ABSTRACT Several studies have demonstrated a multiphasic role for Wnt signaling during embryonic cardiogenesis and developed protocols that enrich for cardiac derivatives during in vitro differentiation of human pluripotent stem cells (hPSCs). However, few studies have investigated the role of Wnt signaling in the specification of cardiac progenitor cells (CPCs) toward downstream fates. Using transgenic mice and hPSCs, we tracked endothelial cells (ECs) that originated from CPCs expressing NKX2.5. Analysis of EC-fated CPCs at discrete phenotypic milestones during hPSC differentiation identified reduced Wnt activity as a hallmark of EC specification, and the enforced activation or inhibition of Wnt reduced or increased, respectively, the degree of vascular commitment within the CPC population during both hPSC differentiation and mouse embryogenesis. Wnt5a, which has been shown to exert an inhibitory influence on Wnt signaling during cardiac development, was dynamically expressed during vascular commitment of hPSC-derived CPCs, and ectopic Wnt5a promoted vascular specification of hPSC-derived and mouse embryonic CPCs.
Infertility is a frequent side effect of chemotherapy and/or radiotherapy and for some patients, cryopreservation of oocytes or embryos is not an option.As an alternative, an increasing number of these patients are choosing to cryopreserve ovarian tissue for autograft following recovery and remission.Despite improvements in outcomes among patients undergoing auto-transplantation of cryopreserved ovarian tissue, efficient revascularization of grafted tissue remains a major obstacle.To mitigate ischemia and thus improve outcomes in patients undergoing auto-transplantation, we developed a vascular cell-based strategy for accelerating perfusion of ovarian tissue.We describe a method for cotransplantation of exogenous endothelial cells (ExECs) with cryopreserved ovarian tissue in a mouse xenograft model.We extend this approach to employ ExECs that have been engineered to constitutively express Anti-Mullerian hormone (AMH), thus enabling sustained paracrine signaling input to ovarian grafts.Co-transplantation with ExECs increased follicular volume and improved antral follicle development, and AMHexpressing ExECs promoted retention of quiescent primordial follicles.This combined strategy may be a useful tool for mitigating ischemia and modulating follicular activation in the context of fertility preservation and/or infertility at large.
The WASH complex is highly conserved and consists of the actin nucleation promoter, WASH, and several regulatory subunits; Strumpellin, SWIP, ccdc53 and FAM21. Previously, it has been shown that WASH directs construction of actin coats on lysosomes. This actin coat is required for removal of V-ATPase complexes from lysosomal membranes, allowing neutralization and maturation to post-lysosomes. WASH null cells are blocked at the acidic lysosome stage and are thus unable to perform exocytosis.
We now show that FAM21 acts at a different step in the same pathway. FAM21 nulls are still blocked in exocytosis, but the remaining complex is functional in removal of V-ATPase, allowing progression to post-lysosome. We hypothesize that the role of FAM21 is to release the WASH complex from post-lysosome membranes in order to allow recycling back to newly formed acidic lysosomes. We have also shown that capping protein interacts with the WASH complex through FAM21, and this interaction is essential for progression to exocytosis, likely contributing to the mechanism by which FAM21 regulates and releases the WASH complex from post-lysosomal membranes.
Prognostication of patients with cirrhosis is complex, depending on more than just the severity of liver disease. Scores such as the model for end-stage liver disease (MELD) and Child Pugh can assist with prognostication, yet by focusing on physiological parameters they fail to completely capture the elements contributing to a patient's clinical status. Evidence is increasing to support an important role for physical functioning in patient outcomes. Frailty has been increasingly recognised in medical literature over recent years, including in hepatology where it is identified in nearly half of cirrhosis patients. It is a complex construct consisting of multisystemic physiological decline and increased vulnerability to stressors. Diagnosis is complicated by lack of a consensus definition and measurement tool for frailty in cirrhosis. Frailty heralds a poor prognosis, predicting increased morbidity and mortality both pre- and postliver transplant, independent of MELD score. It is thought to be reversible, with promising data supporting prehabilitation and lifestyle intervention programs. In the future, assessment of patients with cirrhosis is likely to incorporate a measure of frailty, however, further research is required.
Aflatoxin (2.5ug/g diet) was fed to broiler chicks for 24-26 days in five separate feeding trials in which the effects of supplementary choline, folate, threonine, lysine, and lysine plus arginine were examined. Weight gain, feed intake, feed conversion, and hepatic lipid responded in a manner typical for aflatoxicosis. Plasma concentrations of LDH, taurine, tyrosine, phenylalanine, arginine, ornithine, citrulline, glutamine, ammonia and perhaps BUN were increased in response to aflatoxin, while plasma levels of threonine, lysine, total protein, albumin/globulin (A/G) ratio, uric acid, cholesterol, calcium, inorganic phosphate, total iron, total iron binding capacity, and percent saturated transferrin, decreased. -- Intraperitoneal (IP) administration of choline, but not dietary choline, moderated the influence of aflatoxin on the majority of the biochemical parameters. -- Lysine supplementation improved the performance of chicks with aflatoxicosis, while threonine had a negative effect. This may be related to ornithine detoxification of aflatoxin through the opposing effects of these two amino acids on the activity of the enzyme arginase, which catalyzes the conversion of arginine to ornithine and urea. -- Plasma lysine concentration varies considerably as a result of genetic differences in lysine metabolism. Data indicates that chicks with high plasma lysine concentration are more resistant to aflatoxicosis than chicks with low plasma concentrations of lysine.
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