Biomedical subjects
Publications and source records attributed to N Chalhoub.
The authors describe their experience to support the view that training in child psychiatry is an effective way for the paediatrician in training to gain an understanding of that specialty. It is also an efficient way to acquire certain skills, which will be helpful in the future, either in hospital or community paediatrics.
We genotyped 19 NF1 families from the French Canadians of the Québec population with six intragenic polymorphic markers including 2 RFLPs (EcoRI and RsaI) and 4 microsatellites (IVS26-2.3, IVS27AC28.4, IVS27AC33.1, and IVS38GT53.0). Genotype analysis indicated families 7610 and 7473 bear deletions. In Family 7610 the deletion removed the entire NF1 gene except exons 1 to 4b. The breakpoint of the deletion is located between exons 4a and 4b. The deletion 7473 was derived from the maternal chromosome and exons 1 to 5 were deleted. The breakpoint of the deletion is located between exons 7 and 13. Their phenotypes are reported. The allele frequencies of microsatellites IVS27AC28.4 and IVS38GT53.0 are compared to previously reported data from Caucasians, including Spanish and Italians. The difference is statistically significant (P < 0.0036) for marker IVS27AC28.4 between the Québec French Canadian and the Italian population.
Toward the isolation of the grey-lethal (gl) gene, we have genetically localized this locus on mouse Chromosome (Chr) 10 between the Fyn gene and the D10Mit148 microsatellite marker. Here, we have screened five yeast artificial chromosome (YAC) libraries and isolated more than 100 YAC clones mapping to this region. Forty-two clones were characterized and assembled in an approximately 8.5 megabases (Mb) contig showing high linkage conservation with the human 6q16-q21 interval. During this study, 24 specific novel sequence-tagged sites (STSs) were derived from YAC insert ends, and 15 mouse genes were precisely mapped to the contig. The physical and transcriptional map presented here will provide novel resources to isolate the gl locus associated with osteopetrosis, and will also provide candidate loci for other defects mapped on human Chr 6q.
The osteopetrotic grey-lethal (gl) mouse mutant displays many similarities to the human malignant autosomal-recessive form of osteopetrosis. In this study, we show that the gl osteopetrotic bone phenotype is characterized by the presence of numerous differentiated multinucleated osteoclasts. A significant increase in the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts was detected in vivo, suggesting induction of differentiation in the osteoclast lineage as a compensatory mechanism. These gl osteoclast cells demonstrated a defective cytoskeletal reorganization and an underdeveloped ruffled border, a membrane structure essential for active bone resorption. Accordingly, resorption activity of these cells is markedly impaired by four- to tenfold as evaluated with the pit formation assay. This low bone resorption in gl osteoclasts is highly reminiscent of the loss in key enzymes, V-ATPase or cathepsin-K, and in signaling factors, Src or TRAF-6, which were shown not to be significantly altered in gl osteoclasts. Thus, independently of a deficiency in V-ATPase, Src, cathepsin-K, and TRAF-6, the gl mutation results in increased number of osteoclasts, characterized by a disrupted cytoskeleton and an underdeveloped ruffled border.
Bulimia nervosa is very rare in children below the age of 14 years, and no reliable reports of prepubertal bulimia nervosa have been published. We describe two cases of early-onset bulimia nervosa who presented before the age of 14 years, and with premenarchal onset in one patient. Both girls demonstrated high levels of the risk factors known to play a part in the etiology of bulimia nervosa. Implications of these cases regarding the etiology and occurrence of bulimia nervosa in younger adolescents are discussed.