Placental pathology and neonatal encephalopathy.

Neonatal encephalopathy (NE) is an important cause of neonatal morbidity and mortality worldwide; however, there remain gaps in our knowledge about its pathogenesis. The placenta has been implicated in the pathogenesis of this disease but conclusive evidence related to the placental factors that influence it is sparse. This review aims to outline the current knowledge on the role of the placenta with particular attention to its role in NE as a consequence of hypoxia-ischemia. A total of 26 original articles/review papers were used to compile this review. Three themes were identified from these publications: fetal vascular malperfusion including umbilical cord pathology, inflammatory changes in the placenta, and maternal vascular malperfusion including placental weight. These features were identified as being significant in the development of NE. Advancing our understanding of this relationship between placental pathology and NE may facilitate the development of additional antenatal screening to better identify at-risk fetuses. We highlight areas for further research through antenatal screening and placental histology.

Use of tissue samples in diagnosing diploid triploid mosaicism.

Diploid triploid mosaicism (DTM) is a rare genetic condition where there is an extra haploid set of chromosomes in mosaic form. We describe an infant for whom DTM was detected antenatally through amniocentesis. Prenatal counselling suggested a guarded prognosis. The infant's phenotypic presentation and postnatal course reflect the varied presentation and prognosis associated with DTM. We highlight potential challenges in diagnosing DTM postnatally, with many having normal blood karyotype with 46 chromosomes.

Revised antiemetics guidelines and the impact on nutritional status during induction chemotherapy in children with high-risk neuroblastoma.

BACKGROUND: High-risk neuroblastoma (HR NBL) treatment requires intensive induction chemotherapy. The profoundly emetogenic agents used can compromise nutritional status. Our institution introduced a new antiemetic guideline in 2010 incorporating regular dexamethasone, in addition to ondansetron, for all highly emetogenic protocols. PROCEDURE: A retrospective comparative review of pediatric patients diagnosed with HR NBL who received rapid COJEC induction chemotherapy as per HR-SIOPEN NBL trial. Prophylactic antiemetics were prescribed regardless of chemotherapy emetogenicity in group A (2004-2010) but for defined time periods considering chemotherapy emetogenicity in group B (2010-2017). RESULTS: Sixty-three children were eligible for inclusion (median age, 31 months; range, 1-88 months). Group A had more episodes of emesis than group B (189 vs. 116, P < 0.0001). There was a significant difference in weight-for-age Z score change between the groups by induction end (P = 0.0027). Four children (13%) in group A lost >10% body weight versus none in group B. Nutrition support (NS) was utilized by 29 children (94%) in group A and 22 children (69%) in group B. Group A had a median of 3 (range, 1-7) admissions for febrile neutropenia (FN) versus a median of 1.5 (range, 0-4) for group B (P = 0.003) during induction. CONCLUSION: The review of our guidelines led to reduced emesis frequency for group B. They also required less NS, followed expected growth trajectories more closely and had fewer FN admissions. We propose that this may have occurred due to better emesis control resulting in improved nutritional status and associated enhanced immune function.

Molecular characterization and environmental mapping of Campylobacter isolates in a subset of intensive poultry flocks in Ireland.

Irish breeder and intensive broiler flocks together with the corresponding poultry farm environment were sampled for the presence of Campylobacter with the aim of identifying potential sources and transmission routes of poultry flock contamination. The genetic diversity of a subset of Campylobacter isolates was examined by analysis of the flaA-short variable region (SVR). Additional discrimination for a further subset of these isolates was achieved using multilocus sequence typing (MLST) analysis. Twenty-four flaA-SVR alleles and 15 FlaA peptides were detected among 92 Campylobacter jejuni and Campylobacter coli isolates. MLST data have been determined for 30 of 92 (32.6%) flaA-SVR-typed isolates with 13 sequence types (STs) present, which were assigned to seven clonal complexes. ST45 was the most common ST identified. Vertical transmission was not found to have played a role in transmission of the pathogen to the poultry flocks. Subtyping by flaA-SVR and MLST identified the practice of partial thinning of flocks as a potential source and route of flock contamination on one broiler farm and implicated a probable source of flock contamination on another. Although there have been several studies reported in the scientific literature, the findings from this study confirmed previous studies and suggested some new transmission pathways including via transport crates. Cross-contamination from adjacent cattle is a new development, and molecular evidence of the role of transport crates in introducing Campylobacter spp. into the broiler house is a recent finding. Further, this study reports the discovery of five new flaA-SVR allele types and eight new STs. These were widespread and persistent in the poultry environment. This new knowledge may explain why despite the on-farm Campylobacter data published to date, there are still no completely effective on-farm control measures to prevent Campylobacter contamination of broiler flocks.

Identification of the biosynthetic gene cluster for the Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid.

L-2-amino-4-methoxy-trans-3-butenoic acid (AMB) is a potent antibiotic and toxin produced by Pseudomonas aeruginosa. Using a novel biochemical assay combined with site-directed mutagenesis in strain PAO1, we have identified a five-gene cluster specifying AMB biosynthesis, probably involving a thiotemplate mechanism. Overexpression of this cluster in strain PA7, a natural AMB-negative isolate, led to AMB overproduction.

Emergence of secretion-defective sublines of Pseudomonas aeruginosa PAO1 resulting from spontaneous mutations in the vfr global regulatory gene.

Pseudomonas aeruginosa undergoes spontaneous mutation that impairs secretion of several extracellular enzymes during extended cultivation in vitro in rich media, as well as during long-term colonization of the cystic fibrosis lung. A frequent type of strong secretion deficiency is caused by inactivation of the quorum-sensing regulatory gene lasR. Here we analyzed a spontaneously emerging subline of strain PAO1 that exhibited moderate secretion deficiency and partial loss of quorum-sensing control. Using generalized transduction, we mapped the secretion defect to the vfr gene, which is known to control positively the expression of the lasR gene and type II secretion of several proteases. We confirmed this secretion defect by sequencing and complementation of the vfr mutation. In a reconstruction experiment conducted with a 1:1 mixture of wild-type strain PAO1 and a vfr mutant of PAO1, we observed that the vfr mutant had a selective advantage over the wild type after growth in static culture for 4 days. Under these conditions, spontaneous vfr emerged in a strain PAO1 population after four growth cycles, and these mutants accounted for more than 40% of the population after seven cycles. These results suggest that partial or complete loss of quorum sensing and secretion can be beneficial to P. aeruginosa under certain environmental conditions.

Purification, crystallization and preliminary X-ray analysis of an unusual thioredoxin from the gastric pathogen Helicobacter pylori.

Thioredoxin-2 (HP1458) from Helicobacter pylori is a member of the thioredoxin family, but possesses the unusual active-site motif CPDC (compared with CGPC in other thioredoxins). H. pylori is deficient in the glutaredoxin system, making the thioredoxin system the sole reduction system in the bacterium and critical for its ability to survive oxidative stress. The recombinant protein has been overexpressed, purified and crystallized. This is the first reported crystallization of a thioredoxin possessing this unusual active site. Single crystals have been obtained using the sitting-drop technique. Crystals diffract to 2.4 A resolution and belong to space group P4(1), with unit-cell parameters a = b = 40.21, c = 64.65 A. Molecular replacement using AMoRe proved unsuccessful; however, implementation of the program BEAST gave successful molecular-replacement solutions.