Thesis (Ph. D.)--University of Virginia, 1997. / Spine title: Characterization of PT receptors. Includes bibliographical references (111-128). Also available online through Digital Dissertations.

No description available.

La virulence de Bordetella pertussis, agent de la coqueluche, est liée à un arsenal de facteurs de virulence dont l’expression est régulée par le système à deux composants BvgAS. BvgA est le régulateur de réponse et BvgS le capteur du système, qui possède 3 domaines putatifs de perception de signaux. Il s’agit de 2 domaines périplasmiques « Venus FlyTrap » (VFT), reliés par un segment transmembranaire à un domaine PAS (Per-ARNT-Sim) cytoplasmique qui fait la jonction avec l’histidine-kinase. Les signaux perçus par ces domaines capteurs sont inconnus, mais une température de 37°C est suffisante pour maintenir le système actif en laboratoire. Cette activité peut être modulée négativement par des composés chimiques, comme le MgSO4 ou le nicotinate, qui à concentrations suffisantes entraînent le passage de la bactérie en phase avirulente.Nous nous sommes intéressés aux domaines VFT de BvgS. Ces domaines, ubiquitaires, sont composés de 2 lobes reliés par une charnière délimitant une cavité qui permet la fixation d’un ligand spécifique stabilisant le VFT sous une forme fermée.Les domaines VFT de BvgS ont pu être cristallisés et s’organisent en un dimère entrelacé définissant de larges interfaces entre les 4 VFTs. Les VFT2 sont fermés sans ligand et les VFT1 ouverts, et la fermeture artificielle de ces domaines par des ponts disulfure a montré qu’il s’agit de la conformation active de BvgS. L’importance des interfaces entre les domaines VFT pour la fonction de BvgS a été démontrée par mutagenèse dirigée. Un signal positif proviendrait du périplasme pour être transmis à travers la membrane par les interfaces entre les VFT et intégré via un couplage fonctionnel en trans entre ces domaines et les hélices pré-membranaires, dites H19.Ces hélices se prolongeraient à travers la membrane et dans le cytoplasme jusqu’au domaine PAS. Les domaines PAS sont ubiquitaires, avec une structure fortement conservée en feuillet  à 5 brins recouvert d’hélices  délimitant une cavité. Ils sont impliqués dans diverses fonctions biologiques, selon leur capacité de liaison d’un ligand. Certains domaines PAS fonctionneraient sans ligand et pourraient servir d’adaptateurs ou d’amplificateurs de signal.Nous avons pu mettre en évidence la capacité de dimérisation de PASBvg, confirmant la nature dimérique du capteur BvgS. Des substitutions de résidus de la cavité de PASBvg indiqueraient que l’intégrité de la cavité de PASBvg est nécessaire au passage de signaux positifs et négatifs provenant du périplasme. La fixation de ligand dans la cavité n’a pu être démontrée mais n’est pas exclue. D’autre part, certains résidus sont nécessaires au couplage du domaine PAS avec ses hélices flanquantes pour la transmission de signal. La perte de ces interactions déstabilise significativement PASBvg et rend BvgS inactif.Un message positif proviendrait du périplasme et serait maintenu par le domaine PAS, dans une conformation rigide, permettant aussi la transmission des signaux modulateurs. / Virulence of Bordetella pertussis, the whooping cough agent, is due to a plethora of virulence factors which expression is regulated by the two-component system BvgAS. BvgA is a classical response regulator and BvgS the sensor. BvgS contains 3 putative sensor domains, 2 periplasmic Venus FlyTrap (VFT), linked through a transmembrane segment to a cytoplasmic PAS domain preceding the histidine-kinase. Signals perceived by those sensor domains are still unknown, but a 37°C temperature is sufficient to maintain the system active under laboratory conditions. This activity can be down-modulated by chemical compounds, such as MgSO4 or nicotinate, which at sufficient concentration allows the bacteria to switch to avirulent phase.We investigated the role of BvgS VFT domains. VFTs are ubiquitous domains composed of 2 lobes linked by a hinge hence forming a cleft where a specific ligand can bind and stabilize the VFT in its closed conformation.BvgS VFT domains were crystalized and form an intricate dimer defining large interfaces between the 4 VFTs. VFT2s are closed without a ligand and VFT1s are opened, artificial closure of these domains via a disulfide bond indicates that this is the active conformation of BvgS. The role of the interfaces was probed by site-directed mutagenesis. A positive signal might originate from the periplasm to be transmitted through the membrane by the interfaces and integrated by a functional coupling between the VFT2s and the helices preceding the membrane, H19.These helices should be continued through the membrane and the cytoplasm to the PAS domain. Pas domains are ubiquitous with a highly conserved structure, a 5 stranded sheet surrounded by  helices defining a cavity. Pas domains are involved in a wide variety of physiological processes, depending on their ability to bind a ligand. Some PAS might function without a ligand and could then be signal adaptors or amplifiers.We demonstrated PASBvg was dimeric, confirming the dimeric nature of BvgS. Cavity residues were substituted indicating that integrity of the cavity is necessary to maintain activity and modulation capacity coming from the periplasmic moiety. Ligand binding wasn’t demonstrated but couldn’t be excluded. Some residues are needed for the correct coupling of the PAS domain to its flanking helices and hence signal transmission. Loss of these connections generates a strong destabilization of PASBvg and turns BvgS inactive.A positive signal might come from the periplasmic moiety and shoul be maintaines by the PAS domain, which is in a rigid conformation also allowing the transmission of negative signals.

Thesis (Ph. D.)--University of Virginia, 2001. / Includes bibliographical references (leaves 146-168). Also available online through Digital Dissertations.

Darbo tikslas Ištirti kosulio reflekso jautrumo pokyčius metus rūkyti sveikiems asmenims ir sergantiems lėtine obstrukcine plaučių liga. Darbo uždaviniai 1. Ištirti ir įvertinti rūkymo metimo poveikį sveikų asmenų kosulio reflekso jautrumui. 2. Ištirti ir įvertinti metusių ir vėl pradėjusių rūkyti sveikų asmenų kosulio reflekso jautrumą. 3. Ištirti ir palyginti sergančių lėtine obstrukcine plaučių liga rūkorių ir sergančių lėtine obstrukcine plaučių liga buvusių rūkorių kosulio reflekso jautrumą. 4. Palyginti sergančių lėtine obstrukcine plaučių liga rūkorių ir sergančių lėtine obstrukcine plaučių liga buvusių rūkorių bei sveikų rūkorių ir sveikų nerūkančiųjų kosulio reflekso jautrumą 5. Ištirti bronchoalveolinio lavažo skysčio ląstelių sudėtį ir uždegimo žymenų (interleukino-8, leukotrieno B4, leukotrieno E4) koncentraciją sergantiems lėtine obstrukcine plaučių liga rūkoriams, sergantiems lėtine obstrukcine plaučių liga buvusiems rūkoriams ir sveikiems rūkoriams. 6. Įvertinti galimas kosulio reflekso jautrumo sąsajas su uždegimo ląstelių kiekiu ir uždegimo žymenų (interleukino-8, leukotrieno B4, leukotrieno E4) koncentracija bronchoalveolinio lavažo skystyje sergantiems lėtine obstrukcine plaučių liga rūkoriams, sergantiems lėtine obstrukcine plaučių liga buvusiems rūkoriams ir sveikiems rūkoriams. Šiame darbe pirmą kartą ištirtas rūkymo metimo poveikis sveikų asmenų kosulio reflekso jautrumui ir sveikų asmenų kosulio reflekso jautrumas jiems metus ir vėl... [toliau žr. visą tekstą] / The aim of the study To evaluate changes of cough reflex sensitivity after smoking cessation in healthy subjects and patients with chronic obstructive pulmonary disease (COPD). Objectives of the study 1. To evaluate the effect of smoking cessation on cough reflex sensitivity changes in healthy subjects. 2. To investigate cough reflex sensitivity changes after cessation and resumption of smoking in healthy subjects. 3. To evaluate and compare cough reflex sensitivity in COPD smokers and COPD ex-smokers. 4. To compare cough reflex sensitivity in COPD smokers and COPD ex-smokers with the cough reflex sensitivity in healthy smokers and healthy never smokers. 5. To evaluate the inflammatory cells count and the concentration of inflammatory mediators (IL-8, LTB4, LTE4) in bronchoalveolar lavage (BAL) fluid from COPD smokers, COPD ex-smokers and healthy smokers. 6. To investigate probable association between cough reflex sensitivity and inflammatory cells count and concentration of inflammatory mediators (IL-8, LTB4, LTE4) in BAL fluid in COPD smokers, COPD ex-smokers and healthy smokers. This is the first study, where the effect of smoking cessation on cough reflex sensitivity in healthy subjects was evaluated and this is the first time, when cough reflex sensitivity in COPD smokers and COPD ex-smokers was evaluated and compared.

Silent aspiration is associated with pneumonia and mortality, and is poorly identified by traditional clinical swallowing evaluation (CSE). Currently, there is no reliable test for detecting silent aspiration during CSE. There is, however, increasing evidence for the validity of cough reflex testing (CRT) for identifying silent aspiration. This test has the potential to significantly improve clinical assessment of dysphagia. The aim of this research programme was to further investigate the validity, reliability and clinical utility of CRT for identifying patients at risk of silently aspirating. Several aspects of CRT were explored during this research programme. Two correlational studies were conducted to validate CRT for identifying silent aspiration against videofluoroscopic swallowing study (VFSS) and flexible endoscopic evaluation of swallowing (FEES). Cough reflex threshold testing was completed on 181 patients using inhaled, nebulised citric acid. Within one hour, 80 patients underwent VFSS and 101 patients underwent FEES. All tests were recorded and analysed by two researchers blind to the result of the alternate test. Significant associations between CRT result and cough response to aspiration on VFSS (p = .003) and FEES (p < .001) were identified. Sensitivity and specificity were optimised at 0.6mol/L in patients undergoing VFSS (71%, 60% respectively) and at 0.4mol/L in patients undergoing FEES (69%, 71% respectively). A concentration of 0.8mol/L had the highest odds ratio (OR) for detecting silent aspiration (8 based on VFSS, 7 based on FEES). Coughing on lower concentrations of citric acid (0.4mol/L compared with 1.2mol/L) was a better predictive measure of silent aspiration. Diminished cough strength has also been associated with aspiration and increased risk of pneumonia. Reflexive cough is our primary defensive mechanism against aspiration and a measure of reflexive cough strength therefore holds greater relevance than one of voluntary cough strength. Despite common use and clinical applicability, the reliability of subjective cough judgements has received little attention. The inter- and intra-rater reliability of subjective judgements of cough in patients following inhalation of citric acid was assessed. Forty-five speech-language therapists (SLTs) were recruited to the first study. Of these, 11 SLTs were currently using CRT in their clinical practice (experienced raters) and 34 SLTs reported no experience with CRT (inexperienced raters). Participants provided a rating of strong, weak or absent to ten video segments of cough responses elicited by inhalation of nebulised citric acid. The same video segments presented in a different sequence were re- evaluated by the same clinicians following a 15-minute break. Inter-rater reliability for experienced raters was calculated with a Fleiss’ generalised kappa of .49; intra-rater reliability was higher with a kappa of .70. Inexperienced raters showed similar reliability with kappa values for inter-rater and intra-rater reliability of .36 and .62, respectively. SLTs demonstrated only fair to moderate reliability in subjectively judging a patient’s cough response to citric acid. Experience in making cough judgements did not improve reliability significantly. In a second study, specific training in cough physiology and cough judgement was provided to 58 trained SLTs. Inter-rater reliability of subjective judgements of cough in patients following inhalation of citric acid was assessed. Participants provided a rating of present or absent, and if present then a rating of strong or weak, to ten video segments of cough responses. Inter-rater reliability for cough presence was calculated with a Fleiss’ generalised kappa of .71 and cough strength was calculated at .61. Years of clinical experience did not improve inter-rater reliability significantly. Experience in using CRT did improve inter-rater reliability. Further validity and reliability research would be beneficial for guiding clinical guidelines and training programmes. By identifying patients at risk of silent aspiration, more informed management decisions can be made that consequently lead to a reduction in preventable secondary complications such as pneumonia. The clinical utility of CRT for reducing pneumonia in acute stroke patients was assessed through a randomised, controlled trial. Three hundred and eleven patients referred for swallowing evaluation were assigned to either 1) a control group receiving standard evaluation or 2) an experimental group receiving standard evaluation with CRT. Participants in the experimental group were administered nebulised citric acid with test results contributing to clinical decisions. Outcomes for both groups were measured by pneumonia rates at three months post stroke and other clinical indices of swallowing management. Analysis of the data identified no significant differences between groups in pneumonia rate (p = .38) or mortality (p = .15). Results of CRT were shown to influence diet recommendations (p < .0001) and referrals for instrumental assessment (p <.0001). Despite differences in clinical management between groups, the end goal of reducing pneumonia in post stroke dysphagia was not achieved. Through this research, the characteristics and outcomes associated with dysphagia secondary to stroke in New Zealand were identified. Baseline characteristics of 311 patients with dysphagia following acute stroke were collected during their hospital stay and outcomes were measured at three months post stroke. Mortality rates were 16% and pneumonia rates 27%. Mean length of stay was 24 days and only 45% of patients were in their own home at three months post stroke. Pneumonia was significantly associated with mortality and increased length of stay. Only 13% of patients received referral for instrumental assessment of swallowing. These data are discussed in reference to the National Acute Stroke Services Audit 2009 and internationally published data. The outcomes for stroke patients with dysphagia in New Zealand are poor with a high risk of pneumonia and long hospital stays when compared internationally. In summary, this research programme has contributed to our understanding of the use of CRT in patients with dysphagia. The addition of a measure of reflexive cough strength may add to clinical assessment but specific training is required to reach adequate reliability. CRT results are significantly associated with aspiration response on instrumental assessment and lower concentrations of citric acid provide a better predictive measure of silent aspiration. CRT can be standardised and therefore is not as susceptible to interpretative variance that plagues much of CSE. Sensitivity and specificity values using this CRT methodology are adequate for CRT to be incorporated into clinical protocols. Inclusion of CRT alone was not shown to be sufficient to change clinical outcomes however integration of CRT into clinical pathways may prove more successful. Further research evaluating the addition of CRT to a comprehensive CSE would add greatly to the field of dysphagia assessment.

No description available.

Thesis (M.A.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 120-124). Also available on the Internet.

Thesis (M.A.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 120-124). Also available on the Internet.

Pertussis is an infectious disease caused by the Gram-negative bacterium Bordetella pertussis. In Peru, actual public health programs indicate that vaccination against B. pertussis must be mandatory and generalized, besides all detected cases must be reported. The objective of this study was to determine the prevalence of B. pertussis among children under five years of age with a presumptive diagnosis of whopping cough in Cajamarca, a region located in northern Peru. / Background and Objectives: Pertussis is an infectious disease caused by the Gram-negative bacterium Bordetella pertussis. In Peru, actual public health programs indicate that vaccination against B. pertussis must be mandatory and generalized, be-sides all detected cases must be reported. The objective of this study was to determine the prevalence of B. pertussis among children under five years of age with a presumptive diagnosis of whopping cough in Cajamarca, a region located in northern Peru. Materials and Methods: The population of this cross-sectional study were children under 5 years old hospitalized as presumptive cases of pertussis during December 2017 to December 2018. The nasopharyngeal samples were analyzed by real-time PCR for the detection of B. pertussis. Results: B. pertussis was identified as PCR + in 42.3% of our sample (33/78). The clinical presentation that was observed most frequently includes paroxysmal coughing (97%), difficulty breathing (69.7%), cyanosis (72.7%) and post-tussive em-esis (60.6%). Additionally, pneumonia was the most observed complication (33.3%). Four of the patients with PCR+ for B. pertussis presented only lymphocytosis, five only leukocytosis, two patients with decreased leukocytosis and lymphocytes and only one patient with leukopenia and relative lymphocytosis. There was a percentage of 84.8% of unvaccinated children in the PCR+ group. Finally, the mother was the most frequent symptom carrier (18.2%). Conclusion: In conclusion, in the studied population there is a high rate of PCR+ cases for B. pertussis. Laboratory values may show leukopenia or lymphopenia in patients with pertussis. It is necessary to use appropriate laboratory diagnostic tests in all infants with respiratory symptoms for B. pertussis. Since, the clinical diagnosis overestimates the diagnosis of pertussis. / Revisión por pares