Estimation of the risk of Salmonella shedding by finishing pigs using a logistic model obtained from a survey

An analytic epidemiological survey was carried out in 105 French farms to identify factors associated with Salmonella shedding by finishing pigs. This study gave out a list of 7 risk factors using a logistic model. The aim of the present survey was to validate this model on a second sample of batches of pigs in order to estimate their Salmonella status. The validation study was carried out from April 2003 to August 2005 on 64 finishing pig batches distinct from those used originally to generate the logistic model. In each farm, Salmonella shedding of a batch of pigs at the end of the finishing phase was assessed using swabs as described in the analytical study. Questionnaires were filled in with the farmer to collect data related to management routines. Blood samples from10 growing and 10 finishing pigs were taken to assess sanitary risk factors: status vs Lawsonia intracellularis and Porcine Respiratory Coronavirus. Salmonella contamination status of a finishing room before loading, a further identified risk factor, was tested by environmental swabbing procedure. The estimated risk with the standard error, of Salmonella shedding was calculated using the logistic model and compared to the bacteriological Salmonella status of each batch. Several thresholds are proposed and sensitivity, specificity, positive and negative predictive values related to each cut-off value were calculated. A cut-off value of 0.34 maximised both sensitivity (76.9%) and specificity (68.6%) of the model. Whatever the threshold, the accuracy of the Salmonella non-shedding predicted status is better than the Salmonella shedding predicted status. In a bacteriological sampling programme, this model could be a useful tool to identify batches with low risk of Salmonella shedding and to focus attention on those getting a high probability for being positive

X-ray and Infrared Microanalyses of <i>Mona Lisa</i>'s Ground Layer and Significance Regarding Leonardo da Vinci's Palette

An exceptional microsample from the ground layer of Leonardo da Vinci's Mona Lisa was analyzed by high-angular resolution synchrotron X-ray diffraction and micro Fourier transform infrared spectroscopy, revealing a singular mixture of strongly saponified oil with high lead content and a cerussite (PbCO3)-depleted lead white pigment. The most remarkable signature in the sample is the presence of plumbonacrite (Pb5(CO3)3O(OH)2), a rare compound that is stable only in an alkaline environment. Leonardo probably endeavored to prepare a thick paint suitable for covering the wooden panel of the Mona Lisa by treating the oil with a high load of lead II oxide, PbO. The review of Leonardo's manuscripts (original and latter translation) to track the mention of PbO gives ambiguous information. Conversely, the analysis of fragments from the Last Supper confirms that not only PbO was part of Leonardo's palette, through the detection of both litharge (α-PbO) and massicot (β-PbO) but also plumbonacrite and shannonite (Pb2OCO3), the latter phase being detected for the first time in a historical painting.</p

Bacteriological assessment of the Salmonella status of market-aged pigs

The subclinical Salmonella enterica infection in pigs is associated with public health problems and can constitute a hindrance towards national and international trade. Many countries are starting the implementation of Salmonella national surveillance programs in pork. In spite of the increase of available data on the subject, no consensus seems to exist when assessing Salmonella status of finishing pigs

An exploratory study about contamination of pens of finishing pigs by ubiquitous Salmonella

Salmonella is one of the most common food-borne pathogens transmitted to humans and human salmonellosis is primarily caused by contaminated food. Porcine products have been identified as important food vehicles in outbreaks of salmonellosis (I, 2, 3). In France, the majority of Salmonella infected pig herds are sub-clinically infected. S. Choleraesuis does not occur and only ubiquitous serotypes are isolated (4). Sub-clinically infection is characterized by intermittent shedding of small numbers of Salmonella. In these sub-clinically infected pig herds, an infectioncontamination-infection cycle is maintained with mainly an endemic house flora of Salmonella enterica (5). When contaminated batches from these farms are processed on the slaughter line, slaughtering practices contribute to Salmonella dissemination and carcass contamination. Within batches, there is a strong correlation between the proportion of animals with Salmonella spp. in their feces and the proportion of contaminated carcasses at the end of the line (6, 7). As a result of subclinical Salmonella infection in pig herds, Salmonella contamination of pork carcasses constitutes a threat to human health. The influence of a wide range of factors on subclinical Salmonella contamination of pig farms is not well known. A good understanding of risk factors for Salmonella contamination of pig herds is an essential stake in order to avoid Salmonella spread within herds and between herds and slaughterhouses. Thus, the aim of this study was to investigate potential risk factors for the presence of ubiquitous Salmonella in the finishing sheds of farrow-to-finish farms in France

Study of Salmonella contamination of pig slurry in France

A study was carried out from April 2003 to August 2005 In 69 French pig farms to detect Salmonella contaminated pig batches and to assess the level of contamination of their slurry. In each herd, a batch of finishing pigs was included in the survey. In the selected room, Salmonella shedding was assessed using swabs method, pools of faecal material and 4 litres of slurry stored in the pit below the pigs. All samples were analysed for the presence of Salmonella enlerica in a classical bacteriological four-step protocol. Quantification of Salmonella was performed in pools of faecal material and slurry samples according to the most probable number method. Using the swabbing procedure, 20.3% of the batches tested Salmonella positive at the end of the finish1ng phase and 11 .6 % according to the pools of faeces (8/69). Quantification of Salmonella 1n faeces could be performed 1n 6 out of 8 pos1tive batches with levels ranging from 2.4 to 350 Salmonella/gram. The slurry of 11 .8% of the batches (8/68) was found to be Salmonella contaminated. A quantification was achieved in 3 of them Levels of less than 11 0 Salmonellalml were found. The study Indicates that pig slurry may be contammated by Salmonella enterica. However, the percentage of pos1tive samples was rather low and Salmonella could only be detected 1n slurry stored 1n the pit under the slatted floor of moderately or highly shedding batches. Since storage without introduction of new fresh slurry is known to reduce Salmonella surv1val, the probability of spreading the bactena in the environment IS expected to be low as far as adequate storage conditions are applied

High genetic diversity at the extreme range edge: nucleotide variation at nuclear loci in Scots pine (Pinus sylvestris L.) in Scotland

Nucleotide polymorphism at 12 nuclear loci was studied in Scots pine populations across an environmental gradient in Scotland, to evaluate the impacts of demographic history and selection on genetic diversity. At eight loci, diversity patterns were compared between Scottish and continental European populations. At these loci, a similar level of diversity (θsil=~0.01) was found in Scottish vs mainland European populations, contrary to expectations for recent colonization, however, less rapid decay of linkage disequilibrium was observed in the former (ρ=0.0086±0.0009, ρ=0.0245±0.0022, respectively). Scottish populations also showed a deficit of rare nucleotide variants (multi-locus Tajima's D=0.316 vs D=−0.379) and differed significantly from mainland populations in allelic frequency and/or haplotype structure at several loci. Within Scotland, western populations showed slightly reduced nucleotide diversity (πtot=0.0068) compared with those from the south and east (0.0079 and 0.0083, respectively) and about three times higher recombination to diversity ratio (ρ/θ=0.71 vs 0.15 and 0.18, respectively). By comparison with results from coalescent simulations, the observed allelic frequency spectrum in the western populations was compatible with a relatively recent bottleneck (0.00175 × 4Ne generations) that reduced the population to about 2% of the present size. However, heterogeneity in the allelic frequency distribution among geographical regions in Scotland suggests that subsequent admixture of populations with different demographic histories may also have played a role

Structural decoding of netrin-4 reveals a regulatory function towards mature basement membranes

Netrins, a family of laminin-related molecules, have been proposed to act as guidance cues either during nervous system development or the establishment of the vascular system. This was clearly demonstrated for netrin-1 via its interaction with the receptors DCC and UNC5s. However, mainly based on shared homologies with netrin-1, netrin-4 was also proposed to play a role in neuronal outgrowth and developmental/pathological angiogenesis via interac- tions with netrin-1 receptors. Here, we present the high-resolution structure of netrin-4, which shows unique features in comparison with netrin-1, and show that it does not bind directly to any of the known netrin-1 receptors. We show that netrin-4 disrupts laminin networks and basement membranes (BMs) through high-affinity binding to the laminin g1 chain. We hypothesize that this laminin-related function is essential for the previously described effects on axon growth promotion and angiogenesis. Our study unveils netrin-4 as a non-enzymatic extracellular matrix protein actively disrupting pre-existing BMs

Down-Regulation of Neogenin Accelerated Glioma Progression through Promoter Methylation and Its Overexpression in SHG-44 Induced Apoptosis

Dependence receptors have been proved to act as tumor suppressors in tumorigenesis. Neogenin, a DCC homologue, well known for its fundamental role in axon guidance and cellular differentiation, is also a dependence receptor functioning to control apoptosis. However, loss of neogenin has been reported in several kinds of cancers, but its role in glioma remains to be further investigated.Western blot analysis showed that neogenin level was lower in glioma tissues than in their matching surrounding non-neoplastic tissues (n = 13, p<0.01). By immunohistochemical analysis of 69 primary and 16 paired initial and recurrent glioma sections, we found that the loss of neogenin did not only correlate negatively with glioma malignancy (n = 69, p<0.01), but also glioma recurrence (n = 16, p<0.05). Kaplan-Meier plot and Cox proportional hazards modelling showed that over-expressive neogenin could prolong the tumor latency (n = 69, p<0.001, 1187.6 ± 162.6 days versus 687.4 ± 254.2 days) and restrain high-grade glioma development (n = 69, p<0.01, HR: 0.264, 95% CI: 0.102 to 0.687). By Methylation specific polymerase chain reaction (MSP), we reported that neogenin promoter was methylated in 31.0% (9/29) gliomas, but absent in 3 kinds of glioma cell lines. Interestingly, the prevalence of methylation in high-grade gliomas was higher than low-grade gliomas and non-neoplastic brain tissues (n = 33, p<0.05) and overall methylation rate increased as glioma malignancy advanced. Furthermore, when cells were over-expressed by neogenin, the apoptotic rate in SHG-44 was increased to 39.7% compared with 8.1% in the blank control (p<0.01) and 9.3% in the negative control (p<0.01).These observations recapitulated the proposed role of neogenin as a tumor suppressor in gliomas and we suggest its down-regulation owing to promoter methylation is a selective advantage for glioma genesis, progression and recurrence. Furthermore, the induction of apoptosis in SHG-44 cells after overexpression of neogenin, indicated that neogenin could be a novel target for glioma therapy