Low temperature effects on the transcriptome of Yersinia pestis and its transmissibility by Oropsylla montana fleas

2016 Spring.Includes bibliographical references.Yersinia pestis, the causative agent of plague, is primarily a rodent-associated, flea-borne zoonosis. Transmission to humans is mediated most commonly by the flea vector, Oropsylla montana, and occurs predominantly in the Southwestern United States. In these studies, we hypothesized that Y. pestis-infected O. montana fleas held at temperatures as low as 6ºC could serve as reservoirs of the plague bacillus during the winter months in temperate regions with endemic plague foci. With few exceptions, previous studies showed O. montana to be an inefficient vector at transmitting Y. pestis at 22-23°C particularly when such fleas were fed on susceptible hosts more than a few days after ingesting an infectious blood meal. We examined whether holding fleas at sub-ambient temperatures (for purposes of these studies, ambient temperature is defined as 23°C) affected the transmissibility of Y. pestis by this vector. Colony-reared O. montana fleas were given an infectious blood meal containing a virulent Y. pestis strain (CO96-3188), and potentially infected fleas were maintained at different temperatures (6ºC, 10°C, 15°C, or 23ºC). Transmission efficiencies were tested by allowing groups of ~15 infectious fleas to feed on each of seven naïve CD-1 mice on days 1-4, 7, 10, 14, 17, and 21, 28, 35, and 42 post infection (p.i.). Fleas held at 6ºC, 10°C and 15°C were able to effectively transmit at every time point p.i. The percentage of transmission to naïve mice by fleas maintained at low temperatures was higher than for fleas maintained at 23ºC and indicates that O. montana fleas efficiently transmit Y. pestis at low temperatures. Moreover, bacterial loads of flea cohorts maintained at temperatures of 6ºC, 10ºC and 15ºC were statistically higher than fleas maintained at 23ºC. In addition, whole transcriptomes of Y. pestis bacteria grown at 6ºC, 10°C, 15°C and 23ºC were analyzed to assess differential gene expression at each temperature to identify genes which may contribute to an increase in virulence or survivability of the plague pathogen at the lower temperatures when compared to ambient temperature. This is the first comprehensive study to demonstrate efficient transmission of Y. pestis by O. montana fleas maintained at temperatures as low as 6ºC. Our findings further contribute to the understanding of plague ecology in temperate climates by providing support for the hypothesis that Y. pestis is able to overwinter within the flea gut and potentially cause infection during the following transmission season. The findings also might hold implications for explaining the focality of plague in tropical regions where plague occurs in cooler environments, primarily located at higher elevations

Listeria monocytogenes and other Listeria species in small and very small ready-to-eat meat processing plants

2010 Fall.Includes bibliographical references.Listeria monocytogenes is the causative agent of listeriosis, a severe foodborne disease associated with a high case fatality rate. To prevent product contamination with L. monocytogenes, it is crucial to understand Listeria contamination patterns in the food processing plant environment. The aim of this study was to monitor Listeria contamination patterns for two years in six small or very small ready-to-eat (RTE) meat processing plants using a routine combined cultural and molecular typing program. Each of the six plants enrolled in the study were visited on a bi-monthly basis for a two-year period where samples were collected, microbiologically analyzed for Listeria and isolates from positive samples were characterized by molecular subtyping. Year one of the project focused only on non-food contact environmental samples within each plant, and year two focused again on non-food contact environmental samples as well as food contact surfaces and finished RTE meat product samples from participating plants. Between year one and year two of sampling, we conducted an in-plant training session involving all employees at each plant. During this training session, we informed employees about general Listeria knowledge such as ecology, transmission and control strategies. Also, we informed each plant of the testing and molecular subtyping results obtained in the first year of the study. Employees also were given a pre- and post-training evaluation, which included 23 questions on Listeria, to probe knowledge gained through the training session. A common characteristic among almost all plants enrolled in our study was the persistence of a single or few predominant L. monocytogenes and/or other Listeria spp. molecular subtype(s) in the plant environment. Identification of persistent strains and their associated harborage sites in the environment of each plant highlight the continued need for adequate cleaning and sanitation practices to eliminate harborage sites and reduce the risk of transmission to the finished product. Interestingly, we not only observed a significant increase in plant employee knowledge regarding Listeria following the in-plant training sessions, but we also detected a significant decrease in Listeria contamination across all six plants when comparing testing results from year 1 and 2. With combined molecular detection and subtyping, we were able to help increase plant awareness about Listeria contamination patterns, identify harborage sites and intervention strategies to better control Listeria in the plant environment

Do children unintentionally report maltreatment? Comparison of disclosures of neglect versus sexual abuse

Background and aimsChildren's initial reports often play a key role in the identification of maltreatment, and a sizeable amount of scientific research has examined how children disclose sexual and physical abuse. Although neglect constitutes a large proportion of maltreatment experiences, relatively little attention has been directed toward understanding whether and how children disclose neglect. The overarching aim of the present study was to document this process by comparing disclosure patterns in cases of neglect to those in cases of sexual abuse.MethodRedacted jurisdiction reports (N = 136) of substantiated dependency cases of neglect (n = 71) and sexual abuse (n = 65) in 4- to 17-year-olds were coded for why maltreatment was suspected, and for children's perceived awareness and disclosure of the maltreatment.ResultsNeglect was most often initially suspected via contact with emergency services (e.g., police, emergency medical services), whereas sexual abuse was most often initially suspected as a result of children's statements. Children evidenced greater perceived awareness of sexual abuse than neglect and were more likely to disclose the former in their first investigative interview. Perceived awareness was further associated with a higher likelihood of children's statements initiating discovery of maltreatment and disclosing in the first investigative interview.ConclusionsChildren may benefit from greater knowledge about their needs for safety, supervision, and provision in the home, which could increase the likelihood they would disclose neglect. Such, in turn, could lead to earlier interventions for children and families

Pseudotemporal invitations: 6- to 9-year-old maltreated children’s tendency to misinterpret invitations referencing “time” as solely requesting conventional temporal information

Forensic interviewers ask children broad input-free recall questions about individual episodes in order to elicit complete narratives, often asking about “the first time,” “the last time,” and “one time.” An overlooked problem is that the word “time” is potentially ambiguous, referring both to a particular episode and to conventional temporal information. We examined 191 6-9-year-old maltreated children’s responses to questions about recent events varying the wording of the invitations, either asking children to “tell me about” or “tell me what happened” one time/the first time/the last time the child experienced recent recurrent events. Additionally, half of the children were asked a series of “when” questions about recurrent events before the invitations. Children were several times more likely to provide exclusively conventional temporal information to “tell me about” invitations compared to “tell me what happened” invitations, and asking “when” questions before the invitations increased children’s tendency to give exclusively conventional temporal information. Children who answered a higher proportion of “when” questions with conventional temporal information were also more likely to do so in response to the invitations. The results suggest that children may often fail to provide narrative information because they misinterpret invitations using the word “time.

Chronic allergen challenge induces bronchial mast cell accumulation in BALB/c but not C57BL/6 mice and is independent of IL-9

As genetically engineered mutant mice deficient in single genes are usually generated on a C57BL/6 background, to study mast cell trafficking in mutant mice, we initially investigated whether mast cells accumulated in bronchi in C57BL/6 mice challenged with OVA allergen acutely or chronically for 1 to 3 months. The total number of bronchial mast cells were quantitated using toluidine blue staining in airways of different sizes, i.e. , small (<90 µm), medium (90–155 µm), or large (>150 µm) airways. Non-OVA challenged and acute OVA challenged mice (C57BL/6 and BALB/c) had no detectable bronchial mast cells. Chronic OVA challenge in BALB/c mice for 1 or 3 months induced a significant increase in the number of bronchial mast cells in small-, medium-, and large-sized airways but minimal change in the number of bronchial mast cells in C57BL/6 mice. Both BALB/c and C57BL/6 mice developed significant lung eosinophilia following acute or chronic OVA challenge. Studies of IL-9-deficient mice on a BALB/c background demonstrated a significant increase in the number of bronchial mast cells in IL-9-deficient mice suggesting that IL-9 was not required for the bronchial accumulation of mast cells. Overall, these studies demonstrate that the chronic OVA challenge protocol we have utilized in BALB/c mice provides a model to study the mechanism of bronchial mast cell accumulation and that bronchial mast cell accumulation in chronic OVA challenged mice is independent of IL-9 in this model

Effects of temperature on the transmission of Yersinia Pestis by the flea, Xenopsylla Cheopis, in the late phase period

<p>Abstract</p> <p>Background</p> <p>Traditionally, efficient flea-borne transmission of <it>Yersinia pestis</it>, the causative agent of plague, was thought to be dependent on a process referred to as blockage in which biofilm-mediated growth of the bacteria physically blocks the flea gut, leading to the regurgitation of contaminated blood into the host. This process was previously shown to be temperature-regulated, with blockage failing at temperatures approaching 30°C; however, the abilities of fleas to transmit infections at different temperatures had not been adequately assessed. We infected colony-reared fleas of <it>Xenopsylla cheopis </it>with a wild type strain of <it>Y. pestis </it>and maintained them at 10, 23, 27, or 30°C. Naïve mice were exposed to groups of infected fleas beginning on day 7 post-infection (p.i.), and every 3-4 days thereafter until day 14 p.i. for fleas held at 10°C, or 28 days p.i. for fleas held at 23-30°C. Transmission was confirmed using <it>Y. pestis</it>-specific antigen or antibody detection assays on mouse tissues.</p> <p>Results</p> <p>Although no statistically significant differences in per flea transmission efficiencies were detected between 23 and 30°C, efficiencies were highest for fleas maintained at 23°C and they began to decline at 27 and 30°C by day 21 p.i. These declines coincided with declining median bacterial loads in fleas at 27 and 30°C. Survival and feeding rates of fleas also varied by temperature to suggest fleas at 27 and 30°C would be less likely to sustain transmission than fleas maintained at 23°C. Fleas held at 10°C transmitted <it>Y. pestis </it>infections, although flea survival was significantly reduced compared to that of uninfected fleas at this temperature. Median bacterial loads were significantly higher at 10°C than at the other temperatures.</p> <p>Conclusions</p> <p>Our results suggest that temperature does not significantly effect the per flea efficiency of <it>Y. pestis </it>transmission by <it>X. cheopis</it>, but that temperature is likely to influence the dynamics of <it>Y. pestis </it>flea-borne transmission, perhaps by affecting persistence of the bacteria in the flea gut or by influencing flea survival. Whether <it>Y. pestis </it>biofilm production is important for transmission at different temperatures remains unresolved, although our results support the hypothesis that blockage is not necessary for efficient transmission.</p

Deep Phenotyping of Post-infectious Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Post-infectious myalgic encephalomyelitis/chronic fatigue syndrome (PI-ME/CFS) is a disabling disorder, yet the clinical phenotype is poorly defined, the pathophysiology is unknown, and no disease-modifying treatments are available. We used rigorous criteria to recruit PI-ME/CFS participants with matched controls to conduct deep phenotyping. Among the many physical and cognitive complaints, one defining feature of PI-ME/CFS was an alteration of effort preference, rather than physical or central fatigue, due to dysfunction of integrative brain regions potentially associated with central catechol pathway dysregulation, with consequences on autonomic functioning and physical conditioning. Immune profiling suggested chronic antigenic stimulation with increase in naïve and decrease in switched memory B-cells. Alterations in gene expression profiles of peripheral blood mononuclear cells and metabolic pathways were consistent with cellular phenotypic studies and demonstrated differences according to sex. Together these clinical abnormalities and biomarker differences provide unique insight into the underlying pathophysiology of PI-ME/CFS, which may guide future intervention

The development of lie-telling: the role of executive functioning and theory of mind in children’s prosocial and antisocial lying

Lying is a frequent behaviour in our daily interactions and emerges early in children’s development. Deceiving others is a cognitively demanding task, as lie-telling has been found to place greater mental demands upon the individual than truth-telling. Although researchers have highlighted the role of cognitive skills on the capacity to tell a lie, these investigations have been limited in scope. Specifically, the majority of inquiries have focused on antisocial lie-telling of preschool and elementary school-aged children; yet children tell various forms of lies (i.e., prosocial and antisocial). Yet observational accounts of parents and researchers have found that children lie much younger than experimentally observed in laboratory settings. However, little empirical research has been conducted on the emergence of children’s lie-telling (i.e., lies told prior to 3 years old). As a result, our understanding of children’s lie-telling, both the emergence and use of various forms of lies, remains limited in scope. The current dissertation sought to address these gaps in the empirical research. The first manuscript of the dissertation examines the contribution of the executive functioning skills of working memory and inhibitory control to children’s ability to tell prosocial lies (i.e., lies told for another individual’s benefit). Children’s ToM was also investigated in relation to prosocial lying through measures of second-order false-belief understanding. The Stroop and Digit Span tasks were used to measure inhibitory control and working memory. A total of 79 children between the ages of 6 and 12 years old completed a disappointing gift paradigm (i.e., DGP), designed to elicit prosocial lies and to measure children’s ability to maintain such lies. Results reveal that children who told prosocial lies had significantly higher scores on measures of working memory and inhibitory control. Those children who were able to maintain their prosocial lies throughout questioning also had significantly higher performance on measures of second-order false-belief. These results provide evidence that prosocial lies are supported through the maturation of both executive functioning and ToM. The second manuscript examines the relation between preschool aged children’s rudimentary lies, executive functioning, ToM and conceptual understanding of lies and truths. A total of 65 children between the ages of 2.5 and 3.5 years old participated in a modified temptation resistance paradigm (TRP). To examine executive functioning, children completed measures of inhibitory control and planning. Children’s abilities to identify both truths and lies were also examined in relation to their actual lie-telling behaviour. Overall, a total of 29% of young children lied during the TRP. Results revealed significant differences between lie-tellers and truth-tellers on all measures of executive functioning, with lie-tellers having significantly better scores than truth-tellers. Moreover, lie-tellers also had significantly better accuracy in identifying both truths and lies. No significant differences between truth and lie-tellers were found on measures of ToM. As such, the results provide support for the role of executive functioning skills in the emergence of antisocial lie-telling. Taken together, the current research program provides support for a developmental model of lie-telling. Notably, results support the argument that children acquire lie-telling in developmental stages, with rudimentary lies being supported by the executive functioning skills of inhibitory control and planning. With age, executive functioning skills and ToM support other forms of lie-telling (i.e., prosocial), as well as improved lie-telling capacities (i.e., maintenance of lies through control of semantic leakage).Mentir est un comportement fréquent qui émerge tôt dans le développement de l’enfant. Tromper les gens est une tâche demandante au plan cognitif. Spécifiquement, la majorité des recherches s’attardaient au mensonge antisocial chez les enfants d’âge préscolaire et primaire. Toutefois, les enfants utilisent différentes formes de mensonges (c.-à-d., prosocial et antisocial). De plus, peu d’études ont porté sur l’émergence de l’utilisation des mensonges chez l’enfant (c.-à-d., avant l’âge de trois ans). La présente thèse tentait donc d’explorer cette question. Le premier article examine la contribution des fonctions exécutives, de la mémoire de travail et de l’inhibition dans l’habileté de l’enfant à utiliser les mensonges prosociaux (c.-à-d., des mensonges dits au bénéfice d’une autre personne). La théorie de l’esprit des enfants a été évaluée en relation avec l’utilisation de mensonges prosociaux par le biais d’une mesure de la compréhension de fausses croyances de deuxième ordre. Soixante-dix-neuf enfants, âgés de 6 à 12 ans, ont participé à un paradigme de cadeau désappointant. Celui-ci est conçu afin d’inciter l’utilisation de mensonges prosociaux et, subséquemment, pour mesurer l’habileté de l’enfant à maintenir ceux-ci durant la réponse à des questions. Les enfants utilisant les mensonges prosociaux ont obtenus des résultats significativement plus élevés en ce qui a trait à la mémoire de travail et à l’inhibition. De plus, les enfants ayant démontré la capacité à maintenir leurs mensonges prosociaux durant la période de questions avaient également une plus grande compréhension des fausses croyances de deuxième ordre. Ces résultats démontrent que les mensonges prosociaux découlent de la maturation des habiletés cognitives, tel que précédemment démontré dans la littérature concernant l’utilisation des mensonges antisociaux.Le deuxième article porte sur la relation entre l’utilisation de mensonges rudimentaires chez les enfants d’âge préscolaire, les fonctions exécutives, la théorie de l’esprit et la compréhension conceptuelle des mensonges et de la vérité. Soixante-cinq enfants, âgés de 2,5 à 3,5 ans, ont participé à un paradigme de résistance à la tentation. Afin de mesurer les fonctions exécutives, les enfants ont complété des mesures de planification, d’inhibition et de mémoire de travail. L’habileté des enfants à identifier la vérité et les mensonges a également été mesurée en relation avec leur propre utilisation du mensonge. En somme, 29,31% des enfants ont menti durant le paradigme de résistance à la tentation. Les résultats révèlent une différence significative entre les enfants utilisant le mensonge et ceux ne l’utilisant pas, et ce, sur toutes les mesures des fonctions exécutives. Effectivement, les enfants ayant utilisé le mensonge ont obtenu des résultats significativement plus élevés. De surcroît, ces enfants avaient également une plus grande exactitude dans leur identification des mensonges et de la vérité. Toutefois, aucune différence significative n’a été obtenue entre ces deux groupes en ce qui concerne la théorie de l’esprit. En ce sens, les résultats supportent l’hypothèse du rôle des fonctions exécutives dans l’émergence de l’utilisation de mensonges antisociaux. Lorsque considérés ensembles, les résultats semblent confirmer le modèle développemental de l’émergence de l’utilisation du mensonge. Globalement, ceux-ci supportent l’hypothèse que les enfants apprennent à mentir selon des étapes développementales. Les mensonges rudimentaires découleraient alors d’habiletés cognitives de base sur le plan de la planification et de l’inhibition. Avec l’âge, ces habiletés cognitives seraient également impliquées dans différentes formes de mensonges ainsi que dans la présence de plus grandes capacités d’utilisation de ceux-ci