Addition of a small amount of polar solvent (i.e. modifier) which contains an ionic component (i.e. additive) to a CO2 mobile phase has shown major improvement in the elution of ionic analytes via packed column supercritical fluid chromatography (SFC). Firstly, we focused on the elution of sodium arylsulfonate analytes by using various ionic additives, such as lithium acetate, ammonium acetate, tetramethylammonium acetate, tetrabutylammonium acetate, and ammonium chloride. The analytes were successfully eluted with all additives with good peak shape under isocratic/isobaric/isothermal conditions. Three stationary phases with different degrees of deactivation were considered. They were conventional Cyanopropyl, Deltabond Cyanopropyl, and non-chemically bonded silica. The effect of additive concentration and additive functionality on retention was also investigated. Secondly, solid state NMR of the silica packing material before and after being flushed with supercritical CO2 modified by methanol containing the ionic additives was performed to gain some insight into the retention mechanism(s). A fraction of silanol protons were undetected after being treated with the mobile phase which suggested replacement by the cationic component of the additive. CaChe calculations were carried out on several of the additives in an attempt to explain why different ionic additives produce different effects on chromatographic retention. Modification of the stationary phase and ion pairing with the analyte are two possible retention mechanisms being considered. As ion-pair formation was considered to be one of the retention mechanisms, the use of sodium sulfonates as mobile phase additives to elute secondary and quaternary ammonium salts was then studied. Propranolol HCl, benzyltrimethylammonium chloride, and cetylpyridium chloride were chosen as the probe analytes. Sodium ethansulfonate, sodium 1-heptanesulfonate, and sodium 1-decanesulfonate were studied as mobile phase additives. The analytes were successfully eluted from Deltabond Cyano phase within 5 minutes, but were retained strongly without additive or with ammonium acetate as the additive. An Ethylpyridine column showed dramatic advantages on the elution of these ammonium analytes. No additive was required to elute these ionic compounds. Protonation of some fraction of the pyridine functional groups and the deactivation of active silanol sites were believed to be the major mechanisms responsible for this behavior. Lastly, we successfully eluted large peptides (up to 40 mers) containing a variety of acidic and basic residues in SFC. We used trifluoroacetic acid as additive in a CO2/methanol mobile phase to suppress deprotonation of peptide carboxylic acid groups and to protonate peptide amino groups. The Ethylpyridine column was used for the majority of this work. The relatively simple mobile phase was compatible with mass spectrometric (MS) detection. To our knowledge, this is the first report of the elution of peptides of this size with a simple, MS-compatible mobile phase. Fast analysis speed, the possibility of coupling multiple columns to achieve desired resolution, a normal-phase retention mechanism, and less use of organic solvents are the advantages of SFC approach for peptide separation. / Ph. D.

Foodborne illnesses caused by Listeria monocytogenes have long been associated with ready-to-eat (RTE) meats contaminated after the primary thermal process has been applied. It is believed that brine solutions used to chill cooked RTE products may serve as a reservoir for L. monocytogenes becoming a potential point of post-processing contamination for RTE meats. Re-circulating ultraviolet light (UV) systems are being used to inactivate L. monocytogenes in chill brines; however very little has been reported on the dose response of healthy and stressed L. monocytogenes to UV in brine solutions. The objectives of this research were to determine 1) minimum dose of UV required to inactivate L. monocytogenes in distilled water, fresh brine, undiluted spent brine, and diluted spent brine, 2) if adaptation to food processing stresses affects the dose response, and 3) if the acquisition of antibiotic resistance mechanisms provides resistance to ultraviolet light 4) effect of stress adaptation on survival in brine solutions. After UV exposure, populations were reduced as follows from greatest to least: water > fresh brine > 5% spent brine > 35% spent brine > 55% spent brine > 100% spent brine (P ≤ 0.05). There were no population differences between acid stressed and antibiotic resistant or healthy and heat shocked (P > 0.05). However, acid-stressed and sulfanilamide-resistant were more resistant to UV light than healthy and heat shocked L. monocytogenes (P ≤ 0.05). Survival in brine solutions (no UV) followed the trend, from greatest to least (P ≤ 0.05): sulfanilamide-resistant > acid-stressed > healthy > heat-shocked. Population estimates decreased from initial inoculation to final sampling for each cell type suspended in spent brine (P ≤ 0.05), but only healthy and heat- shocked cells suspended in fresh brine were significantly reduced (P ≤ 0.05). Knowledge of UV dosing required to control L. monocytogenes in brines used during RTE meat processing, and a greater understanding of the interactions that may influence dose will aid manufacturers in establishing appropriate food safety interventions for these products. / Ph. D.

Chill brines used in ready-to-eat meat processing may be an important source of post-processing contamination by Listeria monocytogenes. The purpose of this study was to determine the efficacy of ultraviolet light (UV) in combination with antimicrobials to reduce L. monocytogenes in fresh and used chill brines. Three different antimicrobials were used in combination with UV; citric acid (CA, 0.2 and 0.5%), dimethyl dicarbonate (DMDC, 250 and 500 ppm), and hydrogen peroxide (HP, 2000 and 4000 ppm). For fresh brine studies, brine (8.0% w/v NaCl) was prepared and inoculated with a cocktail of three L. monocytogenes strains (approximately 6 log CFU/mL). Brine was treated with UV alone, antimicrobials alone, and combination of UV and antimicrobials. Moreover, to observe the effect of treatment temperature and brine circulation through the UV system on survival of listeriae cells, inoculated brine was circulated through the system without any treatment that served as control for all the treatments. For UV treatment, inoculated brine solution was exposed to UV in an Ultraviolet Water Treatment Unit (Model: AMD 150B/1/2T D; Aquionics Inc., Peak output: 254 nm) fitted with an inline chiller to maintain brine temperature of -1°C. Samples were withdrawn at regular intervals for 120 minutes. When L. monocytogenes population was no longer detectable via direct plating on MOX, enrichment was performed and suspect colonies were confirmed using API-Listeria. For antimicrobial-only (i.e., no UV) treatments, a specific concentration of antimicrobial was added in inoculated brine and samples were taken for 120 minutes. For the brine that received combination of UV and antimicrobial treatments, UV was turned on once a specific concentration of antimicrobial was added in inoculated brine and samples were withdrawn at regular intervals for 120 minutes. When treated with UV alone, L. monocytogenes population decreased from approximately 6 log CFU/mL to below the detection limit (i.e., 1 log CFU/mL) in 15 minutes with the reduction rate of 0.87 log CFU/mL per minute. However, cells were detectable by enrichment through 120 minutes. The highest rate of decline (0.90 log CFU/mL per minute) was achieved by the combination of UV and 500 ppm DMDC (UV+500 ppm DMDC), which was not significantly different from the reduction rates of UV and UV+0.5% CA. UV+500 ppm DMDC reduced L. monocytogenes to the detection limit in 15 minutes and the organism was not detected by enrichment after 60 minutes. Though the reduction rate of UV+0.5% CA was not significantly lower than the rate of UV+500 ppm DMDC (P>0.05), the former treatment resulted in non-detectable levels more quickly (45 minutes) than the latter (60 minutes). Thus, based on enrichment studies UV+0.5% CA was the most effective treatment in reducing the population of L. monocytogenes in fresh brine. Moreover, when brine was treated with 0.5% CA alone the population decreased to below detection limit in 15 minutes with the rate significantly lower than UV+500 ppm DMDC and UV+0.5% CA (P<0.05). However, L. monocytogenes was not detectable by enrichment from 60 minutes. To summarize, through enrichment studies we observed that UV+0.5% CA, UV+500 DMDC, and 0.5% CA Control were more effective than other treatments in reducing the listeriae population to a non-detectable level. Spent brine is recycled brine that was obtained from a frankfurter processor after its maximum usage. Results of spent brine studies showed that when brine was treated with UV+4000 ppm HP and UV+2000 ppm HP, L. monocytogenes population decreased to the detection limit in 45 minutes and was not detected by enrichment from 120 minutes. These treatments were observed to be the most effective treatments with a reduction rate of 0.12 log CFU/mL per minute. The reduction rate of some other treatments such as, UV+250 and 500 ppm DMDC, UV+0.2% and 0.5% CA, and UV alone was not significantly different from UV+4000 and 2000 ppm HP. However, the population was detected through enrichment up to 120 minutes in all other treatments. The results of these studies indicate that combinations of UV and antimicrobial may be more effective than either treatment alone (except 0.5% CA treatment) to process fresh chill brines. However, the antimicrobials and UV were less effective for controlling L. monocytgoenes in spent brine; presumably due to the presence of organic matter. / Ph. D.

Oil spills have long been recognized as a significant threat to wildlife. Historically, mortality estimates have served as the basis for assessing impact to natural resources. However, these mortality estimates alone neglect the more wide-spread impact of oil spills on wildlife including birds, many of which may not immediately succumb to exposure, but instead suffer sublethal injury that may negatively affect physiological homeostasis, reproduction, and long-term survival. Therefore, there is a need to improve our understanding of the risk of exposure and effect of sublethal oiling during damage assessments. In this dissertation I evaluated the extent of sublethal oil exposure in the immediate aftermath of the Deepwater Horizon spill on American oystercatchers (Haematopus palliatus), black skimmers (Rynchops niger), brown pelicans (Pelecanus occidentalis), clapper rails (Rallus crepitans), and seaside sparrows (Ammodramus maritimus) through both visual evaluation of and under the application of ultraviolet light to individual birds potentially exposed to oil. I found that there were many individual birds with modest oil exposure, demonstrating that more birds are exposed to oil than are accounted for by mortality estimates. Additionally, I developed a field-adapted technique using an in vitro method in brown pelicans that was effective in determining oxidative hematologic injury as measured by a suite of parameters including a reduction in circulating erythrocytes and hemoglobin, formation of Heinz bodies, and an increase in reticulocytes, in birds exposed to oil. I then applied this suite of parameters to individual birds affected in the aftermath of the Deepwater Horizon spill, and found that birds with modest visible or UV-detectible oil exposure suffer hematologic injury, a quantifiable adverse sublethal effect of modest oil exposure. Finally, I used an experimental approach to evaluate the pathologic effects of crude oil exposure in zebra finches (Taeniopygia guttata), evaluating the same suite of hematologic parameters as well as gross pathology, histopathology, and electron microscopy. This controlled study provided evidence that there may be significant variability in the response of birds to oil exposure that may be attributable to species-specific sensitivity and/or other factors such as the use of dispersants after oil spills. Collectively, this body of work demonstrated that many more birds are exposed to oil during spill events than are accounted for by mortality estimates alone, and that these birds can suffer quantifiable sublethal hematologic injury. The ability to accurately assess the extent of exposure and hematologic damage caused by oil spills is critical to determine the appropriate approach to management needed to offset impacts to fisheries, wildlife, habitats, and economic resources impacted by oil spills. / Doctor of Philosophy / Fossil fuels are the world's primary energy source and are an important part of everyday life. Our reliance on petroleum requires extraction, transportation, storage, and refinement of millions of gallons of crude oil each day. As an unintended consequence, some of this oil is inadvertently spilled into the environment, and these oil spills have long been recognized as a threat to wildlife. Assessing the impact of oil spills on wildlife is a major concern to industries, government, and the general public. Historically, mortality estimates have served as the basis for assessing impact to natural resources. However, these mortality estimates alone neglect the more wide-spread impact of oil spills on wildlife including birds, many of which may not immediately succumb to exposure, but instead suffer sublethal physiologic injury that negatively affects physiology, reproduction, and long-term survival. Therefore, there is a need to improve our understanding of the risk of exposure and effects of sublethal oiling during damage assessments. In this dissertation, I evaluated the extent of sublethal exposure to oil from The Deepwater Horizon spill for several species of birds through both visual evaluation of and under the application of ultraviolet light. This demonstrated that many more birds are affected by oil exposure than are accounted for by mortality estimates. Additionally, I developed a field-adapted technique in a controlled setting that is effective in determining oxidative injury to red blood cells in birds exposed to oil, and applied this approach to several species in the field during the aftermath of the Deepwater Horizon spill. Finally, I used an experimental approach to evaluate the extent of pathologic effects of Deepwater Horizon crude oil exposure in individuals under controlled dosages. The ability to accurately assess the extent of damage caused by oil spills is critical to determine the appropriate approach to management needed to offset impacts to fisheries, wildlife, habitats, and economic resources impacted by oil spills.

The present study examined adverse effects of sunlight exposure (mimicked by intradermal cis-urocanic acid, cUCA) on local and systemic immune responses, with or without co-exposure to the immunotoxic insecticide permethrin. A single exposure to cUCA caused diminished splenic macrophage phagocytosis that was persistent up to 30 days post-exposure. Five-day exposure to cUCA subtly increased splenocyte proliferation in response to the T cell mitogen Concanavalin A. Four-week exposure to cUCA caused increased splenic lymphocyte cellularity, thymic hypocellularity, and enhanced hydrogen peroxide production by splenic leukocytes. Single exposure to topical permethrin resulted in decreased thymic and splenic weight and cellularity, and inhibited antibody production by splenic B cells. cUCA worsened the negative effect of permethrin on both thymic weight and cellularity, and depressed splenocyte blastogenesis, hydrogen peroxide production, and antibody production. Five-day exposure to either cUCA or permethrin also caused persistent decreased contact hypersensitivity responses, an effect that became more than additive when the chemicals were administered concurrently. Defects in antigen processing and presentation by cutaneous Langerhans cells were evaluated as possible contributing mechanisms to the cutaneous immunosuppression, using mice with deleted genes. Vehicle-exposed IFNg knockout mice displayed approximately a 22.1% depression in the ear swelling response as compared to control C57BL/6N mice, suggesting that this cytokine may be required for mounting a control-level hypersensitivity response. Ear swelling in cUCA-exposed IFNg knockout mice displayed a 21.4% depressed response as compared to cUCA-exposed wild-type C57BL/6N mice, again suggesting that IFNg is an important cytokine in the contact hypersensitivity (CH) response. TNFaR knockout mice exposed to cUCA displayed 33.9% greater ear swelling than cUCA-exposed wild-type C57BL/6N mice, suggesting that increased TNFa may be involved in inhibited CH by cUCA. TNFaR knockout mice exposed to permethrin displayed 33.9% greater ear swelling than permethrin-exposed C57BL/6N mice, suggesting that increased TNFa may also be involved in inhibited CH by permethrin. C57BL/6N mice exposed to cUCA + permethrin displayed severe reduction of the CH response to 8.7% of the control level. IFNg knockout mice exposed to permethrin + cUCA showed essentially identical depression of the CH response as IFNg knockout mice exposed to either permethrin or cUCA alone. These results suggest that IFNg is required for the greater than additive immunotoxic effect that occurred when these two agents were co-administered. TNFaR knockout mice exposed to cUCA + permethrin displayed 8.7 fold greater ear swelling than similarly exposed C57BL/6N mice, again suggesting that increased TNFa is involved in inhibited CH by both cUCA and permethrin. / Ph. D.

Sun protection has gained worldwide attention because repetitive overexposure to ultraviolet radiation can result in harmful effects on human skin, including sunburn, premature skin ageing, and in the worst case, skin cancer (Eckhardt and Rohwer, 2000; Sengupta and Blain, 2001). The diminishing stratospheric ozone layer, due to environmental degradation in the past few decades, combined with the modern outdoor-oriented lifestyles, are leading to unexpected levels of skin cancer (Davis, Capjack, Kerr, and Fedosejevs, 1997). Wearing Ultraviolet protective clothing is a simple way of practicing sun safety; however, regular cotton generally has very low ultraviolet protection and it is one of the most environmentally damaging crops despite of it is commonly used to make summer clothing. With the increased interest of public awareness related to sustainability and environmental issues, naturally colored cotton was recommended as it provides better ultraviolet protection than regular cotton. In addition, the production of naturally colored cotton is more environmentally friendly than regular cotton. Although several studies have been conducted on the UVR protection of naturally colored cotton, many questions regarding the factors that influence the UVR protection of fabrics remain unanswered. The primary purpose of the study was to examine the effects of perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering on the UVR protection of a NC lightweight cotton fabric. In addition, five fabric property changes in the test specimen after the treatments of perspiration, weathering exposure, washing action, and repeated laundering (i.e., fabric count change, thickness change, weight change, color change and dimensional change) were included in this study to serve as secondary dependent variables to examine if the four treatment factors (i.e., perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering) will cause changes in these five fabric properties, and if these changes will lead to changes of UVR protection of NC lightweight cotton fabric. Based on the purpose and objectives of the study, a split-plot repeated measures experimental design was used for the current study. In this study, the whole plot treatment was the weathering exposure, which contained three levels (i.e., semi-tropical climate without water spray, semi-arid climate, and standard conditioning), and the split plot treatments were the combinations of two treatment factors. In order to understand the effects of repeated laundering on the UVR protection and the five fabric properties, except for the control group, all test specimens were laundered after being treated with the three treatment factors (i.e., perspiration, weathering exposure, and washing action), and this process was repeated 15 times. The UVR protection (i.e., express in UPF value change in current study) and the five fabric properties of these treated test specimens were measured before laundering, and after each laundering cycle. The results of UPF value change showed that test specimens treated with perspiration had a lower change in UPF value than the specimens without treatment. The test specimens exposed to Florida condition had the most UPF value change, followed by Arizona and Standard textile testing conditions. A significant difference also found in test specimens that laundered in a traditional washer after ninth cycle and the UPF value decreased as the number of laundering cycle increased. However, test specimens that laundered in a front-loading HE washer showed no significant UPF value change. For the five fabric properties that listed in secondary objective, all four treatments significantly influenced fabric count, fabric thickness and fabric weight. However, perspiration treatment had no significant effect on the dimensional change in warp direction of test specimens, and washing action had no significant effect on the dimensional change in filling direction of the test specimen as well as both Delta E and Delta L of color change. For testing the relationship between the changes of the five fabric properties and UPF value change, Delta E and Delta L of color change had the highest correlation coefficient with UPF value change. Therefore, it is possible that the changes of these two properties caused by the four treatments and lead to the UPF value change. Future research is needed to confirm this relationship. In conclusion, of perspiration application, weathering exposures, washing action of automatic home clothes washers, and repeated laundering do have influence on the ultraviolet protection of the naturally colored cotton. The color change of the test specimens caused by these four treatments possible lead to the change of the ultraviolet protection of the test specimens. More studies are needed to confirm this relationship. / Ph. D.

Ce travail de thèse présente trois grands axes. Le premier axe traite de la synthèse de microsphères de polyméthacrylate de méthyle (PMMA) encapsulant des absorbeurs d’UV organiques (UVA) et des piégeurs de radicaux (HALS) nécessaires à la protection UV des finitions. Le second axe étudie un système d’encapsulation stimuli-sensible pour la libération des stabilisateurs de lumière. Le dernier axe a pour but de comparer l’efficacité des deux systèmes par rapport à leur protection UV dans une application de finition claire acrylique extérieure pour le bois. Dans le premier axe, des microsphères de PMMA contenant des UVA et des HALS ont été synthétisées par la méthode de séparation de phase interne. Les microsphères ont été ajoutées à une résine claire destinée à des applications extérieures, puis appliquées sur du bois d’épinette blanche. Plusieurs formulations ont été réalisées avec des composés libres ou des composés encapsulés. Certaines contiennent des absorbeurs UV et HALS libres, ce qui est comparable aux formulations commerciales disponibles sur le marché présentement, d’autres possèdent plusieurs concentrations différentes en composés encapsulés. La performance des finitions a été évaluée après un vieillissement artificiel. La comparaison permet d’évaluer l’utilité de microsphères avec des stabiliseurs UV dans des finitions claires extérieures pour le bois. Une bonne résistance des finitions contre les UV se traduit par une bonne tenue esthétique de la finition et du bois, un faible changement de couleur du bois ainsi qu’une faible dégradation chimique. Les analyses telles que la spectroscopie infrarouge à transformée de Fourier (FTIR), la microscopie électronique à transmission (MET) et la colorimétrie ont permis d’obtenir les résultats. Dans le second axe, le système est amélioré de façon à le rendre sensible à l’intensité lumineuse. L’utilisation d’un polymère changeant de conformation suivant le rayonnement peut permettre d’optimiser la libération des stabiliseurs UV. Le poly(1-(4-(3-carboxy-4-hydroxyphényl-azo)benzènesulfonamido)-1 ,2-éthanediyl) ou (PAZO) est additionné sur des supports en CaCO3 contenant les stabiliseurs UV. L’encapsulation des composés se fait par coprécipitation de carbonate de sodium (Na2CO3) et de chlorure de calcium (CaCl2). L’assemblage couche par couche permet de déposer des polymères chargés sur le support. Le PAZO est déposé après une couche de chlorure de poly(diallyldiméthylammonium) (PDADMAC). Les particules obtenues sont ajoutées à une formulation de finition claire complète. Les échantillons ont été placés en chambre de vieillissement accéléré. L’encapsulation a été démonté par spectrométrie photoélectronique des rayons X (XPS), MET et par analyse thermogravimétrique (TGA). La transition du polymère PAZO a été observée par colorimétrie. Dans le dernier axe, les deux systèmes ont été comparés en utilisation dans des finitions claires. Les films secs ont été placés en chambre de vieillissement artificiel pour tester leur efficacité. Après 1000 h de vieillissement artificiel, les films sont analysés et comparés au film initial. La technique d’imagerie en spectroscopie Raman permet de visualiser la distribution des protecteurs UV libres. L’analyse mécanique dynamique (DMA) a permis de calculer les modules mécaniques ainsi que la température de transition vitreuse (Tg) des films étudiés. Le dernier axe permet de relier la distribution des protecteurs UV et l’efficacité de protection du film. / The work presented in this thesis is divided in three research axis. The first axis regards the poly(methyl methacrylate) (PMMA) microspheres synthesis containing UV absorbers (UVA) and hindered amine light stabilizers (HALS). UVA and HALS work synergistically to prevent UV degradation in coatings. The second axis studies the synthesis of stimuli-sensitive encapsulation system for the tailored release of the UV stabilizers. The last axis compares the system efficiency in the case of UV protection for clear coat for exterior wood. In the first axis, PMMA microspheres with UVA and HALS were synthesized by the internal phase separation method. Microspheres are added to an exterior clear coat binder then applied onto white spruce panels. Some formulations are realized. Some contains free UVA and HALS similar to commercial paint and others have different concentrations in encapsulated compounds. Paint performance is evaluated after accelerated weathering. The comparison of formulations allow the evaluation of the efficiency of encapsulation of UV stabilizers inside the wood clear coat. The performance of coating consists on a good aesthetic resistance, a small color change and low chemical degradation. Obtained results are based on analysis with FTIR, TEM and colorimetry. In the second axis, the release of UVA is improved by the UV sensitive polymer. This polymer is able to change its own molecular conformation under UV rays. The poly(1-(4-(3-carboxy-4-hydroxyphenyl-azo)benzenesulfonamido)-1,2 -ethanediyl) or (PAZO) is deposited onto CaCO3 templates containing UVA encapsulated. The encapsulation is done by coprecipitation of Na2CO3 and CaCl2.The layer by layer allow the deposition of charged polymers. PAZO is adsorbed after a layer of poly(diallyldimethylammonium chloride) (PDADMAC). The obtained particles are added to a complete clear coat formulation. Samples are placed in an accelerated weathering chamber. The encapsulation is proved by analysis techniques of XPS, TEM and TGA. Polymer PAZO transition is observed by colorimetry. In the last axis of this work, the two encapsulation systems are compared using encapsulated UV stabilizers inside a formulation of wood clear coat. Dried films are placed in accelerated weathering chamber in order to test their efficiency. After 1000 h of artificial weathering, films are analyzed and compared to the initial state. The mapping Raman technique allows to visualize the free UV stabilizers distribution inside the dried film. DMA calculate mechanical modulus and Tg of studied films. This last axis allows to connect distribution of UV protectors and efficiency of coating protection.

Hazard Analysis Critical Control Point (HACCP) regulations for juice manufacture require the application of a process that will result in a 5-log reduction (99.999%) of the pertinent pathogen in the juice being processed. The use of ultraviolet (UV) light, as an alternative to traditional thermal processing, has been adopted by some juice processors as a means of meeting the HACCP 5-log performance standard. However, little research had been performed to determine the effect of UV when used in combination with antimicrobial agents that are commonly added to juice products. Therefore, the objectives of this work were (1) to determine if chemical preservatives and ultraviolet light have a combined effect on the reduction of Escherichia coli in apple cider, and (2) to determine the influence of adding chemical preservatives at different points in the processing of juice (i.e., either prior to or after ultraviolet light processing) on the reduction of Escherichia coli in apple cider. In this study, refrigerated (4°C) pasteurized apple cider that contained no added preservatives was inoculated with E. coli ATCC 25922, a surrogate strain for E. coli O157:H7, and exposed to UV (peak output: 254 nm). The following chemical preservatives were added to apple cider either prior to or after UV exposure: dimethyl dicarbonate (75 and 150 ppm), hydrogen peroxide (75 and 150 ppm), potassium sorbate (1000 and 2000 ppm), and sodium benzoate (1000 and 2000 ppm). Following UV exposure and chemical preservative application, inoculated juices were stored at 4°C for 72 hours. Samples were collected prior to and immediately after UV exposure and at 24, 48, and 72 hours of storage. At each sampling point, juice portions (0.1 ml) were serially diluted in peptone diluent (0.1%) and surface plated onto Tryptic Soy Agar (TSA). Counts of the bacterial colonies were made 48 hours after incubating plates at 35°C. Overall, reductions of E. coli were greater in cider treated with preservatives after UV processing than when preservatives were added prior to UV processing (P < 0.05). Furthermore, dimethyl dicarbonate and hydrogen peroxide were more effective than potassium sorbate and sodium benzoate in reducing E. coli populations in conjunction with UV (P < 0.05). When added prior to UV exposure, potassium sorbate was the least effective, allowing for the greatest survival (P < 0.05). This study describes the use of UV in conjunction with hydrogen peroxide and dimethyl dicarbonate as an effective method for producing a 5-log or greater reduction of E. coli O157:H7 in apple cider. / Master of Science

No / Erythema occurs in human skin following excessive exposure to ultraviolet radiation (UVR), and this is in part mediated by the vasodilator prostaglandin E2 (PGE2). While keratinocytes are a major source of this pro-inflammatory eicosanoid, epidermal melanocytes (EM) also express some of the cellular machinery required for PGE2 production. The primary aim of this study is to determine whether EM can produce PGE2 and so potentially also contribute to UVR-induced skin inflammation. Furthermore, we investigate the likely pathway by which this PGE2 production is achieved and investigate whether PGE2 production by EM is correlated with melanogenic capacity. Primary cultures of EM were established from nine normal healthy individuals with skin phototype-1 (n=4) and 4 (n=5), and PGE2 production and melanogenic status were assessed. EM produced PGE2 under baseline conditions and this was increased further upon stimulation with arachidonic acid. Moreover, EM expressed cytoplasmic phospholipase A2, cyclooxygenase-1 and cytoplasmic prostaglandin E synthase. However, no EM culture expressed cyclooxygenase-2 under baseline conditions or following arachidonic acid, UVB- or H2O2 treatments. PGE2 production in response to UVB was highly variable in EM cultures derived from different donors but when pooled for skin phototype exhibited a positive correlation only with SPT-1 derived EM. Interestingly, PGE2 production by EM in response to UVB showed no correlation with baseline levels of melanin, tyrosinase expression/activity or tyrosinase-related protein-1 expression. However, there was an apparent negative correlation with baseline expression of dopachrome tautomerase (DCT), a melanogenic enzyme with reported anti-oxidant potential. These findings suggest that EM have the potential to contribute to UVR-induced erythema via PGE2 production, but that this response may be more related to oxidative stress than to their melanogenesis status. / The Wellcome Trust

No / High personal UVR doses can be gained during leisure activities, causing intense self-resolving inflammation (sunburn) of unprotected skin. UVR activates release of membrane fatty acids and upregulates their metabolism by cyclooxygenases (COX) and lipoxygenases (LOX) to different eicosanoids. While COX-derived prostaglandin (PG)E2 is a potent mediator of sunburn vasodilatation, LOX-derived 15-hydroxyeicosatetraenoic acid (HETE) and its lipoxin metabolites may contribute to sunburn limitation. We explored the relationships between expression of these lipid mediators and the clinical and histological outcomes, comparing responses of individuals prone and more resistant to sunburn. An acute UVR exposure of 12 SED (standard erythema dose) was applied to buttock skin of 32 white Caucasians (n = 16 phototype I/II, n = 16 phototype III/IV), and over the subsequent 72 h assessments were made of skin erythema, immunohistochemical expression of leukocyte markers, COX-2, 12-LOX, 15-LOX and nitric oxide synthase (NOS), and eicosanoid levels by LC/ESI-MS/MS. Evidence of a significant inflammatory response was seen earlier in phototype I/II with regard to expression of erythema (4h, p < 0.001), neutrophil infiltration (24 h, p = 0.01), epidermal COX-2 (24 h, p < 0.05) and 12-LOX (24 h, p < 0.01), and dermal eNOS (24 h, p < 0.05) proteins, although CD3+ lymphocyte infiltration showed an earlier increase in phototype III/IV (24 h, p < 0.05). Although erythema was equivalent at 72 h in both groups, phototype I/II showed higher PGE2 accompanied by elevated 15-HETE, and a strong positive correlation was seen between these mediators (n = 18, r = 0.805, p = 0.0001). Hence anti-inflammatory eicosanoid 15-HETE may temper the pro-inflammatory milieu in sunburn, having greater influence in those prone to sunburn than those more resistant, given the same high UVR exposure conditions. / The Wellcome Trust