Caenorhabditis elegans: a model to monitor bacterial air quality

<p>Abstract</p> <p>Background</p> <p>Low environmental air quality is a significant cause of mortality and morbidity and this question is now emerging as a main concern of governmental authorities. Airborne pollution results from the combination of chemicals, fine particles, and micro-organisms quantitatively or qualitatively dangerous for health or for the environment. Increasing regulations and limitations for outdoor air quality have been decreed in regards to chemicals and particles contrary to micro-organisms. Indeed, pertinent and reliable tests to evaluate this biohazard are scarce. In this work, our purpose was to evaluate the <it>Caenorhaditis elegans </it>killing test, a model considered as an equivalent to the mouse acute toxicity test in pharmaceutical industry, in order to monitor air bacterial quality.</p> <p>Findings</p> <p>The present study investigates the bacterial population in dust clouds generated during crop ship loading in harbor installations (Rouen harbor, Normandy, France). With a biocollector, airborne bacteria were impacted onto the surface of agar medium. After incubation, a replicate of the colonies on a fresh agar medium was done using a velvet. All the replicated colonies were pooled creating the "Total Air Sample". Meanwhile, all the colonies on the original plate were isolated. Among which, five representative bacterial strains were chosen. The virulence of these representatives was compared to that of the "Total Air Sample" using the <it>Caenorhaditis elegans </it>killing test. The survival kinetic of nematodes fed with the "Total Air Sample" is consistent with the kinetics obtained using the five different representatives strains.</p> <p>Conclusions</p> <p>Bacterial air quality can now be monitored in a one shot test using the <it>Caenorhaditis elegans </it>killing test.</p

An efficient system for the generation of marked genetic mutants in members of the genus Burkholderia

To elucidate the function of a gene in bacteria it is vital that targeted gene inactivation (allelic replacement) can be achieved. Allelic replacement is often carried out by disruption of the gene of interest by insertion of an antibiotic-resistance marker followed by subsequent transfer of the mutant allele to the genome of the host organism in place of the wild-type gene. However, due to their intrinsic resistance to many antibiotics only selected antibiotic-resistance markers can be used in members of the genus Burkholderia, including the Burkholderia cepacia complex (Bcc). Here we describe the construction of improved antibiotic-resistance cassettes that specify resistance to kanamycin, chloramphenicol or trimethoprim effectively in the Bcc and related species. These were then used in combination with and/or to construct a series enhanced suicide vectors, pSHAFT2, pSHAFT3 and pSHAFT-GFP to facilitate effective allelic replacement in the Bcc. Validation of these improved suicide vectors was demonstrated by the genetic inactivation of selected genes in the Bcc species Burkholderia cenocepacia and B. lata, and in the non-Bcc species, B. thailandensis

Comparative genomics of Pseudomonas fluorescens subclade III strains from human lungs

Abstract Background While the taxonomy and genomics of environmental strains from the P. fluorescens species-complex has been reported, little is known about P. fluorescens strains from clinical samples. In this report, we provide the first genomic analysis of P. fluorescens strains in which human vs. environmental isolates are compared. Results Seven P. fluorescens strains were isolated from respiratory samples from cystic fibrosis (CF) patients. The clinical strains could grow at a higher temperature (>34 °C) than has been reported for environmental strains. Draft genomes were generated for all of the clinical strains, and multi-locus sequence analysis placed them within subclade III of the P. fluorescens species-complex. All strains encoded type- II, −III, −IV, and -VI secretion systems, as well as the widespread colonization island (WCI). This is the first description of a WCI in P. fluorescens strains. All strains also encoded a complete I2/PfiT locus and showed evidence of horizontal gene transfer. The clinical strains were found to differ from the environmental strains in the number of genes involved in metal resistance, which may be a possible adaptation to chronic antibiotic exposure in the CF lung. Conclusions This is the largest comparative genomics analysis of P. fluorescens subclade III strains to date and includes the first clinical isolates. At a global level, the clinical P. fluorescens subclade III strains were largely indistinguishable from environmental P. fluorescens subclade III strains, supporting the idea that identifying strains as ‘environmental’ vs ‘clinical’ is not a phenotypic trait. Rather, strains within P. fluorescens subclade III will colonize and persist in any niche that provides the requirements necessary for growth.http://deepblue.lib.umich.edu/bitstream/2027.42/116129/1/12864_2015_Article_2261.pd

The human keratins: biology and pathology

The keratins are the typical intermediate filament proteins of epithelia, showing an outstanding degree of molecular diversity. Heteropolymeric filaments are formed by pairing of type I and type II molecules. In humans 54 functional keratin genes exist. They are expressed in highly specific patterns related to the epithelial type and stage of cellular differentiation. About half of all keratins—including numerous keratins characterized only recently—are restricted to the various compartments of hair follicles. As part of the epithelial cytoskeleton, keratins are important for the mechanical stability and integrity of epithelial cells and tissues. Moreover, some keratins also have regulatory functions and are involved in intracellular signaling pathways, e.g. protection from stress, wound healing, and apoptosis. Applying the new consensus nomenclature, this article summarizes, for all human keratins, their cell type and tissue distribution and their functional significance in relation to transgenic mouse models and human hereditary keratin diseases. Furthermore, since keratins also exhibit characteristic expression patterns in human tumors, several of them (notably K5, K7, K8/K18, K19, and K20) have great importance in immunohistochemical tumor diagnosis of carcinomas, in particular of unclear metastases and in precise classification and subtyping. Future research might open further fields of clinical application for this remarkable protein family

Réhospitalisation précoce des personnes âgées d’au moins 75 ans admises dans un service de médecine polyvalente post-urgence : taux et facteurs prédictifs

International audienceINTRODUCTION:Given the implications of rehospitalization at the individual and societal level, it seems important to identify elderly persons (EP) at risk. We analyzed the predictive factors of early rehospitalization in EP aged 75 years or more hospitalized in a medicine department.METHODS:A single-center retrospective study that included EP aged 75 years or more hospitalized in a polyvalent medical department following an emergency admission. Patients who died during the hospitalization, who had been transferred or hospitalized during the previous month, were excluded. The impact of sociodemographic, administrative and biomedical data on rehospitalization at one month was analyzed.RESULTS:A total of 319 hospitalizations were collected (mean age of patients: 84.7±5.7 years). Most lived at home (80.2%) and among these 8.4% had no home help. The rehospitalization rate was 16.3%, among which 2/3 were related to the reason for the initial hospitalization. Among the predictive factors found in the univariate analysis (male sex, multiple diseases, polypharmacy, multiple hospitalizations, cognitive disorders and calls to emergency services), only the presence of at least two previous hospitalizations in the year (odds ratio [OR]=2.10; 95% confidence interval [95%CI] [1.01-4.39]; P=0.048) and the presence of confusion without dementia (OR=3.78; IC 95% [1.09-13.06]; P=0.04) were significant. Discharge to a rehabilitation unit and increased support at home did not affect the likelihood of rehospitalization.CONCLUSION:The rehospitalization of EP is frequent and difficult to anticipate because there are few predictors and their impact is weak. The most important factors were medical: multiple hospitalizations and confusion without dementia.IntroductionCompte tenu des implications de la réhospitalisation à l’échelon individuel et sociétal, le dépistage des personnes âgées (PA) à risque apparaît fondamental. Nous avons analysé les facteurs prédictifs de réhospitalisation précoce des PA d’au moins 75 ans hospitalisées en médecine.MéthodesÉtude rétrospective monocentrique ayant inclus des PA d’au moins 75 ans hospitalisées en médecine polyvalente via le service d’accueil des urgences. Les patients décédés durant l’hospitalisation, mutés et hospitalisés le mois précédent étaient exclus. L’influence sur la réhospitalisation à un mois de données sociodémographiques, administratives et biomédicales a été analysée.RésultatsAu total, 319 hospitalisations ont été colligées (âge moyen des patients : 84,7±5,7 ans), vivant majoritairement à domicile (80,2 %) dont 8,4 % sans aidant. Le taux de réhospitalisation était de 16,3 % dont deux tiers étaient liés au motif d’hospitalisation initial. Parmi les facteurs prédictifs retrouvés en analyse univariée (sexe masculin, polypathologie, polymédication, hospitalisations multiples, troubles cognitifs et recours au Centre 15), seules la présence d’au moins deux hospitalisations dans l’année (odds ratio [OR]=2,10 ; intervalle de confiance à 95 % [IC95 %] [1,01–4,39] ; p =0,048) et l’existence d’une confusion hors démence (OR=3,78 ; IC95 % [1,09–13,06] ; p =0,04) étaient significatives. La sortie vers un service de soins de suite et réadaptation (SSR) et la majoration des aides à domicile n’influençaient pas la réhospitalisation.ConclusionLes réhospitalisations de PA sont fréquentes et difficiles à anticiper car peu d’éléments sont prédictifs et leur effet est modeste. Les facteurs les plus influents sont médicaux : hospitalisations multiples et confusion sans démence

Regulation of Pseudomonas virulence and surface interactions by eukaryotic communication messengers.

International audienc