Emerging pathogens are organisms whose incidence has increased within the past two decades. In the last 40 years, several pathogens have emerged to cause infectious waterborne and foodborne diseases, thus causing a significant public health concern. Enterobacter sakazakii and Naegleria fowleri are emerging pathogens that have been documented to cause fatal infections. E. sakazakii is an emerging foodborne pathogen that represents a significant health risk by causing infections resulting in septicemia, meningitis and necrotizing enterocolitis in neonates, premature infants and also elderly immunocompromised individuals. Naegleria fowleri is a water-based protozoan flagellate that is the cause of primary amoebic meningoencephalitis; a fatal disease that mostly infects children and young adults through water-related recreational activities. The focus of this dissertation is to identify environmental reservoirs of Enterobacter sakazakii and to determine inactivation strategies to control Naegleria fowleri by chlorine and ultraviolet disinfection. In Appendix A, samples from various household kitchens were collected to determine the presence of E.sakazakii. The highest percentage of E.sakazakii was isolated from kitchen sponges (8%; n=50) and dishrags (10%; n=50). This study provided information on the presence of E.sakazakii on environmental surfaces in the kitchen. In Appendix B, our recent research has determined that N. fowleri is present in 8% (n=143) of municipal drinking water wells in central and southern Arizona. Therefore, guidelines need to be established for treatment of water with various disinfectants to control the growth and proliferation of N.fowleri. In Appendix C, the Ct values (concentration (mg/l) × exposure time) for chlorine inactivation of N. fowleri trophozoites and cysts were determined using the Efficiency Hom Kinetic Model (EHM). The Ct values for 99% inactivation of trophozoites and cysts were estimated to be 9 and 31, respectively. The ultraviolet light dose required for the 99% inactivation of N.fowleri trophozoites and cysts was determined to be 63 mW.sec/cm² and 13 mW.sec/cm², respectively.

Platelets are small fragments, but they are of crucial importance for the coagulation. The risk of spontaneous bleeding increases when the level of platelets falls below a thrombocyte particle concentration threshold value of 50 x 109/L. In those cases a platelet transfusion might be compulsory. Ongoing research tries to improve the quality of the platelets and to increase the safety of the method used. However, we still need to better understand which factors that affect how patients react upon platelet transfusion. In this study, 100 transfusions performed at Uppsala University Hospital during 2009 were examined. The platelets used had been produced with apheresis followed by pathogen inactivation by Intercept Blood SystemTM. Platelets were counted before and after transfusions and the increase was calculated in purpose to examine how well the patients responded to the platelet transfusions. These values were plotted against platelet storage time in order to examine the possible impact on the result of treatment.

Antimicrobial peptides (AMPs) and photosensitizers (PS) have gained attention as potential alternatives to traditional antibiotics for the treatment of microbial infection due to the decreased likelihood for acquired resistance. However, many AMPs and PS suffer from insufficient activity, specificity, or a combination thereof. AMPs can require high concentrations for effective activity, leading to non-specific side effects and increased costs. PS, on the other hand, are quite active, but are typically hydrophobic and suffer from non-specific binding and damage to host tissues. To solve these problems, we report a novel PS-AMP construct of the soluble PS eosin Y conjugated to the selective AMP (KLAKLAK)_(2). Eosin Y has a high singlet oxygen quantum yield, which is suitable for photodynamic activity, although the solubility of eosin Y results in poor binding and activity toward membranes on its own. On the other hand, the specificity of (KLAKLAK)_(2) is high for an AMP, but could still benefit from enhanced activity at lower concentrations. The killing activity and binding specificity of eosin-(KLAKLAK)_(2) toward both bacteria and mammalian cells was assessed using microbiology, biochemistry, and fluorescence microscopy techniques. Additionally, the mechanism of eosin-(KLAKLAK)_(2) activity was investigated using liposome models to determine factors involved in binding and membrane disruption. Furthermore, novel applications of transmission electron microscopy (TEM) methods were employed to observe the photodynamic effects of eosin-(KLAKLAK)_(2) against bacteria. The PS-AMP conjugate eosin-(KLAKLAK)_(2) displays synergistic activity between PS and AMP in model liposome systems, and is capable of killing several clinically relevant bacteria, including the multi-drug resistant Acinetobacter baumannii AYE strain. Furthermore, bacterial killing is achieved in the presence of red blood cells (RBCs) and other mammalian cell lines without significant toxicity. Liposome models reveal that the lipid composition of bacteria is a potential factor responsible for the observed binding specificity and corresponding activity. Additionally, TEM methods show that eosin-(KLAKLAK)_(2) causes extensive membrane damage to both Gram positive Staph aureus and Gram negative Escherichia coli, indicating a primary cause of cell death. A model is proposed where the activities of the PS and AMP, respectively, facilitate the activity of one another, leading to enhanced membrane disruption, and effective antibacterial activity while maintaining cell selectivity.

No description available.

High voltage treatment technology has been developed in this thesis and had initially shown promise in its effectiveness in reducing microorganisms found in water supplies. Initial testing found that the high voltage could destroy over 99.9% of the bacteria S. marcescens (a 3-log reduction). Cited literature on the effects of high voltage pulsed electric fields (PEFs) on various microorganisms have shown that high destruction rates of up to 9-log can be achieved. Thus by increasing the electric field strength or exposure time, or by improving the design of the electrode flow chamber, better results should be achieved using high voltage on water. However, contrary to this, upon further design improvements the 99.9% destruction threshold was rarely increased. The initial slow flow device of one litre-per-minute (1 LPM) was scaled up to flows of 10 LPM and 33 LPM. However, these faster flow devices were even less effective in the destruction of bacteria, destroying only 99% of S. marcescens (2-log reduction). No physical or technical design parameters could account for this low performance. One possible reason for these low results was in the preparation of the bacteria themselves. It was discovered that the growth stage of bacteria prepared for experiments had a large effect on the results. Bacteria harvested in the early growth stage could be nearly all destroyed by the high voltage (greater then 4-log reduction), whereas those harvested in the late stationary stage were much more resistant (less than 0.5-log reduction). Bacteria naturally occurring in water supplies will mostly be in a non-metabolising state. This implies that they will be more resistant to high voltage exposure than bacteria grown in a laboratory under standard testing procedures. Thus standard testing procedures for this device do not give accurate results. Further research into the mechanism behind the bacterial resistance is required to improve the performance of high voltage devices. A combination of different technologies may also prove effective in overcoming the resistance mechanism. These improvements are required before high voltage treatment can be properly developed and commercially exploited.

Thesis (Ph.D.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 102 pages. Includes Vita. Includes bibliographical references.

Viral transmission from the environment can occur via fomites, but there is uncertainty about which factors most affect viral persistence on fomites. Children are a population highly susceptible to viral infection, and sharing common fomites like toys may spread infection. The objective of this research was to assess the survival of enveloped viruses on the surfaces of children’s toys, using bacteriophage ϕ6 as a surrogate for enveloped human viruses. The survival of infectious ϕ6 virions was observed over a 24 hour period at 22°C and relative humidities of 40% & 60%. On the surface of children’s toys, ϕ6 was better able to persist at 60% RH (log10 reduction< 2 log10) over a 24 hour period than it was at 40% RH (log10 reduction> 6 log10). If ϕ6 virus persists on toy material for up to 24 hours, then viral transmission via shared fomites is certainly significant.

Made available in DSpace on 2014-06-11T19:23:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-06-02Bitstream added on 2014-06-13T19:29:44Z : No. of bitstreams: 1 kamimura_gkf_me_arafcf.pdf: 713918 bytes, checksum: 90d6ccb478cdaac799bbb870832f99ec (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os frutos e vegetais apresentam-se fisiologicamente ativos após a colheita, dessa forma as perdas pós-colheita ocorrem pela influência de diferentes fatores onde se destacam a respiração, a temperatura, a umidade, a concentração de oxigênio e gás carbônico, a produção de etileno e a ação de enzimas endógenas associadas com processos de deterioração. As raízes de yacon têm sido cada vez mais consumidas devido à revelação de qualidades medicinais. A manutenção de sua qualidade in natura é um sério problema nos processos pós-colheita devido a inúmeras reações metabólicas. A peroxidase (POD, E.C.1.11.1.7) é largamente encontrada nos vegetais apresentando importante papel fisiológico/bioquímico embora uma precisa função não tenha ainda sido estabelecida. Sua importância para ciência dos alimentos evidencia-se pelas relações com alterações indesejáveis na qualidade e resistência dos vegetais, tornando interessante sua supressão parcial ou total no pós-colheita. Os objetivos desse trabalho foram isolar, purificar e caracterizar a peroxidase de raízes de yacon. Condições de extração para a POD de yacon foram estabelecidas e a enzima foi isolada por precipitação com sulfato de amônio, eluição em Sephadex G-25 e DEAE-celulose. Somente um pico de atividade foi eluído no processo de purificação com um fator de purificação de 222,33. O peso molecular determinado foi 34.8 kDa com valores de pH e temperatura ótima de 5,5 e 35°C, respectivamente. As constantes Km e Vmax foram de 14,227 mM e 17409 UA/mL, para s-dianisidina, e de 14,434 mM e 14830 UA/mL, para H2O2. Foram testados os efeitos inibidores de sais, quelantes, compostos sulfidrila, ácidos fenólicos e outros. Estudos de inativação térmica da POD foram realizados, nos quais se verificou o efeito protetor da sacarose na inativação enzimática e o efeito promotor de inativação pela... / The fruits and vegetables still continue physiologically active after the crop, in that way the postharvest losses occurs by the influence of different factors, like the respiration, temperature, humidity, concentration of oxygen and carbonic gas, ethylene production and the action of endogenous enzymes associated with deterioration processes. Yacon (Smallanthus sonchifolius) roots has been more and more consumed by the revelation of prebiotic and medicinal properties. The maintenance of its quality in the postharvest is a serious problem due to several metabolic reactions. Peroxidase (POD, E.C.1.11.1.7) is widely found in plants, having physiological/biochemical importance, although a precise function has not still been established. The POD importance for food science is due to its relationships with alteration of the quality and resistance of the vegetables to the postharvest factors. Its total or partial suppression by thermal inactivation or inhibitor compounds may be interesting for postharvest interests. The objectives of this work were to isolate, purify and characterize the POD from yacon roots. Extraction conditions for yacon POD were determined and the enzyme was isolated by precipitation with ammonium sulfate, elution on Sephadex G-25 and DEAE-cellulose. Only one peak of enzyme activity was eluted on the purification process with a 222.33 fold purification factor. The determined molecular weight was 34.8 kDa. The optimum pH and temperature values were pH 5.5 and 35°C, respectively. Km and Vmax for ï-dianisidine was 14.227 mM and 17409 UA/mL, and 14.434 mM and 14830 UA/mL for H2O2, respectively. The effects of metals, chelating agents, sulphidryl, phenolic acids and other compounds as POD inhibitors were evaluated... (Complete abstract, click electronic address below).

The study was made at Lubigi sewage treatment plant in Kampala, Uganda, during February and March 2018. The aim of this master thesis was to treat faecal sludge with two different methods, urea and lime, to investigate the efficiency of the chemicals to inactivate pathogens and to estimate the feasibility and the costs of the treatment. The chemical treatments were performed on sludge of two different moisture contents. The results from the treated sludge were compared with an untreated drying bed filled at the start of the study period to use as a control. The investigated pathogens were E. coli, bacteriophages and Ascaris eggs. The total solids and volatile solids were analysed, and the pH was measured. The results of the study including a calculation of costs were used to assess the feasibility of these treatment methods at Lubigi sewage treatment plant. The results show that the treatment using lime and urea reduces the level of active pathogens in the faecal sludge. The drying process in the beds at the treatment plant also decreases the level of detected pathogens in the sludge, but not to the same extent as when adding chemicals. The E. coli in the treated sludge were under the detection limit before the study period was done. Ascaris eggs were still detected in the sludge by the final sampling occasion. Further monitoring of the treated sludge might show an additional decrease of Ascaris since the time of storage after treatment enables pathogen die-off. The bacteriophages analyses only succeeded for two sampling occasions, although a decrease of detected phages is visible in the results. Again, the time of storage is significant for pathogen reduction, which is why a decrease of bacteriophages is expected if the sludge were to be further monitored. The feasibility of the two treatment methods is mainly restricted by costs. Lime treatment is approximately seven times more expensive than urea treatment and is also required in a larger amount to treat the sludge. On the other hand, using lime to treat faecal sludge is a proven and effective method. Further studies would improve the knowledge of the sludge characteristics at Lubigi and help determine the most preferable treatment for the sludge to protect the environment and public health. For example, by focusing on one treatment method, more detailed information can be gathered, and if performing a study in a larger scale, the representativeness would increase. To make sure there is no risk of spreading pathogens to the environment, further analyses should be carried out directly before selling the sludge to farmers.

Sex chromosomes represent a unique part of the genome in many eukaryotic organisms. They differ significantly from autosomes by their evolution, specific features, and meiotic behaviour. Recent advances in the knowledge of sex chromosomes in non-model organisms have been largely enabled by modern cytogenetic methods. The present study explores several topics related to sex chromosomes in Lepidoptera, the largest group of animals with female heterogamety, using methods of molecular cytogenetics, immunocytogenetics, and molecular biology. These topics include physical mapping of chromosomes by BAC-FISH, molecular differentiation and composition of the W chromosome, differences in the evolution of the W and Z chromosome, and meiotic sex chromosome inactivation. The results obtained brought new information not only about the W and Z chromosomes in Lepidoptera, but also about the evolution and specific features of sex chromosomes in general.