Synchronized in vivo measurements of skin hydration and trans-epidermal water loss. Exploring their mutual influences.

OBJECTIVE: To explore the relationship between skin surface hydration and Trans-Epidermal Water Loss (TEWL) when simultaneously measured. METHODS: Six circular skin areas of the forearms (3 per forearm, 3 cm in diameter) of 12 Caucasian women were used as models. 4 prototypes of formulae of different compositions containing glycerol at different concentrations 7%, 10% and 40% were used as models of hydrating products. One formula (glycerol-free) was used as control vehicle. Standardized applications of formulae (2 mg/cm2 ) were performed on 5 skin sites chosen at random, the other being left as bare/control. A recently marketed instrumental device that records the skin surface hydration and TEWL on a small skin area in a simultaneous manner was used. Measurements were carried out at T0 (pre-application), at 1 h (T1) and 5 h (T5) post applications on two close sites within the 6 defined areas of both forearms. RESULTS: The new instrumental device allowed to clearly differentiate the 5 formulae (i.e. 7% vs. 10%) with regard the dose effect brought by glycerol (7%, 10%, 40%) and to record their lingering effects at T1 and T5. Both parameters were found significantly and negatively correlated, i.e. the higher the skin hydration, the lower the TEWL. The 40% concentration of glycerol, that leads to the highest skin hydration, brings a drop in the TEWL by about a two-fold factor. Skin hydration of bare skin and control/vehicle sites showed minor and non-significant changes along 5 h. Instead, the control/ vehicle slowed down the TEWL to a slight extent. CONCLUSION: The use of this new instrumental device shed a new light on the mutual and inverse relationships between skin hydration and TEWL. Results suggest that, at high concentration, glycerol leads to largely increase the water content of both epidermal and dermal compartments, possibly leading to structural changes in the skin relief.

OBJECTIF: D'explorer les relations mutuelles entre l'hydratation cutanée et la perte insensible en eau (PIE) quand elles sont mesurées simultanément. MÉTHODES: 6 zones circulaires des avant-bras (3 par zone, diamètre 3 cm) de 12 femmes Caucasiennes ont été utilisées comme modèles. 4 prototypes de formules, de compositions différentes contenant du glycérol à différentes concentrations (7%, 10%, 40%) furent réalisés et utilisés comme modèles de produits hydratants. Une formule sans glycérol fut utilisée en tant que contrôle. Des applications standardisées (2 mg/cm2 ) ont été effectuées sur 5 zones de façon aléatoire, la sixième restant nue en tant que contrôle. Un appareil nomade récemment disponible sur le marché qui enregistre l'hydratation et la PIE simultanément sur une petite surface cutanée a été utilisé. Deux mesures à deux endroits voisins de chaque zone ont été conduites à T0 (avant applications), 1 heure (T1) et 5 heures (T5) après. RÉSULTATS: Ce nouvel instrument permet de clairement différencier les 5 formules dans l'effet dose apporté par le glycérol (0, 7%, 10%, 40%) et de suivre leur rémanence dans le temps (T5 vs. T1). Les deux paramètres ont été trouvés négativement corrélés de manière significative, c'est-à-dire qu'une plus forte hydratation correspondant à une plus faible PIE. La formule à 40% de glycérol, qui a conduit à la plus forte hydratation, a ainsi entrainé une chute de la PIE d'environ 50%. La peau nue comme celle de la formule contrôle n'ont pas conduit à de modifications notables et significatives de l'hydratation. La formule contrôle a conduit à une légère chute de la PIE. CONCLUSION: L'utilisation de ce nouvel instrument semble apporter un éclairage nouveau sur les relations mutuelles (et inverses) entre l'hydratation cutanée et la PIE. Les résultats suggèrent qu'à forte concentration, le glycérol conduit à un fort accroissement de la teneur en eau de l'épiderme et du derme, avec de possibles conséquences structurelles du relief cutané.

Clostridium difficile forms variable biofilms on abiotic surface.

Clostridium difficile can form biofilms. Thirty-seven strains were characterized for their ability to form a biofilm, adhesion on an inert surface and hydrophobicity. No correlation between the ability to form a biofilm and the strain virulence was highlighted. However, non-motile strains were not able to form a high biofilm.

Advances in the study of transmissible respiratory tumours in small ruminants.

Sheep and goats are widely infected by oncogenic retroviruses, namely Jaagsiekte Sheep RetroVirus (JSRV) and Enzootic Nasal Tumour Virus (ENTV). Under field conditions, these viruses induce transformation of differentiated epithelial cells in the lungs for Jaagsiekte Sheep RetroVirus or the nasal cavities for Enzootic Nasal Tumour Virus. As in other vertebrates, a family of endogenous retroviruses named endogenous Jaagsiekte Sheep RetroVirus (enJSRV) and closely related to exogenous Jaagsiekte Sheep RetroVirus is present in domestic and wild small ruminants. Interestingly, Jaagsiekte Sheep RetroVirus and Enzootic Nasal Tumour Virus are able to promote cell transformation, leading to cancer through their envelope glycoproteins. In vitro, it has been demonstrated that the envelope is able to deregulate some of the important signaling pathways that control cell proliferation. The role of the retroviral envelope in cell transformation has attracted considerable attention in the past years, but it appears to be highly dependent of the nature and origin of the cells used. Aside from its health impact in animals, it has been reported for many years that the Jaagsiekte Sheep RetroVirus-induced lung cancer is analogous to a rare, peculiar form of lung adenocarcinoma in humans, namely lepidic pulmonary adenocarcinoma. The implication of a retrovirus related to Jaagsiekte Sheep RetroVirus is still controversial and under investigation, but the identification of an infectious agent associated with the development of lepidic pulmonary adenocarcinomas might help us to understand cancer development. This review explores the mechanisms of induction of respiratory cancers in small ruminants and the possible link between retrovirus and lepidic pulmonary adenocarcinomas in humans.

Pleiotropic role of the RNA chaperone protein Hfq in the human pathogen Clostridium difficile.

Clostridium difficile is an emergent human pathogen and the most common cause of nosocomial diarrhea. Our recent data strongly suggest the importance of RNA-based mechanisms for the control of gene expression in C. difficile. In an effort to understand the function of the RNA chaperone protein Hfq, we constructed and characterized an Hfq-depleted strain in C. difficile. Hfq depletion led to a growth defect, morphological changes, an increased sensitivity to stresses, and a better ability to sporulate and to form biofilms. The transcriptome analysis revealed pleiotropic effects of Hfq depletion on gene expression in C. difficile, including genes encoding proteins involved in sporulation, stress response, metabolic pathways, cell wall-associated proteins, transporters, and transcriptional regulators and genes of unknown function. Remarkably, a great number of genes of the regulon dependent on sporulation-specific sigma factor, SigK, were upregulated in the Hfq-depleted strain. The altered accumulation of several sRNAs and interaction of Hfq with selected sRNAs suggest potential involvement of Hfq in these regulatory RNA functions. Altogether, these results suggest the pleiotropic role of Hfq protein in C. difficile physiology, including processes important for the C. difficile infection cycle, and expand our knowledge of Hfq-dependent regulation in Gram-positive bacteria.

Rapid diagnosis of Clostridium difficile infection by multiplex real-time PCR.

The gold standards for the diagnosis of Clostridium difficile infections (CDIs) are the cytotoxicity assay and the toxigenic culture. However, both methods are time-consuming and the results are not available before 24-48 h. We developed and evaluated a multiplex in-house real-time polymerase chain reaction (PCR) assay for the simultaneous detection of toxigenic strains of C. difficile and the presumptive identification of the epidemic NAP1/027/BI strain from stools. Amplifications were performed using specific primers for tcdB and tcdC on an ABI Prism 7300 (Applied Biosystems). The detection of amplicons was done using TaqMan probes. The analytical sensitivity of the multiplex real-time PCR for detecting tcdB was estimated to 10 CFU/g of stools. This assay was assessed from 881 consecutive unformed stools from patients suspected of having CDI. The gold standard was the toxigenic culture for the diagnosis of CDI and PCR ribotyping for the identification of the NAP1/027/BI strain. The prevalence of positive toxigenic culture was 9.31%. Compared to the toxigenic culture, the sensitivity, specificity, and positive and negative predictive values were 86.59%, 97.43%, 78.02%, and 98.57%, respectively, for the real-time PCR and 70.73%, 100%, 100%, and 97.08%, respectively, for the cytotoxicity assay.

Effect of serial subculturing on the genetic composition and cytotoxic activity of Mycobacterium tuberculosis.

Continuous subculture has been observed to produce changes in the virulence of micro-organisms, e.g. rabies virus, poliovirus and Mycobacterium bovis BCG. The latter has been used as a vaccine for tuberculosis for the last 100 years; however, in some instances its efficacy has been observed to be very low. In order to determine whether similar changes can be produced in Mycobacterium tuberculosis, we selected four isolates, M. tuberculosis H37Rv, a Beijing strain (DR-689), and two more isolates with deletion of the phospholipase C locus (plcA-plcB-plcC ), and subjected them to serial culturing on Middlebrook 7H9 medium, with or without ox bile. After 100 passages, we performed RFLP-IS6110 analysis to determine whether genomic changes were produced. We also checked their genomic composition by microarray analysis. Changes in virulence were studied by measuring the cytotoxic effect of parental and subcultured isolates on a THP-1 macrophage monolayer. The most visible change was the change of position of an IS6110 band of approximately 1400 bp to approximately 1600 bp in the Beijing isolate subcultured in the ox bile medium. Analysis by microarray and PCR confirmation did not reveal any genomic changes. Cytotoxic activity was decreased in the isolates at levels close to that of BCG, and more consistently in those subcultured in the presence of ox bile.

In vivo epidermal thickness measurement: ultrasound vs. confocal imaging.

BACKGROUND/PURPOSE: In this study, in vivo skin imaging methods, ultrasound (US) and confocal microscopy (CM) were compared with regards to their accuracy in measuring the epidermal thickness. In addition an attempt was made to clarify the biological significance of the second echo-rich line observed on US skin images, i.e. whether it represents the dermal-epidermal junction or the papillar-reticular dermis limit. METHODS: US images were obtained with an in-house device (22 MHz probe) and the CM images with the VivaScope 1000 (Lucid Inc., Rochester, NY, USA). Skin from the dorsal forearm, the back of hand and the palm skin of 11 subjects (25-40 years) were examined. Repeatability of the procedure and reproducibility of the results were evaluated on repeated measurements taken at 1-month interval. RESULTS: Both techniques are correlated. When a CM measurement is performed from the stratum corneum (SC) surface to the bottom of the papillae, results obtained with US and CM are very similar. Thus, the second echo-rich line on US skin imaging is likely to reflect a virtual line joining the bottom of the papillae. CM is limited to the measurement of a relative thin epidermis, due to the signal-to-noise ratio, which decreases with depth. US technique offers a better repeatability and reproducibility, particularly for SC measurement. This is mainly due to the small size of the investigated field of view in CM. CONCLUSIONS: This study confirms the accuracy of US and the feasibility of CM imaging techniques for in vivo epidermal thickness measurement. Echography probably measures a maximal epidermal thickness since it encompasses the bottom of the papillae.