeast strains: exploiting natural and artificial diversity

Science.gov (United States)

Steensels, Jan; Snoek, Tim; Meersman, Esther; Nicolino, Martina Picca; Voordeckers, Karin; Verstrepen, Kevin J

2014-01-01

Yeasts have been used for thousands of years to make fermented foods and beverages, such as beer, wine, sake, and bread. However, the choice for a particular yeast strain or species for a specific industrial application is often based on historical, rather than scientific grounds. Moreover, new biotechnological yeast applications, such as the production of second-generation biofuels, confront yeast with environments and challenges that differ from those encountered in traditional food fermentations. Together, this implies that there are interesting opportunities to isolate or generate yeast variants that perform better than the currently used strains. Here, we discuss the different strategies of strain selection and improvement available for both conventional and nonconventional yeasts. Exploiting the existing natural diversity and using techniques such as mutagenesis, protoplast fusion, breeding, genome shuffling and directed evolution to generate artificial diversity, or the use of genetic modification strategies to alter traits in a more targeted way, have led to the selection of superior industrial yeasts. Furthermore, recent technological advances allowed the development of high-throughput techniques, such as ‘global transcription machinery engineering’ (gTME), to induce genetic variation, providing a new source of yeast genetic diversity. PMID:24724938

Survival of Five Strains of Shiga Toxigenic Escherichia coli in a Sausage Fermentation Model and Subsequent Sensitivity to Stress from Gastric Acid and Intestinal Fluid

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Tone Mari Rode

2017-01-01

Full Text Available The ability of foodborne pathogens to exhibit adaptive responses to stressful conditions in foods may enhance their survival when passing through the gastrointestinal system. We aimed to determine whether Escherichia coli surviving stresses encountered during a model dry-fermented sausage (DFS production process exhibit enhanced tolerance and survival in an in vitro gastrointestinal model. Salami sausage batters spiked with five E. coli isolates, including enterohaemorrhagic E. coli strains isolated from different DFS outbreaks, were fermented in a model DFS process (20°C, 21 days. Control batters spiked with the same strains were stored at 4°C for the same period. Samples from matured model sausages and controls were thereafter exposed to an in vitro digestion challenge. Gastric exposure (pH 3 resulted in considerably reduced survival of the E. coli strains that had undergone the model DFS process. This reduction continued after entering intestinal challenge (pH 8, but growth resumed after 120 min. When subjected to gastric challenge for 120 min, E. coli that had undergone the DFS process showed about 2.3 log10⁡​ lower survival compared with those kept in sausage batter at 4°C. Our results indicated that E. coli strains surviving a model DFS process exhibited reduced tolerance to subsequent gastric challenge at low pH.

Subcutaneous or oral immunization of mice with Lactococcus lactis expressing F4 fimbrial adhesin FaeG.

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Liu, Shujie; Li, Yongming; Xu, Ziwei; Wang, Yicheng

2013-01-01

Enterotoxigenic Escherichia coli (ETEC) is one of the most common causes of diarrhea in neonatal and postweaning piglets. Fimbrial adhesion of ETEC has been considered an important colonization factor with antigenicity. To safely and effectively deliver the F4 (K88) fimbrial adhesin FaeG to the immune system, we have previously constructed the secretory expression vector pNZ8112-faeG, and FaeG was produced in cytoplasmic form in Lactococcus lactis. In this work, BALB/c mice were immunized with recombinant L. lactis to further determine the immunogenicity of recombinant FaeG (rFaeG) via the subcutaneous or oral route. Subcutaneous immunization in mice with recombinant L. lactis induced a significant increase in the F4-specific serum IgG titer and the number of antibody-secreting cells (ASCs) in the spleen. Oral immunization of mice with recombinant L. lactis induced mucosal and systemic F4-specific immune responses and increased the number of ASCs in the spleen, mesenteric lymph nodes and Peyer's patches. High-dose (2.8 × 10(11) CFU) recombinant strains and adjuvant cholera toxin B subunit enhanced specific mucosal immune responses. The results suggest the feasibility of delivering rFaeG expressed in L. lactis to the immune system in order to induce an F4-specific immune response.

Variation in the strain anisotropy of Zircaloy with temperature and strain

International Nuclear Information System (INIS)

Hindle, E.D.; Worswick, D.

1984-04-01

Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

Infection studies with two highly pathogenic avian influenza strains (Vietnamese and Indonesian) in Pekin ducks (Anas platyrhynchos), with particular reference to clinical disease, tissue tropism and viral shedding.

Science.gov (United States)

Bingham, John; Green, Diane J; Lowther, Sue; Klippel, Jessica; Burggraaf, Simon; Anderson, Danielle E; Wibawa, Hendra; Hoa, Dong Manh; Long, Ngo Thanh; Vu, Pham Phong; Middleton, Deborah J; Daniels, Peter W

2009-08-01

Pekin ducks were infected by the mucosal route (oral, nasal, ocular) with one of two strains of Eurasian lineage H5N1 highly pathogenic avian influenza virus: A/Muscovy duck/Vietnam/453/2004 and A/duck/Indramayu/BBVW/109/2006 (from Indonesia). Ducks were killed humanely on days 1, 2, 3, 5 and 7 after challenge, or whenever morbidity was severe enough to justify euthanasia. Morbidity was recorded by observation of clinical signs and cloacal temperatures; the disease was characterized by histopathology; tissue tropism was studied by immunohistochemistry and virus titration on tissue samples; and viral shedding patterns were determined by virus isolation and titration of oral and cloacal swabs. The Vietnamese strain caused severe morbidity with fever and depression; the Indonesian strain caused only transient fever. Both viruses had a predilection for a similar range of tissue types, but the quantity of tissue antigen and tissue virus titres were considerably higher with the Vietnamese strain. The Vietnamese strain caused severe myocarditis and skeletal myositis; both strains caused non-suppurative encephalitis and a range of other inflammatory reactions of varying severity. The principal epithelial tissue infected was that of the air sacs, but antigen was not abundant. Epithelium of the turbinates, trachea and bronchi had only rare infection with virus. Virus was shed from both the oral and cloacal routes; it was first detected 24 h after challenge and persisted until day 5 after challenge. The higher prevalence of virus from swabs from ducks infected with the Vietnamese strain indicates that this strain may be more adapted to ducks than the Indonesia strain.

Rapid Engineering of Foot-and-Mouth Disease Vaccine and Challenge Viruses.

Science.gov (United States)

Lee, Seo-Yong; Lee, Yeo-Joo; Kim, Rae-Hyung; Park, Jeong-Nam; Park, Min-Eun; Ko, Mi-Kyeong; Choi, Joo-Hyung; Chu, Jia-Qi; Lee, Kwang-Nyeong; Kim, Su-Mi; Tark, Dongseob; Lee, Hyang-Sim; Ko, Young-Joon; Seo, Min-Goo; Park, Jung-Won; Kim, Byounghan; Lee, Myoung-Heon; Lee, Jong-Soo; Park, Jong-Hyeon

2017-08-15

There are seven antigenically distinct serotypes of foot-and-mouth disease virus (FMDV), each of which has intratypic variants. In the present study, we have developed methods to efficiently generate promising vaccines against seven serotypes or subtypes. The capsid-encoding gene (P1) of the vaccine strain O1/Manisa/Turkey/69 was replaced with the amplified or synthetic genes from the O, A, Asia1, C, SAT1, SAT2, and SAT3 serotypes. Viruses of the seven serotype were rescued successfully. Each chimeric FMDV with a replacement of P1 showed serotype-specific antigenicity and varied in terms of pathogenesis in pigs and mice. Vaccination of pigs with an experimental trivalent vaccine containing the inactivated recombinants based on the main serotypes O, A, and Asia1 effectively protected them from virus challenge. This technology could be a potential strategy for a customized vaccine with challenge tools to protect against epizootic disease caused by specific serotypes or subtypes of FMDV. IMPORTANCE Foot-and-mouth disease (FMD) virus (FMDV) causes significant economic losses. For vaccine preparation, the selection of vaccine strains was complicated by high antigenic variation. In the present study, we suggested an effective strategy to rapidly prepare and evaluate mass-produced customized vaccines against epidemic strains. The P1 gene encoding the structural proteins of the well-known vaccine virus was replaced by the synthetic or amplified genes of viruses of seven representative serotypes. These chimeric viruses generally replicated readily in cell culture and had a particle size similar to that of the original vaccine strain. Their antigenicity mirrored that of the original serotype from which their P1 gene was derived. Animal infection experiments revealed that the recombinants varied in terms of pathogenicity. This strategy will be a useful tool for rapidly generating customized FMD vaccines or challenge viruses for all serotypes, especially for FMD-free countries

Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

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Dharanesh Gangaiah

Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

Science.gov (United States)

Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

2009-12-01

The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

Drop of egg production in chickens by experimental infection with an avian metapneumovirus strain PLE8T1 derived from swollen head syndrome and the application to evaluate vaccine.

Science.gov (United States)

Sugiyama, Miki; Koimaru, Hiroyuki; Shiba, Masahiro; Ono, Eriko; Nagata, Tadashi; Ito, Toshihiro

2006-08-01

Decreases in egg production and increased incidence of abnormal eggs due to malformation of egg shells were observed in specific pathogen free (SPF) 173-day-old laying hens inoculated intravenously with an avian metapneumovirus (aMPV) strain PLE8T1. This strain was derived from an isolate from broiler birds exhibiting swollen head syndrome (SHS). Some SPF birds inoculated with the virus showed, slight diarrhea without any respiratory symptoms. Thus, the PLE8T1 strain was used as a challenge virus to evaluate efficacy of aMPV vaccines. SPF chickens which received a live attenuated aMPV vaccine (NEMOVAC; Merial) at 7 or 77 days old and an inactivated aMPV vaccine (OVO-4; Merial) at 105 days old were protected against poor egg production caused by the challenge with the PLE8T1 strain. Thus, aMPV, the PLE8T1 strain passaged 22 times after isolation, from birds exhibiting SHS, could induce a drop in egg production in laying hens accompanied by malformation of egg shells. It was suggested that this challenge system could be applied to evaluate the efficacy of aMPV vaccine.

Systems biology solutions for biochemical production challenges.

Science.gov (United States)

Hansen, Anne Sofie Lærke; Lennen, Rebecca M; Sonnenschein, Nikolaus; Herrgård, Markus J

2017-06-01

There is an urgent need to significantly accelerate the development of microbial cell factories to produce fuels and chemicals from renewable feedstocks in order to facilitate the transition to a biobased society. Methods commonly used within the field of systems biology including omics characterization, genome-scale metabolic modeling, and adaptive laboratory evolution can be readily deployed in metabolic engineering projects. However, high performance strains usually carry tens of genetic modifications and need to operate in challenging environmental conditions. This additional complexity compared to basic science research requires pushing systems biology strategies to their limits and often spurs innovative developments that benefit fields outside metabolic engineering. Here we survey recent advanced applications of systems biology methods in engineering microbial production strains for biofuels and -chemicals. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development.

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Tiffany M Mott

Full Text Available In this study, a Burkholderia mallei tonB mutant (TMM001 deficient in iron acquisition was constructed, characterized, and evaluated for its protective properties in acute inhalational infection models of murine glanders and melioidosis.Compared to the wild-type, TMM001 exhibits slower growth kinetics, siderophore hyper-secretion and the inability to utilize heme-containing proteins as iron sources. A series of animal challenge studies showed an inverse correlation between the percentage of survival in BALB/c mice and iron-dependent TMM001 growth. Upon evaluation of TMM001 as a potential protective strain against infection, we found 100% survival following B. mallei CSM001 challenge of mice previously receiving 1.5 x 10(4 CFU of TMM001. At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls. At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001. In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected. While wild type was cleared in all B. mallei challenge studies, mice failed to clear TMM001.Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

3D printing of highly elastic strain sensors using polyurethane/multiwall carbon nanotube composites

Science.gov (United States)

Christ, Josef F.; Hohimer, Cameron J.; Aliheidari, Nahal; Ameli, Amir; Mo, Changki; Pötschke, Petra

2017-04-01

As the desire for wearable electronics increases and the soft robotics industry advances, the need for novel sensing materials has also increased. Recently, there have been many attempts at producing novel materials, which exhibit piezoresistive behavior. However, one of the major shortcomings in strain sensing technologies is in the fabrication of such sensors. While there is significant research and literature covering the various methods for developing piezoresistive materials, fabricating complex sensor platforms is still a manufacturing challenge. Here, we report a facile method to fabricate multidirectional embedded strain sensors using additive manufacturing technology. Pure thermoplastic polyurethane (TPU) and TPU/multiwall carbon nanotubes (MWCNT) nanocomposites were 3D printed in tandem using a low-cost multi-material FDM printer to fabricate uniaxial and biaxial strain sensors with conductive paths embedded within the insulative TPU platform. The sensors were then subjected to a series of cyclic strain loads. The results revealed excellent piezoresistive responses of the sensors with cyclic repeatability in both the axial and transverse directions and in response to strains as high as 50%. Further, while strain-softening did occur in the embedded printed strain sensors, it was predictable and similar to the results found in the literature for bulk polymer nanocomposites. This works demonstrates the possibility of manufacturing embedded and multidirectional flexible strain sensors using an inexpensive and versatile method, with potential applications in soft robotics and flexible electronics and health monitoring.

Comparative susceptibility of veliger larvae of four bivalve mollusks to a Vibrio alginolyticus strain.

Science.gov (United States)

Luna-González, A; Maeda-Martínez, A N; Sainz, J C; Ascencio-Valle, F

2002-06-03

The susceptibility of 7 d old veliger larvae of the scallops Argopecten ventricosus and Nodipecten subnodosus, the penshell Atrina maura, and the Pacific oyster Crassostrea gigas to a pathogenic strain of Vibrio alginolyticus was investigated by challenging the larvae with different bacterial concentrations in a semi-static assay. The results indicate that the larvae of the 2 scallop species are more susceptible to the V. alginolyticus strain than those of the oyster and the penshell. Signs of the disease were similar to bacillary necrosis described in previous work. Interspecies differences in susceptibility to pathogens are discussed.

Bacillus 'next generation' diagnostics: Moving from detection towards sub-typing and risk related strain profiling

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Monika eEhling-Schulz

2013-02-01

Full Text Available The highly heterogeneous genus Bacillus comprises the largest species group of endospore forming bacteria. Because of their ubiquitous nature, Bacillus spores can enter food production at several stages resulting in significant economic losses and posing a potential risk to consumers due the capacity of certain Bacillus strains for toxin production. In the past, food microbiological diagnostics was focused on the determination of species using conventional culture based methods, which are still widely used. However, due to the extreme intraspecies diversity found in the genus Bacillus, DNA based identification and typing methods are gaining increasing importance in routine diagnostics. Several studies showed that certain characteristics are rather strain dependent than species specific. Therefore, the challenge for current and future Bacillus diagnostics is not only the efficient and accurate identification on species level but also the development of rapid methods to identify strains with specific characteristics (such as stress resistance or spoilage potential, trace contamination sources, and last but not least discriminate potential hazardous strains from non-toxic strains.

Oral vaccination with LcrV from Yersinia pestis KIM delivered by live attenuated Salmonella enterica serovar Typhimurium elicits a protective immune response against challenge with Yersinia pseudotuberculosis and Yersinia enterocolitica.

Science.gov (United States)

Branger, Christine G; Torres-Escobar, Ascención; Sun, Wei; Perry, Robert; Fetherston, Jacqueline; Roland, Kenneth L; Curtiss, Roy

2009-08-27

The use of live recombinant attenuated Salmonella vaccines (RASV) synthesizing Yersinia proteins is a promising approach for controlling infection by Yersinia species. In this study, we constructed attenuated Salmonella strains which synthesize a truncated form of LcrV, LcrV196 and evaluated the immune response and protective efficacy elicited by these strains in mice against two other major species of Yersinia: Yersinia pseudotuberculosis and Yersinia enterocolitica. Surprisingly, we found that the RASV strain alone was sufficient to afford nearly full protection against challenge with Y. pseudotuberculosis, indicating the likelihood that Salmonella produces immunogenic cross-protective antigens. In contrast, lcrV196 expression was required for protection against challenge with Y. enterocolitica strain 8081, but was not sufficient to achieve significant protection against challenge with Y. enterocolitica strain WA, which expressed a divergent form of lcrV. Nevertheless, we are encouraged by these findings to continue pursuing our long-term goal of developing a single vaccine to protect against all three human pathogenic species of Yersinia.

Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics

DEFF Research Database (Denmark)

Gorfman, S.; Simons, Hugh; Iamsasri, T.

2016-01-01

and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice...

3D printed high performance strain sensors for high temperature applications

Science.gov (United States)

Rahman, Md Taibur; Moser, Russell; Zbib, Hussein M.; Ramana, C. V.; Panat, Rahul

2018-01-01

Realization of high temperature physical measurement sensors, which are needed in many of the current and emerging technologies, is challenging due to the degradation of their electrical stability by drift currents, material oxidation, thermal strain, and creep. In this paper, for the first time, we demonstrate that 3D printed sensors show a metamaterial-like behavior, resulting in superior performance such as high sensitivity, low thermal strain, and enhanced thermal stability. The sensors were fabricated using silver (Ag) nanoparticles (NPs), using an advanced Aerosol Jet based additive printing method followed by thermal sintering. The sensors were tested under cyclic strain up to a temperature of 500 °C and showed a gauge factor of 3.15 ± 0.086, which is about 57% higher than that of those available commercially. The sensor thermal strain was also an order of magnitude lower than that of commercial gages for operation up to a temperature of 500 °C. An analytical model was developed to account for the enhanced performance of such printed sensors based on enhanced lateral contraction of the NP films due to the porosity, a behavior akin to cellular metamaterials. The results demonstrate the potential of 3D printing technology as a pathway to realize highly stable and high-performance sensors for high temperature applications.

Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric

DEFF Research Database (Denmark)

Walker, Julian; Simons, Hugh; Alikin, Denis O

2016-01-01

Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb)-based ferroe......Electromechanical properties such as d33 and strain are significantly enhanced at morphotropic phase boundaries (MPBs) between two or more different crystal structures. Many actuators, sensors and MEMS devices are therefore systems with MPBs, usually between polar phases in lead (Pb......)-based ferroelectric ceramics. In the search for Pb-free alternatives, systems with MPBs between polar and non-polar phases have recently been theorized as having great promise. While such an MPB was identified in rare-earth (RE) modified bismuth ferrite (BFO) thin films, synthesis challenges have prevented its...... realization in ceramics. Overcoming these, we demonstrate a comparable electromechanical response to Pb-based materials at the polar-to-non-polar MPB in Sm modified BFO. This arises from 'dual' strain mechanisms: ferroelectric/ferroelastic switching and a previously unreported electric-field induced...

Characterization of two recent Japanese field isolates of canine distemper virus and examination of the avirulent strain utility as an attenuated vaccine.

Science.gov (United States)

Takenaka, Akiko; Yoneda, Misako; Seki, Takahiro; Uema, Masashi; Kooriyama, Takanori; Nishi, Toshiya; Fujita, Kentaro; Miura, Ryuichi; Tsukiyama-Kohara, Kyoko; Sato, Hiroki; Kai, Chieko

2014-12-05

Recently, several new strains of canine distemper virus (CDV) have been isolated in Japan. To investigate their pathogenesis in dogs, the Yanaka and Bunkyo-K strains were investigated by infecting dogs and determining clinical signs, amount of virus, and antibody responses. The Yanaka strain is avirulent and induced an antibody response. The Bunkyo-K strain induced typical CDV clinical signs in infected dogs and virulence was enhanced by brain passage. Molecular and phylogenetic analyses of H genes demonstrated the Bunkyo-K strains were of a different lineage from Asia-1 group including the Yanaka strain and Asia-2 group that contain recent Japanese isolates, which were recently identified as major prevalent strains worldwide but distinct from old vaccine strains. Based on these data, we tested the ability of the Yanaka strain for vaccination. Inoculation with the Yanaka strain efficiently induced CDV neutralizing antibodies with no clinical signs, and the protection effects against challenge with either old virulent strain or Bunkyo-K strain were equal or greater when compared with vaccination by an original vaccine strain. Thus, the Yanaka strain is a potential vaccine candidate against recent prevalent CDV strains. Copyright © 2014 Elsevier B.V. All rights reserved.

Integrated challenge test: a new approach evaluating quantitative risk assessment of Listeria in ready to eat foods

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Paolo Matteini

2012-02-01

Full Text Available The study was aimed to predict the maximum concentration of Listeria monocytogenes during the shelf life in chicken liver paté. The prediction has been performed using the integrated challenge test: a test based on the interaction between indigenous lactic flora and L. monocytogenes and their growth parameters. Two different approaches were investigated: the former is based on the time difference between the onset of the L. monocytogenes and the lactic flora stationary phases, while the latter is based on the lactic flora concentration capable to induct the stationary phase of L. monocytogenes. Three different strains of L. monocytogenes, isolated from meat products, were used to perform three challenge tests. Triplicate samples from three different batches of liver paté were inoculated with a single-strain inoculum of 1.8 Log CFU/g. Samples were then stored at 4°C, 8°C and 12°C. Lactobacillus spp. (ISO 15214:1998 and L. monocytogenes (UNI EN ISO 11290-02:2005 plate counts were performed daily on each sample until the stationary phase was reached by both populations. The challenge test results were input in the Combase software to determine the growth parameters, later used for the calculation method. Predictive data were then statically assessed against the results of two additional challenge tests using triplicate samples from two different batches, the same strains and the same single-strain inoculum. Samples from the first batch were stored for 5 days at 4°C + 5 days at 8°C + 5 days at 12°C; samples from the second batch were stored for 3 days at 4°C + 3 days at 8°C + 4 days at 12°C. The results obtained showed that both approaches provided results very close to the reality. Therefore the Integrated challenge test is useful to determine the maximum concentration of L. monocytogenes, by simply knowing the concentration of the concerned microbial populations at a given time.

Safety and efficacy of an attenuated Chinese QX-like infectious bronchitis virus strain as a candidate vaccine.

Science.gov (United States)

Zhao, Ye; Cheng, Jin-long; Liu, Xiao-yu; Zhao, Jing; Hu, Yan-xin; Zhang, Guo-zhong

2015-10-22

Infectious bronchitis (IB) is a highly contagious respiratory and urogenital disease of chickens caused by infectious bronchitis virus (IBV). This disease is of considerable economic importance and is primarily controlled through biosecurity and immunization with live attenuated and inactivated IB vaccines of various serotypes. In the present study, we tested the safety and efficacy of an attenuated predominant Chinese QX-like IBV strain. The results revealed that the attenuated strain has a clear decrease in pathogenicity for specific-pathogen-free (SPF) chickens compared with the parent strain. Strain YN-inoculated birds had clinical signs of varying severity with 30% mortality, while the attenuated group appeared healthy, with less tissue damage. The attenuated strain also had relatively low tissue replication rates and higher antibody levels. The superior protective efficacy of the attenuated strain was observed when vaccinated birds were challenged with a homologous or heterologous field IBV strain, indicating the potential of the attenuated YN (aYN) as a vaccine. Producing a vaccine targeting the abundant serotype in China is essential to reducing the economic impact of IB on the poultry industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Real time expression of ACC oxidase and PR-protein genes mediated by Methylobacterium spp. in tomato plants challenged with Xanthomonas campestris pv. vesicatoria.

Science.gov (United States)

Yim, W J; Kim, K Y; Lee, Y W; Sundaram, S P; Lee, Y; Sa, T M

2014-07-15

Biotic stress like pathogenic infection increases ethylene biosynthesis in plants and ethylene inhibitors are known to alleviate the severity of plant disease incidence. This study aimed to reduce the bacterial spot disease incidence in tomato plants caused by Xanthomonas campestris pv. vesicatoria (XCV) by modulating stress ethylene with 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity of Methylobacterium strains. Under greenhouse condition, Methylobacterium strains inoculated and pathogen challenged tomato plants had low ethylene emission compared to pathogen infected ones. ACC accumulation and ACC oxidase (ACO) activity with ACO related gene expression increased in XCV infected tomato plants over Methylobacterium strains inoculated plants. Among the Methylobacterium spp., CBMB12 resulted lowest ACO related gene expression (1.46 Normalized Fold Expression), whereas CBMB20 had high gene expression (3.42 Normalized Fold Expression) in pathogen challenged tomato. But a significant increase in ACO gene expression (7.09 Normalized Fold Expression) was observed in the bacterial pathogen infected plants. In contrast, Methylobacterium strains enhanced β-1,3-glucanase and phenylalanine ammonia-lyase (PAL) enzyme activities in pathogen challenged tomato plants. The respective increase in β-1,3-glucanase related gene expressions due to CBMB12, CBMB15, and CBMB20 strains were 66.3, 25.5 and 10.4% higher over pathogen infected plants. Similarly, PAL gene expression was high with 0.67 and 0.30 Normalized Fold Expression, in pathogen challenged tomato plants inoculated with CBMB12 and CBMB15 strains. The results suggest that ethylene is a crucial factor in bacterial spot disease incidence and that methylobacteria with ACC deaminase activity can reduce the disease severity with ultimate pathogenesis-related protein increase in tomato. Copyright © 2014 Elsevier GmbH. All rights reserved.

Improving industrial yeast strains: exploiting natural and artificial diversity.

Science.gov (United States)

Steensels, Jan; Snoek, Tim; Meersman, Esther; Picca Nicolino, Martina; Voordeckers, Karin; Verstrepen, Kevin J

2014-09-01

Yeasts have been used for thousands of years to make fermented foods and beverages, such as beer, wine, sake, and bread. However, the choice for a particular yeast strain or species for a specific industrial application is often based on historical, rather than scientific grounds. Moreover, new biotechnological yeast applications, such as the production of second-generation biofuels, confront yeast with environments and challenges that differ from those encountered in traditional food fermentations. Together, this implies that there are interesting opportunities to isolate or generate yeast variants that perform better than the currently used strains. Here, we discuss the different strategies of strain selection and improvement available for both conventional and nonconventional yeasts. Exploiting the existing natural diversity and using techniques such as mutagenesis, protoplast fusion, breeding, genome shuffling and directed evolution to generate artificial diversity, or the use of genetic modification strategies to alter traits in a more targeted way, have led to the selection of superior industrial yeasts. Furthermore, recent technological advances allowed the development of high-throughput techniques, such as 'global transcription machinery engineering' (gTME), to induce genetic variation, providing a new source of yeast genetic diversity. © 2014 The Authors. FEMS Microbiology Reviews published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

Stress-strain properties of railway steel at strain rates of upto 105 per second

International Nuclear Information System (INIS)

Hashmi, M.S.J.; Islam, M.N.

1985-01-01

This paper presents the stress-strain characteristics of railway steel at strain rates of up to 10 5 /s at room temperature determined by a new technique. In determining the results, account has been taken of the strain-rate variation, the total strain and the strain rate history. The effect of friction, material inertia and temperature rise is also assessed and an empirical constitutive equation describing the strain-rate and strain sensitive flow stress for this type of steel is proposed. (orig.)

Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

International Nuclear Information System (INIS)

Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock

2014-01-01

One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

Toxin-mediated effects on the innate mucosal defenses: implications for enteric vaccines

DEFF Research Database (Denmark)

Glenn, Gregory M; Francis, David H; Danielsen, E Michael

2009-01-01

mucosal barrier as a key step in enteric pathogen survival. We review key observations relevant to the roles of LT and cholera toxin in protective immunity and the effects of these toxins on innate mucosal defenses. We suggest either that toxin-mediated fluid secretion mechanically disrupts the mucus...... layer or that toxins interfere with innate mucosal defenses by other means. Such a breach gives pathogens access to the enterocyte, leading to binding and pathogenicity by enterotoxigenic E. coli (ETEC) and other organisms. Given the common exposure to LT(+) ETEC by humans visiting or residing...... unexpectedly broad protective effects against LT(+) ETEC and mixed infections when using a toxin-based enteric vaccine. If toxins truly exert barrier-disruptive effects as a key step in pathogenesis, then a return to classic toxin-based vaccine strategies for enteric disease is warranted and can be expected...

Prevention of enterotoxigenic Escherichia coli infections in pigs by dairy-based nutrition

DEFF Research Database (Denmark)

Sugiharto, Sugiharto; Jensen, Bent Borg; Jensen, Karin Hjelholt

2015-01-01

bacterial disease outbreaks in piglets, the use of antibiotics at subtherapeutic concentrations has been banned in the European Union because of the increasing prevalence of resistance to antibiotics in pigs. The removal of in-feed antibiotics from piglet diets has negative economic consequences...... as it dramatically increases the rate of morbidity and mortality due to ETEC as well as the use of antibiotics for therapeutic purposes. Other than subtherapeutic antibiotics, zinc oxide (ZnO) has been reported to ameliorate and/or prevent the development of PWD in piglets, but its excretion may have negative...... impacts on the environment. Thus, other alternatives that can control ETEC infections in piglets postweaning will be of great advantage. A number of nutritional strategies have been proposed as alternative means of preventing ETEC infections, of which feeding dairy-based products to piglets could be one...

Limitations of Hollomon and Ludwigson stress-strain relations in assessing the strain hardening parameters

International Nuclear Information System (INIS)

Samuel, K G

2006-01-01

It is shown that the deviation from the ideal Hollomon relation in describing the stress-strain behaviour is characteristic of all materials at low strains. The Ludwigson relation describing the deviation from the Hollomon relation at low strains is critically analysed and it is shown that the deviation at low strains is a consequence of some unknown 'plastic strain equivalent' present in the material. Stress strain curves obeying an ideal Hollomon relation as well as that of a structurally modified (prior cold worked) material were simulated and compared. The results show that the yield strength and the flow strength of a material at constant strain rate and temperature are dictated by the magnitude of the 'plastic strain equivalent' term. It is shown that this component need not necessarily mean a prior plastic strain present in the material due to prior cold work alone and that prior cold work strain will add to this. If this component is identified, the stress-strain behaviour can be adequately described by the Swift relation. It is shown that in both formalisms, the strain hardening index is a function of the yield strength of the material

Strained Silicon Photonics

Directory of Open Access Journals (Sweden)

Ralf B. Wehrspohn

2012-05-01

Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

CRISPR–Cas system enables fast and simple genome editing of industrial Saccharomyces cerevisiae strains

Directory of Open Access Journals (Sweden)

Vratislav Stovicek

2015-12-01

Full Text Available There is a demand to develop 3rd generation biorefineries that integrate energy production with the production of higher value chemicals from renewable feedstocks. Here, robust and stress-tolerant industrial strains of Saccharomyces cerevisiae will be suitable production organisms. However, their genetic manipulation is challenging, as they are usually diploid or polyploid. Therefore, there is a need to develop more efficient genetic engineering tools. We applied a CRISPR–Cas9 system for genome editing of different industrial strains, and show simultaneous disruption of two alleles of a gene in several unrelated strains with the efficiency ranging between 65% and 78%. We also achieved simultaneous disruption and knock-in of a reporter gene, and demonstrate the applicability of the method by designing lactic acid-producing strains in a single transformation event, where insertion of a heterologous gene and disruption of two endogenous genes occurred simultaneously. Our study provides a foundation for efficient engineering of industrial yeast cell factories. Keywords: CRISPR–Cas9, Genome editing, Industrial yeast, Biorefineries, Chemical production

A Structural Basis for Sustained Bacterial Adhesion – Biomechanical Properties of CFA/I Pili

OpenAIRE

Andersson, Magnus; Björnham, Oscar; Svantesson, Mats; Badahdah, Arwa; Uhlin, Bernt Eric; Bullitt, Esther

2011-01-01

Enterotoxigenic Escherichia coli (ETEC) are a major cause of diarrheal disease worldwide. Adhesion pili (or fimbriae), such as the CFA/I (colonization factor antigen I) organelles that enable ETEC to attach efficiently to the host intestinal tract epithelium, are critical virulence factors for initiation of infection. We characterized at single organelle level the intrinsic biomechanical properties and kinetics of individual CFA/I pili, demonstrating that weak external forces (7.5 pN) are suf...

Devil's carpet of topological entropy and complexity of global dynamical behavior

International Nuclear Information System (INIS)

Cao, K.-F.; Zhang, X.-S.; Zhou Zhong; Peng, S.-L.

2003-01-01

For bimodal maps the concept of an equal topological entropy class (ETEC) is established by the dual star products. All the infinitely many ETEC plateaus and single points are harmonically organized in the kneading parameter plane, they construct a multifractal devil's carpet, which possesses a perfect subregion similarity and a dual central symmetry. The entropy devil's carpet reveals the complexity of global dynamical behavior in the whole parameter plane of bimodal systems

The strain path dependence of plastic deformation response of AA5754: Experiment and modeling

International Nuclear Information System (INIS)

Pham, Minh-Son; Hu, Lin; Iadicola, Mark; Creuziger, Adam; Rollett, Anthony D.

2013-01-01

This work presents modeling of experiments on a balanced biaxial (BB) pre-strained AA5754 alloy, subsequently reloaded uniaxially along the rolling direction and transverse direction. The material exhibits a complex plastic deformation response during the change in strain path due to 1) crystallographic texture, 2) aging (interactions between dislocations and Mg atoms) and 3) recovery (annihilation and re-arrangement of dislocations). With a BB prestrain of about 5 %, the aging process is dominant, and the yield strength for uniaxially deformed samples is observed to be higher than the flow stress during BB straining. The strain hardening rate after changing path is, however, lower than that for pre-straining. Higher degrees of pre-straining make the dynamic recovery more active. The dynamic recovery at higher strain levels compensates for the aging effect, and results in: 1) a reduction of the yield strength, and 2) an increase in the hardening rate of re-strained specimens along other directions. The yield strength of deformed samples is further reduced if these samples are left at room temperature to let static recovery occur. The synergistic influences of texture condition, aging and recovery processes on the material response make the modeling of strain path dependence of mechanical behavior of AA5754 challenging. In this study, the influence of crystallographic texture is taken into account by incorporating the latent hardening into a visco-plastic self-consistent model. Different strengths of dislocation glide interaction models in 24 slip systems are used to represent the latent hardening. Moreover, the aging and recovery effects are also included into the latent hardening model by considering strong interactions between dislocations and dissolved atom Mg and the microstructural evolution. These microstructural considerations provide a powerful capability to successfully describe the strain path dependence of plastic deformation behavior of AA5754

Population structure of Spodoptera frugiperda maize and rice host forms in South America: are they host strains?

NARCIS (Netherlands)

Juárez, M.L.; Schöfl, G.; Vera, M.T.; Vilardi, J.C.; Murúa, M.G.; Willink, E.; Hänniger, S.; Heckel, D.G.; Groot, A.T.

2014-01-01

Determining which factors contribute to the formation and maintenance of genetic divergence to evaluate their relative importance as a cause of biological differentiation is among the major challenges in evolutionary biology. In Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) two host strains

Fatigue life prediction for pressure cast transmission housings using the strain life approach

Energy Technology Data Exchange (ETDEWEB)

Varenkamp, M. [ZF Friedrichshafen AG, Abteilung TB-1, 88038 Friedrichshafen (Germany); Schoen, M.

2011-04-15

Pressure cast transmission housings are structural components of complex shape, which have to fulfil, amongst others, the requirements of structural durability, saving as much weight as possible. The numerical proof of structural durability is carried out using the local strain approach. One challenge is to consider the inhomogeneous material properties, as a consequence of the casting process. It shows, that local porosity is the determining factor for the components fatigue life. Coming from the experiences made using the basic version of the local strain approach the methods used to successfully adjust the procedure for calculating pressure cast components under constant and variable amplitudes are described. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[Survival properties of ETEC surface-displayed K88ac-LT(B) on Lactobacillus casei].

Science.gov (United States)

Wei, Chunhua; Liu, Jiankui; Hou, Xilin; Wang, Guihua; Yu, Liyun

2009-01-01

K88ac-LT(B) gene derived from pQE30-K88ac-LT(B) was cloned into the expression vector pLA and then the recombinant vector was transformed into the competent cells Lactobacillus casei 525. The recombinant bacteria were grown at 37 degrees C, in MRS broth. Western blotting analysis with rabbit-anti-K88ac-LT(B) polyclonal serum indicated that the recombinant protein reacted with the specific antibodies. The results showed that the molecular weight of the recombinant protein was about 71.2 kD. The K88ac-LT(B) fusion protein on the cell surface was confirmed by immunofluorescence mciroscopy and flow cytometric analysis. In addition, the survival of recombinant Lactobacillus casei 525 was studied in imitative gastrointestinal environments such as artificial gastro fluid (pH 1.5-5.5), artificial intestinal fluid, bile(0.3-3.0 g/L). The results indicated that the recombinant strain survived well in artificial gastric fluids at pH 2.5-4.5 in 5 h. The recombinant Lactobacillus casei 525 could slowly grow in the artificial intestinal fluid for different time, and could survive in 0.3% bile.

Influence of virus strain and antigen mass on efficacy of H5 avian influenza inactivated vaccines.

Science.gov (United States)

Swayne, D E; Beck, J R; Garcia, M; Stone, H D

1999-06-01

The influence of vaccine strain and antigen mass on the ability of inactivated avian influenza (AI) viruses to protect chicks from a lethal, highly pathogenic (HP) AI virus challenge was studied. Groups of 4-week-old chickens were immunized with inactivated vaccines containing one of 10 haemagglutinin subtype H5 AI viruses, one heterologous H7 AI virus or normal allantoic fluid (sham), and challenged 3 weeks later by intra-nasal inoculation with a HP H5 chicken-origin AI virus. All 10 H5 vaccines provided good protection from clinical signs and death, and produced positive serological reactions on agar gel immunodiffusion and haemagglutination inhibition tests. In experiment 1, challenge virus was recovered from the oropharynx of 80% of chickens in the H5 vaccine group. In five H5 vaccine groups, challenge virus was not recovered from the cloaca of chickens. In the other five H5 vaccine groups, the number of chickens with detection of challenge virus from the cloaca was lower than in the sham group (P turkey/Wisconsin/68 (H5N9) was the best vaccine candidate of the H5 strains tested (PD50= 0.006 μg AI antigen). These data demonstrate that chickens vaccinated with inactivated H5 whole virus AI vaccines were protected from clinical signs and death, but usage of vaccine generally did not prevent infection by the challenge virus, as indicated by recovery of virus from the oropharynx. Vaccine use reduced cloacal detection rates, and quantity of virus shed from the cloaca and oropharynx in some vaccine groups, which would potentially reduce environmental contamination and disease transmission in the field.

Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

Directory of Open Access Journals (Sweden)

Maria G Domínguez-Bello

Full Text Available We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1, all from Spanish were European (hpEurope and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination. The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

Rapid Aggregation of Biofuel-Producing Algae by the Bacterium Bacillus sp. Strain RP1137

Science.gov (United States)

Powell, Ryan J.

2013-01-01

Algal biofuels represent one of the most promising means of sustainably replacing liquid fuels. However, significant challenges remain before alga-based fuels become competitive with fossil fuels. One of the largest challenges is the ability to harvest the algae in an economical and low-energy manner. In this article, we describe the isolation of a bacterial strain, Bacillus sp. strain RP1137, which can rapidly aggregate several algae that are candidates for biofuel production, including a Nannochloropsis sp. This bacterium aggregates algae in a pH-dependent and reversible manner and retains its aggregation ability after paraformaldehyde fixation, opening the possibility for reuse of the cells. The optimal ratio of bacteria to algae is described, as is the robustness of aggregation at different salinities and temperatures. Aggregation is dependent on the presence of calcium or magnesium ions. The efficiency of aggregation of Nannochloropsis oceanica IMET1 is between 70 and 95% and is comparable to that obtained by other means of harvest; however, the rate of harvest is fast, with aggregates forming in 30 s. PMID:23892750

Changes in Holstein cow milk and serum proteins during intramammary infection with three different strains of Staphylococcus aureus

Directory of Open Access Journals (Sweden)

Robert Claude

2011-09-01

Full Text Available Abstract Background Staphylococcus aureus is one of the most prevalent pathogens to cause mastitis in dairy cattle. Intramammary infection of dairy cows with S. aureus is often subclinical, due to the pathogen's ability to evade the innate defense mechanisms, but this can lead to chronic infection. A sub-population of S. aureus, known as small colony variant (SCV, displays atypical phenotypic characteristics, causes persistent infections, and is more resistant to antibiotics than parent strains. Therefore, it was hypothesized that the host immune response will be different for SCV than its parental or typical strains of S. aureus. In this study, the local and systemic immune protein responses to intramammary infection with three strains of S. aureus, including a naturally occurring bovine SCV strain (SCV Heba3231, were characterized. Serum and casein-depleted milk cytokine levels (interleukin-8, interferon-γ, and transforming growth factor-β1, as well as serum haptoglobin concentrations were monitored over time after intramammary infection with each of the three S. aureus strains. Furthermore, comparative proteomics was used to evaluate milk proteome profiles during acute and chronic phases of S. aureus intramammary infection. Results Serum IL-8, IFN-γ, and TGF-β1 responses differed in dairy cows challenged with different strains of S. aureus. Changes in overall serum haptoglobin concentrations were observed for each S. aureus challenge group, but there were no significant differences observed between groups. In casein-depleted milk, strain-specific differences in the host IFN-γ response were observed, but inducible IL-8 and TGF-β1 concentrations were not different between groups. Proteomic analysis of the milk following intramammary infection revealed unique host protein expression profiles that were dependent on the infecting strain as well as phase of infection. Notably, the protein, component-3 of the proteose peptone (CPP3, was

Protein design in systems metabolic engineering for industrial strain development.

Science.gov (United States)

Chen, Zhen; Zeng, An-Ping

2013-05-01

Accelerating the process of industrial bacterial host strain development, aimed at increasing productivity, generating new bio-products or utilizing alternative feedstocks, requires the integration of complementary approaches to manipulate cellular metabolism and regulatory networks. Systems metabolic engineering extends the concept of classical metabolic engineering to the systems level by incorporating the techniques used in systems biology and synthetic biology, and offers a framework for the development of the next generation of industrial strains. As one of the most useful tools of systems metabolic engineering, protein design allows us to design and optimize cellular metabolism at a molecular level. Here, we review the current strategies of protein design for engineering cellular synthetic pathways, metabolic control systems and signaling pathways, and highlight the challenges of this subfield within the context of systems metabolic engineering. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of upregulated immune-related genes in Vibrio harveyi challenged Penaeus monodon postlarvae

Digital Repository Service at National Institute of Oceanography (India)

Nayak, S.; Singh, S.K.; Ramaiah, N.; Sreepada, R.A.

at the early life-stages of shrimps are of great significance. An understanding therefore, of molecular responses and defense mechanism(s) in shrimps against bacterial pathogens is essential. Besides production of antimicrobial biomolecules, the innate... of this strain grown for 24h in seawater nutrient broth were used for the experimental challenge. Cells were harvested by centrifugation and re-suspended in sterilized seawater and the PL were ‘bath’ challenged by adding the harvested cells to attain 2.5- 3...

Evidence-Based Practices to Reduce Challenging Behaviors of Young Children with Autism

Science.gov (United States)

Rahn, Naomi L.; Coogle, Christan Grygas; Hanna, Alexajo; Lewellen, Traysha

2017-01-01

Challenging behaviors refer to those behaviors that decrease the child's ability to engage and participate in classroom routines (Dunlap, Wilson, Strain, & Lee, 2013), and therefore, the dilemma in the scenario above is common to early childhood and early childhood special education teachers due to an increase in children experiencing autism…

Microbial production of nattokinase: current progress, challenge and prospect.

Science.gov (United States)

Cai, Dongbo; Zhu, Chengjun; Chen, Shouwen

2017-05-01

Nattokinase (EC 3.4.21.62) is a profibrinolytic serine protease with a potent fibrin-degrading activity, and it has been produced by many host strains. Compared to other fibrinolytic enzymes (urokinase, t-PA and streprokinase), nattokinase shows the advantages of having no side effects, low cost and long life-time, and it has the potential to be used as a drug for treating cardiovascular disease and served as a functional food additive. In this review, we focused on screening of producing strains, genetic engineering, fermentation process optimization for microbial nattokinase production, and the extraction and purification of nattokinase were also discussed in this particular chapter. The selection of optimal nattokinase producing strain was the crucial starting element for improvement of nattokinase production. Genetic engineering, protein engineering, fermentation optimization and process control have been proved to be the effective strategies for enhancement of nattokinase production. Also, extraction and purification of nattokinase are critical for the quality evaluation of nattokinase. Finally, the prospect of microbial nattokinase production was also discussed regarding the recent progress, challenge, and trends in this field.

A three-frame digital image correlation (DIC) method for the measurement of small displacements and strains

International Nuclear Information System (INIS)

Cofaru, C; Philips, W; Van Paepegem, W

2012-01-01

Digital image correlation (DIC) has become a well-established approach for the calculation of full-field displacement and strains within the field of experimental mechanics. Since their introduction, DIC methods have been relying on only two images to measure the displacements and strains that materials undergo under load. It can be foreseen that the use of additional image information for the calculus of displacements and strains, although computationally more expensive, can positively impact DIC method accuracy under both ideal and challenging experimental conditions. Such accuracy improvements are especially important when measuring very small deformations, which still constitutes a great challenge: small displacements and strains translate into equally small digital image intensity changes on the material’s surface, which are affected by the digitization processes of the imaging hardware and by other image acquisition effects such as image noise. This paper proposes a new three-frame Newton–Raphson DIC method and evaluates it from the standpoints of accuracy and speed. The method models the deformations that are to be measured under the assumption that the deformation occurs at approximately the same rate between each two consecutive images in the three image sequences that are employed. The aim is to investigate how the use of image data from more than two images impacts accuracy and what is the effect on the computational speed. The proposed method is compared with the classic two-frame Newton–Raphson method in three experiments. Two experiments rely on numerically deformed images that simulate heterogeneous deformations. The third experiment uses images from a real deformation experiment. Results indicate that although it is computationally more demanding, the three-frame method significantly improves displacement and strain accuracy and is less sensitive to image noise. (paper)

Studying the Genetics of Resistance to CyHV-3 Disease Using Introgression from Feral to Cultured Common Carp Strains

Science.gov (United States)

Tadmor-Levi, Roni; Asoulin, Efrat; Hulata, Gideon; David, Lior

2017-01-01

Sustainability and further development of aquaculture production are constantly challenged by outbreaks of fish diseases, which are difficult to prevent or control. Developing fish strains that are genetically resistant to a disease is a cost-effective and a sustainable solution to address this challenge. To do so, heritable genetic variation in disease resistance should be identified and combined together with other desirable production traits. Aquaculture of common carp has suffered substantial losses from the infectious disease caused by the cyprinid herpes virus type 3 (CyHV-3) virus and the global spread of outbreaks indicates that many cultured strains are susceptible. In this research, CyHV-3 resistance from the feral strain “Amur Sassan” was successfully introgressed into two susceptible cultured strains up to the first backcross (BC1) generation. Variation in resistance of families from F1 and BC1 generations was significantly greater compared to that among families of any of the susceptible parental lines, a good starting point for a family selection program. Considerable additive genetic variation was found for CyHV-3 resistance. This phenotype was transferable between generations with contributions to resistance from both the resistant feral and the susceptible cultured strains. Reduced scale coverage (mirror phenotype) is desirable and common in cultured strains, but so far, cultured mirror carp strains were found to be susceptible. Here, using BC1 families ranging from susceptible to resistant, no differences in resistance levels between fully scaled and mirror full-sib groups were found, indicating that CyHV-3 resistance was successfully combined with the desirable mirror phenotype. In addition, the CyHV-3 viral load in tissues throughout the infection of susceptible and resistant fish was followed. Although resistant fish get infected, viral loads in tissues of these fish are significantly lesser than in those of susceptible fish, allowing them

DNA vaccines encoding proteins from wild-type and attenuated canine distemper virus protect equally well against wild-type virus challenge.

Science.gov (United States)

Nielsen, Line; Jensen, Trine Hammer; Kristensen, Birte; Jensen, Tove Dannemann; Karlskov-Mortensen, Peter; Lund, Morten; Aasted, Bent; Blixenkrone-Møller, Merete

2012-10-01

Immunity induced by DNA vaccines containing the hemagglutinin (H) and nucleoprotein (N) genes of wild-type and attenuated canine distemper virus (CDV) was investigated in mink (Mustela vison), a highly susceptible natural host of CDV. All DNA-immunized mink seroconverted, and significant levels of virus-neutralizing (VN) antibodies were present on the day of challenge with wild-type CDV. The DNA vaccines also primed the cell-mediated memory responses, as indicated by an early increase in the number of interferon-gamma (IFN-γ)-producing lymphocytes after challenge. Importantly, the wild-type and attenuated CDV DNA vaccines had a long-term protective effect against wild-type CDV challenge. The vaccine-induced immunity induced by the H and N genes from wild-type CDV and those from attenuated CDV was comparable. Because these two DNA vaccines were shown to protect equally well against wild-type virus challenge, it is suggested that the genetic/antigenic heterogeneity between vaccine strains and contemporary wild-type strains are unlikely to cause vaccine failure.

A Wireless Sensor Network with Enhanced Power Efficiency and Embedded Strain Cycle Identification for Fatigue Monitoring of Railway Bridges

OpenAIRE

Feltrin, Glauco; Popovic, Nemanja; Flouri, Kallirroi; Pietrzak, Piotr

2016-01-01

Wireless sensor networks have been shown to be a cost-effective monitoring tool for many applications on civil structures. Strain cycle monitoring for fatigue life assessment of railway bridges, however, is still a challenge since it is data intensive and requires a reliable operation for several weeks or months. In addition, sensing with electrical resistance strain gauges is expensive in terms of energy consumption. The induced reduction of battery lifetime of sensor nodes increases the mai...

Laser-engraved carbon nanotube paper for instilling high sensitivity, high stretchability, and high linearity in strain sensors

KAUST Repository

Xin, Yangyang

2017-06-29

There is an increasing demand for strain sensors with high sensitivity and high stretchability for new applications such as robotics or wearable electronics. However, for the available technologies, the sensitivity of the sensors varies widely. These sensors are also highly nonlinear, making reliable measurement challenging. Here we introduce a new family of sensors composed of a laser-engraved carbon nanotube paper embedded in an elastomer. A roll-to-roll pressing of these sensors activates a pre-defined fragmentation process, which results in a well-controlled, fragmented microstructure. Such sensors are reproducible and durable and can attain ultrahigh sensitivity and high stretchability (with a gauge factor of over 4.2 × 10(4) at 150% strain). Moreover, they can attain high linearity from 0% to 15% and from 22% to 150% strain. They are good candidates for stretchable electronic applications that require high sensitivity and linearity at large strains.

Viability and Stress Response of Putative Probiotic Lactobacillus plantarum Strains in Honey Environment.

Science.gov (United States)

Landry, Bemmo Kamdem Ulrich; François, Zambou Ngoufack; Wang, Rui-Yan; Taicheng, Zhu; Li, Yin

2017-12-01

Due to problem of preservation of dairy products which serve as a matrix for probiotics, it is challenging to use these probiotics as food supplements in many developing countries. To determine the suitability of the Lactobacillus strains for exploitation as probiotics in honey, we investigated the effect of their storage on the viability, functionality, and the mechanism associated with their protective effect. Three isolates obtained from our laboratory collection were identified through amplification of the 16S rRNA gene. The viability of the strains in honey at different storage conditions was studied. Three genes (hdc, gtf, and clpL) responsible for the resistance of bacteria in acidic environments were screened. SDS-PAGE analysis of total protein was performed to observe protein profile changes of the strains after exposure to honey. All the three isolates, namely, GGU, GLA51, and GLP56, were identified as Lactobacillus plantarum strains. After 28 days of storage in honey at 4 °C, viable cell concentrations of the three strains were higher than 2.04 × 10 6  CFU/ml. During the same period at room temperature, only the Lactobacillus plantarum GLP56 strain remained viable with a cell concentration of 1.86 × 10 4  CFU/ml. The clpL gene coding for ATPase was detected in all the three strains. The protein of molecular weight ~ 50 kDa was absent in the protein profile of Lactobacillus plantarum GGU after 60 days of storage in honey at 4 °C. The Lactobacillus plantarum GLP56, Lactobacillus plantarum GLA51, and Lactobacillus plantarum GGU strains exposed to honey can withstand acidic environmental stress but their viability declines over time.

Effect of Mouse Strain in a Model of Chemical-induced Respiratory Allergy

OpenAIRE

Nishino, Risako; Fukuyama, Tomoki; Watanabe, Yuko; Kurosawa, Yoshimi; Ueda, Hideo; Kosaka, Tadashi

2014-01-01

The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical–related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical–related respiratory allergens by using a long-term sensitization–challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences ...

An Equal-Strain Analytical Solution for the Radial Consolidation of Unsaturated Soils by Vertical Drains considering Drain Resistance

Directory of Open Access Journals (Sweden)

Feng Zhou

2018-01-01

Full Text Available Developing an analytical solution for the consolidation of unsaturated soils remains a challenging task due to the complexity of coupled governing equations for air and water phases. This paper presents an equal-strain model for the radial consolidation of unsaturated soils by vertical drains, and the effect of drain resistance is also considered. Simplified governing equations are established, and an analytical solution to calculate the excess pore-air and pore-water pressures is derived by using the methods of matrix analysis and eigenfunction expansion. The average degrees of consolidation for air and water phases and the ground surface settlement are also given. The solutions of the equal-strain model are verified by comparing the proposed free-strain model with the equal-strain model, and reasonably good agreement is obtained. Moreover, parametric studies regarding the drain resistance effect are graphically presented.

Characterization and Virulence Assessment of Two 091:821 Enterohemorrhagic Escherichia Coli Isolates

Science.gov (United States)

1993-04-30

stable toxin (ST) . ETEC cause profuse watery diarrhea similar to the diarrhea caused by Vibrio cholerae infection (Sack, 1975). EIEC, unlike ETEC...Fr •• ley, R. B. Sack, W. B. Cr •• ch, A. Z. Itapikian, B. J. Gang_ro ••• 1976. Travelers diarrhea in Mexico . A prospective study of physicians...p.153- 158 . Proceedings of the U. S.-Japan 27th Joint Conference on Cholera and Related Diarrheal Diseases. Virginia. Charlottesville, Yu, J

Different resistance patterns of reference and field strains of Brucella abortus

Directory of Open Access Journals (Sweden)

Karina L. Miranda

2015-03-01

Full Text Available The aim of this study was to evaluate the growth of the B. abortus reference strains and field isolates on media containing different inhibitor agents. Reference strains were seeded on tryptose agar containing: i-erythritol (1.0 mg/mL, fuchsin (20 μg/mL and 80 μg/mL, thionin (2.5 μg/mL and 10 μg/mL, rifampicin (200 μg/mL and safranin O (200 μg/mL. Field isolates were tested only on media containing i-erythritol, rifampicin and thionin. Furthermore, each suspension was also inoculated on tryptose agar incubated in air, to test its ability to grow without CO2. Sensitivity to fuchsin was similar among reference strains evaluated. Growth of S19, 544 and 2308 but not RB51 were inhibited on media containing rifampicin. Medium with safranin O showed no inhibition for RB51, 544 and 2308, but it partially inhibited the S19 growth as well as medium containing i-erythritol. Treatment/control growth ratio for 2308 on tryptose agar containing thionin (2.5 μg/mL was approximatelly 1.0, whereas S19 and RB51 showed 0.85 and 0.89 ratios, respectively. Growth of 544, S19 and RB51 but not 2308 was completely inhibited on medium with thionin (10 μg/mL. All field strains grew on medium containing i-erythritol, but were completelly inhibited by rifampicin. With exception of A1 (B. abortus biovar 3 all field isolates grew on medium with thionin, although some strains showed a treatment/control growth ratio of 0.75–0.80 (10 μg/mL. These results showed that tryptose agar with thionin, i-erythritol or rifampicin could be useful for differentiating vaccine, challenge and field strains of B. abortus.

Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

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Ben Lane

2018-03-01

Full Text Available The aim of this investigation was to establish the strains and strain rates experienced by tennis ball cores during impact to inform material characterisation testing and finite element modelling. Three-dimensional surface strains and strain rates were measured using two high-speed video cameras and corresponding digital image correlation software (GOM Correlate Professional. The results suggest that material characterisation testing to a maximum strain of 0.4 and a maximum rate of 500 s−1 in tension and to a maximum strain of −0.4 and a maximum rate of −800 s−1 in compression would encapsulate the demands placed on the material during impact and, in turn, define the range of properties required to encapsulate the behavior of the material during impact, enabling testing to be application-specific and strain-rate-dependent properties to be established and incorporated in finite element models.

Oral administration of a select mixture of Bacillus probiotics generates Tr1 cells in weaned F4ab/acR pigs challenged with an F4+ ETEC/VTEC/EPEC strain

DEFF Research Database (Denmark)

Zhou, Dong; Zhang, Wei; Wang, Meng-Ling

2015-01-01

Although breeding of F4 receptor − negative (F4R−) pigs may prevent post-weaning diarrhea, the underlying immunity is poorly understood. Here, various doses of a Bacillus licheniformis and Bacillus subtilis mixture (BLS-mix) were orally administered to F4ab/acR− pigs for 1 week before F4 (K88) − ...... of BLS-mix during episodes of intestinal inflammation that is caused by enteric pathogens might prohibit clearance of the pathogen. Select probiotic mixtures may allow for tailoring strategies to prevent infectious diseases....

3D Tendon Strain Estimation Using High-frequency Volumetric Ultrasound Images: A Feasibility Study.

Science.gov (United States)

Carvalho, Catarina; Slagmolen, Pieter; Bogaerts, Stijn; Scheys, Lennart; D'hooge, Jan; Peers, Koen; Maes, Frederik; Suetens, Paul

2018-03-01

Estimation of strain in tendons for tendinopathy assessment is a hot topic within the sports medicine community. It is believed that, if accurately estimated, existing treatment and rehabilitation protocols can be improved and presymptomatic abnormalities can be detected earlier. State-of-the-art studies present inaccurate and highly variable strain estimates, leaving this problem without solution. Out-of-plane motion, present when acquiring two-dimensional (2D) ultrasound (US) images, is a known problem and may be responsible for such errors. This work investigates the benefit of high-frequency, three-dimensional (3D) US imaging to reduce errors in tendon strain estimation. Volumetric US images were acquired in silico, in vitro, and ex vivo using an innovative acquisition approach that combines the acquisition of 2D high-frequency US images with a mechanical guided system. An affine image registration method was used to estimate global strain. 3D strain estimates were then compared with ground-truth values and with 2D strain estimates. The obtained results for in silico data showed a mean absolute error (MAE) of 0.07%, 0.05%, and 0.27% for 3D estimates along axial, lateral direction, and elevation direction and a respective MAE of 0.21% and 0.29% for 2D strain estimates. Although 3D could outperform 2D, this does not occur in in vitro and ex vivo settings, likely due to 3D acquisition artifacts. Comparison against the state-of-the-art methods showed competitive results. The proposed work shows that 3D strain estimates are more accurate than 2D estimates but acquisition of appropriate 3D US images remains a challenge.

Strain measurement based battery testing

Science.gov (United States)

Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

2017-05-23

A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

Comparative proteome analysis of two Streptococcus agalactiae strains from cultured tilapia with different virulence.

Science.gov (United States)

Li, Wei; Su, You-Lu; Mai, Yong-Zhan; Li, Yan-Wei; Mo, Ze-Quan; Li, An-Xing

2014-05-14

Streptococcus agalactiae is a major piscine pathogen, which causes significant morbidity and mortality among numerous fish species, and results in huge economic losses to aquaculture. Many S. agalactiae strains showing different virulence characteristics have been isolated from infected tilapia in different geographical regions throughout South China in the recent years, including natural attenuated S. agalactiae strain TFJ0901 and virulent S. agalactiae strain THN0901. In the present study, survival of tilapia challenged with S. agalactiae strain TFJ0901 and THN0901 (10(7)CFU/fish) were 93.3% and 13.3%, respectively. Moreover, there are severe lesions of the examined tissues in tilapia infected with strain THN0901, but no significant histopathological changes were observed in tilapia infected with the strain TFJ0901. In order to elucidate the factors responsible for the invasive potential of S. agalactiae between two strains TFJ0901 and THN0901, a comparative proteome analysis was applied to identify the different protein expression profiles between the two strains. 506 and 508 cellular protein spots of S. agalactiae TFJ0901 and THN0901 were separated by two dimensional electrophoresis, respectively. And 34 strain-specific spots, corresponding to 27 proteins, were identified successfully by MALDI-TOF mass spectrometry. Among them, 23 proteins presented exclusively in S. agalactiae TFJ0901 or THN0901, and the other 4 proteins presented in different isomeric forms between TFJ0901 and THN0901. Most of the strain-specific proteins were just involved in metabolic pathways, while 7 of them were presumed to be responsible for the virulence differences of S. agalactiae strain TFJ0901 and THN0901, including molecular chaperone DnaJ, dihydrolipoamide dehydrogenase, thioredoxin, manganese-dependent inorganic pyrophosphatase, elongation factor Tu, bleomycin resistance protein and cell division protein DivIVA. These virulence-associated proteins may contribute to identify new

Strain measurement technique

International Nuclear Information System (INIS)

1987-01-01

The 10 contributions are concerned with selected areas of application, such as strain measurements in wood, rubber/metal compounds, sets of strain measurements on buildings, reinforced concrete structures without gaps, pipes buried in the ground and measurements of pressure fluctuations. To increase the availability and safety of plant, stress analyses were made on gas turbine rotors with HT-DMS or capacitive HT-DMS (high temperature strain measurements). (DG) [de

A chimeric measles virus with canine distemper envelope protects ferrets from lethal distemper challenge.

Science.gov (United States)

Rouxel, Ronan Nicolas; Svitek, Nicholas; von Messling, Veronika

2009-08-06

CDV infects a broad range of carnivores, and over the past decades it has caused outbreaks in a variety of wild carnivore populations. Since the currently available live-attenuated vaccine is not sufficiently safe in these highly susceptible species, we produced a chimeric virus combining the replication complex of the measles Moraten vaccine strain with the envelope of a recent CDV wild type isolate. The resulting virus did not cause disease or immunosuppression in ferrets and conferred protection from challenge with a lethal wild type strain, demonstrating its potential value for wildlife conservation efforts.

Development and Efficacy Assessment of an Enteric Coated Porous Tablet Loaded With F4 Fimbriae for Oral Vaccination of Piglets against F4+ Escherichia coli Infections.

Science.gov (United States)

Srivastava, Atul; Gowda, D V; Madhunapantula, SubbaRao V; Siddaramaiah

2016-01-01

Enterotoxigenic Escherichia coli (ETEC) infection is one of the major causes contributing to the development of diarrhoea and mortality in new born, suckling and newly weaned piglets. To date, no preventive/treatment strategy showed promising results, which could be due to the lack of potent vaccines, and/or due to the development of resistance of ETEC to antibiotics. Therefore, in the present investigation, a novel porous sodium alginate (SA) tablet formulation loaded with F4 fimbriae antigen was developed and tested for efficacy against ETEC infections in piglet models. Precompression parameters of the powder mixes and post compression parameters of tablets have been evaluated and results were found to be satisfactory. Loading of F4 fimbrial antigens into the tablets was achieved by inducing pores in the tablets via the sublimation of camphor followed by incubation with purified F4 fimbriae. The loaded tablets have been coated with Eudragit L100 to protect the F4 fimbriae from (a) highly acidic gastric environment; (b) proteolytic cleavage by pepsin; and (c) to promote subsequent release in the intestine. Evaluation of developed F4 fimbrial tablets in a Pig model demonstrated induction of mucosal immunity, and a significant reduction of F4+ E. coli in faeces. Therefore, F4 fimbriae loaded porous tablets could be a novel oral vaccination candidate to induce mucosal and systemic immunity against ETEC infections.

Memory B cells and CD8⁺ lymphocytes do not control seasonal influenza A virus replication after homologous re-challenge of rhesus macaques.

Directory of Open Access Journals (Sweden)

Timothy D Carroll

Full Text Available This study sought to define the role of memory lymphocytes in the protection from homologous influenza A virus re-challenge in rhesus macaques. Depleting monoclonal antibodies (mAb were administered to the animals prior to their second experimental inoculation with a human seasonal influenza A virus strain. Treatment with either anti-CD8α or anti-CD20 mAbs prior to re-challenge had minimal effect on influenza A virus replication. Thus, in non-human primates with pre-existing anti-influenza A antibodies, memory B cells and CD8α⁺ T cells do not contribute to the control of virus replication after re-challenge with a homologous strain of influenza A virus.

Ethical challenges in neonatal intensive care nursing.

Science.gov (United States)

Strandås, Maria; Fredriksen, Sven-Tore D

2015-12-01

Neonatal nurses report a great deal of ethical challenges in their everyday work. Seemingly trivial everyday choices nurses make are no more value-neutral than life-and-death choices. Everyday ethical challenges should also be recognized as ethical dilemmas in clinical practice. The purpose of this study is to investigate which types of ethical challenges neonatal nurses experience in their day-to-day care for critically ill newborns. Data were collected through semi-structured qualitative in-depth interviews. Phenomenological-hermeneutic analysis was applied to interpret the data. Six nurses from neonatal intensive care units at two Norwegian hospitals were interviewed on-site. The study is designed to comply with Ethical Guidelines for Nursing Research in the Nordic Countries and the Helsinki declaration. Findings suggest that nurses experience a diverse range of everyday ethical challenges related to challenging interactions with parents and colleagues, emotional strain, protecting the vulnerable infant, finding the balance between sensitivity and authority, ensuring continuity of treatment, and miscommunication and professional disagreement. A major finding in this study is how different agents involved in caring for the newborn experience their realities differently. When these realities collide, ethical challenges arise. Findings suggest that acting in the best interests of the child becomes more difficult in situations involving many agents with different perceptions of reality. The study presents new aspects which increases knowledge and understanding of the reality of nursing in a neonatal intensive care unit, while also demanding increased research in this field of care. © The Author(s) 2014.

Adaptive response in Drosophila melanogaster heat shock proteins mutant strains

International Nuclear Information System (INIS)

Shaposhnikov, M.V.; Moskalev, A.A.; Turysheva, E.V.

2007-01-01

Complete text of publication follows. The members of the heat shock proteins (Hsp) family function as molecular chaperones and assist intracellular folding of newly synthesized proteins. Also it is possible that molecular chaperones are induced during adaptive response to oxidative stress and radiation. The aim of our research was to exam the role of heat shock proteins in adaptive response to oxidative stress after low dose rate gamma-irradiation in Drosophila melanogaster. Drosophilamelanogaster strains were kindly provided by Bloomington Drosophila Stock Center (University of state of Indiana, Bloomington, USA). We used wild type strain (CS), heat shock protein mutant strains (Hsp22, Hsp70, Hsp83), and heat shock factor mutant strain (Hsf). Strains were chronically exposured to adaptive dose of gamma-irradiation in dose rate of 0.17 cGy/h during all stages of life history (from the embrional stage to the stage of matured imago). The rate of absorbed dose was 60 cGy. For oxidative-stress challenge twodays old flies were starved in empty vials for 6 h and then transferred to vials containing only filter paper soaked with 20 mM paraquat in 5% sucrose solution. Survival data were collected after 26 h of treatment. Dead flies were counted daily. The obtained data were subjected to survival analysis by Kaplan and Meier method and presented as survival curves. Statistical analysis was held by non-parametric methods. To test the significance of the difference between the two age distributions Kolmogorov-Smirnov test was applied. Gehan-Braslow- Wilcoxon and Cox-Mantel tests were used for estimation of median life span differences. In addition the minimal and maximal life span, time of 90% death, and mortality rate doubling time (MRDT) were estimated. The obtained results will be discussed in presentation.

Rat Strain Ontology: structured controlled vocabulary designed to facilitate access to strain data at RGD.

Science.gov (United States)

Nigam, Rajni; Munzenmaier, Diane H; Worthey, Elizabeth A; Dwinell, Melinda R; Shimoyama, Mary; Jacob, Howard J

2013-11-22

The Rat Genome Database (RGD) ( http://rgd.mcw.edu/) is the premier site for comprehensive data on the different strains of the laboratory rat (Rattus norvegicus). The strain data are collected from various publications, direct submissions from individual researchers, and rat providers worldwide. Rat strain, substrain designation and nomenclature follow the Guidelines for Nomenclature of Mouse and Rat Strains, instituted by the International Committee on Standardized Genetic Nomenclature for Mice. While symbols and names aid in identifying strains correctly, the flat nature of this information prohibits easy search and retrieval, as well as other data mining functions. In order to improve these functionalities, particularly in ontology-based tools, the Rat Strain Ontology (RS) was developed. The Rat Strain Ontology (RS) reflects the breeding history, parental background, and genetic manipulation of rat strains. This controlled vocabulary organizes strains by type: inbred, outbred, chromosome altered, congenic, mutant and so on. In addition, under the chromosome altered category, strains are organized by chromosome, and further by type of manipulations, such as mutant or congenic. This allows users to easily retrieve strains of interest with modifications in specific genomic regions. The ontology was developed using the Open Biological and Biomedical Ontology (OBO) file format, and is organized on the Directed Acyclic Graph (DAG) structure. Rat Strain Ontology IDs are included as part of the strain report (RS: ######). As rat researchers are often unaware of the number of substrains or altered strains within a breeding line, this vocabulary now provides an easy way to retrieve all substrains and accompanying information. Its usefulness is particularly evident in tools such as the PhenoMiner at RGD, where users can now easily retrieve phenotype measurement data for related strains, strains with similar backgrounds or those with similar introgressed regions. This

Efficacy of dart or booster vaccination with strain RB51 in protecting bison against experimental Brucella abortus challenge

Science.gov (United States)

Vaccination is an effective tool for reducing the prevalence of brucellosis in natural hosts. In this study, we characterized the efficacy of the Brucella abortus strain RB51 (RB51) vaccine in bison when delivered by single intramuscular vaccination (Hand RB51), single pneumatic dart delivery (Dart ...

Variation in the strain anisotropy of Zircaloy with temperature and strain

International Nuclear Information System (INIS)

Hindle, E.D.; Worswick, D.

1984-01-01

The strong crystallographic texture which is developed during the fabrication of zirconium-based alloys causes pronounced anisotropy in their mechanical properties, particularly deformation. The tendency for circular-section tension specimens with a high concentration of basal poles in one direction to become elliptical when deformed in tension has been used in this study to provide quantitative data on the effects of both strain and temperature on strain anisotropy. Tension tests were carried out over a temperature range of 293 to 1193 K on specimens machined from Zircaloy-2 plate. The strain anisotropy was found to increase markedly at temperatures over 923 K, reaching a maximum in the region of 1070 K. The strain anisotropy increased with increasing strain in this temperature region. The study was extended to Zircaloy-4 pressurized-water reactor fuel cladding by carrying out tube swelling tests and evaluating the axial deformation produced. Although scatter in the test results was higher than that exhibited in the tension tests, the general trend in the data was similar. The effects of the strain anisotropy observed are discussed in relation to the effects of temperature on the ductility of Zircaloy fuel cladding tubes during postulated largebreak loss-of-coolant accidents

Bacteriocinogenic LAB Strains for Fermented Meat Preservation: Perspectives, Challenges, and Limitations.

Science.gov (United States)

Favaro, Lorenzo; Todorov, Svetoslav Dimitrov

2017-12-01

Over the last decades, much research has focused on lactic acid bacteria (LAB) bacteriocins because of their potential as biopreservatives and their action against the growth of spoilage microbes. Meat and fermented meat products are prone to microbial contamination, causing health risks, as well as economic losses in the meat industry. The use of bacteriocin-producing LAB starter or protective cultures is suitable for fermented meats. However, although bacteriocins can be produced during meat processing, their levels are usually much lower than those achieved during in vitro fermentations under optimal environmental conditions. Thus, the direct addition of a bacteriocin food additive would be desirable. Moreover, safety and technological characteristics of the bacteriocinogenic LAB must be considered before their widespread applications. This review describes the perspectives and challenges toward the complete disclosure of new bacteriocins as effective preservatives in the production of safe and "healthy" fermented meat products.

Three dimensional strained semiconductors

Science.gov (United States)

Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

2016-11-08

In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

Experimental Study on Strain Reliability of Embroidered Passive UHF RFID Textile Tag Antennas and Interconnections

Directory of Open Access Journals (Sweden)

Xiaochen Chen

2017-01-01

Full Text Available We present embroidered antennas and interconnections in passive UHF RFID textile tags and test their strain reliability. Firstly, we fabricate tag antennas on two different stretchable fabric substrates by five different embroidery patterns and choose the most stretchable ones for testing. Next, the tag ICs are attached by sewing and gluing, and the tag reliability during repeated stretching cycles is evaluated through wireless measurements. Initially, the chosen tags achieve read ranges of 6–8 meters and can strain up to 140–150% of their original length. After 100 stretching cycles to 80% of their maximum strain, the read ranges of the tags with glued interconnections are similar to the initial values. In addition, also the read ranges of the tags with sewed interconnections are still more than 70%–85% of their initial values. However, some challenges with the reproducibility need to be solved next.

The first pathogenic Yersinia enterocolitica bioserotype 4/O:3 strain isolated from a hunted wild boar (Sus scrofa) in Poland.

Science.gov (United States)

Bancerz-Kisiel, A; Platt-Samoraj, A; Szczerba-Turek, A; Syczyło, K; Szweda, W

2015-10-01

The objective of this study was to identify the bioserotypes and virulence markers of Yersinia enterocolitica strains isolated from wild boars in Poland. Bacteriological examination of 302 rectal swabs from 151 wild boars resulted in the isolation of 40 Y. enterocolitica strains. The majority of the examined strains (n = 30), belonged to bioserotype 1A/NI. The presence of individual Y. enterocolitica strains belonging to bioserotypes 1B/NI (3), 1A/O:8 (2), 1A/O:27 (2), 2/NI (1), 2/O:9 (1) and 4/O:3 (1) was also demonstrated. Amplicons corresponding to ail and ystA genes were observed only in one Y. enterocolitica strain--bioserotype 4/O:3. The ail and ystB gene amplicons were noted in 11 Y. enterocolitica biotype 1A strains, although single amplicons of ystB gene were found in 28 of the tested samples. In four out of eight cases when two Y. enterocolitica strains were isolated from the same animal, the strains differed in biotype, serotype or virulence markers. The European population of wild boars continues to grow and spread to new areas, therefore, wild boars harbouring potentially pathogenic Y. enterocolitica 4/O:3 strains pose a challenge to public health.

Strain rate sensitivity studies on bulk nanocrystalline aluminium by nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Varam, Sreedevi; Rajulapati, Koteswararao V., E-mail: kvrse@uohyd.ernet.in; Bhanu Sankara Rao, K.

2014-02-05

Nanocrystalline aluminium powder synthesized using high energy ball milling process was characterized by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The studies indicated the powder having an average grain size of ∼42 nm. The consolidation of the powder was carried out by high-pressure compaction using a uni-axial press at room temperature by applying a pressure of 1.5 GPa. The cold compacted bulk sample having a density of ∼98% was subjected to nanoindentation which showed an average hardness and elastic modulus values of 1.67 ± 0.09 GPa and 83 ± 8 GPa respectively at a peak force of 8000 μN and a strain rate of 10{sup −2} s{sup −1}. Achieving good strength along with good ductility is challenging in nanocrystalline metals. When enough sample sizes are not available to measure ductility and other mechanical properties as per ASTM standards, as is the case with nanocrystalline materials, nanoindentation is a very promising technique to evaluate strain rate sensitivity. Strain rate sensitivity is a good measure of ductility and in the present work it is measured by performing indentation at various loads with varying loading rates. Strain rate sensitivity values of 0.024–0.054 are obtained for nanocrystalline Al which are high over conventional coarse grained Al. In addition, Scanning Probe Microscopy (SPM) image of the indent shows that there is some plastically flown region around the indent suggesting that this nanocrystalline aluminium is ductile.

Hamstring strain - aftercare

Science.gov (United States)

Pulled hamstring muscle; Sprain - hamstring ... There are 3 levels of hamstring strains: Grade 1 -- mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends ...

Strain-Modulated Epitaxy

National Research Council Canada - National Science Library

Brown, April

1999-01-01

Strain-Modulated Epitaxy (SME) is a novel approach, invented at Georgia Tech, to utilize subsurface stressors to control strain and therefore material properties and growth kinetics in the material above the stressors...

Methodology to measure strains at high temperatures using electrical strain gages with free filaments

International Nuclear Information System (INIS)

Atanazio Filho, Nelson N.; Gomes, Paulo T. Vida; Scaldaferri, Denis H.B.; Silva, Luiz L. da; Rabello, Emerson G.; Mansur, Tanius R.

2013-01-01

An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

In situ measurement using FBGs of process-induced strains during curing of thick glass/epoxy laminate plate

DEFF Research Database (Denmark)

Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Hattel, Jesper Henri

2012-01-01

For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre...... Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary...... conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model...

Characterization of high-strain rate mechanical behavior of AZ31 magnesium alloy using 3D digital image correlation

Energy Technology Data Exchange (ETDEWEB)

Wang, Yanli; Xu, Hanbing; Erdman, Donald L.; Starbuck, Michael J.; Simunovic, Srdjan [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

2011-10-15

Characterization of the material mechanical behavior at sub-Hopkinson regime (0.1 to 1 000 s{sup -1}) is very challenging due to instrumentation limitations and the complexity of data analysis involved in dynamic loading. In this study, AZ31 magnesium alloy sheet specimens are tested using a custom designed servo-hydraulic machine in tension at nominal strain rates up to 1 000 s{sup -1}. In order to resolve strain measurement artifacts, the specimen displacement is measured using 3D Digital Image correlation instead from actuator motion. The total strain is measured up to {approx} 30%, which is far beyond the measurable range of electric resistance strain gages. Stresses are calculated based on the elastic strains in the tab of a standard dog-bone shaped specimen. Using this technique, the stresses measured for strain rates of 100 s{sup -1} and lower show little or no noise comparing to load cell signals. When the strain rates are higher than 250 s{sup -1}, the noises and oscillations in the stress measurements are significantly decreased from {approx} 250 to 50 MPa. Overall, it is found that there are no significant differences in the elongation, although the material exhibits slight work hardening when the strain rate is increased from 1 to 100 s{sup -1}. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Soft network materials with isotropic negative Poisson's ratios over large strains.

Science.gov (United States)

Liu, Jianxing; Zhang, Yihui

2018-01-31

Auxetic materials with negative Poisson's ratios have important applications across a broad range of engineering areas, such as biomedical devices, aerospace engineering and automotive engineering. A variety of design strategies have been developed to achieve artificial auxetic materials with controllable responses in the Poisson's ratio. The development of designs that can offer isotropic negative Poisson's ratios over large strains can open up new opportunities in emerging biomedical applications, which, however, remains a challenge. Here, we introduce deterministic routes to soft architected materials that can be tailored precisely to yield the values of Poisson's ratio in the range from -1 to 1, in an isotropic manner, with a tunable strain range from 0% to ∼90%. The designs rely on a network construction in a periodic lattice topology, which incorporates zigzag microstructures as building blocks to connect lattice nodes. Combined experimental and theoretical studies on broad classes of network topologies illustrate the wide-ranging utility of these concepts. Quantitative mechanics modeling under both infinitesimal and finite deformations allows the development of a rigorous design algorithm that determines the necessary network geometries to yield target Poisson ratios over desired strain ranges. Demonstrative examples in artificial skin with both the negative Poisson's ratio and the nonlinear stress-strain curve precisely matching those of the cat's skin and in unusual cylindrical structures with engineered Poisson effect and shape memory effect suggest potential applications of these network materials.

Comparison of bacterial culture and qPCR testing of rectal and pen floor samples as diagnostic approaches to detect enterotoxic Escherichia coli in nursery pigs

DEFF Research Database (Denmark)

Weber, N. R.; Nielsen, J. P.; Hjulsager, Charlotte Kristiane

2017-01-01

Enterotoxigenic E. coli (ETEC) are a major cause of diarrhoea in weaned pigs. The objective of this study was to evaluate the agreement at pen level among three different diagnostic approaches for the detection of ETEC in groups of nursery pigs with diarrhoea. The diagnostic approaches used were......: bacterial culturing of faecal samples from three pigs (per pen) with clinical diarrhoea and subsequent testing for virulence genes in E. coli isolates; bacterial culturing of pen floor samples and subsequent testing for virulence genes in E. coli isolates; qPCR testing of pen floor samples in order...... to determine the quantity of F18 and F4 genes. The study was carried out in three Danish pig herds and included 31 pens with a pen-level diarrhoea prevalence of > 25%, as well as samples from 93 diarrhoeic nursery pigs from these pens. All E. coli isolates were analysed by PCR and classified as ETEC when genes...

Finite Element Verification of Non-Homogeneous Strain and Stress Fields during Composite Material Testing

DEFF Research Database (Denmark)

Mikkelsen, Lars Pilgaard

2015-01-01

Uni-directional glass fiber reinforced polymers play a central role in the task increasing the length of wind turbines blades and thereby lowering the cost of energy from wind turbine installations. During this, optimizing the mechanical performance regarding material stiffness, compression...... strength and fatigue performance is essential. Nevertheless, testing composites includes some challenges regarding stiffness determination using conventional strain gauges and achieving correct material failure unaffected by the gripping region during fatigue testing. Challenges, which in the present study......, has been addressed using the finite element method. During this, a verification of experimental observations, a deeper understanding on the test coupon loading and thereby improved test methods has been achieved....

Health care providers under pressure: making the most of challenging times.

Science.gov (United States)

Davis, Scott B; Robinson, Phillip J

2010-01-01

Whether the slowing economic recovery, tight credit markets, increasing costs, or the uncertainty surrounding health care reform, the health care industry faces some sizeable challenges. These factors have put considerable strain on the industry's traditional financing options that the industry has relied on in the past--bonds, banks, finance companies, private equity, venture capital, real estate investment trusts, private philanthropy, and grants. At the same time, providers are dealing with rising costs, lower reimbursement rates, shrinking demand for elective procedures, higher levels of charitable care and bad debt, and increased scrutiny of tax-exempt hospitals. Providers face these challenges against a back ground of uncertainty created by health care reform.

Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

Energy Technology Data Exchange (ETDEWEB)

Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Lacroute, Y.; Markey, L.; Salazar, M.; Vignal, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France)

2011-05-15

Research highlights: > Surface strains measured using nanogauge were compared to the texture obtained by EBSD. > Statistics of the principal strain discern the grains according to the Schmid factor. > Strain hotspots were localized near a triple junction of alloy 600 under tensile loading. > Asymetrical profile of the GB strains is a criterion for surface cracking initiation. - Abstract: A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then investigated both statistically for each grain and locally at the grain boundaries. The superimposition of microstructure and strain maps allows the high strain gradient (reaching 3-fold the applied strain) to be localized at preferential grain boundaries near the triple junction. The Schmid factors and the KAM were compared to the maximum principal strain and the in-plane shear strain respectively. The polycrystalline deformation was attributable first to the rotation of some grains, followed by the elongation of all grains along their preferential activated slip systems.

A live oral Lawsonia intracellularis vaccine does not result in protective immunity comparable to that of a virulent strain

DEFF Research Database (Denmark)

Hvass, Henriette Cordes; Riber, Ulla; Ståhl, Marie

in subclinical disease. Both groups were treated with antibiotics from day 21 to 26 and challenged at day 49 with the virulent strain. A control group (CC) only received challenge. We here report on clinical outcome, L. intracellularis infection of the intestines and immunological responses. While Re-I pigs had...... in both Vac and Re-I groups after primary inoculation/vaccination compared to the CC group. After challenge, however Vac and CC levels were high and Re-I levels low, indicating that Re-I pigs were protected from disease whereas vaccinated pigs were not. These results show that the vaccination does...

Towards efficient bioethanol production from agricultural and forestry residues: Exploration of unique natural microorganisms in combination with advanced strain engineering.

Science.gov (United States)

Zhao, Xinqing; Xiong, Liang; Zhang, Mingming; Bai, Fengwu

2016-09-01

Production of fuel ethanol from lignocellulosic feedstocks such as agricultural and forestry residues is receiving increasing attention due to the unsustainable supply of fossil fuels. Three key challenges include high cellulase production cost, toxicity of the cellulosic hydrolysate to microbial strains, and poor ability of fermenting microorganisms to utilize certain fermentable sugars in the hydrolysate. In this article, studies on searching of natural microbial strains for production of unique cellulase for biorefinery of agricultural and forestry wastes, as well as development of strains for improved cellulase production were reviewed. In addition, progress in the construction of yeast strains with improved stress tolerance and the capability to fully utilize xylose and glucose in the cellulosic hydrolysate was also summarized. With the superior microbial strains for high titer cellulase production and efficient utilization of all fermentable sugars in the hydrolysate, economic biofuels production from agricultural residues and forestry wastes can be realized. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pathogenic outcome following experimental infection of sheep with Chlamydia abortus variant strains LLG and POS.

Science.gov (United States)

Livingstone, Morag; Wheelhouse, Nicholas; Ensor, Hannah; Rocchi, Mara; Maley, Stephen; Aitchison, Kevin; Wattegedera, Sean; Wilson, Kim; Sait, Michelle; Siarkou, Victoria; Vretou, Evangelia; Entrican, Gary; Dagleish, Mark; Longbottom, David

2017-01-01

This study investigated the pathogenesis of two variant strains (LLG and POS) of Chlamydia abortus, in comparison to a typical wild-type strain (S26/3) which is known to be responsible for late term abortion in small ruminants. Challenge with the three strains at mid-gestation resulted in similar pregnancy outcomes, with abortion occurring in approximately 50-60% of ewes with the mean gestational lengths also being similar. However, differences were observed in the severity of placental pathology, with infection appearing milder for strain LLG, which was reflected in the lower number of organisms shed in vaginal swabs post-partum and less gross pathology and organisms present in placental smears. Results for strain POS were somewhat different than LLG with a more focal restriction of infection observed. Post-abortion antibody responses revealed prominent differences in seropositivity to the major outer membrane protein (MOMP) present in elementary body (EB) preparations under denaturing conditions, most notably with anti-LLG and anti-POS convalescent sera where there was no or reduced detection of MOMP present in EBs derived from the three strains. These results and additional analysis of whole EB and chlamydial outer membrane complex preparations suggest that there are conformational differences in MOMP for the three strains. Overall, the results suggest that gross placental pathology and clinical outcome is not indicative of bacterial colonization and the severity of infection. The results also highlight potential conformational differences in MOMP epitopes that perhaps impact on disease diagnosis and the development of new vaccines.

Pathogenic outcome following experimental infection of sheep with Chlamydia abortus variant strains LLG and POS.

Directory of Open Access Journals (Sweden)

Morag Livingstone

Full Text Available This study investigated the pathogenesis of two variant strains (LLG and POS of Chlamydia abortus, in comparison to a typical wild-type strain (S26/3 which is known to be responsible for late term abortion in small ruminants. Challenge with the three strains at mid-gestation resulted in similar pregnancy outcomes, with abortion occurring in approximately 50-60% of ewes with the mean gestational lengths also being similar. However, differences were observed in the severity of placental pathology, with infection appearing milder for strain LLG, which was reflected in the lower number of organisms shed in vaginal swabs post-partum and less gross pathology and organisms present in placental smears. Results for strain POS were somewhat different than LLG with a more focal restriction of infection observed. Post-abortion antibody responses revealed prominent differences in seropositivity to the major outer membrane protein (MOMP present in elementary body (EB preparations under denaturing conditions, most notably with anti-LLG and anti-POS convalescent sera where there was no or reduced detection of MOMP present in EBs derived from the three strains. These results and additional analysis of whole EB and chlamydial outer membrane complex preparations suggest that there are conformational differences in MOMP for the three strains. Overall, the results suggest that gross placental pathology and clinical outcome is not indicative of bacterial colonization and the severity of infection. The results also highlight potential conformational differences in MOMP epitopes that perhaps impact on disease diagnosis and the development of new vaccines.

Structural health monitoring of cylindrical bodies under impulsive hydrodynamic loading by distributed FBG strain measurements

International Nuclear Information System (INIS)

Fanelli, Pierluigi; Ubertini, Stefano; Biscarini, Chiara; Jannelli, Elio; Ubertini, Filippo

2017-01-01

Various mechanical, ocean, aerospace and civil engineering problems involve solid bodies impacting the water surface and often result in complex coupled dynamics, characterized by impulsive loading conditions, high amplitude vibrations and large local deformations. Monitoring in such problems for purposes such as remaining fatigue life estimation and real time damage detection is a technical and scientific challenge of primary concern in this context. Open issues include the need for developing distributed sensing systems able to operate at very high acquisition frequencies, to be utilized to study rapidly varying strain fields, with high resolution and very low noise, while scientific challenges mostly relate to the definition of appropriate signal processing and modeling tools enabling the extraction of useful information from distributed sensing signals. Building on previous work by some of the authors, we propose an enhanced method for real time deformed shape reconstruction using distributed FBG strain measurements in curved bodies subjected to impulsive loading and we establish a new framework for applying this method for structural health monitoring purposes, as the main focus of the work. Experiments are carried out on a cylinder impacting the water at various speeds, proving improved performance in displacement reconstruction of the enhanced method compared to its previous version. A numerical study is then carried out considering the same physical problem with different delamination damages affecting the body. The potential for detecting, localizing and quantifying this damage using the reconstruction algorithm is thoroughly investigated. Overall, the results presented in the paper show the potential of distributed FBG strain measurements for real time structural health monitoring of curved bodies under impulsive hydrodynamic loading, defining damage sensitive features in terms of strain or displacement reconstruction errors at selected locations along

Protestant Origins of Human Rights Challenged

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Mogens Chrom Jacobsen

2017-08-01

Full Text Available This paper will challenge common views about Protestantism as the originator or foremost promoter of human rights. The idea of a Protestant origin is launched by Georg Jellinek and disputed by Emile Boutmy. The idea is still current and John Witte can thus claim that Protestantism was in part a human rights movement. The point of departure for this strain of thinking is religious toleration, which is seen as a particularly Protestant achievement. We will argue that a more precise notion of what 18th-century human rights were and a closer look at mainstream Protestant political philosophy will tell another story.

Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

Science.gov (United States)

Cox, Brian N.; Landis, Chad M.

2018-02-01

We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

Screening of the Enterocin-Encoding Genes and Antimicrobial Activity in Enterococcus Species.

Science.gov (United States)

Ogaki, Mayara Baptistucci; Rocha, Katia Real; Terra, MÁrcia Regina; Furlaneto, MÁrcia Cristina; Maia, Luciana Furlaneto

2016-06-28

In the current study, a total of 135 enterococci strains from different sources were screened for the presence of the enterocin-encoding genes entA, entP, entB, entL50A, and entL50B. The enterocin genes were present at different frequencies, with entA occurring the most frequently, followed by entP and entB; entL50A and L50B were not detected. The occurrence of single enterocin genes was higher than the occurrence of multiple enterocin gene combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene(+) strains") were screened for antimicrobial activity. A total of 82.5% of the Gene(+) strains inhibited at least one of the indicator strains, and the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicator strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition included Listeria innocua strain CLIP 12612 (ATCC BAA-680), Listeria monocytogenes strain CDC 4555, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Salmonella enteritidis ATCC 13076, Salmonella typhimurium strain UK-1 (ATCC 68169), and Escherichia coli BAC 49LT ETEC. Inhibition due to either bacteriophage lysis or cytolysin activity was excluded. The growth inhibition of antilisterial Gene+ strains was further tested under different culture conditions. Among the culture media formulations, the MRS agar medium supplemented with 2% (w/v) yeast extract was the best solidified medium for enterocin production. Our findings extend the current knowledge of enterocin-producing enterococci, which may have potential applications as biopreservatives in the food industry due to their capability of controlling food spoilage pathogens.

Mycobacterium tuberculosis strains exhibit differential and strain-specific molecular signatures in pulmonary epithelial cells.

Science.gov (United States)

Mvubu, Nontobeko Eunice; Pillay, Balakrishna; Gamieldien, Junaid; Bishai, William; Pillay, Manormoney

2016-12-01

Although pulmonary epithelial cells are integral to innate and adaptive immune responses during Mycobacterium tuberculosis infection, global transcriptomic changes in these cells remain largely unknown. Changes in gene expression induced in pulmonary epithelial cells infected with M. tuberculosis F15/LAM4/KZN, F11, F28, Beijing and Unique genotypes were investigated by RNA sequencing (RNA-Seq). The Illumina HiSeq 2000 platform generated 50 bp reads that were mapped to the human genome (Hg19) using Tophat (2.0.10). Differential gene expression induced by the different strains in infected relative to the uninfected cells was quantified and compared using Cufflinks (2.1.0) and MeV (4.0.9), respectively. Gene expression varied among the strains with the total number of genes as follows: F15/LAM4/KZN (1187), Beijing (1252), F11 (1639), F28 (870), Unique (886) and H37Rv (1179). A subset of 292 genes was commonly induced by all strains, where 52 genes were down-regulated while 240 genes were up-regulated. Differentially expressed genes were compared among the strains and the number of induced strain-specific gene signatures were as follows: F15/LAM4/KZN (138), Beijing (52), F11 (255), F28 (55), Unique (186) and H37Rv (125). Strain-specific molecular gene signatures associated with functional pathways were observed only for the Unique and H37Rv strains while certain biological functions may be associated with other strain signatures. This study demonstrated that strains of M. tuberculosis induce differential gene expression and strain-specific molecular signatures in pulmonary epithelial cells. Specific signatures induced by clinical strains of M. tuberculosis can be further explored for novel host-associated biomarkers and adjunctive immunotherapies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating challenge load due to disease outbreaks and other challenges using reproduction records of sows.

Science.gov (United States)

Mathur, P K; Herrero-Medrano, J M; Alexandri, P; Knol, E F; ten Napel, J; Rashidi, H; Mulder, H A

2014-12-01

A method was developed and tested to estimate challenge load due to disease outbreaks and other challenges in sows using reproduction records. The method was based on reproduction records from a farm with known disease outbreaks. It was assumed that the reduction in weekly reproductive output within a farm is proportional to the magnitude of the challenge. As the challenge increases beyond certain threshold, it is manifested as an outbreak. The reproduction records were divided into 3 datasets. The first dataset called the Training dataset consisted of 57,135 reproduction records from 10,901 sows from 1 farm in Canada with several outbreaks of porcine reproductive and respiratory syndrome (PRRS). The known disease status of sows was regressed on the traits number born alive, number of losses as a combination of still birth and mummified piglets, and number of weaned piglets. The regression coefficients from this analysis were then used as weighting factors for derivation of an index measure called challenge load indicator. These weighting factors were derived with i) a two-step approach using residuals or year-week solutions estimated from a previous step, and ii) a single-step approach using the trait values directly. Two types of models were used for each approach: a logistic regression model and a general additive model. The estimates of challenge load indicator were then compared based on their ability to detect PRRS outbreaks in a Test dataset consisting of records from 65,826 sows from 15 farms in the Netherlands. These farms differed from the Canadian farm with respect to PRRS virus strains, severity and frequency of outbreaks. The single-step approach using a general additive model was best and detected 14 out of the 15 outbreaks. This approach was then further validated using the third dataset consisting of reproduction records of 831,855 sows in 431 farms located in different countries in Europe and America. A total of 41 out of 48 outbreaks detected

Comparison of detection methods for extended-spectrum beta-lactamases in Escherichia coli strains

Directory of Open Access Journals (Sweden)

Ewelina Kałużna

2014-06-01

Full Text Available Introduction: Detection of extended-spectrum beta-lactamases (ESBLs could be a major challenge for microbiologists – the difficulties arise mainly from the phenotypic differences among strains.Materials and Methods: Evaluation of ESBLs was performed on 42 strains of E. coli by: 1 DDST on MHA, 2 DDST on MHA with cloxacillin, 3 CT on MHA, according to CLSI, 4 CT on MHA with cloxacillin, 5 Etest ESBL (AB Biodisk, 6 CHROMagarTM ESBL (GRASO, 7 ChromID® ESBL (bioMérieux, and 8 automatic system VITEK2 ESBL test (bioMérieux.Result: Positive results were obtained for 20 strains using method 1, for 18 strains using method 2, 17 by method 3, 14 by method 4, 11 by method 5, 39 by method 6, 40 by method 7, and 15 by method 8. Using Etest ESBL 6.0 non-determinable results were obtained. The most consistent results were obtained when comparing the results of method 3 with results of method 2 (97.6%, and comparing the results obtained using methods 3 and 8 (95.2%.Conclusions: Based on our study we conclude that the chromogenic media can only be used as a screening method for the detection of ESBLs in E. coli rods. Etest is less useful compared to other phenotype methods, due to the impossibility of obtaining results for all the tested strains. Adding cloxacillin to MHA does not increase the frequency of detection of ESBLs in E. coli strains. DDST seems to be the most reliable among phenotypic methods for the detection of ESBLs in E. coli rods.

Comparison of antimicrobial resistance in E. coli isolated from rectal and floor samples in pens with diarrhoeic nursery pigs in Denmark

DEFF Research Database (Denmark)

Weber, Nicolai Rosager; Nielsen, Jens Peter; Jorsal, Sven Erik Lind

2017-01-01

Introduction. The prudent use of antibiotics in veterinary medicine necessitates the selection of antibiotic compounds with narrow-spectrums targeted against the specific pathogens involved. The same pathotype of enterotoxigenic E. coli (ETEC) was recently found both in diarrhoeic pigs...... was observed in the sampled ETEC isolates. In addition, there was generally good or excellent agreement when comparing resistance profiles from isolates from the same pen (pen floor and pig samples), and perfect agreement (Kappa = 1.000, SE = 0.316) was observed for ampicillin, apramycin, gentamycin...

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria.

Science.gov (United States)

Motwalli, Olaa; Essack, Magbubah; Jankovic, Boris R; Ji, Boyang; Liu, Xinyao; Ansari, Hifzur Rahman; Hoehndorf, Robert; Gao, Xin; Arold, Stefan T; Mineta, Katsuhiko; Archer, John A C; Gojobori, Takashi; Mijakovic, Ivan; Bajic, Vladimir B

2017-01-05

Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. To our knowledge FFASC is the first

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

KAUST Repository

Motwalli, Olaa Amin

2017-01-05

Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. Conclusion To

Flexible piezotronic strain sensor.

Science.gov (United States)

Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

2008-09-01

Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

Science.gov (United States)

Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A

2012-03-01

In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

Effects of the Strain Rate Sensitivity and Strain Hardening on the Saturated Impulse of Plates

Directory of Open Access Journals (Sweden)

Ling Zhu

Full Text Available Abstract This paper studies the stiffening effects of the material strain rate sensitivity and strain hardening on the saturated impulse of elastic, perfectly plastic plates. Finite element (FE code ABAQUS is employed to simulate the elastoplastic response of square plates under rectangular pressure pulse. Rigid-plastic analyses for saturated impulse, which consider strain rate sensitivity and strain hardening, are conducted. Satisfactory agreement between the finite element models (FEM and predictions of the rigid-plastic analysis is obtained, which verifies that the proposed rigid-plastic methods are effective to solve the problem including strain rate sensitivity and strain hardening. The quantitative results for the scale effect of the strain rate sensitivity are given. The results for the stiffening effects suggest that two general stiffening factors n 1 and n 2, which characterizes the strain rate sensitivity and strain hardening effect, respectively can be defined. The saturated displacement is inversely proportional to the stiffening factors (i.e. n 1 and n 2 and saturated impulse is inversely proportional to the square roots of the stiffening factors (i.e. n 1 and n 2. Formulae for displacement and saturated impulse are proposed based on the empirical analysis.

Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

DEFF Research Database (Denmark)

Blucher, J.T.; Knudsen, Per; Grant, N.J.

1968-01-01

Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

Sport psychiatry and psychotherapy. Mental strains and disorders in professional sports. Challenge and answer to societal changes.

Science.gov (United States)

Markser, Valentin Z

2011-11-01

Professional athletes are subject to massive somatic, social, and mental stress. Despite great public interest for athletic achievements, the emotional strains thereof are very poorly investigated and discussed. The main reason for this is the widespread assumption that only emotionally very strong athletes are able to compete at the highly professional level and therefore mental disorders do not exist in professional sports. But available research data about the prevalence of mental disorders in this area suggest that this hypothesis must be revised. With respect to depression and the overtraining syndrome, attempts have been made to demonstrate the difficulties with etiology, diagnostics, and treatment for sports psychiatry and psychotherapy. Scientifically, sport psychiatry and psychotherapy can be defined as a discipline, whose focus is the investigation, treatment, and prevention of the extreme and sports-specific emotional strains and disorders. In addition to sport psychology, which focuses mainly on performance enhancement, mental stress, and disorders can hereby be recognized, disorders be treated and the athletic performance sustained. With the foundation of the Task Force for Sports Psychiatry and Psychotherapy at the German Association for Psychiatry and Psychotherapy, scientific research, further education, prevention, and treatment for mental disorders in professional sports will be improved.

Strain profiles in ion implanted ceramic polycrystals: An approach based on reciprocal-space crystal selection

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Palancher, H., E-mail: herve.palancher@cea.fr; Martin, G.; Fouet, J. [CEA, DEN, DEC, F-13108 Saint Paul lez Durance (France); Goudeau, P. [Institut Pprime, CNRS-Université de Poitiers–ENSMA, SP2MI, F-86360 Chasseneuil (France); Boulle, A. [Science des Procédés Céramiques et Traitements de Surface (SPCTS), CNRS UMR 7315, Centre Européen de la Céramique, 12 rue Atlantis, 87068 Limoges (France); Rieutord, F. [CEA, DSM, INAC, F-38054 Grenoble Cedex 9 (France); Favre-Nicolin, V. [Université Grenoble-Alpes, F-38041 Grenoble, France, Institut Universitaire de France, F-75005 Paris (France); Blanc, N. [Institut NEEL, CNRS-Univ Grenoble Alpes, F-38042 Grenoble (France); Onofri, C. [CEA, DEN, DEC, F-13108 Saint Paul lez Durance (France); CEMES, CNRS UPR 8011, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 4 (France)

2016-01-18

The determination of the state of strain in implanted materials is a key issue in the study of their mechanical stability. Whereas this question is nowadays relatively easily solved in the case of single crystals, it remains a challenging task in the case of polycrystalline materials. In this paper, we take benefit of the intense and parallel beams provided by third generation synchrotron sources combined with a two-dimensional detection system to analyze individual grains in polycrystals, hence obtaining “single crystal-like” data. The feasibility of the approach is demonstrated with implanted UO{sub 2} polycrystals where the in-depth strain profile is extracted for individual grains using numerical simulations of the diffracted signal. The influence of the implantation dose is precisely analyzed for several diffracting planes and grains. This work suggests that, at low fluences, the development of strain is mainly due to ballistic effects with little effect from He ions, independently from the crystallographic orientation. At higher fluences, the evolution of the strain profiles suggests a partial and anisotropic plastic relaxation. With the present approach, robust and reliable structural information can be obtained, even from complex polycrystalline ceramic materials.

Stress-strain response of plastic waste mixed soil.

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Babu, G L Sivakumar; Chouksey, Sandeep Kumar

2011-03-01

Recycling plastic waste from water bottles has become one of the major challenges worldwide. The present study provides an approach for the use plastic waste as reinforcement material in soil. The experimental results in the form of stress-strain-pore water pressure response are presented. Based on experimental test results, it is observed that the strength of soil is improved and compressibility reduced significantly with addition of a small percentage of plastic waste to the soil. The use of the improvement in strength and compressibility response due to inclusion of plastic waste can be advantageously used in bearing capacity improvement and settlement reduction in the design of shallow foundations. Copyright © 2010 Elsevier Ltd. All rights reserved.

Influence of gastrointestinal system conditions on adhesion of exopolysaccharide-producing Lactobacillus delbrueckii subsp. bulgaricus strains to caco-2 cells

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Derya Onal Darilmaz

2011-10-01

Full Text Available This study aimed to assess the transit tolerance of potential probiotic dairy Lactobacillus strains in human uppergastrointestinal tract in vitro, and to evaluate the effect of EPS production on the viability and adhesion of these strains. Survival and adhesion of two exopolysaccharide (EPS-producing L. delbrueckii subsp. bulgaricus strains (B3 and B2 and E. coli ATCC11229 were assessed after the exposure of different pH (gastric juice and gastric plus pancreatic juice challenges. In the artificial gastric juice (pH 2, both the viability of the strain B3 and B2 was decreased. Artificial juice treatments significantly reduced the adhesion to caco-2 cells (P< 0.05. High EPS-producing B3 survived better in the adverse gastrointestinal conditions and showed better ability of adhesion to Caco-2 cells when assessed for competition with E. coli ATCC 11229 compared to low EPS-producing B2. This investigation showed that EPS production could be affected or be involved in the viability, adherence and competition of L. delbrueckii subsp. bulgaricus strains and support the potential of B3 strain for development of new probiotic products.

Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains.

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Elaheh Movahed

Full Text Available The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B and C. neoformans reference clinical strain (H99 were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1, Mitochondrial matrix factor 1 (MMF1, Bud-site-selection protein 8 (BUD8, High affinity glucose transporter 3 (SNF3 and Rho GTPase-activating protein 2 (RGA2. Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.

Life Stress, Strain, and Deviance Across Schools: Testing the Contextual Version of General Strain Theory in China.

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Zhang, Jinwu; Liu, Jianhong; Wang, Xin; Zou, Anquan

2017-08-01

General Strain Theory delineates different types of strain and intervening processes from strain to deviance and crime. In addition to explaining individual strain-crime relationship, a contextualized version of general strain theory, which is called the Macro General Strain Theory, has been used to analyze how aggregate variables influence aggregate and individual deviance and crime. Using a sample of 1,852 students (Level 1) nested in 52 schools (Level 2), the current study tests the Macro General Strain Theory using Chinese data. The results revealed that aggregate life stress and strain have influences on aggregate and individual deviance, and reinforce the individual stress-deviance association. The current study contributes by providing the first Macro General Strain Theory test based on Chinese data and offering empirical evidence for the multilevel intervening processes from strain to deviance. Limitations and future research directions are discussed.

Physical studies of strained Si/SiGe heterostructures. From virtual substrates to nanodevices

Energy Technology Data Exchange (ETDEWEB)

Minamisawa, Renato Amaral

2011-10-21

During the past two decades, the decrease in intrinsic delay of MOSFETs has been driven by the scaling of the device dimensions. The performance improvement has relied mostly in the increase of source velocity with gate scaling, while the transport properties of the channel have remained constant, i.e., those of conventional Si. Starting at the 90 nm node, uniaxial strain has been introduced in the transistor channel in order to further increase the source velocity. Beyond the 32 nm node, novel channel materials, with superior carrier velocities, and novel device architectures are required in order to continue the performance enhancement of MOSFETs while preserving the electrostatic control. In this Thesis, different physical aspects of strained Si and SiGe materials are investigated as a mean to increase carrier velocity in MOSFET channels. Novel approaches for the fabrication of strained Si based on ion implantation and anneal induced relaxation of virtual substrates are developed. The strain relaxation of SiGe layers is improved using a buried thin Si:C layer in the Si(100) substrate. Further, a Si{sup +} ion implantation and annealing method is investigated for relaxing virtual substrates using lower implantation dose. Finally, the uniaxial relaxation of {l_brace}110{r_brace} surface oriented substrates is demonstrated using a He ion implantation and anneal technique. Apart of channel material studies, the fundamental and technological challenges involved in the integration of strained Si and SiGe into MOSFETs are assessed. The impact of source and drain formation on the elastic strain and electrical properties of strained Si layers and nanowires is examined. Also, the formation of ultra-shallow junction in strained Si/strained Si{sub 0.5}Ge{sub 0.5}/SSOI heterostructures is investigated using different types of ion implanted specie and annealing. The results show that BF{sup +}{sub 2} implantation and low temperature annealing are suitable approaches for

A New Strain Collection for Improved Expression of Outer Membrane Proteins

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Ina Meuskens

2017-11-01

Full Text Available Almost all integral membrane proteins found in the outer membranes of Gram-negative bacteria belong to the transmembrane β-barrel family. These proteins are not only important for nutrient uptake and homeostasis, but are also involved in such processes as adhesion, protein secretion, biofilm formation, and virulence. As surface exposed molecules, outer membrane β-barrel proteins are also potential drug and vaccine targets. High production levels of heterologously expressed proteins are desirable for biochemical and especially structural studies, but over-expression and subsequent purification of membrane proteins, including outer membrane proteins, can be challenging. Here, we present a set of deletion mutants derived from E. coli BL21(DE3 designed for the over-expression of recombinant outer membrane proteins. These strains harbor deletions of four genes encoding abundant β-barrel proteins in the outer membrane (OmpA, OmpC, OmpF, and LamB, both single and in all combinations of double, triple, and quadruple knock-outs. The sequences encoding these outer membrane proteins were deleted completely, leaving only a minimal scar sequence, thus preventing the possibility of genetic reversion. Expression tests in the quadruple mutant strain with four test proteins, including a small outer membrane β-barrel protein and variants thereof as well as two virulence-related autotransporters, showed significantly improved expression and better quality of the produced proteins over the parent strain. Differences in growth behavior and aggregation in the presence of high salt were observed, but these phenomena did not negatively influence the expression in the quadruple mutant strain when handled as we recommend. The strains produced in this study can be used for outer membrane protein production and purification, but are also uniquely useful for labeling experiments for biophysical measurements in the native membrane environment.

The Evolution of Strain Typing in the Mycobacterium tuberculosis Complex.

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Merker, Matthias; Kohl, Thomas A; Niemann, Stefan; Supply, Philip

2017-01-01

Tuberculosis (TB) is a contagious disease with a complex epidemiology. Therefore, molecular typing (genotyping) of Mycobacterium tuberculosis complex (MTBC) strains is of primary importance to effectively guide outbreak investigations, define transmission dynamics and assist global epidemiological surveillance of the disease. Large-scale genotyping is also needed to get better insights into the biological diversity and the evolution of the pathogen. Thanks to its shorter turnaround and simple numerical nomenclature system, mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR) typing, based on 24 standardized plus 4 hypervariable loci, optionally combined with spoligotyping, has replaced IS6110 DNA fingerprinting over the last decade as a gold standard among classical strain typing methods for many applications. With the continuous progress and decreasing costs of next-generation sequencing (NGS) technologies, typing based on whole genome sequencing (WGS) is now increasingly performed for near complete exploitation of the available genetic information. However, some important challenges remain such as the lack of standardization of WGS analysis pipelines, the need of databases for sharing WGS data at a global level, and a better understanding of the relevant genomic distances for defining clusters of recent TB transmission in different epidemiological contexts. This chapter provides an overview of the evolution of genotyping methods over the last three decades, which culminated with the development of WGS-based methods. It addresses the relative advantages and limitations of these techniques, indicates current challenges and potential directions for facilitating standardization of WGS-based typing, and provides suggestions on what method to use depending on the specific research question.

Association of vitamin D status with incidence of enterotoxigenic, enteropathogenic and enteroaggregative Escherichia coli diarrhoea in children of urban Bangladesh.

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Ahmed, A M S; Soares Magalhaes, R J; Long, K Z; Ahmed, T; Alam, Md A; Hossain, Md I; Islam, Md M; Mahfuz, M; Mondal, D; Haque, R; Mamun, A A

2016-08-01

To evaluate the association between vitamin D status and diarrhoeal episodes by enterotoxigenic (ETEC), enteropathogenic (EPEC) and enteroaggregative (EAEC) E. coli in underweight and normal-weight children aged 6-24 months in urban Bangladesh. Cohorts of 446 normal-weight and 466 underweight children were tested separately for ETEC, EPEC and EAEC from diarrhoeal stool samples collected during 5 months of follow-up while considering vitamin D status at enrolment as the exposure. Cox proportional hazards models with unordered failure events of the same type were used to determine diarrhoeal risk factors after adjusting for sociodemographic and concurrent micronutrient status. Vitamin D status was not independently associated with the risk of incidence of ETEC, EPEC and EAEC diarrhoea in underweight children, but moderate-to-severe retinol deficiency was associated with reduced risk for EPEC diarrhoea upon adjustment. Among normal-weight children, insufficient vitamin D status and moderate-to-severe retinol deficiency were independently associated with 44% and 38% reduced risk of incidence of EAEC diarrhoea, respectively. These children were at higher risk of ETEC diarrhoea with vitamin D deficiency status when adjusted for micronutrient status only. This study demonstrates for the first time that normal-weight children with insufficient vitamin D status have a reduced risk of EAEC diarrhoea than children with sufficient status. Moderate-to-severe deficiency of serum retinol is associated with reduced risk of EPEC and EAEC diarrhoea in underweight and normal-weight children. © 2016 John Wiley & Sons Ltd.

SHuffle, a novel Escherichia coli protein expression strain capable of correctly folding disulfide bonded proteins in its cytoplasm

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Lobstein Julie

2012-05-01

Full Text Available Abstract Background Production of correctly disulfide bonded proteins to high yields remains a challenge. Recombinant protein expression in Escherichia coli is the popular choice, especially within the research community. While there is an ever growing demand for new expression strains, few strains are dedicated to post-translational modifications, such as disulfide bond formation. Thus, new protein expression strains must be engineered and the parameters involved in producing disulfide bonded proteins must be understood. Results We have engineered a new E. coli protein expression strain named SHuffle, dedicated to producing correctly disulfide bonded active proteins to high yields within its cytoplasm. This strain is based on the trxB gor suppressor strain SMG96 where its cytoplasmic reductive pathways have been diminished, allowing for the formation of disulfide bonds in the cytoplasm. We have further engineered a major improvement by integrating into its chromosome a signal sequenceless disulfide bond isomerase, DsbC. We probed the redox state of DsbC in the oxidizing cytoplasm and evaluated its role in assisting the formation of correctly folded multi-disulfide bonded proteins. We optimized protein expression conditions, varying temperature, induction conditions, strain background and the co-expression of various helper proteins. We found that temperature has the biggest impact on improving yields and that the E. coli B strain background of this strain was superior to the K12 version. We also discovered that auto-expression of substrate target proteins using this strain resulted in higher yields of active pure protein. Finally, we found that co-expression of mutant thioredoxins and PDI homologs improved yields of various substrate proteins. Conclusions This work is the first extensive characterization of the trxB gor suppressor strain. The results presented should help researchers design the appropriate protein expression conditions using

Strain Pattern in Supercooled Liquids

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Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

2016-11-01

Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

A multivalent Mannheimia-Bibersteinia vaccine protects bighorn sheep against Mannheimia haemolytica challenge.

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Subramaniam, Renuka; Shanthalingam, Sudarvili; Bavananthasivam, Jegarubee; Kugadas, Abirami; Potter, Kathleen A; Foreyt, William J; Hodgins, Douglas C; Shewen, Patricia E; Barrington, George M; Knowles, Donald P; Srikumaran, Subramaniam

2011-10-01

Bighorn sheep (BHS) are more susceptible than domestic sheep (DS) to Mannheimia haemolytica pneumonia. Although both species carry M. haemolytica as a commensal bacterium in the nasopharynx, DS carry mostly leukotoxin (Lkt)-positive strains while BHS carry Lkt-negative strains. Consequently, antibodies to surface antigens and Lkt are present at much higher titers in DS than in BHS. The objective of this study was to determine whether repeated immunization of BHS with multivalent Mannheimia-Bibersteinia vaccine will protect them upon M. haemolytica challenge. Four BHS were vaccinated with a culture supernatant vaccine prepared from M. haemolytica serotypes A1 and A2 and Bibersteinia trehalosi serotype T10 on days 0, 21, 35, 49, and 77. Four other BHS were used as nonvaccinated controls. On the day of challenge, 12 days after the last immunization, the mean serum titers of Lkt-neutralizing antibodies and antibodies to surface antigens against M. haemolytica were 1:160 and 1:4,000, respectively. Following intranasal challenge with M. haemolytica A2 (1 × 10(5) CFU), all four control BHS died within 48 h. Necropsy revealed acute fibrinonecrotic pneumonia characteristic of M. haemolytica infection. None of the vaccinated BHS died during the 8 weeks postchallenge observation period. Radiography at 3 weeks postchallenge revealed no lung lesions in two vaccinated BHS and mild lesions in the other two, which resolved by 8 weeks postchallenge. These results indicate that if BHS can be induced to develop high titers of Lkt-neutralizing antibodies and antibodies to surface antigens, they are likely to survive M. haemolytica challenge which is likely to reduce the BHS population decline due to pneumonia.

Feasibility of Detecting Natural Frequencies of Hydraulic Turbines While in Operation, Using Strain Gauges.

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Valentín, David; Presas, Alexandre; Bossio, Matias; Egusquiza, Mònica; Egusquiza, Eduard; Valero, Carme

2018-01-10

Nowadays, hydropower plays an essential role in the energy market. Due to their fast response and regulation capacity, hydraulic turbines operate at off-design conditions with a high number of starts and stops. In this situation, dynamic loads and stresses over the structure are high, registering some failures over time, especially in the runner. Therefore, it is important to know the dynamic response of the runner while in operation, i.e., the natural frequencies, damping and mode shapes, in order to avoid resonance and fatigue problems. Detecting the natural frequencies of hydraulic turbine runners while in operation is challenging, because they are inaccessible structures strongly affected by their confinement in water. Strain gauges are used to measure the stresses of hydraulic turbine runners in operation during commissioning. However, in this paper, the feasibility of using them to detect the natural frequencies of hydraulic turbines runners while in operation is studied. For this purpose, a large Francis turbine runner (444 MW) was instrumented with several strain gauges at different positions. First, a complete experimental strain modal testing (SMT) of the runner in air was performed using the strain gauges and accelerometers. Then, the natural frequencies of the runner were estimated during operation by means of analyzing accurately transient events or rough operating conditions.

Biological assay of attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus.

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Mengeling, W L; Pejsak, Z; Paul, P S

1984-11-01

Attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus (PPV) were titrated in vivo and in vitro under similar conditions to provide a better understanding of some of the factors involved in virulence of PPV in causing maternal reproductive failure of swine. Both strains cause fetal death when they are injected directly into fetal fluids, but only strain NADL-8 does so when administered to pregnant swine. The strains were tested for their hemagglutinating activity (HA), median cell culture infective dose (CCID50), median fetal infective dose (FID50), and median fetal lethal dose (FLD50). The FID50 and FLD50 were determined by injecting virus directly into the amniotic fluid of fetuses in utero at 44 +/- 2 days of gestation and collecting the fetuses 15 +/- 1 days later. Both strains had an HA titer of 64, suggesting that there is a similar number of virions in stock preparations. However, other measurements differed markedly. The CCID50, FID50, and FLD50 were 10(5.5), 10(3.5), and 10(0.5), respectively, for strain NADL-2, and 10(4.5), 10(7.7), and 10(6.3), respectively, for strain NADL-8. Collectively, the values indicate that more than 10,000 times as much strain NADL-2 would need to reach the conceptus transplacentally to establish infection. These observations may help to explain the different consequences of oronasal exposure of pregnant swine to these strains of PPV.

Haldane model under nonuniform strain

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Ho, Yen-Hung; Castro, Eduardo V.; Cazalilla, Miguel A.

2017-10-01

We study the Haldane model under strain using a tight-binding approach, and compare the obtained results with the continuum-limit approximation. As in graphene, nonuniform strain leads to a time-reversal preserving pseudomagnetic field that induces (pseudo-)Landau levels. Unlike a real magnetic field, strain lifts the degeneracy of the zeroth pseudo-Landau levels at different valleys. Moreover, for the zigzag edge under uniaxial strain, strain removes the degeneracy within the pseudo-Landau levels by inducing a tilt in their energy dispersion. The latter arises from next-to-leading order corrections to the continuum-limit Hamiltonian, which are absent for a real magnetic field. We show that, for the lowest pseudo-Landau levels in the Haldane model, the dominant contribution to the tilt is different from graphene. In addition, although strain does not strongly modify the dispersion of the edge states, their interplay with the pseudo-Landau levels is different for the armchair and zigzag ribbons. Finally, we study the effect of strain in the band structure of the Haldane model at the critical point of the topological transition, thus shedding light on the interplay between nontrivial topology and strain in quantum anomalous Hall systems.