Wavelet decomposition and radial basis function networks for systemmonitoring

Two approaches are coupled to develop a novel collection of black box models for monitoring operational parameters in a complex system. The idea springs from the intention of obtaining multiple predictions for each system variable and fusing them before they are used to validate the actual measurement. The proposed architecture pairs the analytical abilities of the discrete wavelet decomposition with the computational power of radial basis function networks. Members of a wavelet family are constructed in a systematic way and chosen through a statistical selection criterion that optimizes the structure of the network. Network parameters are further optimized through a quasi-Newton algorithm. The methodology is demonstrated utilizing data obtained during two transients of the Monju fast breeder reactor. The models developed are benchmarked with respect to similar regressors based on Gaussian basis functions     

High compression image coding via directional filtering

A new image coding technique is presented as derived from an image decomposition into a low frequency component and many high frequency directional components. The directional filters and their properties are introduced. Then the implementation of the directional decomposition and the selection of the information to be coded are described. The combination of transform domain coding of the low frequency component and spatial domain coding of the directional components led to acceptable results with compression ratios higher than 30 to 1.     

Real-time PCR-based methods for detection of Mycobacterium avium subsp. paratuberculosis in water and milk

A real-time PCR assay for quantitative detection of Mycobacterium avium paratuberculosis has been developed. It targets and amplifies sequences from the IS900 insertion element which is specific for this bacterium, and includes an internal amplification control. The assay was tested against 18 isolates of M. avium paratuberculosis, 17 other mycobacterial strains, and 25 non-mycobacterial strains, and was fully selective. It is capable of detecting <3 genomic DNA copies with 99% probability or alternatively, using cells directly in the reaction, 12 cells can be detected with 99% probability. Using prior centrifugation, the assay was able to consistently and quantifiably detect 10(2) M. avium paratuberculosis cells in 20 ml artificially contaminated drinking water. With a simple detergent and enzymatic sample pretreatment before centrifugation and nucleic acid extraction, the assay was able to consistently detect 10(2) M. avium paratuberculosis in 20 ml artificially contaminated semi-skimmed milk. The assay will be a useful addition to the range of diagnostic tools available for the study of M. avium paratuberculosis.     

Evaluation of the Microbial Safety of Child Food of Animal Origin in Greece

Foodborne illness is a major cause of morbidity and mortality especially for children, even in the developed world. The aim of this study was to assess the microbial safety of food of animal origin intended for consumption by children in Greece. Sampling involved 8 categories of retail products and was completed with a collection of 850 samples. These were tested by PCR and/or culture for Listeria monocytogenes, Campylobacter spp., Escherichia coli O157, Salmonella spp., Cronobacter sakazakii, Brucella spp., and Mycobacterium avium subsp paratuberculosis (MAP). The number of positive results recorded collectively for the pathogens under investigation over the total number of samples tested was 3.52% and 0.12% by PCR and culture, respectively. The most frequently detected pathogen was enterohemorrhagic E. coli (1.29%) followed by Brucella (0.82%) and Listeria (0.82%). DNA belonging to MAP was detected in 0.35% of samples, which was also the percentage of positivity recorded for Campylobacter. The percentage for Salmonella was 0.12%. It can be concluded from the results that there is no indication of noncompliance for the tested food samples. However, detection of DNA belonging to pathogens that are transmissible to humans through food is indicative that constant vigilance regarding food safety is an absolute necessity.     

Validation of a Loop-Mediated Amplification/ISO 6579-Based Method for Analysing Soya Meal for the Presence of <Emphasis Type="Italic">Salmonella enterica</Emphasis>

An alternative method for detection of Salmonella spp. in animal feed, based on the use of loop-mediated amplification (LAMP) in conjunction with a standard culturing procedure, was compared with the standard ISO 6579 as reference method, using soya meal as the test matrix. In the method comparison study, the sensitivities for both the alternative and reference methods were 100 %. The relative level of detection was 1.000. Tested against 100 Salmonella and 30 non-Salmonella strains, the LAMP-based method was 99 % inclusive and 100 % exclusive. The interlaboratory trial involved ten laboratories from eight European countries, testing eight samples at three contamination levels: 0 cfu/100 g, 1–5 cfu/100 g and 14–68 cfu/100 g. The trial specificity, or percentage correct identification of uncontaminated samples, was 96.3 % for both the reference methods and the LAMP/ISO 6579 alternative method, thus demonstrating its suitability for adoption as a procedure for rapid identification of Salmonella uncontaminated soya meal.     

Development and characterization of oligonucleotide-tagged dye-encapsulating EPC/DPPG liposomes

Liposomes applications in health care include meanly their ability to carry drugs and genes inside the human body for therapeutic purposes. Nevertheless their applicability can extend far beyond and could be used as analytical tools in order to perform rapid, low-cost, sensitive and specific analyses. Their physical characteristics, such as large internal volume and extended surface area, render them ideal for these applications and specifically for improving the specificity and sensitivity of the analytical assay. The purpose of this study was to develop a simple, stable and low-cost oligonucleotide-tagged liposomal formulation consisting of EggPC and DPPG with a simple to synthesize thiol-reactive conjugate (Mal-SA) incorporated into the lipid bilayer of liposomes. The prepared liposomes, having also the water soluble dye Sulforhodamine B encapsulated in their inner cavity, were characterized in terms of their physicochemical (size, size distribution, zeta-potential, lipid content) and mechanical (morphology, rigidity) properties. The results showed that the final liposomal formulation could be used in the future as analytical tool for detecting pathogen strains of microorganism in biological milieu.     

Effects of p53 mutants derived from lung carcinomas on the p53-responsive element (p53RE) of the MDM2 gene

The present study represents a continuation of previous works in which we observed that lung carcinomas co-expressing MDM2 protein and p53 mutants (mt p53) exhibited more aggressive behaviour. In the above studies, we suggested a 'gain of function' mechanism of mt p53 proteins based on the fact that the MDM2 gene possesses a p53-responsive element (MDM2-p53RE). In this study, to prove our hypothesis, we selected 12 cases from a series of 51 bronchogenic carcinomas. In these 12 cases, we examined the ability of the expressed mt p53 to bind the MDM2-p53RE and correlated the findings with MDM2 expression. Furthermore, we constructed four of these p53 mutants and studied their transactivation properties by co-transfecting them with a reporter plasmid carrying MDM2-p53RE in the p53 null non-small-cell lung carcinoma cell line (NSCLC) H1299. We observed mutant p53 protein DNA-binding activity, which depended on the nature and the position of the amino acid substitution. The fact that the cases with DNA-binding activity were accompanied with MDM2 protein isoforms' overexpression is indicative of a 'gain of function' phenotype. This hypothesis was enforced by the findings of the transfection experiments, which revealed that certain p53 mutants enhanced the expression of the luciferase reporter gene either directly or indirectly via a dominant positive effect on the wild-type p53. In conclusion, this work is one first attempt to examine if the deregulation of the p53/MDM2 autoregulatory feedback loop is due to novel properties of certain p53 mutants in the specific environment of a subset of bronchogenic carcinomas.