Direct assessment of skin epithelial barrier by electrical impedance spectroscopy.

BACKGROUND: Many skin and mucosal inflammatory disorders, such as atopic dermatitis, have been associated with an impaired epithelial barrier function, which allows allergens, pollutants, or microbes to enter the tissue and activate the immune response. The aim of this study was to establish a method to directly assess in vivo the epidermal barrier function by electrical impedance (EI) spectroscopy. METHODS: Mice epidermal barrier was damaged by epicutaneous application of proteases and cholera toxin and by tape stripping. EI and transepidermal water loss (TEWL) were measured before and after the application. Additionally, histological analysis, immunofluorescence staining, and RT-PCR were performed on skin biopsies to evaluate the epithelial barrier. RESULTS: A few hours after papain application, a dose-dependent reduction of EI was detected, reflecting the decreased barrier function. At the same time, an increase of TEWL was observed, with a significant negative correlation with EI, demonstrating that EI changes were directly linked to barrier defects. Twenty-four and 48 hours after the treatment, EI starts to increase to background levels, indicating tissue healing and restoration of skin barrier. Barrier disruption was confirmed by histological analysis showing an impaired stratum corneum and higher cellular infiltration after papain application. In addition, immunofluorescence staining and RT-PCR showed downregulation of molecules involved in the barrier function, such as filaggrin, occludin, and claudin-1, and mRNA levels of filaggrin, loricrin, and involucrin. Comparable results were observed after tape stripping and cholera toxin treatment. CONCLUSION: Electrical impedance spectroscopy is a rapid and reliable diagnostic tool to detect skin barrier defects.

Evidence for bystander signalling between human trophoblast cells and human embryonic stem cells.

Maternal exposure during pregnancy to toxins can occasionally lead to miscarriage and malformation. It is currently thought that toxins pass through the placental barrier, albeit bi-layered in the first trimester, and damage the fetus directly, albeit at low concentration. Here we examined the responses of human embryonic stem (hES) cells in tissue culture to two metals at low concentration. We compared direct exposures with indirect exposures across a bi-layered model of the placenta cell barrier. Direct exposure caused increased DNA damage without apoptosis or a loss of cell number but with some evidence of altered differentiation. Indirect exposure caused increased DNA damage and apoptosis but without loss of pluripotency. This was not caused by metal ions passing through the barrier. Instead the hES cells responded to signalling molecules (including TNF-α) secreted by the barrier cells. This mechanism was dependent on connexin 43 mediated intercellular 'bystander signalling' both within and between the trophoblast barrier and the hES colonies. These results highlight key differences between direct and indirect exposure of hES cells across a trophoblast barrier to metal toxins. It offers a theoretical possibility that an indirectly mediated toxicity of hES cells might have biological relevance to fetal development.

N-butyl-2-cyanoacrylate (NBCA) tissue adhesive as a haemostatic agent in a venous malformation of the mandible.

Cyanoacrylate tissue glue has many uses. We describe a case involving a 27-year-old man with a low-flow venous malformation that affected the right side of his face including the mandible. After extraction of the lower right eight, torrential haemorrhage was successfully arrested using N-butyl-2-cyanoacrylate (NBCA) glue. We think that it may be of use not only in the management of patients with vascular malformations, but also in the treatment of recalcitrant haemorrhage after dentoalveolar surgery.

Validation of virtual reality simulation for obstetric ultrasonography: a prospective cross-sectional study.

INTRODUCTION: Ultrasonography is an important skill for obstetricians and gynecologists; however, trainees have highlighted ultrasonography as an area of deficiency in their training. We undertook a prospective cross-sectional comparative study to assess content and construct validity of an ultrasound virtual reality (VR) simulator (UltraSim). METHODS: Twenty-six physicians and sonographers of varied ultrasonography experience were recruited and divided into trainees (no formal ultrasonography training) and expert (certified) categories. They performed a VR simulation crown-rump length (CRL) ultrasound scan and growth ultrasound scan measuring biparietal diameter, occipitofrontal diameter, abdominal anteroposterior and transverse diameters, and femur length. Maximum pool depth (MPD), placental site, and fetal presentation were also assessed. Outcome measures included the mean absolute deviation and the variance of the absolute deviation from true measurements. Accuracy of determining placental site, fetal presentation, and MPD was assessed. The time taken to perform each type of scan was recorded. RESULTS: Trainees had significantly greater variation of measurement of CRL (P = 0.025) than the expert group. For late-pregnancy fetal biometry, the absolute deviation and the degree of variability for all measurements differed. These differences were statistically significant (P < 0.05) for all measurements except abdominal diameters and MPD. Trainees took significantly longer time to obtain CRL and fetal biometric scans (P < 0.001). All subjects correctly identified fetal presentation and placental site. CONCLUSIONS: Clinicians with differing ultrasonography expertise showed differing skill with the UltraSim VR simulator, demonstrating construct validity for skills needed in simulation. Consideration should be given to investigating whether trainees with minimal scanning experience can improve their clinical skills and efficiency with VR simulation.

Quantification of free fetal DNA in multiple pregnancies and relationship with chorionicity.

OBJECTIVE: Free fetal DNA (ffDNA) in the maternal plasma appears to originate mainly from the trophoblast. We tested the hypothesis that ffDNA concentration is increased in multiple pregnancies where trophoblastic mass has been shown to be increased. METHODS: Quantitative real-time PCR was used to measure the plasma concentration of DYS14 in singleton and twin pregnancies with one or two male fetuses. Royston and Wright's regression method was used to relate ffDNA to gestational age in singleton controls; z-scores were calculated for the multiple pregnancy subgroups. RESULTS: Fifty-five singleton and 65 twin pregnancies (36 with one and 29 with two male fetuses) were analysed. There was significantly higher ffDNA concentration in twin pregnancies with two male fetuses compared with pregnancies with one male fetus. In cases with two male fetuses, there was no statistically significant difference between monochorionic and dichorionic pregnancies. CONCLUSIONS: There is higher ffDNA concentration in multiple pregnancies, and this must be taken into account for future quantitative ffDNA applications.