Organ culture storage of pre-prepared corneal donor material for Descemet's membrane endothelial keratoplasty

Purpose To evaluate the effect of media composition and storage method on pre-prepared Descemet's membrane endothelial keratoplasty (DMEK) grafts. Methods 50 corneas were used. Endothelial wound healing and proliferation in different media were assessed using a standard injury model. DMEK grafts were stored using three methods: peeling with free scroll storage; partial peeling with storage on the stroma and fluid bubble separation with storage on the stroma. Endothelial cell (EC) phenotype and the extent of endothelial overgrowth were examined. Global cell viability was assessed for storage methods that maintained a normal cell phenotype. Results 1 mm wounds healed within 4 days. Enhanced media did not increase EC proliferation but may have increased EC migration into the wounded area. Grafts that had been trephined showed evidence of EC overgrowth, whereas preservation of a physical barrier in the bubble group prevented this. In grafts stored in enhanced media or reapposed to the stroma after trephination, endothelial migration occurred sooner and cells underwent endothelial-mesenchymal transformation. Ongoing cell loss, with new patterns of cell death, was observed after returning grafts to storage. Grafts stored as free scrolls retained more viable ECs than grafts prepared with the fluid bubble method (74.2± 3% vs 60.3±6%, p=0.04 (n=8). Conclusion Free scroll storage is superior to liquid bubble and partial peeling techniques. Free scrolls only showed overgrowth of ECs after 4 days in organ culture, indicating a viable time window for the clinical use of pre-prepared DMEK donor material using this method. Methods for tissue preparation and storage media developed for whole corneas should not be used in pre-prepared DMEK grafts without prior evaluation

Global cell-by-cell evaluation of endothelial viability after two methods of graft preparation in Descemet membrane endothelial keratoplasty

PURPOSE: To describe a novel method of global cell viability assessment for Descemet membrane endothelial keratoplasty (DMEK) and the comparison of two contemporary methods of donor tissue preparation. METHODS: DMEK transplants were prepared using two different methods: liquid bubble separation and manual peeling (n=8 each group). Samples were incubated with Hoechst, calcein-AM and ethidium homodimer prior to mounting on a curved imaging chamber. Z-stacked fluorescence microscopy images were combined to produce an in-focus global image capable of resolving all cell nuclei. Image processing software was used to define a calcein-positive live cell area, count all cell nuclei within this area and subtract ethidium-positive dead cells to derive the total viable endothelial cell count. Corrected global cell density was calculated by dividing the number of viable cells by the graft area, which had been corrected for imaging a curved surface. RESULTS: Corrected global cell density was lower than the central endothelial cell density in both groups: 85.5% of the pre-preparation central endothelial cell density in the peel group and 75.8% in the bubble group. Corrected global cell density was significantly lower in the liquid bubble separation group than in the peel group (p=0.04). CONCLUSIONS: Eye bank estimations of central endothelial cell density overestimate true cell density after graft preparation in DMEK. A peel method is less damaging and more consistent than a liquid bubble method. Cell loss correlated strongly with the degree of stromal hydration prior to bubble separation in the liquid bubble group

Concordance in diabetic foot ulcer infection

Introduction: Accurate identification of pathogens, rather than colonising bacteria, is a prerequisite for targeted antibiotic therapy to ensure optimal patient outcome in wounds, such as diabetic foot ulcers. Wound swabs are the easiest and most commonly used sampling technique but most published guidelines recommend instead removal of a tissue sample from the wound bed, which is a more complex process. The aim of this study was to assess the concordance between culture results from wound swabs and tissue samples in patients with suspected diabetic foot infection. Methods and analysis: Patients with a diabetic foot ulcer that is thought to be infected are being recruited from 25 sites across England in a cross-sectional study. The coprimary endpoints for the study are agreement between the two sampling techniques for three microbiological parameters: reported presence of likely isolates identified by the UK Health Protection Agency; resistance of isolates to usual antibiotic agents; and, the number of isolates reported per specimen. Secondary endpoints include appropriateness of the empiric antibiotic therapy prescribed and adverse events. Enrolling 400 patients will provide 80% power to detect a difference of 3% in the reported presence of an organism, assuming organism prevalence of 10%, discordance of 5% and a two-sided test at the 5% level of significance. Assumed overall prevalence is based on relatively uncommon organisms such as Pseudomonas. We will define acceptable agreement as κ>0.6. Ethics and dissemination: Concordance in diabetic foot ulcer infection (CODIFI) will produce robust data to evaluate the two most commonly used sampling techniques employed for patients with a diabetic foot infection. This will help determine whether or not it is important that clinicians take tissue samples rather than swabs in infected ulcers. This study has been approved by the Sheffield NRES Committee (Ref:11/YH/0078) and all sites have obtained local approvals prior starting recruitment. Study registration: NRES Ref:11/YH/0078, UKCRN ID:10440, ISRCTN:52608451

The Influence of Mate Choice Motivation on Non-Financial Altruism

Several studies have found that individuals are more altruistic towards potential mates than others, suggesting altruistic behavior may be a mating signal. Much of the literature focuses on financial altruism using economic games, however altruism can also comprise of non-financial acts, which this experiment examined in an attempt to replicate and refine previous findings. A study was conducted with 199 participants, who viewed both high attractive and low attractive opposite-sex images and were asked how likely they would be to altruistically share their research credits with the person in the image, whilst controlling for self-rated attractiveness. The findings suggest that both men and women were more altruistic towards pictures of high attractive than low attractive potential mating partners (Cohen’s d = 0.37). This study therefore partially replicates previous research examining the role of mate choice effects when exploring non-financial altruism

Physical Attractiveness, Altruism and Cooperation in an Ultimatum Game

Explaining cooperative tendencies through an evolutionary lens has been problematic for theorists. Traditional explanations derive from theories of reciprocity, biological markets, and more recently via partner choice and sexual selection. The sexual selection hypothesis has been tested within game-theoretic frameworks gaining empirical sup- port in explaining the evolution of altruism. Males have been found to be more altruistic towards attractive females. However, previous research has predominantly adopted a design where participants are not engaging with ‘real people’. Instead, participants make decisions when viewing images or hypothetical scenarios without visual cues. The present study aimed to investigate the sexual selection hypothesis using a face-to-face game theoretic framework. One hundred and thirty-eight participants played a 2-round ultimatum game with chocolate coins as the monetary incentive. We find, that physical attractiveness had no influence on generosity and cooperation when participants play a face-to-face ultimatum game. Instead, proposers were fair when allocating stakes, offering an average of half the endowment to responders. This study refutes the link between the sexual selection hypothesis and generosity when playing economic games with real people. Fairness appeared to drive generosity and cooperation

Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation