Tailoring follow-up endoscopy in patients with severe oesophagitis.

Objective: We aimed to investigate the clinical utility of follow-up oesophagogastroduodenoscopy (OGD2) in patients with severe oesophagitis (Los Angeles grades C or D) through evaluating the yield of Barrett's oesophagus (BO), cancer, dysplasia and strictures. Second, we aimed to determine if the Clinical Frailty Scale (CFS) may be used to identify patients to undergo OGD2s. Design/method: Patients in NHS Lothian with an index OGD (OGD1) diagnosis of severe oesophagitis between 1 January 2014 and 31 December 2015 were identified. Univariate analysis identified factors associated with grade. Patients were stratified by frailty and a diagnosis of stricture, cancer, dysplasia and BO. Results: In total 964 patients were diagnosed with severe oesophagitis, 61.7% grade C and 38.3% grade D. The diagnostic yield of new pathology at OGD2 was 13.2% (n=51), new strictures (2.3%), dysplasia (0.5%), cancer (0.3%) and BO (10.1%). A total of 140 patients had clinical frailty (CFS score ≥5), 88.6% of which were deceased at review (median of 76 months). In total 16.4% of frail patients underwent OGD2s and five new pathologies were diagnosed, none of which were significantly associated with grade. Among non-frail patients at OGD2, BO was the only pathology more common (p=0.010) in patients with grade D. Rates of cancer, dysplasia and strictures did not vary significantly between grades. Conclusion: Our data demonstrate that OGD2s in patients with severe oesophagitis may be tailored according to clinical frailty and only be offered to non-frail patients. In non-frail patients OGD2s have similar pick-up rates of sinister pathology in both grades of severe oesophagitis.

Oxidative stress during diabetic pregnancy disrupts cardiac neural crest migration and causes outflow tract defects.

BACKGROUND: Maternal diabetes increases risk for congenital malformations, particularly cardiac outflow tract defects. Maternal diabetes inhibits expression of Pax3 in neuroepithelium through hyperglycemia-induced oxidative stress. The neuroepithelium gives rise to the neural crest, and Pax3 expression in cardiac neural crest (CNC) is required for CNC migration to the heart and for outflow tract septation. Here we tested whether maternal diabetes, through hyperglycemia-induced oxidative stress, before the onset of CNC delamination, impairs CNC migration and cardiac outflow tract septation. METHODS: CNC migration was mapped in mouse embryos whose mothers were diabetic, or transiently hyperglycemic, or in which oxidative stress was transiently induced, using reporters linked to Pax3 expression. CNC apoptosis was examined by TUNEL assay. Outflow tract septation was examined histologically and by gross inspection. RESULTS: Few, if any, migrating CNC cells were observed in embryos of diabetic mice, and this was associated with increased apoptosis along the path of CNC migration. Outflow tract defects were significantly increased in fetuses of diabetic mice. Notably, induction of hyperglycemia or oxidative stress on the day prior to the onset of Pax3 expression and CNC migration also impaired CNC migration, increased apoptosis, and caused outflow tract defects. However, antioxidants administered on the day prior to the onset of Pax3 expression and CNC migration prevented these effects of hyperglycemia or oxidative stress. CONCLUSIONS: In diabetic pregnancy, oxidative stress, which inhibits expression of genes required for CNC viability, causes subsequent CNC depletion by apoptosis during migration, which leads to outflow tract defects.

Pax3 stimulates p53 ubiquitination and degradation independent of transcription.

BACKGROUND: Pax3 is a developmental transcription factor that is required for neural tube and neural crest development. We previously showed that inactivating the p53 tumor suppressor protein prevents neural tube and cardiac neural crest defects in Pax3-mutant mouse embryos. This demonstrates that Pax3 regulates these processes by blocking p53 function. Here we investigated the mechanism by which Pax3 blocks p53 function. METHODOLOGY/PRINCIPAL FINDINGS: We employed murine embryonic stem cell (ESC)-derived neuronal precursors as a cell culture model of embryonic neuroepithelium or neural crest. Pax3 reduced p53 protein stability, but had no effect on p53 mRNA levels or the rate of p53 synthesis. Full length Pax3 as well as fragments that contained either the DNA-binding paired box or the homeodomain, expressed as GST or FLAG fusion proteins, physically associated with p53 and Mdm2 both in vitro and in vivo. In contrast, Splotch Pax3, which causes neural tube and neural crest defects in homozygous embryos, bound weakly, or not at all, to p53 or Mdm2. The paired domain and homeodomain each stimulated Mdm2-mediated ubiquitination of p53 and p53 degradation in the absence of the Pax3 transcription regulatory domains, whereas Splotch Pax3 did not stimulate p53 ubiquitination or degradation. CONCLUSIONS/SIGNIFICANCE: Pax3 inactivates p53 function by stimulating its ubiquitination and degradation. This process utilizes the Pax3 paired domain and homeodomain but is independent of DNA-binding and transcription regulation. Because inactivating p53 is the only required Pax3 function during neural tube closure and cardiac neural crest development, and inactivating p53 does not require Pax3-dependent transcription regulation, this indicates that Pax3 is not required to function as a transcription factor during neural tube closure and cardiac neural crest development. These findings further suggest novel explanations for PAX3 functions in human diseases, such as in neural crest-derived cancers and Waardenburg syndrome types 1 and 3.

Positional specification in a neural stem cell line involves modulation of Musashi1 expression.

In this study, we have used an in vitro co-culture system to investigate the competency of a conditionally immortalized multipotential neural progenitor cell line (MHP36) to adopt "dorsal" or "striatal" telencephalic fates. We report that MHP36 cells, unlike primary fetal neural progenitors cells, do not express either dorsal or ventral telencephalic positional specification genes; at both the mRNA and protein levels, but that they quickly turn on expression of the appropriate set of proteins when cultured in either a dorsal (cortical) or a ventral (striatal) environment. This control has 2 components: transcriptional activation of positional specification genes, and translational control whereby only the appropriate set of mRNAs appears as immunoreactive protein. We show furthermore that this positional specification gene expression is modulated by the RNA-binding protein Musashi1. We postulate that it is the ability of MHP36 cells to adopt either cortical or striatal positional specification that is key to their functional efficacy in a number of models of neurological disease.

Cardiac outflow tract septation failure in Pax3-deficient embryos is due to p53-dependent regulation of migrating cardiac neural crest.

During neural tube closure, Pax3 is required to inhibit p53-dependent apoptosis. Pax3 is also required for migration of cardiac neural crest (CNC) from the neural tube to the heart and septation of the primitive single cardiac outflow tract into the aorta and pulmonary arteries. Whether Pax3 is required for CNC migration and outflow tract septation by inhibiting p53-dependent apoptosis is not known. In this study, mouse strains carrying reporters linked to Pax3 alleles were used to map the fate of CNC cells in embryos which were either Pax3-sufficient (expressing one or two functional Pax3 alleles) or Pax3-deficient (expressing two null Pax3 alleles), and in which p53 had been inactivated or not. Migrating CNC cells were observed in both Pax3-sufficient and -deficient embryos, but CNC cells were sparse and disorganized in Pax3-deficient embryos as migration progressed. The defective migration was associated with increased cell death. Suppression of p53, either by null mutation of the p53 gene, or administration of a p53 inhibitor, pifithrin-alpha, prevented the defective CNC migration and apoptosis in Pax3-deficient embryos, and also restored proper development of cardiac outflow tracts. These results indicate that Pax3 is required for cardiac outflow tract septation because it blocks p53-dependent processes during CNC migration.

The in vitro effects of a bimodal contrast agent on cellular functions and relaxometry.

The in vivo monitoring of cell survival and migration will be essential to the translation of cell-based therapies from the laboratory to clinical studies. The pre-labeling of cells with magnetic resonance imaging (MRI) contrast agents renders them visible in vivo for serial cellular imaging. However, little is known about the impact of the presence of these metal particles inside transplanted cells. The use of the bimodal contrast agent GRID made it possible to demonstrate by means of fluorescent microscopy and inductively coupled plasma mass spectrometry (ICP-MS) that, after 16 h of incubation (without the use of a transfection agent), neural stem cells (NSCs) were saturated and no longer incorporated particles. With this maximal uptake, no significant effect on cell viability was observed. However, a significant decrease in proliferation was evident in cells that underwent 24 h of labeling. A significant increase in reactive oxygen species was observed for all GRID labeling, with a very significant increase with 24 h of labeling. GRID labeling did not affect cell motility in comparison with PKH26-labeled NSCs in a glioma-based migration assay and also allowed differentiation into all major cell types of the brain. GRID-labeled cells induced a signal change of 47% on T(2) measurements and allows a detection of cell clusters of approximately 220 cells/microl. Further in vivo testing will be required to ensure that cell labeling with gadolinium-based MRI contrast agents does not impair their ability to repair.

Microglia release activators of neuronal proliferation mediated by activation of mitogen-activated protein kinase, phosphatidylinositol-3-kinase/Akt and delta-Notch signalling cascades.

Microglia, the resident macrophage of the brain, can release substances that aid neuronal development, differentiation and survival. We have investigated the effects of non-activated microglia on the survival of cultured rat cerebellar granule neurones. Microglial-conditioned medium, collected from primary rat microglial cultures, was used to treat 7-day-in-vitro neurones, and neuronal viability and proliferation was assessed following a further 1 or 7 days in culture. Microglial-conditioned medium enhanced neuronal survival by up to 50% compared with untreated neurones and this effect was completely abated by pretreatment of the microglia with l-leucine methyl ester. The expression of the proliferation marker Ki-67 increased in neuronal cultures treated with microglial-conditioned medium suggesting enhanced proliferation of precursor neurones. Microglial-induced neuronal proliferation could be attenuated by specific inhibition of mitogen-activated protein kinase or phosphatidylinositol-3-kinase/Akt signalling pathways, and by selective fractionation and immunodepletion of the microglial-conditioned medium. Activation of the Notch pathway was enhanced as antibody against the Notch ligand, delta-1, prevented the microglial-induced neuronal proliferation. These results show that microglia release stable neurotrophic factors that can promote neuronal precursor cell proliferation.