Campylobacteriosis in Urban versus Rural Areas: A Case-Case Study Integrated with Molecular Typing to Validate Risk Factors and to Attribute Sources of Infection

Campylobacter infection is a leading cause of bacterial gastroenteritis worldwide, and most clinical cases appear as isolated, sporadic infections for which the source is rarely apparent. From July 2005 to December 2007 we conducted a prospective case-case study of sporadic, domestically-acquired Campylobacter enteritis in rural versus urban areas and a prevalence study of Campylobacter in animal and environmental sources in the Eastern Townships, Quebec. Isolates were typed using Multilocus Sequence Typing (MLST) to reinforce the case-case findings and to assign a source probability estimate for each human isolate. The risk of human campylobacteriosis was 1.89-fold higher in rural than urban areas. Unconditional multivariate logistic regression analysis identified two independent risk factors associated with human Campylobacter infections acquired in rural area: occupational exposure to animals (OR = 10.6, 95% CI: 1.2–91, p = 0.032), and household water coming from a private well (OR = 8.3, 95% CI: 3.4–20.4, p<0.0001). A total of 851 C. jejuni isolates (178 human, 257 chicken, 87 bovine, 266 water, 63 wild bird) were typed using MLST. Among human isolates, the incidence rates of clonal complexes (CC) CC-21, CC-45, and CC-61 were higher in rural than urban areas. MLST-based source attribution analysis indicated that 64.5% of human C. jejuni isolates were attributable to chicken, followed by cattle (25.8%), water (7.4%), and wild birds (2.3%). Chicken was the attributable source for the majority of cases, independent of residential area, sex and age. The increased incidence in rural compared to urban areas was associated with occupational exposure to animals, particularly cattle among those aged 15–34 years, and with consumption of private well water. Both bovine and water exposure appeared to contribute to the seasonal variation in campylobacteriosis. These results provide a basis for developing public education and preventive programs targeting the risk factors identified.     

Glutathione and p53 independently mediate responses against oxidative stress in ES cells.

We have investigated the roles of the antioxidant glutathione and p53 in the response of embryonic stem (ES) cells to oxidative stress. ES cells express gammaGCS, a critical enzyme in glutathione (GSH) biosynthesis. Treatment with the pro-oxidant menadione led to elevation of GSH, a strong apoptotic response and reduced clonogenic survival. Addition of BSO, a specific gammaGCS inhibitor depleted GSH pools and prevented the menadione-induced increase in GSH, sensitizing cells to oxidative insult. Although p53 status had no bearing on either the basal levels of GSH or the menadione-induced GSH response, the levels of menadione-induced apoptosis were reduced in the absence of p53. We conclude that the pathways involving p53 and GSH act independently to protect against the deleterious effects of oxidative damage. Furthermore, the presence of an intact p53 pathway confers a long-term growth advantage post oxidative stress. Thus, in the absence of p53 ES cells bearing genotoxic damage are less likely to be propagated, suggesting that p53-dependent apoptosis acts to limit the deleterious effects of oxidative stress during early development.     

Cryo-electron microscopy of vitreous sections

Since the beginning of the 1980s, cryo-electron microscopy of a thin film of vitrified aqueous suspension has made it possible to observe biological particles in their native state, in the absence of the usual artefacts of dehydration and staining. Combined with 3-d reconstruction, it has become an important tool for structural molecular biology. Larger objects such as cells and tissues cannot generally be squeezed in a thin enough film. Cryo-electron microscopy of vitreous sections (CEMOVIS) provides then a solution. It requires vitrification of a sizable piece of biological material and cutting it into ultrathin sections, which are observed in the vitrified state. Each of these operations raises serious difficulties that have now been overcome. In general, the native state seen with CEMOVIS is very different from what has been seen before and it is seen in more detail. CEMOVIS will give its full potential when combined with computerized electron tomography for 3-d reconstruction.     

Evaluation of models for the evolution of protein sequences and functions under structural constraint

In the field of evolutionary structural genomics, methods are needed to evaluate why genomes evolved to contain the fold distributions that are observed. In order to study the effects of population dynamics in the evolved genomes we need fast and accurate evolutionary models which can analyze the effects of selection, drift and fixation of a protein sequence in a population that are grounded by physical parameters governing the folding and binding properties of the sequence. In this study, various knowledge-based, force field, and statistical methods for protein folding have been evaluated with four different folds: SH2 domains, SH3 domains, Globin-like, and Flavodoxin-like, to evaluate the speed and accuracy of the energy functions. Similarly, knowledge-based and force field methods have been used to predict ligand binding specificity in SH2 domain. To demonstrate the applicability of these methods, the dynamics of evolution of new binding capabilities by an SH2 domain is demonstrated.     

Variations of the candidate SEZ6L2 gene on Chromosome 16p11.2 in patients with autism spectrum disorders and in human populations

Background

Autism spectrum disorders (ASD) are a group of severe childhood neurodevelopmental disorders with still unknown etiology. One of the most frequently reported associations is the presence of recurrent de novo or inherited microdeletions and microduplications on chromosome 16p11.2. The analysis of rare variations of 8 candidate genes among the 27 genes located in this region suggested SEZ6L2 as a compelling candidate.

Methodology/Principal Findings

We further explored the role of SEZ6L2 variations by screening its coding part in a group of 452 individuals, including 170 patients with ASD and 282 individuals from different ethnic backgrounds of the Human Genome Diversity Panel (HGDP), complementing the previously reported screening. We detected 7 previously unidentified non-synonymous variations of SEZ6L2 in ASD patients. We also identified 6 non-synonymous variations present only in HGDP. When we merged our results with the previously published, no enrichment of non-synonymous variation in SEZ6L2 was observed in the ASD group compared with controls.

Conclusions/Significance

Our results provide an extensive ascertainment of the genetic variability of SEZ6L2 in human populations and do not support a major role for SEZ6L2 sequence variations in the susceptibility to ASD.     

Novel phenylamino acetamide derivatives as potent and selective kappa opioid receptor agonists

A novel series of phenylamino acetamide derivatives was synthesized. These amides were shown to be potent and selective kappa opioid receptor agonists.     

The manganese superoxide dismutase Ala16Val dimorphism modulates iron accumulation in human hepatoma cells

The Ala/16Val dimorphism incorporates alanine (Ala) or valine (Val) in the mitochondrial targeting sequence of manganese superoxide dismutase (MnSOD), modifying MnSOD mitochondrial import and activity. In alcoholic cirrhotic patients, the Ala-MnSOD allele is associated with hepatic iron accumulation and an increased risk of hepatocellular carcinoma. The Ala-MnSOD variant could modulate the expression of proteins involved in iron storage (cytosolic ferritin), uptake (transferrin receptors, TfR-1 and-2), extrusion (hepcidin), and intracellular distribution (frataxin) to trigger hepatic iron accumulation. We therefore assessed the Ala/Val-MnSOD genotype and the hepatic iron score in 162 alcoholic cirrhotic patients. In our cohort, this hepatic iron score increased with the number of Ala-MnSOD alleles. We also transfected Huh7 cells with Ala-MnSOD-or Val-MnSOD-encoding plasmids and assessed cellular iron, MnSOD activity, and diverse mRNAs and proteins. In Huh7 cells, MnSOD activity was higher after Ala-MnSOD transfection than after Val-MnSOD transfection. Additionally, iron supplementation decreased transfected MnSOD proteins and activities. Ala-MnSOD transfection increased the mRNAs and proteins of ferritin, hepcidin, and TfR2, decreased the expression of frataxin, and caused cellular iron accumulation. In contrast, Val-MnSOD transfection had limited effects. In conclusion, the Ala-MnSOD variant favors hepatic iron accumulation by modulating the expression of proteins involved in iron homeostasis.