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R Lagace

Publications and source records attributed to R Lagace.

8 recordsLinked to original sources
PubMed2000

A germline mutation at the extreme 3' end of the APC gene results in a severe desmoid phenotype and is associated with overexpression of beta-catenin in the desmoid tumor.

Desmoid tumors arise sporadically or as part of the extraintestinal manifestations of familial adenomatous polyposis (FAP). In FAP, two distinct clinical presentations of the desmoid phenotype are seen: 1) one or a few desmoid tumors present predominantly in the abdominal wall or the abdomen; 2) a florid proliferation of tumors early in life, mostly near the axial skeleton or extremities. These different phenotypes have been associated with different sites of germline mutations in the adenomatous polyposis coli gene (APC gene). We present a large, French-Canadian kindred with a florid desmoid tumor phenotype caused by a germline mutation at codon 2643-2644 of the APC gene. The phenotype was characterized by the early onset of multiple tumors, arising near the axial skeleton and in proximal extremities. The penetrance of desmoid tumors was near 100% in this kindred. However, the expression of the disease was variable amongst the different affected relatives. Many gene carriers had cutaneous cysts. Polyposis of the colon was rarely observed in the affected individuals and we did not document upper gastro-intestinal polyps. The mutant APC allele did not express a stable truncated protein in vivo. Molecular analysis of the proband's tumor DNA revealed a somatic inactivating mutation of the wild-type allele. Immunohistochemistry on the tumor also demonstrated elevated levels of beta-catenin. The present study demonstrates that this extreme 3' APC mutation is associated with a severely penetrant desmoid phenotype and attenuated polyposis coli. It also suggests the involvement of the beta-catenin pathway in the development of desmoid tumors in FAP. The natural history of the disease is variable between individuals, and surgical interventions have to be timed appropriately due to the frequent recurrences.

3' Untranslated Regions↗
PubMed1975

Light and electron microscopic study of cellular proliferation in carcinoid heart disease.

An ultrastructural and histochemical study of the subendocardial lesion in carcinoid heart disease showed six different cell types within a myxoid matrix. The matrix, composed of a mucopolysaccharidic ground substance, collagen, and reticluin fibers, contained stem cells, four types of fusiform cells (fibrocytes, fibroblasts, myofibroblasts, and smooth muscle cells), and intermediary cell type. Our observations suggest that the humoral mediators of the carcinoid syndrome may induce the differentiation of a subendocardial stem cell into contractile elements.

Bradykinin↗
PubMed1971

Submucous cleft palate.

Over 10,000 school children were screened for palatal abnormalities. Nine submucous clefts of the palate were detected, an incidence of 1 : 1,200. Speech defects, ear problems and hearing loss were found as complications in 55% of 50 submucous cleft palate patients studied in detail. Complications were less common (45%) if the palatal abnormality was an isolated defect. Proper management of submucous cleft palate depends upon knowledge of its incidence and natural history.

Cleft Palate↗
PubMedDate not supplied

[Evaluation of the differences of opinion in the histopathologic diagnosis of soft tissue tumors].

Evaluation of observers variation in the histopathologic diagnosis of soft tissue tumors. 260 cases of soft tissue tumors referred to the CTRC (Canadian Tumour Reference Center) for diagnostic opinion were reviewed. These tumors were collected from 98 different hospitals within the 10 canadian provinces and had been submitted to a specialized panel of pathologists having a particular interest in this field. 22 tumors of nonmesenchymal origin have been discarded. The main problem posed by the contributors related to the histologic typing of overtly malignant and sarcomatous tumors (122/238). Comparing the diagnoses proposed by contributors and the panel, a consensus in term of benign and malignant tumor was reached in 89% of the cases. Within this panel, there was consensus in 84% of the cases. However, regarding the histologic typing, a consensus was reached between contributors and the panel in only 65% of the studied cases. Within the panel, there was a majority diagnosis in merely 62% of them. A mean of three different diagnoses were proposed for each case. A review of the literature shows that histologic typing of soft tissue tumors is of only limited prognostic significance. On the other hand, the clinical staging comprising histologic grade, size, depth, local growth and metastases is essential to establish prognosis and treatment. However, since certain tumors respond differently to treatment, a precise histopathologic diagnosis using immunohistochemistry and electron microscopy is mandatory.

Diagnosis, Differential↗