Discarded livers tested by normothermic machine perfusion in the VITTAL trial: Secondary end points and 5-year outcomes.

Normothermic machine perfusion (NMP) enables pretransplant assessment of high-risk donor livers. The VITTAL trial demonstrated that 71% of the currently discarded organs could be transplanted with 100% 90-day patient and graft survivals. Here, we report secondary end points and 5-year outcomes of this prospective, open-label, phase 2 adaptive single-arm study. The patient and graft survivals at 60 months were 82% and 72%, respectively. Four patients lost their graft due to nonanastomotic biliary strictures, one caused by hepatic artery thrombosis in a liver donated following brain death, and 3 in elderly livers donated after circulatory death (DCD), which all clinically manifested within 6 months after transplantation. There were no late graft losses for other reasons. All the 4 patients who died during the study follow-up had functioning grafts. Nonanastomotic biliary strictures developed in donated after circulatory death livers that failed to produce bile with pH >7.65 and bicarbonate levels >25 mmol/L. Histological assessment in these livers revealed high bile duct injury scores characterized by arterial medial necrosis. The quality of life at 6 months significantly improved in all but 4 patients suffering from nonanastomotic biliary strictures. This first report of long-term outcomes of high-risk livers assessed by normothermic machine perfusion demonstrated excellent 5-year survival without adverse effects in all organs functioning beyond 1 year (ClinicalTrials.gov number NCT02740608).

MAP9/MAPH-9 supports axonemal microtubule doublets and modulates motor movement.

Microtubule doublets (MTDs) comprise an incomplete microtubule (B-tubule) attached to the side of a complete cylindrical microtubule. These compound microtubules are conserved in cilia across the tree of life; however, the mechanisms by which MTDs form and are maintained in vivo remain poorly understood. Here, we identify microtubule-associated protein 9 (MAP9) as an MTD-associated protein. We demonstrate that C. elegans MAPH-9, a MAP9 homolog, is present during MTD assembly and localizes exclusively to MTDs, a preference that is in part mediated by tubulin polyglutamylation. We find that loss of MAPH-9 causes ultrastructural MTD defects, including shortened and/or squashed B-tubules with reduced numbers of protofilaments, dysregulated axonemal motor velocity, and perturbed cilia function. Because we find that the mammalian ortholog MAP9 localizes to axonemes in cultured mammalian cells and mouse tissues, we propose that MAP9/MAPH-9 plays a conserved role in regulating ciliary motors and supporting the structure of axonemal MTDs.

MAP9/MAPH-9 supports axonemal microtubule doublets and modulates motor movement.

Microtubule doublets (MTDs) are a well conserved compound microtubule structure found primarily in cilia. However, the mechanisms by which MTDs form and are maintained in vivo remain poorly understood. Here, we characterize microtubule-associated protein 9 (MAP9) as a novel MTD-associated protein. We demonstrate that C. elegans MAPH-9, a MAP9 homolog, is present during MTD assembly and localizes exclusively to MTDs, a preference that is in part mediated by tubulin polyglutamylation. Loss of MAPH-9 caused ultrastructural MTD defects, dysregulated axonemal motor velocity, and perturbed cilia function. As we found that the mammalian ortholog MAP9 localized to axonemes in cultured mammalian cells and mouse tissues, we propose that MAP9/MAPH-9 plays a conserved role in supporting the structure of axonemal MTDs and regulating ciliary motors.

EZH2 modulates retinoic acid signaling to ensure myotube formation during development.

Sequential differentiation of presomitic progenitors into myocytes and subsequently into myotubes and myofibers is essential for the myogenic differentiation program (MDP) crucial for muscle development. Signaling factors involved in MDP are polycomb repressive complex 2 (PRC2) targets in various developmental contexts. PRC2 is active in the developing myotomes during MDP, but how it regulates MDP is unclear. Here, we found that myocyte differentiation to myotubes requires Enhancer of Zeste 2 (EZH2), the catalytic component of PRC2. We observed elevated retinoic acid (RA) signaling in the prospective myocytes in the Ezh2 mutants (E8.5-MusEzh2 ), and its inhibition can partially rescue the myocyte differentiation defect. Together, our data demonstrate a new role for PRC2-EZH2 during myocyte differentiation into myotubes by modulating RA signaling.

Donor acquired visceral leishmaniasis following liver transplantation.

Patients who undergo solid organ transplantation are at risk of opportunistic infection associated with immunosuppression. We report a case of confirmed donor derived visceral leishmaniasis (VL), in a patient following liver transplantation causing fever and pancytopenia. The diagnosis was confirmed by bone marrow biopsy, with confirmed positive donor serology, with no other route of transmission. To our knowledge, this is the first case report in the United Kingdom and Europe, of confirmed organ donor transmission of VL. This case report highlights an important consideration of donor derived infections, in the context of solid organ transplantation.

Dermal EZH2 orchestrates dermal differentiation and epidermal proliferation during murine skin development.

Skin development and patterning is dependent on factors that regulate the stepwise differentiation of dermal fibroblasts concomitant with dermal-epidermal reciprocal signaling, two processes that are poorly understood. Here we show that dermal EZH2, the methyltransferase enzyme of the epigenetic Polycomb Repressive Complex 2 (PRC2), is a new coordinator of both these processes. Dermal EZH2 activity is present during dermal fibroblast differentiation and is required for spatially restricting Wnt/ß-catenin signaling to reinforce dermal fibroblast cell fate. Later in development, dermal EZH2 regulates the expression of reticular dermal markers and initiation of secondary hair follicles. Embryos lacking dermal Ezh2 have elevated epidermal proliferation and differentiation that can be rescued by small molecule inhibition of retinoic acid (RA) signaling. Together, our study reveals that dermal EZH2 is acting like a rheostat to control the levels of Wnt/ß-catenin and RA signaling to impact fibroblast differentiation cell autonomously and epidermal keratinocyte development non-cell autonomously, respectively.

Polycomb Repressive Complex 2: a Dimmer Switch of Gene Regulation in Calvarial Bone Development.

PURPOSE OF REVIEW: Epigenetic regulation is a distinct mechanism of gene regulation that functions by modulating chromatin structure and accessibility. Polycomb Repressive Complex 2 (PRC2) is a conserved chromatin regulator that is required in the developing embryo to control the expression of key developmental genes. An emerging feature of PRC2 is that it not only allows for binary ON/OFF states of gene expression but can also modulate gene expression in feed-forward loops to change the outcome of gene regulatory networks. This striking feature of epigenetic modulation has improved our understanding of musculoskeletal development. RECENT FINDINGS: Recent advances in mouse embryos unravel a range of phenotypes that demonstrate the tissue-specific, temporal, and spatial role of PRC2 during organogenesis and cell fate decisions in vivo. Here, we take a detailed view of how PRC2 functions during the development of calvarial bone and skin. Based on the emerging evidence, we propose that PRC2 serves as a "dimmer switch" to modulate gene expression of target genes by altering the expression of activators and inhibitors. This review highlights the findings from contemporary research that allow us to investigate the unique developmental potential of intramembranous calvarial bones.

Randomized Sirolimus-based Early Calcineurin Inhibitor Reduction in Liver Transplantation: Impact on Renal Function.

BACKGROUND: The long-term use of calcineurin inhibitors (CNIs) after liver transplantation (LT) is associated with nephrotoxicity. METHODS: Five-year follow-up data were retrieved from the randomized controlled multicenter SiLVER trial. Standard CNI-based mammalian target of rapamycin-free immunosuppression (group A, n = 264) was compared with a 50% reduction of CNI and introduction of the mammalian target of rapamycin inhibitor Sirolimus (SIR) within 4-6 weeks after LT (group B, n = 261). RESULTS: Median MELD at LT was low with 10 (7-15) (group A) and 11 (8-15) (group B) in the intention-to-treat approach. CNI dose and CNI trough were reduced by 20% and 8% (group A) versus 55% and 56% (group B) at 3 months posttransplantation. Renal function was preserved at 3 months after LT in the SIR arm (estimated glomerular filtration rate 74 [57-95] versus 67 [55-85] mL/min/1.73m2 P = 0.004) but was similarly impaired thereafter compared with group A. The per protocol analysis identified LT recipients in group B with concomitant early CNI minimization and SIR treatment ≥ year 1 with significantly superior estimated glomerular filtration rate and lowest rate of chronic kidney disease (≥stage 3) from year 1 onwards until study end. Competing risk factors for renal disease (arterial hypertension, fat metabolism disorder, and hyperglycemia) were not associated with worse kidney function. CONCLUSIONS: Prevention of CNI nephrotoxicity by SIR-based early CNI minimization protects renal function only short-term after LT in the intention-to-treat analysis of this low MELD cohort. Yet, selected LT recipients compliant with early CNI minimization and SIR maintenance achieved better long-term renal outcomes compared with real-world practice.

Detonation velocity measurements with uniform fibre Bragg gratings.

In this paper we demonstrate a simple and new fibre optic technique for measuring detonation velocities using uniform fibre Bragg gratings. We compare this new system with chirped fibre Bragg grating diagnostics and show how coherent source illumination can yield spatial uncertainties below ±10 µm - a percentage error that is an order of magnitude lower than the broadband ASE methods we have tested.

Optimised Chirped Fibre Bragg Gratings for Detonation Velocity Measurements.

Over the last decade, the use of chirped fibre Bragg gratings (CFBGs) in detonation velocity experiments has been steadily increasing. In this paper, we show how CFBG design parameters-chirp-rate, reflectivity and apodisation-affect linearity in detonation velocity tests. It is found that the optimal CFBG detonation velocity probe should have a high chirp-rate, a low reflectivity and no apodisation. As a further demonstration of these findings, we measure detonation velocity with a 24 cm optimised CFBG; the longest CFBG test of this kind so far.

Detonation Velocity Measurements Using Rare-Earth Doped Fibres.

In this paper, a simple detonation velocity measurement scheme is presented, which exploits the length-dependent amplified spontaneous emission (ASE) power emitted by off-the-shelf Er-doped fibres. This measurement scheme is first calibrated using cutback tests, so that minimal processing is required between data collection and velocity readout. We then demonstrate the use of this method in an explosive cylinder test and achieve a spatial resolution of approximately ±2 mm, owing to its implementation in a helical geometry. Alongside the standard Er fibres, a specially made, high-concentration Er/Yb-doped fibre is also calibrated, which demonstrates a potential spatial resolution approaching ±20 µ m.

Liver disease in the young adult: the challenges and rewards.

Increasing numbers of children are surviving into adulthood with a diagnosis of liver disease or having undergone liver transplantation. This population presents some challenges for the adult hepatologist, and a formal transition service clearly improves outcomes for patients in this group. Evidence of ongoing neurological development in young people up to the age of 25 years exists, and understanding these physiological processes is important in overcoming some of the challenges that caring for this population presents. A well designed transition service is key to maximising potential for these patients, and should enable young people to take control of their illness and achieve their life goals.

Proximity to transplant center and outcome among liver transplant patients.

In the United States, distance from liver transplant center correlates with worsened outcomes; the effects of geography elsewhere are unassessed. We performed a national registry analysis of United Kingdom listings for liver transplantation (1995-2014) and assessed whether travel time to transplant center correlates with outcome. There were 11 188 listings assessed (8490 transplanted), with a median travel time to center of 60 minutes (range 36-86). Of the national population, 3.38 × 107 (55.1%) reside ≥60 minutes from a center, and 7.65 × 106 (12.5%) >119 minutes. After competing risk analysis, increasing travel time was associated with an increased risk of death after listing (subdistribution hazard ratios relative to <60 minutes of 1.33 for 60-119 and 1.27 for >119 minutes; P < 0.001) and reduced likelihood of transplantation or recovery (0.94 and 0.86; P < 0.001). Among those transplanted, travel time was not associated with retransplant-free survival (P = 0.532). We used our model to examine optimal placement of a new center and identify a single site with a total travel time reduction of ≈10%. Our findings of disparities in accessibility of liver transplantation showed worse outcomes following listing in those distant from their transplant center, and our description of a method to model a new center complement existing data and support similar analyses of other networks.

A tale of two cities: The genetic mechanisms governing calvarial bone development.

The skull bones must grow in a coordinated, three-dimensional manner to coalesce and form the head and face. Mammalian skull bones have a dual embryonic origin from cranial neural crest cells (CNCC) and paraxial mesoderm (PM) and ossify through intramembranous ossification. The calvarial bones, the bones of the cranium which cover the brain, are derived from the supraorbital arch (SOA) region mesenchyme. The SOA is the site of frontal and parietal bone morphogenesis and primary center of ossification. The objective of this review is to frame our current in vivo understanding of the morphogenesis of the calvarial bones and the gene networks regulating calvarial bone initiation in the SOA mesenchyme.

Stage-specific roles of Ezh2 and Retinoic acid signaling ensure calvarial bone lineage commitment.

Development of the skull bones requires the coordination of two stem progenitor populations, the cranial neural crest cells (CNCC) and head paraxial mesoderm (PM), to ensure cell fate selection and morphogenesis. The epigenetic methyltransferase, Ezh2, plays a role in skull bone formation, but the spatiotemporal function of Ezh2 between the CNCC- and PM-derived bone formation in vivo remains undefined. Here, using a temporally-inducible conditional deletion of Ezh2 in both the CNCC- and PM- derived cranial mesenchyme between E8.5 and E9.5, we find a reduction of the CNCC-derived calvarial bones and a near complete loss of the PM-derived calvarial bones due to an arrest in calvarial bone fate commitment. In contrast, deletion of Ezh2 after E9.5 permits PM-derived skull bone development, suggesting that Ezh2 is required early to guide calvarial bone progenitor commitment. Furthermore, exposure to all-trans Retinoic acid at E10.0 can mimic the Ezh2 mutant calvarial phenotype, and administration of the pan retinoic acid receptor (RAR) antagonist, BMS-453, to Ezh2 mutants partially restores the commitment to the calvarial bone lineage and PM-derived bone development in vivo. Exogenous RA signaling activation in the Ezh2 mutants leads to synergistic activation of the anti-osteogenic factors in the cranial mesenchyme in vivo. Thus, RA signaling and EZH2 can function in parallel to guide calvarial bone progenitor commitment by balancing the suppression of anti-osteogenic factors.

Portal hypertension in polycystic liver disease patients does not affect wait-list or immediate post-liver transplantation outcomes.

AIM: To establish the impact of portal hypertension (PH) on wait-list/post-transplant outcomes in patients with polycystic liver disease (PCLD) listed for liver transplantation. METHODS: A retrospective single-centre case controlled study of consecutive patients listed for liver transplantation over 12 years was performed from our centre. PH in the PCLD cohort was defined by the one or more of following parameters: (1) presence of radiological or endoscopic documented varices from our own centre or the referral centre; (2) splenomegaly (> 11 cm) on radiology in absence of splenic cysts accounting for increased imaging size; (3) thrombocytopenia (platelets < 150 × 109/L); or (4) ascites without radiological evidence of hepatic venous outflow obstruction from a single cyst. RESULTS: Forty-seven PCLD patients (F: M = 42: 5) were listed for liver transplantation (LT) (single organ, n = 35; combined liver-kidney transplantation, n = 12) with 19 patients (40.4%) having PH. When comparing the PH group with non-PH group, the mean listing age (PH group, 50.6 (6.4); non-PH group, 47.1 (7.4) years; P = 0.101), median listing MELD (PH group, 12; non-PH group, 11; P = 0.422) median listing UKELD score (PH group, 48; non-PH group, 46; P = 0.344) and need for renal replacement therapy (P = 0.317) were similar. In the patients who underwent LT alone, there was no difference in the duration of ICU stay (PH, 3 d; non-PH, 2 d; P = 0.188), hospital stay length (PH, 9 d; non-PH, 10 d; P = 0.973), or frequency of renal replacement therapy (PH, 2/8; non-PH, 1/14; P = 0.121) in the immediate post-transplantation period. CONCLUSION: Clinically apparent portal hypertension in patients with PCLD listed for liver transplantation does not appear to have a major impact on wait-list or peri-transplant morbidity.