Abstract not available. / Hui, Mamie. / "Dec 2010." / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (M.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 209-236). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.

INTRODUÇÃO: A mortalidade das vítimas de queimaduras tem diminuído nos últimos anos e a lesão inalatória tornou-se a principal causa de morte. As consequências da inalação por fumaça resultam de uma resposta inflamatória que envolve vários mediadores. A proteína 1 relacionada a uteroglobulina (UGRP1) é uma secretoglobulina antinflamatória específica do pulmão que pode desempenhar um papel na inflamação pulmonar. OBJETIVO: Investigar se a expressão precoce da UGRP1 na inalação de fumaça está relacionada com a severidade da injúria inalatória. MÉTODOS: Nós estudamos 16 pacientes críticos vítimas de queimaduras. Todos os pacientes foram mecanicamente ventilados por Síndrome da Angústia Respiratória do Adulto (SARA) secundária a injúria por inalação de fumaça. Uma amostra de sangue foi coletada entre a admissão a UTI até 24h após a injúria inalatória. O grau da injúria por inalação foi avaliado em todos os pacientes. RESULTADOS: A média de idade dos pacientes foi de 23±5 anos, com injúria inalatória: graus 1 (n=3), 2 (n=4) e 3 (n=9). Níveis de UGRP1 foram significativamente relacionados a severidade da injúria (Grau 1 0.389±0.053 DO/mL vs. grau 2 0.474±.0423 DO/mL vs grau 3 0.580±0.094 DO/mL, p=0.007). CONCLUSÕES: Níveis aumentados de UGRP1 no plasma humano após lesão inalatória em pacientes queimados estão associados com a severidade da injúria pulmonar. / INTRODUCTION: The mortality of burn victims has decreased in recent years and the inhalation injury has become the leading cause of death. The consequences of smoke inhalation result from an inflammatory response involving several mediators. Uteroglobin-related protein 1 (UGRP1) is a lungspecific anti-inflammatory secretoglobulin that may play a role in lung inflammation. AIM: To investigate if UGRP1 expression early after smoke inhalation relates to the severity of inhalation injury. METHODS: We studied 16 critically ill burn victims. All patients were mechanically ventilated with Acute Respiratory Distress Syndrome (ARDS) secondary to smoke inhalation injury. A blood sample was collected at ICU admission within 24 hours after the inhalation injury. The grade of inhalation injury was evaluated in all patients. RESULTS: Mean age was 23±5 years, with inhalation injury: grades 1 (n=3), 2 (n=4), and 3 (n=9). UGRP1 levels were significantly related to the severity of inhalation (Grade 1 0.389±0.053 OD/mL vs. grade 2 0.474±.0423 OD/mL vs grade 3 0.580±0.094 OD/mL, p=0.007). CONCLUSIONS: UGRP1 levels in human blood plasma increases after inhalation injury in burn patients and are associated with the severity of inhalation injury.

Made available in DSpace on 2014-07-29T15:26:23Z (GMT). No. of bitstreams: 1 Tese Licia Kamila Assis Melo Thorn.pdf: 442976 bytes, checksum: 07983fd8fed79ef23cfcf92587bde23a (MD5) Previous issue date: 2012-12-06 / Introdução: A pneumonia tem um papel importante na carga das doenças da infância, principalmente nos países pobres. São escassos os estudos avaliando a associação entre pobreza e pneumonias confirmadas por raio-x, embora as radiografias de tórax tem sido utilizadas amplamente em estudos de doença pneumocócica invasiva. Foram utilizados dados do Latin America Epidemiological Assessment of Pneumococcal Invasive Disease (estudo LEAP-Brazil) para localizar aglomerados de pneumonia confirmadas por raio-X de tórax e avaliar a incidência de pneumonias por estrato socioeconômico. Métodos: De maio/2007 a maio/2009 11.474 crianças com idade entre 28 dias a menores 36 meses com suspeita clínica de pneumonia foram registrados em 33 serviços de emergência em Goiânia, Brasil. As radiografias de tórax foram interpretadas por um radiologista treinado em leitura e interpretação pelas normas da OMS e 3.955(34,5%) foram classificadas como pneumonia de provável etiologia bacteriana. A estatística espacial de varredura (modelo de Poisson) foi aplicada sobre um total de 3.867 crianças com pneumonia confirmada por raio-x que foram interativamente geocodificadas no endereço da residência. A hipótese de nulidade é a de que os casos são distribuídos aleatoriamente. A mesma técnica foi aplicada ao conjunto de dados de crianças hospitalizadas, utilizando a hospitalização como uma aproximação para a gravidade. A incidência de pneumonia foi classificada de acordo com o indicador de nível socioeconômico elaborado com variáveis do censo. As variáveis do censo também foram utilizadas em um modelo linear generalizado para identificar quais delas estiveram associadas à pneumonia. Resultados: A incidência no período de dois anos foi significativamente maior nas áreas de renda muito baixa. O aglomerado primário (RR = 1,78; p = 0,001) foi localizado na parte Noroeste da cidade e um conjunto secundário foi identificado na região Sudeste (RR = 1,46; p = 0,001). A análise espacial para crianças com pneumonia confirmada por raio-x hospitalizadas detectou um aglomerado primário (RR = 1,69; p = 0,001), que se sobrepôs ao aglomerado de pneumonia. O percentual de chefes de família com 20 ou mais salários mínimos mensais foi inversamente relacionado à pneumonia enquanto o percentual de mulheres analfabetas apresentou uma relação positiva com a pneumonia no modelo linear generalizado multivariado. Conclusões: Encontramos evidências epidemiológicas da associação direta entre pobreza e pneumonia. Estes resultados oferecem uma base para avaliar a eficácia da vacina pneumocócica na redução da carga da pneumonia na infância de acordo com diferentes níveis socioeconômicos do município.

O transplante pulmonar é terapia estabelecida para pacientes portadores de doença pulmonar em estágio terminal. Os doadores em morte encefálica são a principal fonte de pulmões para transplante. A fisiopatologia da encefálica é complexa e envolve mecanismos simpático, hemodinâmico e inflamatório que determinam o dano pulmonar. A administração de metilprednisolona em modelo animal de morte encefálica e transplante pulmonar diminuiu o dano de reperfusão no enxerto. Métodos- Vinte e quatro ratos Wistar foram anestesiados e randomizados em 4 grupos (n=6): Sham (sham): apenas trepanação; Morte Encefálica (ME): indução de morte encefálica e administração de solução salina; Corticóide 5min (mt5): indução de morte encefálica e após 5min administração de MET e Grupo Corticóide 60min (mt60): indução de morte encefálica e após 60min. administração de MET. Os animais de todos os grupos foram observados e ventilados durante 120min. Avaliou-se dados hemodinâmicos e gasométricos; dosagem de LDH, proteínas totais e citológico diferencial no lavado broncoalveolar (LBA); escore histológico; dosagem de substâncias reativas ao ácido tiobarbitúrico (TBARS), TNF-α, superóxido dismutase (SOD) e catalase em tecido pulmonar. Resultados- Não foi observado diferença estatística entre os grupos nos dados hemodinâmicos e gasométricos, dosagens do LBA, avaliação do escore histológico, dosagem de SOD e catalase. O TBARS aumentou significativamente (P<0,001) em ambos os grupos tratados com MET em relação aos grupos sham e ME. O TNF-α aumentou significativamente (P<0,001) no grupo ME em relação aos grupos tratados com MET. Não ocorreu diferença estatística entre os grupos mt5 e mt60. Conclusão- A administração precoce ou tardia de MET nesse modelo de morte encefálica resulta em efeitos similares nas atividades inflamatória e de peroxidação lipídica no tecido pulmonar. / Lung transplantation is an established therapy for patients with end-stage lung disease. The main source of lungs for transplantation is brain-dead donors. The pathophysiology of brain death is complex and involves sympathetic, hemodynamic and inflammatory mechanisms that can injure the lung. It has been previously shown that brain-dead donor treatment with methylprednisolone reduces reperfusion injury after lung transplantation in animals. We hypothesized that early administration of methylprednisolone after brain death could result in reduced lung inflammatory injury in the donor lung. METHODS: Twenty-four Wistar rats were anesthetized and randomly allocated into four groups (n=6): Sham (sham), Brain Death (BD), methylprednisolone 5min. (mt5) and methylprednisolone 60min. (mt60). BD, met5 and met60 groups were submitted to brain death by extradural space balloon inflation. Methylprednisolone (i.v. 30mg/kg) was administered to met5 and met60 groups, 5 or 60 minutes after brain death confirmation, respectively. The animals of all groups were observed and ventilated for 120 minutes. Hemodynamics, arterial blood gases, wet/dry weight ratio, bronchoalveolar lavage (white cell count, total protein and LDH concentration), histological score, superoxide dismutase (SOD) and catalase determination were analyzed. Lipid peroxidation and TNF-α determination were assessed in lung tissue. RESULTS: No significant differences were observed in hemodynamics, arterial blood gases, wet/dry weight ratio, bronchoalveolar lavage analysis, histological score, SOD and catalase in the different groups. TBARS determination was statistically higher in both methylprednisolone groups when compared to sham (p<0.001) and BD (p<0.001) groups. TNF-α concentration was significantly lower in met5 (p<0.001) and met60 groups (p<0.001) when compared to BD group. CONCLUSIONS: We conclude that early or late administration of methylprednisolone in this model of brain death has similar effect regarding inflammatory and lipid peroxidation activity on lung tissue.

Control of retrotransposon expression in the mammalian germline is regulated by Argonaute family PIWI proteins and their associated small non-coding RNAs known as PIWI-interacting RNAs (piRNAs). To date, no study has demonstrated clear PIWI protein expression nor identified a cellular function(s) for PIWI proteins in the mammalian soma. In contrast to the germline-restricted expression of piRNA associated proteins, we observed that Miwi2 mRNA was induced specifically in epithelial cells during pneumococcal pneumonia. Further investigation showed that similar to its mRNA, MIWI2 protein was indeed expressed outside of the mammalian germline, and was localized to the cytoplasm of a discrete population of multiciliated lung epithelial cells. Immunoprecipitation of MIWI2 from whole lung lysates indicated that it was bound to a small RNA that was longer than a traditional piRNA. Microarray analysis revealed that depletion of MIWI2 in a murine epithelial cell line or in a whole animal model had no effect on retrotransposon expression, further suggesting that lung MIWI2 is independent of nuclear piRNA silencing pathways. Under basal conditions, MIWI2 was required for the normal maintenance of airway epithelial cell fate. In fact, Miwi2 deficiency resulted in an increase in club cells and decrease in ciliated cells indicating that MIWI2 could play a primary role in mucociliary homeostasis or clearance. Similarly, as MIWI2 is induced during lung infection we sought to determine if it participated in host innate immune responses to bacterial infection. Using a clinically relevant model of community acquired pneumonia, Miwi2 deficient mice exhibited an increased expression of inflammatory mediators and immune cell recruitment thus leading to enhanced bacterial clearance. Taken together, these data support the notion that MIWI2 exerts piRNA-independent functions outside of the germline in the ciliated lung epithelium to regulate innate immunity during pneumonia. More broadly, these studies shed light on new areas in PIWI protein and lung ciliated cell biology, and may have implications for multiple diseases including cancer, inflammatory disorders, and infectious diseases.

Staphylococcus aureus causes significant illnesses throughout the world, including toxic shock syndrome (TSS), pneumonia, and infective endocarditis. Major contributors to S. aureus illnesses are secreted virulence factors it produces, including superantigens and cytolysins. Rabbit cardiac physiology is considered similar to humans, and rabbits exhibit susceptibility to S. aureus superantigens and cytolysins. As such, rabbits are an excellent model for studying pneumonia, infective endocarditis, and sepsis, We examined the ability of USA200, USA300 and USA400 strains to cause vegetations and lethal sepsis in rabbits. USA200, TSST-1+ strains that produce only low amounts of Α-toxin, exhibited modest LD50 in sepsis (1x108-5x108) colony-forming units (CFUs), and 3/4 caused significant IE. USA200 strain MNPE, which produces high levels of Α-toxin, was both highly lethal (LD50 5x106 CFUs) and effective in causing IE. In contrast, USA300 strains were highly effective in causing lethal sepsis (LD50s 1 x 106 and 5 x 107 CFUs) but were minimally capable of causing IE. USA400 strains were both highly lethal (LD50s of 1 x 107 and 5 x 107 CFUs) and highly effective causes of IE. Additional studies investigated the role of phenol soluble modulins in infection. We showed that PSMs are important for the ability of S. aureus to cause sepsis but not infective endocarditis. Additionally, immunization against PSMs did not protect rabbits from lethal infection. Our studies show that clonal groups of S. aureus differ in abilities to cause infective endocarditis and lethal sepsis and suggest that secreted virulence factors, including superantigens and cytolysins, account for some of these differences. This thesis also investigates the use of superantigens and cytolysins as staphylococcal vaccine candidates. We generated three TSST-1 mutants; G31S/S32P, H135A, and Q136A. All rabbits administered these TSST-1 toxoids generated strong antibody responses (titers>10,000) that neutralized native TSST-1 in TSS models, both in vitro and in vivo. These TSST-1 mutants lacked detectable residual toxicity. Additionally, the TSST-1 mutants exhibited intrinsic adjuvant activity, increasing antibody responses to a second staphylococcal antigen (Β-toxin). This effect may be due to TSST-1 mutants binding to the immune co-stimulatory molecule CD40. The superantigens TSST-1 and SEC and the cytolysin Α-toxin are known to contribute to staphylococcal pneumonia. Immunization of rabbits against these secreted toxins provided complete protection from highly lethal challenge with a USA200 S. aureus strain producing all three exotoxins; USA200 strains are common causes of staphylococcal infections. The same three exotoxins plus the cytolysins Β-toxin and Γ-toxin contribute to infective endocarditis and sepsis caused by USA200 strains. Immunization against these five exotoxins protected rabbits from infective endocarditis and lethal sepsis. Additionally, a heptavalent vaccine composed of the pentavalent units plus SEB and SE-l X protected rabbits from lethal pneumonia caused by USA100 strain 209. Passive immunization using pooled sera protects previously non-immunized rabbits from lethal pneumonia due to MNPE. These data suggest that immunization against toxoid proteins of S. aureus exotoxins protects from serious illnesses, and concurrently superantigen toxoid mutants provide endogenous adjuvant activity.

Background: Ventilator-associated pneumonia is a major cause of morbidity and mortality for patients in an intensive care unit. Once present, ventilator-associated pneumonia is known to increase the duration of mechanical ventilation, time in the intensive care unit, and length of hospital stay. Patients with acquired brain injury are commonly admitted to the intensive care unit and considered to be at a high risk for the development of respiratory complications such as ventilator-associated pneumonia, which could potentially impact on the intensive care unit costs and outcomes. Respiratory physiotherapy is often provided to prevent and/or treat ventilator-associated pneumonia in patients with acquired brain injury. The theoretical rationale of the respiratory physiotherapy is to improve airway clearance and enhance ventilation which may reduce the incidence of pulmonary infections and thus ventilator-associated pneumonia, and may in turn decrease the duration of mechanical ventilation, prevent the need for tracheostomy and hence result in reduced costs and shorter hospital stay. Although respiratory physiotherapy may be beneficial in reversing or preventing ventilator-associated pneumonia, to date there are no data concerning the effectiveness of respiratory physiotherapy in patients with acquired brain injury. Hence from an evidence-based perspective, at present there is no justification for the role of respiratory physiotherapy in the management of patients with acquired brain injury in the intensive care unit. Aim: This two-part, prospective randomised controlled trial aimed to investigate the effect of regular prophylactic respiratory physiotherapy on the incidence of ventilator-associated pneumonia, duration of mechanical ventilation, and length of intensive care unit stay in adults with acquired brain injury, as compared to a control group (Part A). / The second part of the study (Part B) randomised those subjects from Part A who developed a ventilatorassociated pneumonia into a treatment or control group to establish if the provision of a regimen of regular respiratory physiotherapy influenced the outcome of ventilator-associated pneumonia. Additionally, this study also aimed to provide the first description of the financial costs of respiratory physiotherapy time in providing interventions to patients with acquired brain injury in the intensive care unit and investigated the cost effectiveness of respiratory physiotherapy interventions in decreasing the incidence of ventilator-associated pneumonia, duration of mechanical ventilation and length of intensive care unit stay. Subjects: 144 adult patients with acquired brain injury admitted with a Glasgow Coma Scale of nine or less, requiring intracranial pressure monitoring, and invasive ventilatory support for greater than 24 hours, were randomised to a treatment group or a control group. Methods: For subjects randomised to the treatment groups, the regimen of respiratory physiotherapy treatment was repeated six times per 24-hour period and continued until the subject was weaned from mechanical ventilatory support. Each respiratory physiotherapy intervention of 30 minute duration comprised a regimen of positioning, manual hyperinflation and suctioning. In both Parts A and B, the control group received standard nursing and medical care but no respiratory physiotherapy interventions. Results: Consent was obtained for 144 subjects, with 72 randomised for treatment in Part A. Part A groups were comparable with respect to demographic variables, with the exception of body mass index and gender distribution. / Using intention to treat philosophy, there were no significant differences for incidence of ventilator-associated pneumonia [Treatment Group 14/72 (19.4%) vs. Control 19/72 (26.4%); p = 0.32], duration of mechanical ventilation (hr) [172.8 vs. 206.3); p = 0.18], or length of intensive care unit stay (hr) [224.2 vs. 256.4; p = 0.22]. For subjects with acquired brain injury receiving this prophylactic regimen of respiratory physiotherapy in the intensive care unit, in an attempt to prevent ventilator-associated pneumonia, the cost of physiotherapy was $487 per subject. Comparatively the intensive care unit mechanical ventilation bed day cost was $33,380 per subject. The cost of Part A respiratory physiotherapy time for Treatment Group 1 was 1.7 per cent of the cost of subject's intensive care unit mechanical ventilation bed days. Thirty-three subjects (22.9%) from Part A developed ventilator-associated pneumonia, and were transferred to Part B and re-randomised, 17 to the Treatment Group 3. Part B groups were comparable with respect to demographic variables. No significant differences were detected in the dependent variables for Part B of the study, with similar duration of mechanical ventilation (hr) [342.0 vs. 351.0); p = 0. 89], and length of ICU stay (hr) [384.7 vs. 397.9; p = 0.84] noted. In those subjects with acquired brain injury in whom ventilator-associated pneumonia developed, the regimen of respiratory physiotherapy for the remaining duration of mechanical ventilation following diagnosis of ventilator-associated pneumonia costed an average of $788. Comparatively the intensive care unit bed day cost for the period of mechanical ventilation was $43,865. The cost of Part B respiratory physiotherapy time for Treatment Group 3 was 1.8 per cent of the cost of their intensive care unit mechanical ventilation bed days. / Subjects with a ventilator-associated pneumonia were significantly younger, were admitted with a lower Glasgow coma scale, and more likely to have been admitted with a chest injury than subjects without a ventilator-associated pneumonia. Duration of mechanical ventilation and length of intensive care unit stay were significantly increased in subjects with ventilatorassociated pneumonia, but length of hospital stay was not significantly different. Significant differences in the costs of respiratory physiotherapy and intensive care unit mechanical ventilation bed day costs were evident between those subjects with ventilator-associated pneumonia as compared to those without ventilator-associated pneumonia. For subjects with ventilator-associated pneumonia, the respiratory physiotherapy time cost was $1,029 per subject, compared to $510 for subjects without ventilator-associated pneumonia. The intensive care unit mechanical ventilation bed day cost for subjects with ventilator-associated pneumonia was $61,092 per subject, and $25,142 for those without a ventilator-associated pneumonia, giving an incremental health cost of $35,950 per episode of ventilatorassociated pneumonia. No significant differences were evident in the cost of respiratory physiotherapy as a per cent of the cost of their intensive care unit mechanical ventilation bed days, with findings of 1.4 per cent in those with ventilator-associated pneumonia and 1.1 per cent in those without ventilator-associated pneumonia. / Conclusion: Use of a regular prophylactic respiratory physiotherapy regimen comprising of positioning, manual hyperinflation and suctioning, in addition to routine medical and nursing care, did not appear to prevent ventilator-associated pneumonia, reduce length of ventilation or intensive care unit stay in adults with acquired brain injury. Furthermore, in those acquired brain injury subjects with ventilator-associated pneumonia, regular respiratory physiotherapy did not appear to expedite recovery in terms of reducing length of ventilation or intensive care unit stay. It can be concluded from the findings of this study that the presence of ventilator-associated pneumonia has a significant influence on morbidity and costs in subjects with acquired brain injury. Whilst statistically significant results were not found with clinical variables, it is suggested that the provision of a prophylactic respiratory physiotherapy regimen costing $487 per subject is a worthwhile investment in attempts to avoid the incremental health cost of $35,950 per episode of ventilator-associated pneumonia. In subjects with ventilator-associated pneumonia it is concluded that the cost of respiratory physiotherapy would not appear to be justified in attempts to reduce the duration of mechanical ventilation.

Rhodococcus equi is a common cause of severe pneumonia in foals, and is an opportunistic pathogen in immunocompromised humans. In combination, erythromycin and rifampin are the most commonly used antimicrobials in treating R. equi in foals. To provide reliable treatment, it is imperative to determine the mean inhibitory concentrations (MICs) of other antimicrobial agents in the event that certain strains of R. equi develop resistance to the current treatment. Several strains of R. equi have developed resistance to various antibiotics. In this study, R. equi strain 288 was completely resistant to rifampin with a MIC > 256ug/ml. The MICs of ethambutol, clarithromycin, azithromycin, isoniazide, ethionamide, rifampin, erythromycin, and linezolid of ninety-five R. equi isolates were also determined in this study. These isolates were obtained from the lungs and transtracheal washes of foals. In addition to these strains, three National Committee for Laboratory Clinical Standards (NCCLS) quality control strains were also tested: R. equi ATCC 6939, R. equi ATCC 33701, and S. pneumoniae 49619. Each drug was tested in triplicate and the MIC 50’s and MIC 90’s were determined for each drug. Ethambutol, isoniazide, and ethionamide were completely ineffective against R. equi. with MICs > 250ug/ml. Rhodococcus equi strains were more susceptible to clarithromycin (MIC 90 = 0.23 ug/ml) than to azithromycin (MIC 90 = 2.33 ug/ml), rifampicin (MIC 90 = 0.67ug/ml), erythromycin (MIC 90 = 1.2ug/ml), and linezolid (MIC 90 = 4ug/ml).

Blood was obtained from 5 adult horses and 16 juvenile horses (foals) at the time of birth and subsequently at 2-, 4-, and 8-weeks of age. Neutrophils from adult horses were purified and incubated for 2 h and 4 h with media, avirulent R. equi, virulent R. equi, or recombinant-human granulocyte-macrophage colony stimulating factor (rhGM-CSF). Neutrophils from foals were purified and incubated for 2 h and 4 h with media or virulent R. equi. Total RNA was extracted from both adult and foal neutrophils immediately after purification to measure baseline expression levels (0 h), and immediately after each of the prescribed incubation times. For each sample, 1 µg of total RNA was reverse-transcribed and analyzed for differential gene expression using real-time PCR. After 2 h and 4 h incubation with virulent or avirulent R. equi, neutrophils from adult horses expressed significantly (P< 0.05) greater TNFα, IL-12p40, IL-6, IL-8, and IL-23p19 mRNA relative to expression by unstimulated neutrophils, but not IFNγ or IL-12p35 mRNA. Furthermore, virulent R. equi induced significantly greater IL-23p19 mRNA expression than avirulent R. equi. Stimulation with rhGM-CSF of adult equine neutrophils failed to induce significant changes in cytokine expression. In foal neutrophils, stimulation with virulent R. equi induced significantly greater expression of IFNγ, TNFα, IL-6, IL-8, IL-12p40, and IL-12p35 mRNA relative to expression by unstimulated neutrophils. Furthermore, there were significant effects of age on expression of IL-6, IL-8 and IL-12p40 mRNA. Neutrophil mRNA expression of IL-6 and IL-8 in newborn foals was significantly greater than expression at 2-, 4-, and 8-weeks of age. There was no significant difference between unstimulated and R. equi-stimulated neutrophils from newborn and 2-week-old foals in expression of IL-12p40; however, expression of IL-12p40 by R. equi-stimulated neutrophils from 4- and 8-week-old foals was significantly greater than expression by unstimulated neutrophils. These results demonstrate that R. equi-stimulated neutrophils are a source of many pro-inflammatory cytokines, and that the magnitude of this expression with respect to IL-6, IL-8, and IL-12p40 mRNA expression was influenced by age. Collectively, the data presented indicate a non-phagocytic role for neutrophils that may influence the type of adaptive immune response to R. equi.

<i>Mycoplasma bovis</i> is generally considered the causative pathogen associated with Chronic Pneumonia and Polyarthritis Syndrome (CPPS) in feedlot cattle. However, <i>M. bovis</i> virulence may vary between strains as it is also isolated from asympytomatic cattle. The following study aims to determine the prevalence of <i>M. bovis</i> in the respiratory tract of western Canadian cattle using two sampling methods and at two time points following feedlot entry. Three study groups were sampled. In the first group nasal swabs (NS) and bronchoalveolar lavages (BAL) were taken from 36 clincally healthy cattle at the University of Saskatchewan feedlot at both 14 and 90 days on feed (DOF). In a second experiment, NS were taken from 56 animals upon arrival at a commercial feedlot and one week to three months later upon treatment for respiratory disease. Lung and joint tissue swabs were collected at necropsy from a third group of 19 animals with CPPS clinical pathology originating in 10 different western Canadian feedlots. All samples were selectively cultured for <i>Mycoplasma</i> spp. DNA was extracted from isolated putative <i>Mycoplasma</i> colonies and amplified with universal 16S rRNA gene primers for identification. Amplified Fragment Length Polymorphism (AFLP) was used to genetically differentiate <i>M. bovis</i> positive isolates. More <i>M. bovis</i> was isolated from NS than BAL and <i>M. bovis</i> prevalence increased with DOF in the feedlot in both the University of Saskatchewan and commercial feedlot trials. Three genetically distinct clusters (A, B, and C) were isolated from the necropsy group. Two of these clusters were primarily associated with isolates collected from feedlot cattle and one strain was exclusively found in CPPS-associated mortalities. No significance difference in the prevalence of <i>M. bovis</i> strains was observed between different days on feed or sampling methods. It was concluded that either the difference in disease state is a host dependent outcome, due to a multi-factorial disease complex, or the AFLP assay was not sensitive enough to differentiate strains based on virulence.