Evaluation of Forecasting Models for Fusarium Head Blight of Wheat Under Growing Conditions of Quebec, Canada.

Fusarium head blight (FHB) is a fungal disease of wheat (Triticum aestivum L.) causing frequent economic losses to farmers under growing conditions of Eastern Canada. To assess risks associated with this disease and guide fungicide use decisions, many researchers from numerous countries have developed weather-based forecasting models. This work aims at evaluating which model produces the most accurate predictions of disease infection or deoxynivalenol (DON) content under climatic conditions occurring in Quebec. Spring wheat was grown during two seasons and winter wheat during one season at four experimental sites located in Quebec. Nine selected models for evaluation produced predictions of DON content (Canada and Italy), disease incidence (Argentina and Italy), and probability of epidemics (United States). Data from plots without fungicide (52 samples) were used to test the models listed above. Reliability of the selected forecasting models was evaluated with receiver operating characteristic (ROC) curve analysis. DON content (≥1 ppm) was the best crop damage indicator to differentiate epidemic (cases) and nonepidemic (controls) situations. Two American and the Argentinean forecasting models were more reliable than the others when the thresholds recommended in the literature were adjusted using the results for the ROC curve analyses. Those models are a good starting point for the implementation of an FHB forecasting system adapted to wheat production in Quebec.

[Recent progress in Marfan syndrome]. / Nouveautés dans le syndrome de Marfan.

For 20 years, the clinical, genetic and therapeutic knowledge of Marfan syndrome made great progress. The new classification, allowing the diagnosis and published in 2010, is easier to use. The diagnosis remains sometimes difficult particularly during childhood, because of the great variability of expression of the disease, from neonatal Marfan syndrome, to a weak clinical expression and especially because of the evolution of the signs with the age, which no classification takes into account. The search for amutation in the FBN1 gene is long and expensive and must be reserved only for patients having a very strong diagnostic suspicion. The therapeutics is preventive and based on patient education, limitation of the sport, beta blockade therapy, regular echocardiography as well as aorta replacement. New treatments are at present on approval but did not make the proof of their efficiency. The global care of the patient, by taking into account difficulties about genetic origin of the disease, aesthetic and psychological consequences, allows an improvement of the quality of life.

Localization of surface immunogenic protein on group B streptococcus.

The localization and accessibility of the group B streptococcus (GBS) surface immunogenic protein (Sip) at the surface of intact GBS cells were studied by flow cytometric assay and immunogold electron microscopy. Antibodies present in pooled sera collected from mice after immunization with purified recombinant Sip efficiently recognized native Sip at the surfaces of the different GBS strains tested, which included representatives of all nine serotypes. Examination of GBS cells by immunogold electron microscopy revealed that the Sip-specific antibodies attached preferentially to polar sites and the septal region. This result confirmed that Sip is exposed at the intact-cell surface, but it also suggests that its distribution is restricted to certain regions of the cell.

The causes of organizational citizenship behavior: a motivational analysis.

This study addressed the role of motives in organizational citizenship behavior (OCB). Three motives were identified through factor analyses: prosocial values, organizational concern, and impression management. Scales that measured these motives and other variables known to covary with OCB were administered to 141 municipal employees and were correlated with self-, peer, and supervisor ratings of 5 aspects of OCB. Relative to the other motives, prosocial values motives were most strongly associated with OCB directed at individuals, and organizational concern motives were most strongly associated with OCB directed toward the organization. Each of the motives accounted for unique amounts of variance in OCB. The results suggest that motives may play an important role in OCB.

Isolation and characterization of a capsule-deficient mutant of Actinobacillus pleuropneumoniae serotype 1.

The capsular polysaccharides (CPS) play a major role in pathogenicity of Actinobacillus pleuroIpneumoniae, the causative agent of porcine pleuropneumonia. The purpose of the present study was to isolate a mutant in CPS biosynthesis by using a mini-Tn 10 transposon mutagenesis system and evaluate its adherence to host cells. One mutant apparently did not possess CPS as it did not react with a monoclonal antibody against A. pleuropneumoniae serotype 1 capsular antigen. Absence of capsule was confirmed by flow cytometry and also by transmission electron microscopy after polycationic ferritin labelling. The site of insertion of the mini-Tn 10 was determined and found to be in the cpxC gene. Its gene product, CpxC, is a protein involved in polysaccharide transport across the cytoplasmic membrane during CPS biosynthesis. Use of piglet tracheal frozen sections indicated that the CPS mutant adhered significantly (P=0.0001) more than the parent strain. The non-capsular mutant was less virulent in pigs compared to the parent strain and showed no mortality in experimentally infected pigs. The CPS mutant was however resistant to pig serum. This CPS mutant is the first A. pleuropneumoniae mutant in a CPS transport gene. It is also the first time that adherence of a CPS mutant of A. pleuropneumoniae is evaluated. Our observations indicate that capsular polysaccharides of A. pleuropneumoniae serotype 1 are not involved in adherence to piglet tracheal frozen sections but rather mask, at least in part, the adhesive functions.

Evaluation of the hemoglobin-binding activity of Actinobacillus pleuropneumoniae using fluorescein-labeled pig hemoglobin and flow cytometry.

In the present study, the hemoglobin (Hb)-binding activity of Actinobacillus pleuropneumoniae was examined using fluorescein-labeled pig Hb and flow cytometry. Comparison of the Hb-binding activity of A. pleuropneumoniae serotype 1 strain 4074 grown under iron-restricted conditions with cells grown under iron-sufficient conditions indicated that iron-restriction in A. pleuropneumoniae promotes the expression of Hb receptors, and that Hb-binding activity is, at least in part, iron-repressible. Hb-binding activity was also observed in representative strains of A. pleuropneumoniae belonging to serotypes 1 and 2. In addition, A. pleuropneumoniae serotype 1 LPS or capsule isogenic mutants were tested in flow cytometry in order to understand the influence of surface polysaccharides on Hb-binding activity. Experiments with an acapsulated mutant indicated that surface molecules with Hb-binding activity are more exposed at the cell surface in the absence of capsular polysaccharides. However, the Hb-binding activity of LPS mutants analyzed in this study was unchanged compared to the parent strain. The outer membrane proteins profile of A. pleuropneumoniae serotype 1 grown under iron-restricted or iron-sufficient conditions was also evaluated by polyacrylamide gel electrophoresis. Iron-regulated outer membrane proteins were observed under iron-restricted growth conditions which suggests that one or more of these outer membrane proteins may play a role in the Hb-binding activity detected by flow cytometry.

Isolation and characterization of mini-Tn10 lipopolysaccharide mutants of Actinobacillus pleuropneumoniae serotype 1.

Lipopolysaccharide (LPS) has previously been identified as the major adhesin of Actinobacillus pleuropneumoniae involved in adherence to porcine respiratory tract cells. The purpose of the present study was to isolate and characterize mutants in LPS biosynthesis by using a mini-Tn10 transposon mutagenesis system. Seven mutants appeared to possess a rough LPS (among which two had similar Southern blot profiles) while one mutant (#5.1) expressed the high-molecular-mass LPS, but as visualized by Tricine SDS-PAGE, showed an additional band in the core-lipid A region. The LPS mutants showed sensitivity to pig serum to various degrees, while the parent strain was serum-resistant. Use of piglet frozen tracheal sections indicated that, surprisingly, the rough LPS mutants adhered similarly or in greater numbers than the parent strain. However, the LPS mutant #5.1 adhered significantly less than the parent strain and was also less virulent in pigs. The gene affected by mini-Tn10 in LPS mutant #5.1 is galU, the structural gene for UTP-alpha-D-glucose-1-phosphate uridylyltransferase, involved in LPS core biosynthesis. Complementation analysis confirmed that the phenotypic characteristics of LPS mutant #5.1 are the result of the inactivation of the galU gene. Our data suggest that although the presence of O-antigen does not seem to be essential, an intact core-lipid A region might be required for adherence of A. pleuropneumoniae to porcine respiratory tract cells. To the best of our knowledge, these mutants represent the first isogenic mutants of A. pleuropneumoniae defective in LPS biosynthetic genes.

Evaluation of the protective efficacy of Actinobacillus pleuropneumoniae serotype 1 detoxified lipopolysaccharides or O-polysaccharide-protein conjugate in pigs.

The major adhesin of Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, has been previously identified as the lipopolysaccharide (LPS). Experiments in our laboratory have shown that mice immunised with different A pleuropneumoniae serotype 1 LPS preparations were protected against a challenge with a virulent A pleuropneumoniae serotype 1 isolate. The purpose of the present study was to evaluate the protection of pigs against experimental A pleuropneumoniae infection following immunisation with two of these LPS preparations. Groups of five specific pathogen free (SPF) pigs were injected twice with one of the following antigen preparations: detoxified LPS, O-polysaccharide-BSA conjugate, a commercial bacterin, or PBS. Two weeks after the second injection, pigs were challenged intranasally with a virulent A pleuropneumoniae serotype 1 strain. Upon macroscopic examination, fibrino-haemorrhagic pleuropneumonia, compatible with A pleuropneumoniae infection, was observed in one to four pigs in each group. The more extensive lesions were present in control, unimmunised pigs and in animals vaccinated with the O-polysaccharide-BSA conjugate. The highest survival rate was recorded when the pigs had been immunised with detoxified LPS or the commercial bacterin. Taken together, our results suggest that a protection comparable with the one obtained with a commercial bacterin was observed when pigs were immunised with a single class of molecules, detoxified LPS. Most importantly, these results confirm the important role of A pleuropneumoniae LPS in protection against porcine pleuropneumonia. Finally, our results also support the idea that mice are not an appropriate model for the evaluation of porcine pleuropneumonia vaccines.

Isolation and characterization of LPS mutants of Actinobacillus pleuropneumoniae serotype 1.

The major adhesin of Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, has been previously identified as lipopolysaccharide (LPS). The purpose of the present study was to isolate and characterize A. pleuropneumoniae LPS mutants. Screening of LPS mutants was performed with colony dot and sensitivity to novobiocin. One mutant obtained by colony dot (F19) and one mutant selected for its increased sensitivity to novobiocin (33.1) did not react with a monoclonal antibody against A. pleuropneumoniae serotype 1 O-antigen compared with the parent strain. Mutants F19 and 33.1 did not express high-molecular-mass LPS bands as determined in silver-stained SDS-PAGE gels. The core-lipid A region of mutant 33.1 and of the parent strain had similar relative mobilities and reacted with serum from a pig experimentally infected with the serotype 1 reference strain of A. pleuropneumoniae, while the same region in mutant F19 showed faster migration and did not react with this serum. Use of piglet tracheal frozen sections indicated that mutant F19 was able to adhere to piglet trachea as well as the parent strain, while mutant 33.1 adhered [half as much as] the parent strain. Finally, both LPS mutants were markedly less virulent in mice than the parent strain. Taken together, our observations support the idea that LPS is an important virulence factor of A. pleuropneumoniae.

Evaluation of protective efficacy of an Actinobacillus pleuropneumoniae serotype 1 lipopolysaccharide-protein conjugate in mice.

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The major adhesin of A. pleuropneumoniae has previously been identified as a lipopolysaccharide (LPS), and more recently, we demonstrated that high molecular mass LPS were involved in A. pleuropneumoniae adherence to porcine respiratory tract cells. We postulated that immunization with a LPS-based vaccine may confer a protective immunity. The high molecular mass O-polysaccharides obtained after acid hydrolysis and chromatographic separation were conjugated to bovine serum albumin (BSA) as a protein carrier. Groups of mice were injected twice with the following antigen preparations: whole-cell preparation, outer membrane preparation, O-polysaccharide-BSA conjugate, hydrolyzed LPS and phenol/water extracted LPS. A combination of different adjuvants was also used during these immunization procedures to induce a stronger immunological response to the polysaccharide antigen. Two weeks after the second injection, the mice were challenged intranasally with either homologous A. pleuropneumoniae serotype 1 strain or a serotype 5 strain. The highest survival rate, up to 80%, compared to the control groups (P < 0.05), was recorded when the mice were injected twice with 15 micrograms of carbohydrates of O-polysaccharide-BSA conjugate mixed with the saponin-derived adjuvant Quil A. Survival rates of between 60 and 70%, twice those observed in the control groups immunized with PBS, were recorded in mice injected with the O-polysaccharide-BSA conjugate mixed with other adjuvant preparations such as alhydrogel, peanut oil and Freund's incomplete adjuvant. However, the protection induced by the conjugate antigen preparation was serotype specific, because mice challenged with a serotype 5 strain were killed. Taken together, these results confirm the important role of A. pleuropneumoniae LPS in pathogenesis.

Identification of two core types in lipopolysaccharides of Actinobacillus pleuropneumoniae representing serotypes 1 to 12.

Lipopolysaccharides (LPS) of Actinobacillus pleuropneumoniae were separated by Tricine-SDS-polyacrylamide gel electrophoresis, which has been shown to improve resolution of low-molecular-mass fast migrating bands. Strains representing the 12 serotypes of A. pleuropneumoniae can be divided in two groups according to the gel mobility of the core - lipid A region of their LPS. The first electromorphic core type (core type I), found in serotypes 1, 6, 9, and 11, had a migration slower than Salmonella typhimurium Ra LPS. The second electromorphic core type (core type II), found in the remaining serotypes (i.e., 2, 3, 4, 5, 7, 8, 10, and 12) had a migration similar to S. typhimurium Ra LPS. Furthermore, we observed that these two core types were antigenically different. Western blot analyses indicated that core - lipid A region of LPS from electromorphic core type I strains reacted when probed with serum from a pig experimentally infected with a core type I strain but not when probed with serum from a pig experimentally infected with a core type II strain. Conversely, core - lipid A region of LPS from electromorphic core type II strains reacted only when probed with serum from a pig experimentally infected with a core type II strain. Our results, based on both electrophoretic mobility and antigenicity, suggest the presence of two LPS core types in A. pleuropneumoniae.

High-molecular-mass lipopolysaccharides are involved in Actinobacillus pleuropneumoniae adherence to porcine respiratory tract cells.

Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia. The major adhesin of A. pleuropneumoniae has been identified as the lipopolysaccharides (LPSs) (M. Bélanger, D. Dubreuil, J. Harel, C. Girard, and M. Jacques, Infect. Immun. 58:3523-3530, 1990). Using immunoelectron microscopy and flow cytometry, we showed in the present study that LPSs were well exposed at the surface of this encapsulated microorganism. Immunolocalization with porcine lung and tracheal frozen sections showed that extracted LPS bound to the lung mesenchyme and vascular endothelium and to the tracheal epithelium, respectively. Inhibition of adherence of A. pleuropneumoniae with extracted LPS was also performed with lung and tracheal frozen sections. Acid hydrolysis of LPS revealed that the active component of LPS was not lipid A but the polysaccharides. LPSs from A. pleuropneumoniae serotypes 1 and 2 were separated by chromatography on Sephacryl S-300 SF, in the presence of sodium deoxycholate, according to their molecular masses. The adherence-inhibitory activity was found in the high-molecular-mass fractions. These high-molecular-mass fractions contained 2-keto-3-deoxyoctulosonic acid and neutral sugars, and they were recognized by a monoclonal antibody directed against A. pleuropneumoniae O antigen but not recognized by a monoclonal antibody against capsular antigen.

Affinity for porcine respiratory tract mucus is found in some isolates of Actinobacillus pleuropneumoniae.

The ability of 17 Actinobacillus pleuropneumoniae isolates representing serotypes 1, 2, 5, and 7, to adhere in vitro to porcine respiratory tract mucus was examined. Adherence of bacteria to crude mucus preparations was evaluated by use of a dot-blot assay and an enzyme immunoassay. Seventy per cent (12/17) of the isolates of A. pleuropneumoniae had affinity, to various degrees, for porcine respiratory tract mucus. No relationship was found between affinity for respiratory mucus and serotype, haemagglutination, lipopolysaccharide (LPS) profiles, or adherence to porcine tracheal rings. However, a correlation was found between affinity for respiratory mucus and capsular material thickness; heavily encapsulated isolated showed no or less affinity for mucus than isolates with a thinner layer of capsular material. Moreover, two encapsulated isolates showed less affinity for mucus than their acapsulated variant. Finally, the affinity of A. pleuropneumoniae for respiratory mucus was heat- and proteinase-K-resistant. Our data suggest that capsular material of A. pleuropneumoniae could mask a surface component, possibly LPS, which has affinity for porcine respiratory mucus.

Pseudotumor cerebri associated with obstructive nephropathy.

We report two infants with pseudotumor cerebri associated with renal disease. The pathogenesis of increased intracranial pressure in this clinical setting is unclear, but may be mediated by one or more of the conditions commonly associated with pseudotumor cerebri, including sinus thrombosis, increased intravascular fluid volume, anemia, and endocrine disturbances resulting in abnormal calcium and phosphorus metabolism. The onset of pseudotumor cerebri also may be related to changes in vasopressin levels that affect brain water permeability.

Effects of active and passive EMG biofeedback training on performance of motor and cognitive tasks.

The goal of this study was to compare the effects of general relaxation (passive group) and neuromuscular tension control (active group), both using EMG biofeedback techniques, on the performance of memorization, simple reaction time, and rotary pursuit. 18 subjects were given five consecutive daily sessions of training or were placed under control conditions, after which their performance on these various tasks was evaluated. Results indicate that control of neuromuscular tension seemed to facilitate performance on all tasks over that of the control group. Except for simple reaction time, there was no difference between the "active" and "passive" groups. The results are interpreted in terms of factors in selection of subjects and experimental conditions.