Submitted by (edna.saturno@ufrpe.br) on 2017-03-28T13:22:55Z No. of bitstreams: 1 Chiara Rodrigues de Amorim Lopes.pdf: 1063652 bytes, checksum: 6655c28f0a035e0d1cca00a02296e5fc (MD5) / Made available in DSpace on 2017-03-28T13:22:55Z (GMT). No. of bitstreams: 1 Chiara Rodrigues de Amorim Lopes.pdf: 1063652 bytes, checksum: 6655c28f0a035e0d1cca00a02296e5fc (MD5) Previous issue date: 2010-02-24 / This study was to evaluate, through 3 trials, the efficiency of the lactoperoxidase system (LPS) activation on the preservation of refrigerated and non-refrigerated cow milk in Havana, Cuba. In the first and second trial was used raw milk stored at environmental temperature for 0, 4, 8 and 12 hours of storage and the SLP has been activated in the laboratory and camp, respectively. In the third trial was used raw milk refrigerated for 0, 24, 48, 72 and 120 hours of storage. SLP has been activated by the product STABILAK®, a commercial activator containing sodium thiocyanate and Sodium percarbonate. There was observed effect of treatment (activated and not activated) of storage time (P < 0.01) and of interaction treatment x time (P < 0.05) on the acidity in the three trials, effect of storage time on the lactose (P < 0.05) and total solids (P < 0.01) in trial II and effect of treatment on fat, protein, total solids (P < 0.01) and lactose (P < 0.05 ) in trial III. For the coliforms count, was observed effect of treatment (P < 0.01, trial I; P < 0.01, trial III), of storage time (P < 0.05, trials I and II; P <0.01, trial III) and treatment x time interaction (P < 0.05, trial III). For the psychrotrophic count was observed effect of treatment (P < 0.05) and storage time (P < 0.01). SLP inhibited the growth of coliforms population in raw milk non-refrigerated and kept the normal level of acidity up to 8 hours depending on the initial quality of milk. In refrigerated raw milk the inhibitory effect of SLP on the coliforms count was extended to 120 hours and the acidity was kept the normal level up to 48 hours after activation. There was no effect of SLP on the psychrotrophic population over the storage times. The SLP did not alter the initial concentrations of fat, protein, lactose and solids in all trials, and managed to prevent the degradation such components for periods of up to 120 hours in refrigerated raw milk. / Foram realizados três ensaios com o objetivo de avaliar a eficiência do sistema lactoperoxidase (SLP) na conservação do leite cru refrigerado e não-refrigerado no estado de Havana, Cuba. No primeiro e no segundo ensaio utilizou-se leite cru armazenado sob temperatura ambiente durante 0, 4, 8 e 12 horas de conservação e o SLP foi ativado em condições de laboratório e de campo, respectivamente. No terceiro ensaio foi utilizado leite cru, refrigerado durante 0, 24, 48, 72 e 120 horas de conservação. Para ativação do SLP utilizou-se um ativador do SLP composto por tiocianato e percarbonato de sódio conhecido como STABILAK®. Houve efeito de tratamento (ativado e não-ativado), de tempo de conservação (P < 0,01) e da interação tratamento x tempo (P < 0,05) sobre a acidez titulável nos três ensaios; efeito de tempo sobre o nível de lactose (P < 0,05) e os sólidos totais (P < 0,01) no ensaio II e, efeito de tratamento sobre os níveis de gordura, a proteína, os sólidos totais (P < 0,01) e a lactose (P < 0,05) no ensaio III. Para a contagem de coliformes totais, houve efeito de tratamento (P < 0,01, ensaio I; P < 0,01, ensaio III), de tempo de conservação (P < 0,05, ensaios I e II; P < 0,01, ensaio III) e da interação tratamento x tempo (P < 0,05, ensaio III). Para a contagem de psicrotróficos observou-se efeito de tratamento (P < 0,05) e de tempo de conservação (P < 0,01). O SLP inibiu o crescimento da população de coliformes em leite cru não-refrigerado e manteve o nível de acidez dentro dos limites aceitáveis até 8 horas, dependendo da qualidade inicial do leite. Em leite cru refrigerado o efeito inibitório do SLP sobre a contagem de coliformes totais foi prolongado até 120 horas e a acidez foi mantida dentro dos limites aceitáveis até 48 horas pós-ativação. Não foi observado efeito do SLP sobre a população de psicrotróficos ao longo dos tempos de conservação. O SLP não alterou as concentrações iniciais de gordura, proteína, lactose e sólidos totais, em todos os ensaios realizados, e conseguiu evitar que ocorresse degradação de tais componentes por períodos de até 120 horas, em leite cru refrigerado.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-05-17T16:22:26Z No. of bitstreams: 1 Wandemberg Rocha Freitas.pdf: 661335 bytes, checksum: 5a39f2c88f6a6072e7f239dd74126e79 (MD5) / Made available in DSpace on 2017-05-17T16:22:26Z (GMT). No. of bitstreams: 1 Wandemberg Rocha Freitas.pdf: 661335 bytes, checksum: 5a39f2c88f6a6072e7f239dd74126e79 (MD5) Previous issue date: 2013-02-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Among the several essential requirements for the milk quality, can be highlighted the high counts of total bacteria and somatic cells as the factors that may negatively influence the product quality by decreasing industrial yield and can cause damage to the health of consumers. There are many different types of enzymes in the milk and therefore, many researches are carried out with the aim of determining the biological or physiological role of these compounds. The lactoperoxidase is an enzyme which occurs naturally in the milk and in combination with the thiocyanate ion and the hydrogen peroxide form the lactoperoxidase system, which in turn generates hipotiocianato ions, which is a compound that have antibacterial action. The main biological role of the lactoperoxidase is associated to the protection of the milk itself, of the mammary gland and of the intestinal tract of calves against pathogenic microorganisms that may be present in the milk. The lactoperoxidase activity may be influenced by genetic and environmental factors, which can confer to distinct animals, difference in the activity and, consequently, more or less immunological resistance to the bacteria action, and also, potential to produce milk with higher antimicrobial activity. The aim of this study was to verify the lactoperoxidase activity and the thiocyanate content in the milk from Girolando cows of different genetic groups, besides studying the factors that may influence in these variables. / Dentre os vários requisitos essenciais para a qualidade do leite, pode-se destacar as altas contagens de bactérias totais e de células somáticas como fatores que podem influenciar negativamente na qualidade do produto, por diminuírem o rendimento industrial e poder causar danos a saúde dos consumidores. Existem no leite muitos tipos diferentes de enzimas e com isso, muitas pesquisas são realizadas com o intuito de determinar o papel biológico ou fisiológico desses compostos. A lactoperoxidase é uma enzima que ocorre naturalmente no leite e em combinação com o íon tiocianato e o peróxido de hidrogênio formam o sistema lactoperoxidase, que por sua vez, gera íons hipotiocianato, que é um composto que apresenta ação antibacteriana. O principal papel biológico da lactoperoxidase está associado à proteção do próprio leite, da glândula mamária e do trato intestinal dos lactentes contra microorganismos patogênicos que possam estar presentes no leite. A atividade da lactoperoxidase pode ser influenciada por fatores genéticos e ambientais, o que pode conferir a animais distintos, diferença na atividade e, consequentemente, maior ou menor resistência imunológica a ação de bactérias, e ainda, potencial para produzir leite com maior atividade antimicrobiana. Objetivou-se com este trabalho, verificar a atividade da lactoperoxidase e o teor de tiocianato no leite de vacas Girolando de diferentes grupos genéticos, além de estudar os fatores que podem influenciar nestas variáveis.

This study investigated the effect of the Lactoperoxidase system (LPS) alone and in combination with pasteurisation, on the growth of Listeria monocytogenes (LM) ATTC 7644 in goat milk and goat milk cottage cheese during a shelf life of 10 days at 4 °C. Goat milk was inoculated with LM ATTC 7644 and divided into two samples, one the control and Lactoperoxidase (LP) was activated in the other sample. Both the control and LP activated samples were kept at ambient temperature for 6h. After 6h the control and LP activated samples were again divided into two and one of the respective samples was pasteurised at 72 °C for 15 s. All the four samples were analysed for LM ATTC 7644 immediately after LP activation at 0h, after 6h of LP activation and after pasteurisation. Goat milk cottage cheese was made with all four samples, i.e. control raw, control pasteurised, LP activated raw and LP activated pasteurised goat milk and analysed for LM ATTC 7644 on days 1, 2, 5, and 10. Six hours after LP activation the mean LM ATTC 7644 count for the LP activated milk decreased by log 0.5 cfu/ml where as the LM ATTC 7644 for the control increased by log 0.5 cfu/ml. The reduction of LM ATTC 7644 count in LP activated milk when compared to the control shows that goat milk lactoperoxidase is capable of reducing L. monocytogenes when stored at ambient temperatures. Furthermore, LM ATTC 7644 count in LP activated pasteurised goat milk decreased by log 1.1 cfu/ml more, compared to the control pasteurised goat milk. Therefore, pasteurisation together with LP activation may be more effective than pasteurisation alone in controlling the growth of L. monocytogenes in goat milk. For the control raw goat milk cottage cheese on day 10, the LM ATTC 7644 count was 90 % less than on first day of storage. The LP activated raw goat milk cottage cheese count followed a similar trend to the control raw goat milk cottage cheese, and reached levels of log 2.9 cfu/g on the last day of storage. The control pasteurised goat milk cottage cheese LM ATTC 7644 count on day 10 was 92 % lower compared to day 1 where as the LP activated pasteurised goat milk cottage cheese LM ATTC 7644 count was 98 % less than on day 1. The results of this study indicate that the activation of the LPS significantly (p≤0.05) decreased the LM ATTC 7644 count in goat milk, during a period of 6h. Combined pasteurisation and LP activation had a synergistic effect on the LM ATTC 7644 count in goat milk. The LM ATTC 7644 count declined in cottage cheese made from both control and LP activated goat milk. A greater decrease was observed in LP activated pasteurised goat milk cottage cheese over the storage period of 10 days at 4 °C. This combination may be used to reduce the multiplication of LM ATTC 7644 for production of safer products like goat milk and goat milk cottage cheese. / Dissertation (M Inst Agrar (Food Production and Processing))--University of Pretoria, 2007. / Food Science / M Inst Agrar / unrestricted

Modern, large scale Cheddar cheese manufacture is dependent on reliable acid production by Lactococcus lactis subspecies cremoris and subspecies lactis starter cultures. Any inhibition of acid production may affect cheese quality, disrupt production schedules and reduce profitability. The presence of antibiotic residues in manufacturing milk resulting from the treatment of mastitis in lactating cattle is a potential source of starter culture inhibition. Therefore, a range of antibiotic concentrations was assessed for measurable inhibitory effects on acid production and compared to the minimum detectable concentrations by approved screening test procedures. Antibiotics were selected from formulations approved for use on lactating cattle for the treatment of mastitis. Novobiocin, lincomycin, oleandomycin and oxytetracyline HCl, all non-b-lactam antibiotics, inhibited acid production of one or more L. lactis strains at antibiotic concentrations below the detectable limit of standard screening procedures. / Depending on the antibiotic, either or both the Bacillus stearothermophilus (var. calidolactis) disk assay and/or the Delvo SP assay were ineffective at detecting the antibiotics at concentrations required to inhibit the starter strains. Consequently, antibiotic residues below the detectable limits of these testing procedures could cause significant starter culture inhibition, disrupting cheese making schedules. Another potential source of starter culture inhibition is related to raw milk quality and the practice of refrigerated storage prior to processing. Previous studies differed as to whether the growth of psychrotrophic organisms would have a detrimental impact on subsequent acid production by starter bacteria employed in cheese manufacture. In this study, no inhibition of acid production by a commercial L. lactis subsp. cremoris strain was evident when grown in milk that had undergone short term temperature abuse. Antimicrobial systems native to bovine milk may also have an adverse impact on starter culture performance. The present study assessed the inhibitory effect of an activated lactoperoxidase system (LPS) on a range of L. lactis cultures. All of the strains were significantly inhibited when grown on reconstituted skim milk in the presence of an active LPS. Inhibition of acid production by strains grown on glucose was also observed, leading to further investigations to describe the inhibitory process. A non-phosphoenolpyruvate phosphotransferase (PEP/PTS) dependent glucose transport system, first observed in 1980 in one L. lactis subsp. lactis strain, was hypothesised as a link in strain variations in LPS sensitivity. However, the LPS sensitive L. lactis subsp. cremoris strains tested did not take up glucose in a PEP depleted state, most likely due to their inability to utilise arginine as an ATP generating energy source. The questions remain unanswered whether cremoris strains possess this glucose transport mechanism and whether it could contribute to strain variations in LPS sensitivity. / In a subsequent investigation, galactose phosphotransferase system (PTS) deficient L. lactis strain ATCC 7962 demonstrated log phase growth inhibition when grown on galactose in the presence of the model LPS. Previously reported LPS mediated effects on the glycolytic enzyme hexokinase do not appear to explain this result. The present study confirmed strain variability in sensitivity to the model LPS among both Lactococcus lactis subspecies lactis and subspecies cremoris strains. Further, the observation that dithiothreitol significantly alleviated the inhibition of a highly sensitive cremoris strain, implicated the involvement of sulphydryl groups as the target of the transient inhibitory factors. Data collected excluded the possibility that portions of the metabolic pathways involved in fructose and galactose metabolism are sensitive to the LPS in cells possessing PEP/PTS capability. This study also identified potential directions of further work to elucidate the mechanism(s) of LPS inhibition.

Submitted by (edna.saturno@ufrpe.br) on 2017-04-26T15:01:05Z No. of bitstreams: 1 Leandro Fragoso Lins.pdf: 1237098 bytes, checksum: 1134fcd6d843b8a62731bd3505353e3c (MD5) / Made available in DSpace on 2017-04-26T15:01:05Z (GMT). No. of bitstreams: 1 Leandro Fragoso Lins.pdf: 1237098 bytes, checksum: 1134fcd6d843b8a62731bd3505353e3c (MD5) Previous issue date: 2013-10-30 / Based on the poor quality of the milk produced in Brazil and in the necessary improvements in the sanitary conditions to meet the Brazilian legislation and market products of adequate quality, this study aimed to evaluate the adequacy of raw milk preserved by the lactoperoxidase system under different conditions of preservation and storage for manufacturing "Queijo de Coalho", a fresh cheese from northeastern of Brazil. Were performed three distinct collections of raw milk from a dairy farm in the Brazilian state of Pernambuco and submitted to different conditions of preservation and storage - activation of lactoperoxidase system, refrigeration and pasteurization, totaling eight treatments that were processed to manufacture cheese. Were analyzed the effects of the activation of the lactoperoxidase system and of the conditions of preservation and storage on microbial activity in milk and then evaluated its effects on the yield of cheese manufacturing, physico-chemical composition and in the microbiological counts of Coliforms at 45 ºC, Escherichia coli , Staphylococcus coagulase positive, Salmonella spp. and Listeria monocytogenes. The treatments had significant effects determined by analysis of variance and means were compared by Tukey test at 5% significance. The lactoperoxidase system has determined a significant effect (P < 0.05) for Staphylococcus coagulase positive in milk with mean 38.36% lower. There was no effect of the system lactoperoxidase on the yield of cheese manufacturing, but its interaction with the refrigeration affected the technical yield and decreased the mean of the dry matter content. The system also caused an effect (P < 0.05) in the microbial load of the cheese that showed mean of 14.13 to 30.02% lower when produced from milk preserved by the lactoperoxidase system. / Baseando-se na qualidade insatisfatória do leite produzido no Brasil e nas melhorias necessárias na qualidade higiênico-sanitária para atender à legislação vigente no país e colocar no mercado produtos de qualidade adequada, objetivou-se avaliar a adequação do leite cru preservado pelo sistema lactoperoxidase sob diferentes condições de conservação e armazenamento para fabricação de Queijo de Coalho. Foram realizadas três coletas distintas de leite cru, proveniente de uma propriedade leiteira da Zona da Mata de Pernambuco, e submetido a diferentes condições de conservação e armazenamento – ativação do sistema lactoperoxidase, refrigeração e pasteurização, totalizando oito tratamentos que foram processados para a fabricação de Queijo de Coalho. Foram analisados os efeitos da ativação do sistema lactoperoxidase e das condições de conservação e armazenamento sobre a atividade microbiana no leite e em seguida avaliados seus efeitos no rendimento da fabricação do queijo, nas propriedades físico-químicas e contagens microbiológicas de Coliformes a 45ºC, Escherichia coli, Staphylococcus coagulase positiva, Salmonella spp. e Listeria monocytogenes. Os tratamentos tiveram seus efeitos significativos determinados por análise de variância e as médias foram comparadas pelo Teste de Tukey a 5% de significância. O sistema lactoperoxidase determinou efeito significativo (P < 0,05) apenas para Staphylococcus coagulase positiva no leite, com uma média 38,36% menor. Não foi observado efeito do sistema no rendimento da fabricação do queijo, porém sua interação com a refrigeração afetou o rendimento técnico e diminuiu a média do extrato seco. O sistema também provocou efeito (P < 0,05) na carga microbiana do queijo que apresentou médias de 14,13 a 30,02% menor quando fabricado a partir do leite preservado pelo sistema lactoperoxidase.

Background: The heme enzyme lactoperoxidase is found in body secretions where it significantly contributes to the humoral immune response against pathogens. After activation the peroxidase oxidizes thiocyanate to hypothiocyanite which is known for its microbicidal properties. Yet several pathologies are accompanied by a disturbed hypothiocyanite production which results in a reduced immune defense. Methods: The results were obtained by measuring enzyme-kinetic parameters using UV–vis spectroscopy and a standardized enzyme-kinetic test system as well as by the determination of second order rate constants using stopped-flow spectroscopy. Results: In this study we systematically tested thirty aromatic substrates for their efficiency to promote the lactoperoxidase-mediated hypothiocyanite production by restoring the native ferric enzyme state. Thereby hydrophobic compounds with a 3,4-dihydroxyphenyl partial structure such ashydroxytyrosol and selected flavonoids emerged as highly efficient promotors of the (pseudo-)halogenating lactoperoxidase activity. Conclusions: This study discusses important structure-function relationships of efficient aromatic LPO substrates and may contribute to the development of new agents to promote lactoperoxidase activity in secretory fluids of patients. Significance: This study may contribute to a better understanding of the (patho-)physiological importance of the (pseudo-)halogenating lactoperoxidase activity. The presented results may in future lead to the development of new therapeutic strategies which, by reactivating lactoperoxidase-derived hypothiocyanite production, promote the immunological activity of this enzyme.

A method for purification and radiolabelling phosphoglucose isomerase was devised in order to develop a sensitive quantitative radioimmunoassay for the detection of the enzyme irrespective of its catalytic activity. For four genetic variants of PGI no difference in the molecular specific activity was observed. In one variant (PGI-Denton), liver and heart tissue extracts, and in mature erythrocytes (as compared to normal erythrocytes), a decreased molecular specific activity was observed which initially may imply that these samples contain cross-reactive material which is not catalytically active.

L'exportation des mangues est limitée par le mûrissement rapide et la prolifération microbienne sur les fruits. Cette thèse propose une nouvelle approche sûre et saine utilisant des molécules d'origine naturelle pour améliorer la conservation post-récolte des mangues et ainsi participer à la préservation de la santé des consommateurs et à une amélioration des potentialités du commerce international de certains pays exportateurs. Ces travaux ont montré que l'immobilisation du système lactoperoxydase dans le film de chitosane appliqué sur l'épiderme des mangues pouvait maintenir la qualité microbiologique et physicochimique des fruits traités. Le couplage Chitosane-Système lactoperoxydase a prolongé la durée de conservation des mangues durant plus de deux semaines sans altérer leurs qualités organoleptiques.Ce travail a permis également de mettre en évidence la synergie entre le système lactoperoxydase et la concentration de chitosane. Un enrobage optimum de 1% de chitosane a permis de fixer le système enzymatique et de maintenir les mangues en bon état sanitaire. La présence d'iode dans le système lactoperoxydase n'agit pas de manière significative sur la conservation des mangues. / The mango export is limited by the rapid ripening and microbial growth on the fruit. This thesis proposes a new approach to safe and healthy using natural molecules to improve post-harvest conservation of mango and thus help preserve the health of consumers and improved the potential of international trade in certain exporting countries. This work shown that the immobilization of the lactoperoxidase in the chitosan film and applied as coating of mangoes could maintain the microbiological and physicochemical quality of fruits. Chitosan-coupling lactoperoxidase system extended the shelf life of mangoes for over two weeks without affecting their organoleptic quality.This work also helped to highlight the synergy between the lactoperoxidase and the concentration of chitosan. An optimum coating made from 1% chitosan allowed to fix the enzyme system and to maintain the mangoes in a good sanitary condition. The presence of iodine in the lactoperoxidase does not act significantly on the conservation of mangoes.

Methods for on-farm extraction of low-concentration (minor) proteins from raw whole bovine milk directly after milking were explored. These minor proteins have high commercial value. Lactoferrin (LF) and lactoperoxidase (LP) were used as model proteins for extraction using cation exchange chromatography. Laboratory fractionations showed that milk could be processed by conventional column chromatography without excessive column backpressures if resin with large particles sizes were used and the temperature was high enough so fat in the milk was malleable; ideally the milk should be near the secretion temperature of 37oC. Processing parameters such as equilibrium and dynamic capacities were determined for SP Sepharose ™ (GE Healthcare Technologies) and Bio Rex 70 (BioRad Laboratories) resins. SP Sepharose Big Beads (SP BB) were found to be more suitable than BR 70, for raw whole milk processing due to the larger size (200 um). Design considerations showed that column chromatography was not the most practical method for on-farm processing of fresh, raw whole milk. Trials with a single-stage stirred tank showed that SP BB resin could extract up to 65% of LF (initial LF concentration of 0.5 mg/mL) with a 10-minute adsorption time. The composite non-linear (CNL) model of Rowe et al. (1999) was used to describe LF uptake by SP BB resin in raw whole milk with initial LF concentrations of 0 to 1.0 mg/mL and resin:milk volume ratios of 0.010, 0.012, 0.017 and 0.024 over 45-minute contact times. The CNL model could be used to predict LF yields if initial feed concentration, milk and resin volumes, and contact times were known. Laboratory extractions showed that processing did not significantly affect bulk milk composition (fat, protein, lactose and total solids), indicating that the milk could be used for conventional processing after the minor proteins had been extracted. Resin cleaning and regeneration studies, using a procedure similar to that recommended by the resin supplier, showed that the Sepharose resin had not degraded and there was no significant decrease in binding capacity after 50 extraction cycles. A Protein Fractionation Robot (PFR) prototype based on a single-stage stirred tank and the operating parameters obtained from the laboratory trials was designed, assembled and coupled to an Automated Milking System (AMS) to process fresh, raw whole milk from individual cows immediately after milking. The LF and LP extracted from the milk from 16 individual cows were 19.7 - 55.2% (35.6 10.2%) and 21.2 - 99.5% (87.1 12.0%) respectively. Generally, higher extraction levels were obtained at higher resin:milk ratios. The amount of LF extracted on-farm agreed within 14.1 9.8% of those predicted by the CNL model, with predicted values generally being higher. The experimental on-farm adsorption values were calculated using data of LF recovered after elution, so differences between actual and predicted values may be due to losses during post-adsorption processing. Economic feasibility studies, based on experimental data from the PFR and realistic wholesale prices for LF and LP ($400 and $150/kg respectively) showed that PFR-based processing is economically viable if the farmer is paid for the LF and LP produced as well as the bulk milk. This system would have a payback period of approximately five years and an internal rate of return of 14.5%. Further case studies determined the sensitivity of the economics to various operating parameters and value/cost assumptions, including producing recombinant human protein from transgenic bovine milk. These studies showed that the higher the value of the processed raw milk, the higher the absorptive capacity of the resin, and the higher the value of the extracted protein, the more favourable the economics. In the extreme case of producing a very high value therapeutic protein (e.g. $20 000), the payback period could be as low as 0.3 years, with an internal rate of return of 818%.

The lactoperoxidase (LPO) antimicrobial system has been shown to play an important role in maintaining sterile conditions in several tissues including the mammary gland, the salivary gland, and the airway. The LPO system in the airway consists of the enzyme LPO and its substrates hydrogen peroxide and an anion. LPO catalyzes the oxidation of a halide or pseudohalide ion for example SCN-or I- by hydrogen peroxide producing a product, OSCN- or OI- which have antibacterial, antifungal, and antiviral properties. In order to have a functional antimicrobial system all the components need to be present at appropriate concentrations. The LPO system has been suggested to be deficient in cystic fibrosis. There are three possible regulatory mechanism of this antimicrobial system and these involve the secretion and availability of the three components of the LPO system in the luminal fluid. The studies presented in this dissertation examine two of the possible regulatory mechanisms of the LPO system in the airway; the availability and transport of SCN- to the luminal surface, and the expression of LPO. The knowledge obtained from these studies could be utilized to develop treatments to control infection in diseases characterized by chronic infections such as cystic fibrosis.