Montreal Children's Hospital

About: Montreal Children's Hospital is a healthcare organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 3842 authors who have published 4816 publications receiving 200198 citations.

Mutations in DCC cause isolated agenesis of the corpus callosum with incomplete penetrance

Abstract: Brain malformations involving the corpus callosum are common in children with developmental disabilities. We identified DCC mutations in four families and five sporadic individuals with isolated agenesis of the corpus callosum (ACC) without intellectual disability. DCC mutations result in variable dominant phenotypes with decreased penetrance, including mirror movements and ACC associated with a favorable developmental prognosis. Possible phenotypic modifiers include the type and location of mutation and the sex of the individual.

Lateral neck radiography versus direct video rhinoscopy in assessing adenoid size

Abstract: Objective: To evaluate the usefulness of adynamic lateral neck radiographs and dynamic video rhinoscopy in assessing adenoid size and the relationship of these methods to associated symptoms and thus the severity of the disease. Methods: Children with suspected adenoid hypertrophy underwent standard lateral neck soft tissue radiographs: the percentage of airway occlusion, adenoid to nasopharynx (AN) ratio, airway to soft palate ratio, and adenoid thickness were assessed by a radiologist. The percentage of airway closure was assessed by direct fibre-optic rhinoscopy in an ear, nose, and throat clinic. Associated clinical symptoms were assessed by parents using a standardized questionnaire, evaluating the severity of symptoms (snoring, sleep apnea, mouth breathing, and otitis media) to give a total symptom score out of 16. Results: Nonparametric statistical analysis using Spearman’s correlation coefficients was performed on 32 patients. There was a weak correlation, which approaches significance, between the percentage of airway occlusion assessed by fibre-optic rhinoscopy and the total symptom score (r = .344, p = .054). However, this correlation becomes significant when the frequency of otitis media is omitted (r = .367, p = .039). There was also a significant correlation between airway occlusion assessed by rhinoscopy and the percentage of airway occlusion as determined by lateral neck radiography (r = .431, p = .014). There was no correlation between any of the measurements taken by lateral soft tissue neck radiography and total symptom score. Conclusion: Dynamic video rhinoscopy is more accurate at assessing adenoid hypertrophy, and the percentage of airway occlusion, as estimated by video rhinoscopy, is better correlated to the severity of symptoms than are values obtained by lateral neck radiography. Sommaire

Adverse Effects of 5-Aza-2′-Deoxycytidine on Spermatogenesis Include Reduced Sperm Function and Selective Inhibition of de Novo DNA Methylation

Abstract: The anticancer agent, 5-aza-2'-deoxycytidine (5-azaCdR, decitabine), causes DNA hypomethylation and a robust, dose-dependent disruption of spermatogenesis. Previously, we have shown that altered testicular histology and reduced sperm production in 5-azaCdR-treated animals is associated with decreased global sperm DNA methylation and an increase in infertility and/or a decreased ability to support preimplantation embryonic development. The goal of this study was to determine potential contributors to 5-azaCdR-mediated infertility including alterations in sperm motility, fertilization ability, early embryo development, and sequence-specific DNA methylation. We find that although 5-azaCdR-treatment adversely affected sperm motility and the survival of sired embryos to the blastocyst stage, the major contributor to infertility was a marked (56-70%) decrease in fertilization ability. Sperm DNA methylation was investigated using Southern blot, restriction landmark genomic scanning, and quantitative analysis of DNA methylation by real-time polymerase chain reaction. Interestingly, hypomethylation was restricted to genomic loci that have been previously determined to acquire methylation during spermatogenesis, demonstrating that 5-azaCdR selectively inhibits de novo methylation activity. Similar to previous studies, we show that mice that are heterozygous for a nonfunctional Dnmt1 gene are partially protected against the deleterious effects of 5-azaCdR; however, methylation levels are not restored in these mice, suggesting that adverse effects are due to another mechanism(s) in addition to DNA hypomethylation. These results demonstrate that clinically relevant doses of 5-azaCdR specifically impair de novo methylation activity in male germ cells; however, genotype-specific differences in drug responses suggest that adverse reproductive outcomes are mainly mediated by the cytotoxic properties of the drug.