An Evaluation of Ischaemic Preconditioning as a Method of Reducing Ischaemia Reperfusion Injury in Liver Surgery and Transplantation

Liver Ischaemia Reperfusion (IR) injury is a major cause of post-operative liver dysfunction, morbidity and mortality following liver resection surgery and transplantation. There are no proven therapies for IR injury in clinical practice and new approaches are required. Ischaemic Preconditioning (IPC) can be applied in both a direct and remote fashion and has been shown to ameliorate IR injury in small animal models. Its translation into clinical practice has been difficult, primarily by a lack of knowledge regarding the dominant protective mechanisms that it employs. A review of all current studies would suggest that IPC/RIPC relies on creating a small tissue injury resulting in the release of adenosine and l-arginine which act through the Adenosine receptors and the haem-oxygenase and endothelial nitric oxide synthase systems to reduce hepatocyte necrosis and improve the hepatic microcirculation post reperfusion. The next key step is to determine how long the stimulus requires to precondition humans to allow sufficient injury to occur to release the potential mediators. This would open the door to a new therapeutic chapter in this field

Determinate or indeterminate growth? Revisiting the growth strategy of sea turtles

This is the author's accepted manuscript.The final version is available from Inter Research via the DOI in this record.Traditionally, growth can be either determinate, ceasing during the natural lifespan of individuals, or indeterminate, persisting throughout life. Although indeterminate growth is a widely accepted strategy and believed to be ubiquitous among long-lived species, it may not be as common as previously thought. Sea turtles are believed to be indeterminate growers despite the paucity of long-term studies into post-maturity growth. In this study, we provide the first temporal analysis of post-maturity growth rates in wild living sea turtles, using 26 yr of data on individual measurements of females nesting in Cyprus. We used generalised additive/linear mixed models to incorporate multiple growth measurements for each female and model post-maturity growth over time. We found post-maturity growth to persist in green Chelonia mydas and loggerhead Caretta caretta turtles, with growth decreasing for approximately 14 yr before plateauing around zero for a further decade solely in green turtles. We also found growth to be independent of size at sexual maturity in both species. Additionally, although annual growth and compound annual growth rates were higher in green turtles than in loggerhead turtles, this difference was not statistically significant. While indeterminate growth is believed to be a key life-history trait of ectothermic vertebrates, here, we provide evidence of determinate growth in green and loggerhead turtles and suggest that determinate growth is a life-history trait shared by cheloniid species. Our results highlight the need for long-term studies to refine life-history models and further our understanding of ageing and longevity of wild sea turtles for conservation and management.Fieldwork was supported by the British Associate of Tortoise Keepers, British Chelonia Group, British High Commission in Cyprus, British Residents Society, Carnegie Trust for the Universities of Scotland, Darwin Initiative, Erwin Warth Foundation, Friends of SPOT, Glasgow Uni versity Court, Kuzey Kıbrıs Turkcell, MEDASSET UK, and Natural Environment Research Council

Reliability and Accuracy of Clinical Assessment and Digital Image Analysis for Steatosis Evaluation in Discarded Human Livers

Background Accurate assessment of steatosis in procured livers is crucial to reduce the poor outcome associated with high-grade steatosis and to optimize the utilization of donor grafts. Clinical examination and digital image analysis (DIA) have been used for steatosis evaluation, but the validity of these methods is debated. This study aimed to compare these methods with standard histology for assessment of steatosis severity in human livers and to evaluate a revised classification system for automated fat measurement. Methods Clinical assessment of liver steatosis at time of retrieval and automated measurement were compared with standard histology in paraffinized and hematoxylin and eosin–stained slides, using a 4-grade scale for ordinal data and percentages for numerical values. Results Analysis of 42 human livers that were retrieved but not transplanted showed that clinical examination was not reliable for assigning steatosis grades (κw, 0.12; 95% CI, −0.06 to 0.30), overestimated steatosis severity, and had an accuracy of 67% for discriminating low- and high-grade steatosis. Digital image analysis had a substantial agreement on absolute fat percentage (intraclass correlation coefficient, 0.76; 95% CI, 0.63–0.84) and steatosis grades (κw, 0.70; 95% CI, 0.57–0.82), with 88% accuracy using the revised classification system. Conclusions Clinical assessment of steatosis is inaccurate, and relying on this method alone could result in unnecessary discard of livers. Digital image analysis is feasible with higher accuracy and reliability, but further clinical studies are required to evaluate its clinical validity

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in predicting acute kidney injury following orthotopic liver transplantation: A systematic review

Background: Acute kidney injury (AKI) is common after orthotopic liver transplantation (OLT) usually occurring early post-transplant. Multiple causes include graft preservation injury, blood loss, hypotension but also severity of recipient liver disease. Early intervention in AKI has both short and long term patient benefits. Unfortunately there are no current clinical biomarkers of early AKI. Aim: To assess the value of NGAL in predicting AKI following OLT. Methods: Ovid MEDLINE and EMBASE were searched between the years of 2000 and 2017 for studies using keywords: Neutrophil Gelatinase Associated Lipocalin or NGAL variants combined with synonyms for liver transplantation. Results: 96 studies were identified. 11 studies including 563 patients were considered suitable for analysis. Both urinary (uNGAL) and plasma NGAL (pNGAL) measurement were found to predict AKI after liver transplantation. Optimal reported area under the receiver-operator characteristics curve (AUROC) values of 0.5–0.83 and 0.54–0.86 respectively. Conclusions: NGAL is a good predictor of early AKI post OLT although there is considerable variation in the published results. Further studies with prospectively defined cut-off values, standardized definitions of AKI and rigorous data reporting should be conducted to establish its clinical usefulness and limitations

Cryoprotectants: A review of the actions and applications of cryoprotective solutes that modulate cell recovery from ultra-low temperatures

Cryopreservation has become a central technology in many areas of clinical medicine, biotechnology, and species conservation within both plant and animal biology. Cryoprotective agents (CPAs) invariably play key roles in allowing cells to be processed for storage at deep cryogenic temperatures and to be recovered with high levels of appropriate functionality. As such, these CPA solutes possess a wide range of metabolic and biophysical effects that are both necessary for their modes of action, and potentially complicating for cell biological function. Early successes with cryopreservation were achieved by empirical methodology for choosing and applying CPAs. In recent decades, it has been possible to assemble objective information about CPA modes of action and to optimize their application to living systems, but there still remain significant gaps in our understanding. This review sets out the current status on the biological and chemical knowledge surrounding CPAs, and the conflicting effects of protection versus toxicity resulting from the use of these solutes, which are often required in molar concentrations, far exceeding levels found in normal metabolism. The biophysical properties of CPAs that allow them to facilitate different approaches to cryogenic storage, including vitrification, are highlighted. The topics are discussed with reference to the historical background of applying CPAs, and the relevance of cryoprotective solutes in natural freeze tolerant organisms. Improved cryopreservation success will be an essential step in many future areas such as regenerative medicine, seed banking, or stem cell technology. To achieve this, we will need to further improve our understanding of cryobiology, where better and safer CPAs will be key requirements

The effect of thermal variance on the phenotype of marine turtle offspring.

PublishedJournal ArticleTemperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.We thank all the volunteers of the Marine Turtle Conservation Project (northern Cyprus) who aided in data collection during the 2011/2012 nesting seasons. This work would not have been possible without the Society for the Protection of Turtles (SPOT) and the Department for Environmental Protection. For their continued support we thank the British Chelonia Group, the British High Commission, the British Resident’s Society, Ektam Kıbrıs, Erwin Warth Foundation, Friends of SPOT, Gemini Dataloggers (UK), and Kuzey Kıbrıs Turkcell

Shelf life: Neritic habitat use of a turtle population highly threatened by fisheries

This is the final version. Available on open access from Wiley via the DOI in this recordAim: It is difficult to mitigate threats to marine vertebrates until their habitat use is understood. We report on a decade of satellite tracking loggerhead turtles (Caretta caretta) from an important nesting site to determine priority habitats for their protection in a region where they are known to be heavily impacted by fisheries. Location: Cyprus, Eastern Mediterranean. Method: We tracked 27 adult female loggerheads between 2001 and 2012 from North Cyprus nesting beaches. To eliminate potential biases, we included females nesting on all coasts of our study area, at different periods of the nesting season and from a range of size classes. Results: Foraging sites were distributed over the continental shelf of Cyprus, the Levant and North Africa, up to a maximum distance of 2100 km from nesting sites. Foraging sites were clustered in (1) near-shore waters of Cyprus and Syria, (2) offshore waters of Egypt and (3) offshore and near-shore regions of Libya and Tunisia. The North Cyprus and west Egypt/east Libyan coasts are important areas for loggerhead turtles during migration. Movement patterns within foraging sites strongly suggest benthic feeding in discrete areas. Early nesters visited other rookeries in Turkey, Syria and Israel where they likely laid further clutches. Tracking suggests minimum annual mortality of 11%, comparable to other fishery-impacted loggerhead populations. Main conclusions: This work further highlights the importance of neritic habitats of Libya and Tunisia as areas likely used by loggerhead turtles from many of the Mediterranean rookeries and where the threat of fisheries bycatch is high. Our tracking data also suggest that anthropogenic mortalities may have occurred in North Cyprus, Syria and Egypt; all within near-shore marine areas where small-scale fisheries operate. Protection of this species across many geopolitical units is a major challenge and documenting their distribution is an important first step.Peoples Trust for Endangered SpeciesBritish Chelonia GroupUnited States Agency for International DevelopmentBP EgyptApacheNatural Environment Research Council (NERC)Erwin Warth FoundationKuzey Kıbrıs TurkcellEktam KıbrısSEATURTLE.orgMEDASSETDarwin InitiativeBritish High Commission in CyprusBritish Residents Society of North CyprusMarine Turtle Conservation ProjectMarine Turtle Research GroupSociety for the Protection of Turtles in North Cyprus (SPOT)North Cyprus Department of Environmental Protectio

Defining conservation units with enhanced molecular tools to reveal fine scale structuring among Mediterranean green turtle rookeries

This is the final version. Available on open access from Elsevier via the DOI in this recordData accessibility: the data associated with this article is avaiable in the Dryad Digital Repository: https://datadryad.org/stash/dataset/doi:10.5061/dryad.7db01Understanding the connectivity among populations is a key research priority for species of conservation concern. Genetic tools are widely used for this purpose, but the results can be limited by the resolution of the genetic markers in relation to the species and geographic scale. Here, we investigated natal philopatry in green turtles (Chelonia mydas) from four rookeries within close geographic proximity (~200 km) on the Mediterranean island of Cyprus. We genotyped hypervariable mtSTRs, a mtDNA control region sequence (CR) and 13 microsatellite loci to genetically characterise 479 green turtles using markers with different modes of inheritance. We demonstrated matrilineal stock structure for the first time among Mediterranean green turtle rookeries. This result contradicts previous regional assessments and supports a growing body of evidence that green turtles exhibit a more precise level of natal site fidelity than has commonly been recognised. The microsatellites detected weak male philopatry with significant stock structure among three of the six pairwise comparisons. The absence of Atlantic CR haplotypes and mtSTRs amongst these robust sample sizes reaffirms the reproductive isolation of Mediterranean green turtles and supports their status as a subpopulation. A power analysis effectively demonstrated that the mtDNA genetic markers previously employed to evaluate regional stock identity were confounded by an insufficient resolution considering the recent colonisation of this region. These findings improve the regional understanding of stock connectivity and illustrate the importance of using suitable genetic markers to define appropriate units for management and conservation.Natural Environment Research Council (NERC)Ministerio de Economía y Competitividad, Spai

The importance of passive integrated transponder (PIT) tags for measuring life-history traits of sea turtles

This is the final version. Available from the publisher via the DOI in this record.Capture-mark-recapture studies rely on the identification of individuals through time, using markers or tags, which are assumed to be retained. This assumption, however, may be violated, having implications for population models. In sea turtles, individual identification is typically based on external flipper tags, which can be combined with internal passive integrated transponder (PIT) tags. Despite the extensive use of flipper tags, few studies have modelled tag loss using continuous functions. Using a 26-year dataset for sympatrically nesting green (Chelonia mydas) and loggerhead (Caretta caretta) turtles, this study aims to assess how PIT tag use increases the accuracy of estimates of life-history traits. The addition of PIT tags improved female identification: between 2000 and 2017, 53% of green turtles and 29% of loggerhead turtles were identified from PIT tags alone. We found flipper and PIT tag losses were best described by decreasing logistic curves with lower asymptotes. Excluding PIT tags from our dataset led to underestimation of flipper tag loss, reproductive periodicity, reproductive longevity and annual survival, and overestimation of female abundance and recruitment for both species. This shows the importance of PIT tags in improving the accuracy of estimates of life-history traits. Thus, estimates where tag loss has not been corrected for should be interpreted with caution and could bias IUCN Red List assessments. As such, long-term population monitoring programmes should aim to estimate tag loss and assess the impact of loss on life-history estimates, to provide robust estimates without which population models and stock assessments cannot be derived accuratel

Detecting green shoots of recovery: The importance of long-term individual-based monitoring of marine turtles

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordPopulation monitoring is an essential part of evaluating the effectiveness of management interventions for conservation. Coastal breeding aggregations of marine vertebrate species that come ashore to pup or nest provide an opportunistic window of observation into otherwise widely dispersed populations. Green turtle (Chelonia mydas) nesting on the north and west coasts of northern Cyprus has been monitored consistently and exhaustively since 1993, with an intensive saturation tagging programme running at one key site for the same duration. This historically depleted nesting population is showing signs of recovery, possibly in response to nest protection approaching two decades, with increasing nest numbers and rising levels of recruitment. Strong correlation between year-to-year magnitude of nesting and the proportion of new breeders in the nesting cohort implies that recruitment of new individuals to the breeding population is an important driver of this recovery trend. Recent changes in fishing activities may be impacting the local juvenile neritic stage, however, which may hinder this potential recovery. Individuals returning to breed after two years laid fewer clutches than those returning after three or four years, demonstrating a trade-off between remigration interval and breeding output. Average clutch frequencies have remained stable around a median of three clutches a year per female despite the demographic shift towards new nesters, which typically lay fewer clutches in their first season. We show that where local fecundity has been adequately assessed, the use of average clutch frequencies can be a reliable method for deriving nester abundance from nest counts. Index sites where individual-based monitoring is possible will be important in monitoring long-term climate driven changes in reproductive rates.European Social Fun