O030 Image-analysis algorithm to determine quality of cold perfusion in kidney transplantation

Introduction

Surgeon assessment of visual ‘quality of perfusion’ (QOP) influences kidney discard and predicts transplant outcome. However, this assessment is subjective and bias-prone.

We aimed to design an application utilising a smartphone camera to make this assessment objective and enhance decision making.

Methods

The QOP in photographs of backbench kidneys was graded from 1 (ideal) to 5 (very poor) by three independent surgeons. A training cohort was used to develop an image-analysis algorithm, which was validated in a separate cohort.

Results

Analysing surgeon scores of 174 kidney images revealed that inter-rater agreement was good for kidneys displaying the best (rated 1) and worst (rated 4 or 5) QOP. However, for intermediate scores inter-rater agreement was poor. Inter-rater agreement between surgeons decreased as they graded more images; as surgeons fatigued, their ability to classify images worsened. A training cohort (n=174 kidneys) was used for algorithm development. First, small regions within each image were mapped within the CEILAB colour-space, where well-perfused and poorly perfused areas show clear separation. To generate a score for each kidney these regions are compared with ideally flushed kidney tissue. Testing our algorithm (validation cohort - n=29 kidneys) revealed strong correlation between image-analysis QOP score and surgeon assessment, r=0.789 (0.587–0.899), P<0.001.

Conclusion

Surgeon inter-rater agreement on kidney QOP is low for kidneys with borderline QOP and worsens with fatigue. We provide a QOP score utilising an image-analysis algorithm, which correlates with surgeon scoring. With additional images and training this could provide an objective, numerical, point-of-care assessment of organ quality.

Take-home message

Current visual assessment of transplant organ quality is subjective and bias-prone. This body of work attempts to create a point-of-care image-analysis application to provide an objective numeric organ quality score.

O3 Ex vivo normothermic machine perfusion facilitates gymnotic delivery of RNA interference therapeutics in donor kidneys

Introduction

Normothermic machine perfusion (NMP) of donor kidneys prior to transplantation provides a platform for delivery of novel therapeutics to optimize organ quality. This includes RNA interference (RNAi) therapeutics e.g. antisense oligonucleotides (ASO) that block detrimental microRNAs. The intracellular kinetics of RNAi therapeutics are crucial for their pharmacological effect, however, it remains poorly understood. NMP provides an ideal platform to investigate this further.

Method

During NMP, human kidneys (n = 12) were treated for 6 hours with a fluorescently-labelled ASO designed to block microRNA-24-3p activity. Biopsies were taken at 0, 2, 4, and 6 hours. Kidney sections were stained with antibodies against early endosomes (Rab5), late endosomes (Rab7), RNA-induced silencing complexes (GW182) and lysosomes (LAMP2). Confocal microscopy images were obtained and co-localisation quantified using Hugyens™ software following batch deconvolution. The global transcriptomic impact of ASO therapy was also assessed using RNA sequencing.

Result

Following 2 hours of NMP, ASO was primarily found in tubular epithelial cells. Co-localisation studies revealed ASO uptake via endocytosis and endosomal sorting occurring during NMP. This was followed by cytoplasmic escape and co-localisation of ASO with GW182 proteins. This pattern of co-localisation was not seen in scrambled sequence or cold perfusion controls. RNAseq analysis revealed a decrease in inflammatory pathways and upregulation of microRNA-24-3p targets.

Discussion

This is the first study to demonstrate NMP facilitates gymnotic ASO delivery directly into the RISC, whereby, it blocks microRNA-mediated mRNA silencing and increases bioavailability of protective targets. This study highlights the capacity of NMP to re-programme gene expression in donor kidneys using RNAi therapeutics.

Take-home Message

Ex vivo normothermic machine perfusion of donor kidneys provides a unique window of opportunity prior to transplantation when we can deliver therapies to improve the quality of the organ. Novel genetic therapies designed to protect kidneys against ischemia reperfusion injury could potentially increase organ utilisation and improve post-transplant outcomes for the many patients on the kidney transplant waiting list.

O6: EARLY ANASTOMOTIC BILIARY COMPLICATIONS AFTER LIVER TRANSPLANTATION

Introduction

Biliary leaks and anastomotic strictures are common early biliary complications (EBC) following liver transplantation. However, their impact on outcomes remains controversial and poorly described.

Method

The NHS registry on adult liver transplantation between 2006 and 2017 was retrospectively reviewed (n=8304). Multiple imputations were performed to account for missing data. Adjusted regression models were used to assess predictors of EBC, and their impact on outcomes. 35 potential variables were included, and backwards stepwise selection enabled unbiased selection of variables for inclusion in final models.

Result

EBC occurred in 9.6% of patients. Adjusted cox regression revealed that EBCs have a significant and independent impact on graft survival (Leak HR=1.325; P=0.021, Stricture HR=1.514; P=0.002, Leak plus stricture HR=1.533; P=0.034) and patient survival (Leak HR=1.218; P=0.131, Stricture HR=1.578; P<0.001, Leak plus stricture HR=1.507; P=0.044). Patients with EBC had longer median hospital stay (23 versus 15 days; P<0.001) and increased chance for readmission within the first year (56% versus 32%; P<0.001). On adjusted logistic regression the following were identified as independent risk factors for development of EBC: donation following circulatory death (OR=1.280; P=0.009), accessory hepatic artery (OR=1.324; P=0.005), vascular anastomosis time in minutes (OR=1.005; P=0.032) and ethnicity ‘other’ (OR=1.838; P=0.011).

Conclusion

EBCs prolong hospital stay, increase readmission rates and are independent risk factors for diminished graft survival and increased mortality in liver transplantation. We have identified factors that increase the likelihood of EBC occurrence; further research into interventions to prevent EBCs in these at-risk groups is vital to improve liver transplantation outcomes.

Take-home message

Using a large registry database we have shown that early anastomotic biliary complications are independent risk factors for decreased graft survival and increased mortality after liver transplantation. Research into interventions to prevent biliary complications in high risk groups are essential to improve liver transplant outcomes.

Risk factors and impact of early anastomotic biliary complications after liver transplantation: UK registry analysis

Background

Biliary leaks and anastomotic strictures are common early anastomotic biliary complications (EABCs) following liver transplantation. However, there are no large multicentre studies investigating their clinical impact or risk factors. This study aimed to define the incidence, risk factors and impact of EABC.

Methods

The NHS registry on adult liver transplantation between 2006 and 2017 was reviewed retrospectively. Adjusted regression models were used to assess predictors of EABC, and their impact on outcomes.

Results

Analyses included 8304 liver transplant recipients. Patients with EABC (9·6 per cent) had prolonged hospitalization (23 versus 15 days; P < 0·001) and increased chance for readmission within the first year (56 versus 32 per cent; P < 0·001). Patients with EABC had decreased estimated 5-year graft survival of 75·1 versus 84·5 per cent in those without EABC, and decreased 5-year patient survival of 76·9 versus 83·3 per cent; both P < 0.001. Adjusted Cox regression revealed that EABCs have a significant and independent impact on graft survival (leak hazard ratio (HR) 1·344, P = 0·015; stricture HR 1·513, P = 0·002; leak plus stricture HR 1·526, P = 0·036) and patient survival (leak HR 1·215, P = 0·136, stricture HR 1·526, P = 0·001; leak plus stricture HR 1·509; P = 0·043). On adjusted logistic regression, risk factors for EABC included donation after circulatory death grafts, graft aberrant arterial anatomy, biliary anastomosis type, vascular anastomosis time and recipient model of end-stage liver disease.

Conclusion

EABCs prolong hospital stay, increase readmission rates and are independent risk factors for graft loss and increased mortality. This study has identified factors that increase the likelihood of EABC occurrence; research into interventions to prevent EABCs in these at-risk groups is vital to improve liver transplantation outcomes.

Abstract P2-09-02: Panel testing for familial breast cancer: Tension at the boundary of research and clinical care

Gene panel sequencing is revolutionizing germline risk assessment for hereditary breast cancer. Despite scant evidence supporting the role of many of these genes in breast cancer predisposition, results are often reported to families as the definitive explanation for their family history. We assessed the frequency of mutations in 18 genes commonly included in hereditary breast cancer panels among 2,000 index cases from breast cancer families and 1,997 population controls. Cases were predominantly breast cancer-affected women referred to specialized familial cancer centers (BRCA1 and BRCA2 wild-type). Controls were cancer-free women from the LifePool study (www.lifepool.org). Sequencing data were filtered for known pathogenic or novel loss of function mutations.

The frequency of pathogenic mutations in BRCA1 and BRCA2 in the control group was 0.2% (4 mutations) and 0.4% (8 mutations), respectively, which is consistent with previous indirect estimates for Caucasian populations but to our knowledge this the largest direct assessment of their prevalence.

Excluding 18 mutations identified in BRCA1 and BRCA2 among the cases and controls, a total of 69 cases (3.5%) and 26 controls (1.3%) were found to carry an "actionable mutation". PALB2 was most frequently mutated (22 cases, 3 controls), while no mutations were identified in PTEN or STK11. Among the remaining genes, loss of function mutations were rare with similar frequency between cases and controls.

The frequency of mutations in most breast cancer panel genes among individuals selected for possible hereditary breast cancer is low and in many cases similar or even lower than that observed among cancer-free population controls. While multi-gene panels can significantly aid in cancer risk management, they equally have the potential to provide clinical misinformation and harm at the individual level if the data is not interpreted cautiously.

Citation Format: Campbell IG, Thompson ER, Rowely SM, Li N, McInerny S, Devereux L, Wong-Brown MW, Trainer AH, Mitchell G, Scott RJ, James PA. Panel testing for familial breast cancer: Tension at the boundary of research and clinical care. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-09-02.

Aircraft gas turbine materials and processes

Materials and processing innovations that have been incorporated into the manufacture of critical components for high-performance aircraft gas turbine engines are described. The materials of interest are the nickel- and cobalt-base superalloys for turbine and burner sections of the engine, and titanium alloys and composites for compressor and fan sections of the engine. Advanced processing methods considered include directional solidification, hot isostatic pressing, superplastic foring, directional recrystallization, and diffusion brazing. Future trends in gas turbine technology are discussed in terms of materials availability, substitution, and further advances in air-cooled hardware.

Moral hypocrisy: appearing moral to oneself without being so

How can people appear moral to themselves when they fail to act morally? Two self-deception strategies were considered: (a) misperceive one's behavior as moral and (b) avoid comparing one's behavior with moral standards. In Studies 1 and 2 the authors documented the importance of the 2nd strategy but not the 1st. Among participants who flipped a coin to assign themselves and another participant "fairly" to tasks, even a clearly labeled coin that prevented misperception did not produce a fair result (Study 1). Inducing behavior-standard comparison through self-awareness did (Study 2). Study 3 qualified the self-awareness effect: When moral standards were not salient before acting, self-awareness no longer increased alignment of behavior with standards. Instead, it increased alignment of standards with behavior and produced less moral action. Overall, results showed 3 different faces of moral hypocrisy.

Moral hypocrisy: appearing moral to oneself without being so

How can people appear moral to themselves when they fail to act morally? Two self-deception strategies were considered: (a) misperceive one's behavior as moral and (b) avoid comparing one's behavior with moral standards. In Studies 1 and 2 the authors documented the importance of the 2nd strategy but not the 1st. Among participants who flipped a coin to assign themselves and another participant "fairly" to tasks, even a clearly labeled coin that prevented misperception did not produce a fair result (Study 1). Inducing behavior-standard comparison through self-awareness did (Study 2). Study 3 qualified the self-awareness effect: When moral standards were not salient before acting, self-awareness no longer increased alignment of behavior with standards. Instead, it increased alignment of standards with behavior and produced less moral action. Overall, results showed 3 different faces of moral hypocrisy.

Increases in number and size of osteoclasts in response to calcium or phosphorus deficiency in the rat

In this study, the two determinants of the rate of osteoclastic bone resorption, cell number and cell activity, were evaluated to characterize the response to two chronic resorptive stimuli, a calcium-deficient diet and a phosphorus-deficient diet, fed to rats for 8 days. The number of osteoclast nuclei was determined directly and the resorptive activity of osteoclasts indirectly from cell size. In our sampling site in the tibial diaphysis, there were marked increases in osteoclast layer width (i.e., cell size) and in the number of osteoclasts and osteoclast nuclei in both test groups. Also, in both test groups the increase in the number of osteoclast nuclei was greater than the increase in osteoclast width, emphasizing the importance of osteoclast stem cell activity in the resorptive response. When the data on the control and test animals were pooled, there was a strong correlation between the width of the osteoclast layer and the number of osteoclast nuclei (r = 0.87, P less than 0.001). Thus, these two resoprtive stimuli produced proportional changes in osteoclast cell number and probably activity, raising the possibility that the resorptive response is sterotyped. These results also suggest the existence of a control mechanism which coupled the proliferative activity of osteoclast stem cells and the resorptive activity of osteoclasts. Despite the fact that the rats were subjected to chronic resorptive stimuli, forming surface and the total number of osteoblasts were also increased. Moreover, in data pooled from control and test rats, there was a strong correlation between the number of osteoclast nuclei and the number of osteoblasts (r = 0.92, P less than 0.001). This implies that chronic resorptive stimuli directly or indirectly stimulate osteogenic stem cells to increase production of osteoblasts as well as osteoclasts. The observed coupling of differentiated cell number probably contributes to the established phenomenon of coupling between the rates of bone accretion and resorption.