Detection of Foodborne Pathogens by Micro-filtration using a Continuous Cell Concentrator Device

Protecting consumers from foodborne illness is an important health concern facing the food industry today. An important deficiency exposed by foodborne illness is the inability to track contaminated food back to the source in a timely manner. Although there are established methods that detect bacterial pathogen contamination, they are limited in distinguishing viable bacteria reliably and quickly. Currently, food pathogen testing requires lengthy culture steps, which many times are delayed even longer due to the lack of in-house testing labs. Typically, two to three days elapses between when the food is sampled and the test results are available. This study uses a Cell Continuous Concentration Device (C3D) to recover cells using microfiltration that have been cultured in water and food related solutions. The results of the experiment allow us to see how much we recovered from the original sample. We created a pretreatment that consisted of a surfactant (TWEEN 80) and Sodium hexametaphosphate (SHMP) which will efficiently recover cells depending on the solution being concentrated. This pretreatment recovered 60-70% of the microorganisms (Escherichia coli and Salmonella) when recovering with DI water, PBS, and chicken. The recovery rates were 20% or below before this pretreatment was put into place. The end goal is to detect a single pathogenic cell. This pretreatment will continue to be used on the vegetable wash and chicken to produce results that are more useful to the end goal. These recovery rates are increasing as new pretreatments are being discovered

Novo gênero para Loncheres grandis Wagner, 1845, com comentários taxonômicos sobre outros equimídeos arborícolas (Rodentia, Echimyidae)

A study of arboreal echimyids in Brazilian and European collections revealed a number of morphological traits supporting the recognition of Loncheres grandis Wagner, 1845, currently included in Makalata Husson, 1978, as a full genus. Our proposition of a new genus for L. grandis changed the species content of Makalata, what led us to reformulate the generic diagnosis for this genus and other arboreal echimyids as well. The new genus can be distinguished by several external characters including its color pattern, striking differences in tail pilosity, and palmar and plantar pad morphology. Osteological distinguishing traits includes the shape of nasals, the structure of the postorbital process of the zygomatic arch, petrosal morphology, the presence of a posterior maxillary foramen, the crown pattern of molariform teeth, and baculum morphology.O estudo de equimídeos arbóreos em coleções brasileiras e européias revelou diversas características morfológicas sustentando o reconhecimento de Loncheres grandis Wagner, 1845, atualmente incluído em Makalata Husson, 1978, como um gênero válido. Nossa proposta de um novo gênero para L. grandis alterou o conteúdo específico de Makalata, o que nos levou a reformular a diagnose genérica para este gênero, assim como para outros equimídeos arbóreos. O novo gênero pode ser distinguido através de várias características externas tais como seu padrão de coloração, uma notável distinção da pilosidade caudal e a morfologia das almofadas das patas anteriores e posteriores. Características osteológicas distintivas incluem a forma dos nasais, a estrutura do processo pós-orbital do arco zigomático, a morfologia do petroso, a presença de um foramen maxilar posterior, a morfologia da coroa dos dentes molariformes e a forma do báculo

Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination.

BACKGROUND: In most case control studies the hardest decision is the choice of the control group, as in the ideal control group the proportion exposed is the same as in the population that produced the cases. METHODS: A comparison of two control groups in a case control study of the efficacy of BCG revaccination. One group was selected from subjects presenting to the heath unit the case attended for routine prevention and care; the second group was selected from the neighbourhood of cases. All Health Units from which controls were selected offered BCG revaccination. Efficacy estimated in a randomized control trial of BCG revaccination was used to establish that the neighbourhood control group was the one that gave unbiased results. RESULTS: The proportion of controls with scars indicating BCG revaccination was higher among the control group selected from Health Unit attenders than among neighbourhood controls. This excess was not removed after control for social variables and history of exposure to tuberculosis, and appears to have resulted from the fact that people attending the Health Unit were more likely to have been revaccinated than neighbourhood controls, although we can not exclude an effect of other unmeasured variables. CONCLUSION: In this study, controls selected from people presenting to a Health Unit overrepresented exposure to BCG revaccination. Had the results from the HU attenders control group been accepted this would have resulted in overestimation of vaccine efficacy. When the exposure of interest is offered in a health facility, selection of controls from attenders at the facility may result in over representation of exposure in controls and selection bias

Rapid Sample Processing of Foodborne Pathogens Using Cross-Flow Microfiltration

Foodborne illnesses are a prominent issue, causing 48 million illnesses annually. The Escherichia coli O157:H7 outbreak in romaine lettuce is a recent example. The source of the pathogen was contaminated irrigation water. The most common methods for detecting foodborne pathogens involve cultivation and enrichment of food samples. The enrichment steps are time-consuming, taking 24 to 72 hours to complete. Our study aims to accelerate irrigation water sample preparation for pathogenic microorganism fast detection through cross-flow microfiltration. This is accomplished by a device called a continuous cell concentration and recovery device (C3D). The C3D uses cross-flow microfiltration in a hollow fiber module containing a polyethersulphone membrane with 0.2 µm pore size. This is small enough that the liquids and dissolved particles in the sample will be leaked out into a waste container, and any microorganisms present will be trapped. After concentration, the trapped microorganisms are returned into a sample recovery vial, effectively reducing the sample from 500 mL down to a 5-10 mL sample. Further concentration is achieved by centrifugation to a final volume of 0.5-1.0 mL. This concentrates environmental and pathogenic bacteria that may be present in a water sample to a detectable level. A C3D with four separate hollow fiber modules was developed and calibrated to further increase efficiency. Overall, this process has the potential to decrease the time needed for the sample to reach a detectable level from up to 72 hours down to just 6-8, which is within the window of a single shift of a plant

O Programa PROAMBIENTE na Transamazônica: lições aprendidas.

O objetivo desse artigo é apontar e discutir algumas lições deixadas pelo PROAMBIENTE, programa federal de apoio ao fortalecimento da agricultura familiar na Amazônia brasileira. O local de realização da pesquisa foi o polo transamazônica localizado na região de integração do Xingu, estado do Pará. Através de entrevistas aplicadas aos agricultores familiares, assim como a atores institucionais que participaram do período em que o programa esteve na região (2002 - 2006), chegou-se a um conjunto de lições que devem ser consideradas para o êxito de programas que visem o desenvolvimento rural. São elas: i. Necessidade de seleção de agricultores com real interesse e capacidade de assumir riscos; ii. Eliminação da cultura assistencialista; iii. Prioridade de atividades chaves: o caso do pagamento por serviços ambientais; iv. Utilização de uma nova abordagem do sistema produtivo; v. Assistência técnica e extensão rural com enfoque inovador; vi. Fortalecimento das organizações rurais locais; vii. Investimento na verticalização da produção; viii. O cuidado na geração de expectativas

DNA Bound Avicel Network: The Beginnings of a Self-Healing Material

Self-healing materials could potentially provide many improvements to engineering projects, including reduced maintenance and cost, and increased lifespan. It is desired to create a self-healing material proof of concept, which can then be altered for eventual application to the surfaces of small satellites with the goal of increasing material lifetimes. The intrinsic properties and abilities of DNA base pairing will be studied as a first test of proof of concept. The exploratory research reported in this short communication utilizes oxidation of small (50µm) particles of Avicel using TEMPO, followed by activation of Avicel particles via an EDC (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride) reaction. The cellulose prepared in this manner will next be reacted with short sequences of single stranded DNA (oligonucleotides) with the cellulose, although this has not yet been achieved. Complementary strands will be bound to a second aliquot of particles. The particles will be combined to test if they hybridize (bind in a directed manner), resulting in a network of Avicel particles glued together by DNA. A Malvern wet particle size instrument was used to determine zeta potential of the cellulose particles, and in the future will be used to compare the size of particles before and after chemical alterations. Colored nanoparticles will be used to dye the individual aliquots of the derivatized celluloses so that a change in color may be observed when cellulose derivatized with complimentary strands of DNA are brought in contact with each other. After washing to remove unbound particles, a change in color would be expected to occur, thus indicating binding. While this is a work in progress, key developments at this point are the experimental design, development of research hypotheses, and successful oxidation of cellulose. These experiments are part of a longer term project that is studying whether intrinsic self-healing materials are possible. Alterations in the particle and in binding sequences to be placed on the particles have potential for automobile, airline, satellites and spacecraft, military, and healthcare applications, where self-healing principles at a nano-scale would enable micro-damage to be identified and healing processes to occur