In utero presentation of aggressive systemic mastocytosis in a neonate

Mastocytosis is a clinically heterogenous disease characterized by mast cell hyperplasia in skin, bone marrow and/or visceral organs. Cutaneous mastocytosis is more frequently observed in children, whereas indolent systemic mastocytosis is more commonly observed in adults. Aggressive systemic presentation, particularly of the neonate, is exceptionally rare. We present a rare case of congenital aggressive systemic mastocytosis. The patient was a 37-week-old male, born by caesarean section owing to hepatosplenomegaly and ascites diagnosed in utero, who exhibited extensive cutaneous and systemic manifestations of mastocytosis at birth. Mutation analysis of c-KIT identified D816V mutation in exon 17. Although initial bilateral bone marrow aspirates demonstrated no mast-cell infiltrates or haematological neoplasm, subsequent bone-marrow biopsies postmortem exhibited multifocal mast-cell aggregates. Clinical course was complicated by bacteraemia and cardiorespiratory failure, leading to death at 10 weeks.

CDC42 is required for epicardial and pro-epicardial development by mediating FGF receptor trafficking to the plasma membrane

The epicardium contributes to multiple cardiac lineages and is essential for cardiac development and regeneration. However, the mechanism of epicardium formation is unclear. This study aimed to establish the cellular and molecular mechanisms underlying the dissociation of pro-epicardial cells (PECs) from the pro-epicardium (PE) and their subsequent translocation to the heart to form the epicardium. We used lineage tracing, conditional deletion, mosaic analysis and ligand stimulation in mice to determine that both villous protrusions and floating cysts contribute to PEC translocation to myocardium in a CDC42-dependent manner. We resolved a controversy by demonstrating that physical contact of the PE with the myocardium constitutes a third mechanism for PEC translocation to myocardium, and observed a fourth mechanism in which PECs migrate along the surface of the inflow tract to reach the ventricles. Epicardial-specific Cdc42 deletion disrupted epicardium formation, and Cdc42 null PECs proliferated less, lost polarity and failed to form villous protrusions and floating cysts. FGF signaling promotes epicardium formation in vivo, and biochemical studies demonstrated that CDC42 is involved in the trafficking of FGF receptors to the cell membrane to regulate epicardium formation.

Highlighted article: During epicardial formation in mice, four different mechanisms of pro-epicardial cell translocation to the myocardium can be identified, with CDC42 playing a key role.

Microbiome Associated with Severe Caries in Canadian First Nations Children

Young Indigenous children in North America suffer from a higher degree of severe early childhood caries (S-ECC) than the general population, leading to speculation that the etiology and characteristics of the disease may be distinct in this population. To address this knowledge gap, we conducted the first microbiome analysis of an Indigenous population using modern molecular techniques. We investigated the caries-associated microbiome among Canadian First Nations children with S-ECC. Thirty First Nations children <72 mo of age with S-ECC and 20 caries-free children were recruited in Winnipeg, Canada. Parents or caregivers completed a questionnaire on general and dental health, diet, and demographics. The plaque microbiome was investigated by sequencing the 16S rRNA gene. Sequences were clustered into operational taxonomic units and taxonomy assigned via the Human Oral Microbiome Database, then analyzed at the community level with alpha and beta diversity measures. Compared with those who were caries free, children with S-ECC came from households with lower income; they were more likely to live in First Nations communities and were more likely to be bottle-fed; and they were weaned from the bottle at a later age. The microbial communities of the S-ECC and caries-free groups did not differ in terms of species richness or phylogenetic diversity. Beta diversity analysis showed that the samples significantly clustered into groups based on caries status. Twenty-eight species-level operational taxonomic units were significantly different between the groups, including Veillonella HOT 780 and Porphyromonas HOT 284, which were 4.6- and 9-fold higher, respectively, in the S-ECC group, and Streptococcus gordonii and Streptococcus sanguinis, which were 5- and 2-fold higher, respectively, in the caries-free group. Extremely high levels of Streptococcus mutans were detected in the S-ECC group. Overall, First Nations children with S-ECC have a significantly different plaque microbiome than their caries-free counterparts, with the S-ECC group containing higher levels of known cariogenic organisms.

Changes in localization and density of CD63-positive exosome-like substances in the hen oviduct with artificial insemination and their effect on sperm viability

Avian sperm are stored in the sperm storage tubules (SSTs) of the hen oviduct for a prolonged period. However, the precise mechanisms by which sperm are kept alive in the SSTs are still not fully understood. The aim of this study was to determine whether exosomes are secreted by SST cells and play a role in the survival of sperm. Utero-vaginal junction (UVJ) tissue from approximately 50 wk old White Leghorn hens was collected before (control group) and after intravaginal insemination with seminal plasma (SP group) or semen (AI group). The samples were used to prepare frozen sections and total protein extraction. The localization of the CD63, an exosome marker, was determined by immunohistochemistry and its protein level in the UVJ mucosal tissues was examined by Western blot. Exosomes were isolated from the culture media of UVJ and vaginal mucosa cells by ultracentrifugation and characterized by SDS-PAGE and Western blot. The viability and motility of sperm incubated with exosomes were also examined. CD63 was localized in the apical region of UVJ mucosal epithelium cells and SST cells of control, SP, and AI groups. The CD63 protein decreased in SST cells surrounding resident sperm and tended to appear in the SST lumen in the AI group. The protein level of CD63 in UVJ mucosal tissues was significantly higher in the AI group than control. The CD63 protein (approximately 75 kDa) was detected in ultracentrifugation pellets from the culture medium of UVJ and vagina cells. The viability of sperm incubated with 1 μg/μl vaginal exosomes was significantly decreased but was not affected by UVJ exosomes. These results suggest that exosomes were synthesized by SST cells and may be secreted into SST lumen when sperm were stored in SSTs. The role of SST exosomes in sperm storage needs to be examined further.

Live phylogeny with polytomies: Finding the most compact parsimonious trees

Construction of phylogenetic trees has traditionally focused on binary trees where all species appear on leaves, a problem for which numerous efficient solutions have been developed. Certain application domains though, such as viral evolution and transmission, paleontology, linguistics, and phylogenetic stemmatics, often require phylogeny inference that involves placing input species on ancestral tree nodes (live phylogeny), and polytomies. These requirements, despite their prevalence, lead to computationally harder algorithmic solutions and have been sparsely examined in the literature to date. In this article we prove some unique properties of most parsimonious live phylogenetic trees with polytomies, and their mapping to traditional binary phylogenetic trees. We show that our problem reduces to finding the most compact parsimonious tree for n species, and describe a novel efficient algorithm to find such trees without resorting to exhaustive enumeration of all possible tree topologies.

Schizophrenia-like phenotypes in mice with NMDA receptor ablation in intralaminar thalamic nucleus cells and gene therapy-based reversal in adults

In understanding the mechanism of schizophrenia pathogenesis, a significant finding is that drug abuse of phencyclidine or its analog ketamine causes symptoms similar to schizophrenia. Such drug effects are triggered even by administration at post-adolescent stages. Both drugs are N-methyl-d-aspartate receptor (NMDAR) antagonists, leading to a major hypothesis that glutamate hypofunction underlies schizophrenia pathogenesis. The precise region that depends on NMDAR function, however, is unclear. Here, we developed a mouse strain in which NMDARs in the intralaminar thalamic nuclei (ILN) were selectively disrupted. The mutant mice exhibited various schizophrenia-like phenotypes, including deficits in working memory, long-term spatial memory, and attention, as well as impulsivity, impaired prepulse inhibition, hyperlocomotion and hyperarousal. The electroencephalography analysis revealed that the mutant mice had a significantly reduced power in a wide range of frequencies including the alpha, beta and gamma bands, both during wake and rapid eye movement (REM) sleep, and a modest decrease of gamma power during non-REM sleep. Notably, restoring NMDARs in the adult ILN rescued some of the behavioral abnormalities. These findings suggest that NMDAR dysfunction in the ILN contributes to the pathophysiology of schizophrenia-related disorders. Furthermore, the reversal of inherent schizophrenia-like phenotypes in the adult mutant mice supports that ILN is a potential target site for a therapeutic strategy.

ITD mutation in FLT3 tyrosine kinase promotes Warburg effect and renders therapeutic sensitivity to glycolytic inhibition

Internal tandem duplication (ITD) mutation in Fms-like tyrosine kinase 3 gene (FLT3/ITD) represents an unfavorable genetic change in acute myeloid leukemia (AML) and is associated with poor prognosis. Metabolic alterations have been involved in tumor progression and attracted interest as a target for therapeutic intervention. However, few studies analyzed the adaptations of cellular metabolism in the context of FLT3/ITD mutation. Here, we report that FLT3/ITD causes a significant increase in aerobic glycolysis through AKT-mediated upregulation of mitochondrial hexokinase (HK2), and renders the leukemia cells highly dependent on glycolysis and sensitive to pharmacological inhibition of glycolytic activity. Inhibition of glycolysis preferentially causes severe ATP depletion and massive cell death in FLT3/ITD leukemia cells. Glycolytic inhibitors significantly enhances the cytotoxicity induced by FLT3 tyrosine kinase inhibitor sorafenib. Importantly, such combination provides substantial therapeutic benefit in a murine model bearing FLT3/ITD leukemia. Our study suggests that FLT3/ITD mutation promotes Warburg effect, and such metabolic alteration can be exploited to develop effective therapeutic strategy for treatment of AML with FLT3/ITD mutation via metabolic intervention.

The Oral Health of Preschool Children of Refugee and Immigrant Families in Manitoba

INTRODUCTION

Children of newcomers to Canada have been identified as at moderately high risk for developing early childhood caries (ECC). The purpose of this study was to investigate the oral health of preschool children of refugee and immigrant families in Winnipeg.

METHODS

Children < 72 months of age and their parent or primary caregiver were recruited through several newcomer settlement agencies, dental clinics and community programs. Parents and caregivers completed a short questionnaire with the assistance of a research team member. Children underwent a dental examination. Results of the questionnaire were combined with those of the clinical examination and subjected to statistical analysis.

RESULTS

We recruited 211 children. Their mean age was 40.2 ± 15.4 months, and 54.0% were boys. Overall, 45.5% of the children had ECC and 31.8% had severe ECC (S-ECC). The mean decayed, missing and filled teeth (dmft) score was 2.2 ± 3.8 (range 0-19), while the mean decayed, missing, filled surfaces (dmfs) score was 4.8 ± 11.0 (range 0-63). Infant dental enucleation was observed in 6 children. Logistic regression analyses showed that increasing age, the presence of debris on teeth, parents believing their child has dental problems and the presence of enamel hypoplasia were significantly and independently associated with ECC and S-ECC (p ≤ 0.05).

CONCLUSIONS

ECC is prevalent in children of newcomer families in Manitoba. These data will inform advocacy efforts to improve access to dental care and tailor early childhood oral health promotion and ECC prevention activities for refugees and recent immigrants.