Epithelial restitution in 3D - Revealing biomechanical and physiochemical dynamics in intestinal organoids via fs laser nanosurgery.

Intestinal organoids represent a three-dimensional cell culture system mimicking the mammalian intestine. The application of single-cell ablation for defined wounding via a femtosecond laser system within the crypt base allowed us to study cell dynamics during epithelial restitution. Neighboring cells formed a contractile actin ring encircling the damaged cell, changed the cellular aspect ratio, and immediately closed the barrier. Using traction force microscopy, we observed major forces at the ablation site and additional forces on the crypt sides. Inhibitors of the actomyosin-based mobility of the cells led to the failure of restoring the barrier. Close to the ablation site, high-frequency calcium flickering and propagation of calcium waves occured that synchronized with the contraction of the epithelial layer. We observed an increased signal and nuclear translocation of YAP-1. In conclusion, our approach enabled, for the first time, to unveil the intricacies of epithelial restitution beyond in vivo models by employing precise laser-induced damage in colonoids.

Techniques for In Vivo Assessment of Corneal Biomechanics: Brillouin Spectroscopy and Hydration State - Quo Vadis? / Technologien zur In-vivo-Untersuchung der Biomechanik der Hornhaut: Brillouin-Spektroskopie und Hydratationszustand ­ quo vadis?

To assess the structural integrity of the cornea, non-invasive methods are needed for the local measurement of its mechanical properties. Among a number of established techniques and their associated advantages and disadvantages, Brillouin spectroscopy is still a relatively new technique, capable of determining the compressive modulus of biological tissue, specifically the cornea, in vivo. In the present paper, these various existing and developing technologies for corneal biomechanics are discussed and correlated.

Light-cell interactions in depth-resolved optogenetics.

Light as a tool in medical therapy and biological research has been studied extensively and its application is subject to continuous improvement. However, safe and efficient application of light-based methods in photomedicine or optogenetics requires knowledge about the optical properties of the target tissue as well as the response characteristics of the stimulated cells. Here, we used tissue phantoms and a heart-like light-sensitive cell line to investigate optogenetic stimulation through tissue layers. The input power necessary for successful stimulation could be described as a function of phantom thickness. A model of light transmission through the tissue phantoms gives insights into the expected stimulation efficiency. Cell-type specific effects are identified that result in deviations of the stimulation threshold from the modelled predictions. This study provides insights into the complex interplay between light, tissue and cells during deep-tissue optogenetics. It can serve as an orientation for safe implementation of light-based methods in vivo.

Intern culture, internal resistance: uptake of peer review in two Australian hospital internship programs.

OBJECTIVE: To compare the uptake of peer review among interns in mandatory and voluntary peer-review programs. POPULATION: All first and second year graduates (n=105) in two Australian hospitals. MAIN OUTCOME MEASURES: Completion of peer review, and reported responses by doctors to peer review. RESULTS: Eight of sixty interns undertaking the mandated program completed all steps. In the voluntary program, none of 45 interns did so. Resistance to peer review occurred at all stages of the trial, from the initial briefing sessions to the provision of peer-review reports. DISCUSSION; Hospital internship is a critical period for the development of professional identity among doctors. We hypothesise that resistance to peer review among novice doctors reflects a complex tension between the processes underpinning the development of a group professional identity in hospital, and a managerial drive for personal reflection and accountability. Peer review may be found threatening by interns because it appears to run counter to collegiality or 'team culture'. In this study, resistance to peer review represented a low-cost strategy in which the interns' will could be asserted against management. CONCLUSION: To enhance uptake, peer review should be structured as key to clinical development, and modelled as a professional behaviour by higher-status colleagues.

Assessment of a peer review process among interns at an Australian hospital.

PURPOSE: This study considered how a peer review process could work in an Australian public hospital setting. METHOD: Up to 229 medical personnel completed an online performance assessment of 52 Junior Medical Officers (JMOs) during the last quarter of 2008. RESULTS: Results indicated that the registrar was the most suitable person to assess interns, although other professionals, including interns themselves, were identified as capable of playing a role in a more holistic appraisal system. Significant sex differences were also found, which may be worthy of further study. Also, the affirmative rather than the formative aspect of the assessment results suggested that the criteria and questions posed in peer review be re-examined. CONCLUSION: A peer review process was able to be readily implemented in a large institution, and respondents were positive towards peer review generally as a valuable tool in the development of junior medical staff.

The mini clinical evaluation exercise (mini-CEX) for assessing clinical performance of international medical graduates.

OBJECTIVE: To evaluate the feasibility, reliability and acceptability of the mini clinical evaluation exercise (mini-CEX) for performance assessment among international medical graduates (IMGs). DESIGN, SETTING AND PARTICIPANTS: Observational study of 209 patient encounters involving 28 IMGs and 35 examiners at three metropolitan teaching hospitals in New South Wales, Victoria and Queensland, September-December 2006. MAIN OUTCOME MEASURES: The reliability of the mini-CEX was estimated using generalisability (G) analysis, and its acceptability was evaluated by a written survey of the examiners and IMGs. RESULTS: The G coefficient for eight encounters was 0.88, suggesting that the reliability of the mini-CEX was 0.90 for 10 encounters. Almost half of the IMGs (7/16) and most examiners (14/18) were satisfied with the mini-CEX as a learning tool. Most of the IMGs and examiners enjoyed the immediate feedback, which is a strong component of the tool. CONCLUSION: The mini-CEX is a reliable tool for performance assessment of IMGs, and is acceptable to and well received by both learners and supervisors.