974 resultados para methods : laboratory


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"A.E.C. Contract AT(05-1)-636."

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Mode of access: Internet.

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Prepared by the National Center for Infectious Diseases, Centers for Disease Control and Prevention (CDC) in cooperation with the Pan American Health Organization (PAHO).

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At head of title: [Developmental]

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Mode of access: Internet.

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Errata leaf inserted.

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Includes bibliography.

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Mode of access: Internet.

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Mode of access: Internet.

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A working manual of clinical pathology.

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An investigation of behavioural patterns that form a basis for termite control in the Australasian region was undertaken using laboratory colonies of the subterranean termite Reticulitermes santonensis (Feytaud). The study attempted to build a picture of the behavioural elements of individuals in a colony and based on this, trophallaxis, aggression and cannibalism were investigated in detail. Preliminary study of food transmission showed that 'workers' played a major role in the distribution of food. It was found, that among factors responsible for release of trophallactic behaviour the presence of 'right odour' between participants was important. It also appeared that the role taken by individuals depended on whether they were hungry or fully fed. Antennal palpation was shown by donors and acceptors alike and this seemed to be excitatory in function. Introduction of aliens into nests elicited aggression and these aliens were often killed. Factors eliciting aggression were investigated and colony odour was found to be important. Further investigations revealed that development of colony odour was governed by genetical and environmental mechanisms. Termite response to injury and death was also governed by odour. In the case of injury either the fresh haemolymph from the wound or some component of the haemolymph evoked cannibalism. Necrophagic behaviour was found to be released by fatty acids found in the corpses. Finally, the response of colonies to nestmates carrying arsenic trioxide was investigated. It was found that living and freshly dead arsenic-carrying nestmates were treated like normal nestmates, resulting in high initial mortality. However, poisoned cadavers soon became repellant and were buried thus preventing further spread of the poison to the rest of the colony. This suggested that complete control of subterranean termites by arsenic trioxide is unlikely to be fully effective, especially in those species which are capable of developing secondary reproductives from survivors and thus rebuilding the community.

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Lipid peroxidation products like malondialdehyde, 4-hydroxynonenal and F(2)-isoprostanes are widely used as markers of oxidative stress in vitro and in vivo. This study reports the results of a multi-laboratory validation study by COST Action B35 to assess inter-laboratory and intra-laboratory variation in the measurement of lipid peroxidation. Human plasma samples were exposed to UVA irradiation at different doses (0, 15 J, 20 J), encoded and shipped to 15 laboratories, where analyses of malondialdehyde, 4-hydroxynonenal and isoprostanes were conducted. The results demonstrate a low within-day-variation and a good correlation of results observed on two different days. However, high coefficients of variation were observed between the laboratories. Malondialdehyde determined by HPLC was found to be the most sensitive and reproducible lipid peroxidation product in plasma upon UVA treatment. It is concluded that measurement of malondialdehyde by HPLC has good analytical validity for inter-laboratory studies on lipid peroxidation in human EDTA-plasma samples, although it is acknowledged that this may not translate to biological validity.

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Major food adulteration and contamination events occur with alarming regularity and are known to be episodic, with the question being not if but when another large-scale food safety/integrity incident will occur. Indeed, the challenges of maintaining food security are now internationally recognised. The ever increasing scale and complexity of food supply networks can lead to them becoming significantly more vulnerable to fraud and contamination, and potentially dysfunctional. This can make the task of deciding which analytical methods are more suitable to collect and analyse (bio)chemical data within complex food supply chains, at targeted points of vulnerability, that much more challenging. It is evident that those working within and associated with the food industry are seeking rapid, user-friendly methods to detect food fraud and contamination, and rapid/high-throughput screening methods for the analysis of food in general. In addition to being robust and reproducible, these methods should be portable and ideally handheld and/or remote sensor devices, that can be taken to or be positioned on/at-line at points of vulnerability along complex food supply networks and require a minimum amount of background training to acquire information rich data rapidly (ergo point-and-shoot). Here we briefly discuss a range of spectrometry and spectroscopy based approaches, many of which are commercially available, as well as other methods currently under development. We discuss a future perspective of how this range of detection methods in the growing sensor portfolio, along with developments in computational and information sciences such as predictive computing and the Internet of Things, will together form systems- and technology-based approaches that significantly reduce the areas of vulnerability to food crime within food supply chains. As food fraud is a problem of systems and therefore requires systems level solutions and thinking.