The Genetics of Inherited Cholestatic Disorders in Neonates and Infants: Evolving Challenges.

Many inherited conditions cause cholestasis in the neonate or infant. Next-generation sequencing methods can facilitate a prompt diagnosis in some of these cases; application of these methods in patients with liver diseases of unknown cause has also uncovered novel gene-disease associations and improved our understanding of physiological bile secretion and flow. By helping to define the molecular basis of certain cholestatic disorders, these methods have also identified new targets for therapy as well patient subgroups more likely to benefit from specific therapies. At the same time, sequencing methods have presented new diagnostic challenges, such as the interpretation of single heterozygous genetic variants. This article discusses those challenges in the context of neonatal and infantile cholestasis, focusing on difficulties in predicting variant pathogenicity, the possibility of other causal variants not identified by the genetic screen used, and phenotypic variability among patients with variants in the same genes. A prospective, observational study performed between 2010-2013, which sequenced six important genes (ATP8B1, ABCB11, ABCB4, NPC1, NPC2 and SLC25A13) in an international cohort of 222 patients with infantile liver disease, is given as an example of potential benefits and challenges that clinicians could face having received a complex genetic result. Further studies including large cohorts of patients with paediatric liver disease are needed to clarify the spectrum of phenotypes associated with, as well as appropriate clinical response to, single heterozygous variants in cholestasis-associated genes.

Paediatric Liver Transplantation During COVID-19 Pandemic: Lessons Learned and Unanswered Questions.

COVID-19 pandemic has imposed many challenges on paediatric liver transplantation (PLT) services and has necessitated several adaptations in different stages of the process to ensure transplant centres can still deliver the proposed services in addition to protecting patients and staff against infection. This review article digs through the current literature to clarify the challenges imposed by SARS-CoV2 on PLT centres globally. It provides an overview of current practice as well as suggestions from experts in the field to overcome multiple obstacles. In paediatrics, the reaction to SARS-CoV2 may be less severe than that seen in the adult population, but this can change in view of newly discovered virus strains. Response of transplant centres to the current pandemic was variable depending on the anticipated risk and available resources. Telemedicine has helped PLT programmes to continue their activities while protecting patients, as well as staff against the risk of SARS-CoV2 virus. Further studies are needed to guide immunosuppression management in post-transplant infected candidates; answering this critical question will help PLT centres solve this dilemma.

What is the long-term outlook for young people following liver transplant? A single-centre retrospective analysis of physical and psychosocial outcomes.

LT is a successful treatment for end-stage liver disease. The long-term outcome of patients transplanted in childhood has not previously been widely reported. This project assessed the long-term impact of transplantation in patients surviving >15 years. Retrospective data on growth, end-organ damage and psychosocial development were collected in young people transplanted from 1985 to 2000 in a single centre. Clinical notes were reviewed, and patients interviewed at clinic follow-up. 224 patients were transplanted between 1985 and 2000. 143 recipients (63.8%) survived >15 years with a median survival of 19.52 years. The majority were well, and only 10% had abnormal graft function (biochemical/synthetic), the main cause of which was chronic hepatitis (6%). Renal dysfunction and the necessity for renal transplant were identified in 32.8%, of whom 16.7% of patients had a cGFR <70 mL/min/1.73 m2 and 6% of patients had either undergone or awaiting renal transplant. This cohort was healthier than the average age-matched UK population in terms of body mass index (9% obese), smoking and alcohol consumption. 92% of patients had completed or were in education (93/123 had completed education and 20/123 remained in school). 63.7% of patients had been transitioned into adult services, and 46.3% of these patients were employed. 67.5% were in a relationship, one patient was divorced, and 10.6% of patients had one or more children. 11 patients had symptoms that corresponded to a DSM IV diagnosis of depression. Four patients had anorexia nervosa. Developmental delay was identified in 9 out of 99 patients. The development of malignancy, including PTLD, occurred in 10/143 (7%) patients at a median time post-transplant of 2.76 years (range 0.76-9.06 years). Epstein-Barr infection was implicated in 75% of these malignancies. We conclude the long-term outcome of LT in childhood is good with 63.8% surviving into adulthood and over 60% transferring into adult services. Graft dysfunction and end organ damage are minimal. Our cohort is healthier than the general population, and the majority have completed education, sought employment and formed relationships with peers, contributing well to society.

Cardiac and Liver Disease in Children: Implications for Management Before and After Liver Transplantation.

There is close interaction between the functions of the liver and heart affecting the presentation, diagnosis, and outcome of acute and chronic cardiac and liver disease. Conditions affecting both organ systems should be considered when proposing transplantation because the interaction between cardiac disease and liver disease has implications for diagnosis, management, selection for transplantation, and, ultimately, for longterm outcomes after liver transplantation (LT). The combination of cardiac and liver disease is well recognized in adults but is less appreciated in pediatric patients. The focus of this review is to describe conditions affecting both the liver and heart and how they affect selection and management of LT in the pediatric population.

Plant-pathogen interactions and elevated CO2: morphological changes in favour of pathogens.

Crop losses caused by pests and weeds have been estimated at 42% worldwide, with plant pathogens responsible for almost $10 billion worth of damage in the USA in 1994 alone. Elevated carbon dioxide [ECO(2)] and associated climate change have the potential to accelerate plant pathogen evolution, which may, in turn, affect virulence. Plant-pathogen interactions under increasing CO(2) concentrations have the potential to disrupt both agricultural and natural systems severely, yet the lack of experimental data and the subsequent ability to predict future outcomes constitutes a fundamental knowledge gap. Furthermore, nothing is known about the mechanistic bases of increasing pathogen agressiveness. In the absence of information on crop species, it is shown here that plant pathogen (Erysiphe cichoracearum) aggressiveness is increased under ECO(2), together with changes in the leaf epidermal characteristics of the model plant Arabidopsis thaliana L. Stomatal density, guard cell length, and trichome numbers on leaves developing post-infection are increased under ECO(2) in direct contrast to non-infected responses. As many plant pathogens utilize epidermal features for successful infection, these responses provide a positive feedback mechanism facilitating an enhanced susceptibility of newly developed leaves to further pathogen attack. Furthermore, a screen of resistant and susceptible ecotypes suggest inherent differences in epidermal responses to ECO(2).

Abrogation of the S phase DNA damage checkpoint results in S phase progression or premature mitosis depending on the concentration of 7-hydroxystaurosporine and the kinetics of Cdc25C activation.

DNA damage causes cell cycle arrest in G(1), S, or G(2) to prevent replication on damaged DNA or to prevent aberrant mitosis. The G(1) arrest requires the p53 tumor suppressor, yet the topoisomerase I inhibitor SN38 induces p53 after the G(1) checkpoint such that the cells only arrest in S or G(2). Hence, SN38 facilitates comparison of p53 wild-type and mutant cells with regard to the efficacy of drugs such as 7-hydroxystaurosporine (UCN-01) that abrogate S and G(2) arrest. UCN-01 abrogated S and G(2) arrest in the p53 mutant breast tumor cell line MDA-MB-231 but not in the p53 wild-type breast line, MCF10a. This resistance to UCN-01 in the p53 wild-type cells correlated with suppression of cyclins A and B. In the p53 mutant cells, low concentrations of UCN-01 caused S phase cells to progress to G(2) before undergoing mitosis and death, whereas high concentrations caused rapid premature mitosis and death of S phase cells. UCN-01 inhibits Chk1/2, which should activate the mitosis-inducing phosphatase Cdc25C, yet this phosphatase remained inactive during S phase progression induced by low concentrations of UCN-01, probably because Cdc25C is also inhibited by the constitutive kinase, C-TAK1. High concentrations of UCN-01 caused rapid activation of Cdc25C, which is attributed to inhibition of C-TAK1, as well as Chk1/2. Hence, UCN-01 has multiple effects depending on concentration and cell phenotype that must be considered when investigating mechanisms of checkpoint regulation.