A study of the airplane crash hazard at the PRDC site /

"Study prepared for Prof. W. McGuire, Cornell University."

Extraction of Ascorbate Oxidase from Cucurbita maxima by Continuous Process in Perforated Rotating Disc Contactor Using Aqueous Two-Phase Systems

The ascorbate oxidase is the enzyme used to determine the content of ascorbic acid in the pharmaceutical and food industries and clinics analyses. The techniques currently used for the purification of this enzyme raise its production cost. Thus, the development of alternative processes and with the potential to reduce costs is interesting. The application of aqueous two-phase system is proposed as an alternative to purification because it enables good separation of biomolecules. The objective of this study was to determine the conditions to continuously pre-purify the enzyme ascorbate oxidase by an aqueous two-phase system (PEG/citrate) using rotating column provided with perforated discs. Under the best conditions (20,000 g/mol PEG molar mass, 10% PEG concentration, and 25% citrate concentration), the system showed satisfactory results (partition coefficient, 3.35; separation efficiency, 54.98%; and purification factor, 1.46) and proved suitable for the pre-purification of ascorbate oxidase in continuous process.

Continuous extraction of alpha-toxin from a fermented broth of Clostridium perfringens Type A in perforated rotating disc contactor using aqueous two-phase PEG-phosphate system

A 2(3-1) factorial experimental design was used to evaluate the performance of a perforated rotating disc contactor to extract alpha-toxin from the fermented broth of Clostridium perfringens Type A by aqueous two-phase system of polyethylene glycol-phosphate salts. The influence of three independent variables, specifically the dispersed phase flowrate, the continuous phase flowrate and the disc rotational speed, was investigated on the hold up, the mass transfer coefficient, the separation efficiency and the purification factor, taken as the response variables. The optimum dispersed phase flowrate was 3.0 mL/min for all these responses. Besides, maximum values of hold up (0.80), separation efficiency (0. 10) and purification factor (2.4) were obtained at this flowrate using the lowest disc rotational speed (35 rpm), while the optimum mass transfer coefficient (0. 165 h(-1)) was achieved at the highest agitation level (140 rpm). The results of this study demonstrated that the dispersed phase flowrate strongly influenced the performance of PRDC, in that both the mass transfer coefficient and hold up increased with this parameter. (c) 2007 Elsevier B. V. All rights reserved.

Diagnosis and clinic-pathological findings of influenza virus infection in Brazilian pigs

Influenza A virus (IAV) is a respiratory pathogen of pigs and is associated with the porcine respiratory disease complex (PRDC), along with other respiratory infectious agents. The aim of this study was to diagnose and to perform a clinic-pathological characterization of influenza virus infection in Brazilian pigs. Lung samples from 86 pigs in 37 farrow-to-finish and two farrow-to-feeder operations located in the States of Minas Gerais, São Paulo, Paraná, Rio Grande do Sul, Santa Catarina, and Mato Grosso were studied. Virus detection was performed by virus isolation and quantitative real time reverse-transcription PCR (qRT-PCR). Pathologic examination and immunohistochemistry (IHC) were performed in 60 lung formalin-fixed paraffin-embedded tissue fragments. Affected animals showed coughing, sneezing, nasal discharge, hyperthermia, inactivity, apathy, anorexia, weight loss and growth delay, which lasted for five to 10 days. Influenza virus was isolated from 31 (36.0%) lung samples and 36 (41.9%) were positive for qRT-PCR. Thirty-eight (63.3%) lung samples were positive by IHC and the most frequent microscopic lesion observed was inflammatory infiltrate in the alveoli, bronchiole, or bronchi wall or lumen (76.7%). These results indicate that influenza virus is circulating and causing disease in pigs in several Brazilian states.

Actinobacillus pleuropneumoniae Possesses an Antiviral Activity against Porcine Reproductive and Respiratory Syndrome Virus

Pigs are often colonized by more than one bacterial and/or viral species during respiratory tract infections. This phenomenon is known as the porcine respiratory disease complex (PRDC). Actinobacillus pleuropneumoniae (App) and porcine reproductive and respiratory syndrome virus (PRRSV) are pathogens that are frequently involved in PRDC. The main objective of this project was to study the in vitro interactions between these two pathogens and the host cells in the context of mixed infections. To fulfill this objective, PRRSV permissive cell lines such as MARC-145, SJPL, and porcine alveolar macrophages (PAM) were used. A pre-infection with PRRSV was performed at 0.5 multiplicity of infection (MOI) followed by an infection with App at 10 MOI. Bacterial adherence and cell death were compared. Results showed that PRRSV preinfection did not affect bacterial adherence to the cells. PRRSV and App co-infection produced an additive cytotoxicity effect. Interestingly, a pre-infection of SJPL and PAM cells with App blocked completely PRRSV infection. Incubation of SJPL and PAM cells with an App cell-free culture supernatant is also sufficient to significantly block PRRSV infection. This antiviral activity is not due to LPS but rather by small molecular weight, heat-resistant App metabolites (,1 kDa). The antiviral activity was also observed in SJPL cells infected with swine influenza virus but to a much lower extent compared to PRRSV. More importantly, the PRRSV antiviral activity of App was also seen with PAM, the cells targeted by the virus in vivo during infection in pigs. The antiviral activity might be due, at least in part, to the production of interferon c. The use of in vitro experimental models to study viral and bacterial co-infections will lead to a better understanding of the interactions between pathogens and their host cells, and could allow the development of novel prophylactic and therapeutic tools.

Diagnostica anatomopatologica nelle malattie infettive del suino: co-localizzazione agenti patogeni e lesioni, limiti ed utilità

Il processo di intensificazione dell’allevamento suinicolo ha comportato conseguenze importanti dal punto di vista sanitario. Nei moderni sistemi di produzione la salute è compromessa a causa di malattie multifattoriali e l'identificazione degli agenti casuali di malattia non può basarsi esclusivamente sul risultato di un unico test diagnostico. La maggior parte dei patogeni è ubiquitaria, quindi l'identificazione di un agente infettivo suggerisce solo una possibile diagnosi. La patologia gioca un ruolo chiave nel determinare la causalità nella diagnosi delle malattie infettive. L'istopatologia consente di correlare la presenza dell'agente infettivo con le lesioni microscopiche caratteristiche: in base alla disponibilità di anticorpi o sonde per rilevare rispettivamente la presenza di antigeni o del genoma di virus o batteri nelle sezioni istologiche, l'istopatologia è utile per determinare il nesso causale con la malattia. L'introduzione di questa tesi è incentrata sulla discussione del ruolo della patologia nelle malattie infettive del suino, seguita dalla descrizione del corretto campionamento per l'esame istopatologico nella diagnosi delle malattie respiratorie, enteriche e riproduttive. La sezione sperimentale riporta i risultati delle indagini diagnostiche in patologia suina condotte per definire il ruolo di PCV2 e PRRSV nel complesso delle malattie respiratorie del suino (PRDC)(capitolo 2) e per definire un percorso diagnostico per l'enteropatia proliferativa suina causata da Lawsonia intracellularis ai fini dell'implementazione dell'accuratezza diagnostica (capitolo 3). Il capitolo 4 descrive l'uso dell'istopatologia come componente metodologica essenziale per valutare l'efficacia protettiva dei vaccini negli studi di challenge vaccinazione-infezione. Il capitolo descrive i risultati ottenuti in due successive sperimentazioni per valutare l'efficacia di due vaccini sperimentali per PCV2, il primo formulato con ceppo PCV2b inattivato somministrato a differenti dosi di antigene; il secondo formulato con antigene "Cap" ricombinante non assemblato in particelle simil-virali (VLP).