Biomedical subjects
M Parrens
Publications and source records attributed to M Parrens.
Differential expression of NGF receptors in human thymic epithelial tumors.
NGF receptor (TrkA and p75NGFR) expression was investigated in human thymuses, including normal thymuses, thymic hyperplasias, thymomas and thymic carcinomas. TrkAI but not TrkAII transcripts were demonstrated by RT-PCR. In normal thymuses, immunohistochemistry revealed a restricted TrkA-immunoreactivity to epithelial and interdigitated reticular cells, while only interdigitaded reticular cells were immunoreactive for p75NGFR. Thymocytes were negative for both receptors. A switch from the normal TrkA positive-p75NGFR negative phenotype to a TrkA negative-p75NGFR positive phenotype was found in histologically aggressive epithelial cell tumors, suggesting that NGF and its receptors are potentially involved in thymus stroma organogenesis and proliferation.
Disseminated infection after bacille Calmette-Guérin instillation for treatment of bladder carcinoma.
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[Clear cell adenoma of the parathyroid gland: a rare and misleading lesion].
Parathyroid adenomas are common lesions and are considered to be the cause of most of the primary hyperparathyroidism cases. We report the case of a 73 year-old man who presented with a primary hyperparathyroidism. Clinical and histological explorations revealed the presence of an isolated parathyroid tumor containing exclusively clear cells and devoid of malignancy. This is the second reported case of clear cell parathyroid adenoma. Thus, in spite of its low occurrence, this diagnosis must be considered after rejection of the most frequent parathyroid clear cell hyperplasia and parathyroid carcinoma, or depending of the location, clear cell thyroid tumor and clear cell renal carcinoma metastasis.
Expression of NGF receptors in normal and pathological human thymus.
The expression of NGF receptors was investigated in normal human thymus and in thymic hyperplasias, thymomas and thymic carcinomas. By RT-PCR, we detected TrkAI transcripts encoding for the high-affinity NGF receptor. Western blot analysis showed the presence of both TrkA and p75NGFR proteins. In normal thymuses, epithelial subcapsular and medullar cells were TrkA immunoreactive. Interdigitated medullar cells were stained for both TrkA and p75NGFR. While epithelial cells of normal thymuses or benign thymomas exhibited a TrkA positive-p75NGFR negative phenotype, a switch to a TrkA negative-p75NGFR positive phenotype was observed in malignant epithelial cell tumours and was associated with cell proliferation-associated MIB1 expression. Our results argue for a local role of NGF and its receptors on thymic stromal cells both in normal and neoplastic conditions.
[Littoral cell angioma: a rare vascular splenic tumor].
Littoral cell angioma is a rare primitive vascular tumor of the spleen considered as benign. Its clinical presentation is non specific. The diagnostic is based on histological and immunohistological analysis. The lesion is composed of anastomosing vascular channels often featuring papillary projections. They are lined by tumoral cells which exhibit an immunoreactivity for vascular and histiomonocytic markers. We report one case of littoral cell angioma and we discuss the diagnosis and the histogenesis of this tumor.
[Extranodal lymphoma].
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Distribution of NGF receptors in normal and pathologic human lymphoid tissues.
To identify nerve growth factor (NGF) target cells in normal and pathologic human lymphoid tissues, we have studied the expression of the low-affinity NGF receptor (p75LNGFR) and the high-affinity tropomyosin-related kinase NGF receptor (TrkA). A RNAse protection assay revealed the expression of trk transcripts in thymus, spleen, palatine tonsils and lymph nodes. TrkA immunoreactivity was shown in thymic epithelial cells, cryptic tonsillar epithelium and several monocyte-derived cells including epithelioid and multinucleated Langhans' cells, follicular dendritic cells and interdigitated reticular cells. TrkA immunoreactivity was rarely observed in normal T- and B-lymphocytes, but was intense in lymphoma cells of several B-cell lymphoma subtypes, anaplastic large cell lymphomas and Reed-Sternberg cells. Western blot analysis revealed the presence of p75LNGFR and of p80Trk and glycosylated Trk isoforms (gp110, gp140). p75LNGFR immunoreactivity was detected in epithelial Hassal's bodies, follicular dendritic cells, interdigitated reticular cells, periarteriolar macrophages, endothelial sinusal cells and nerve endings. The broad expression of NGF receptors may be an indicator of neurotrophin activity in lymphoid tissues and suggests their implication in inflammatory or lymphoproliferative disorders.
[Retroperitoneal Castelman disease. Apropos of a new case].
A retroperitoneal localization of Castleman's disease was characterized by angiolymphoid hyperplasia. This rare disease (58 cases of abdominal localization reported to date) raises a question of nosology. The clinical features are not specific. Localized forms in young patients involve deep lymph nodes and have a good prognosis after complete surgical exeresis. Inversely, the clinical picture is much more aggressive in multiple localizations involving preferentially superficial nodes with associated plasmocyte proliferation. The prognosis is mediocre in these forms. Although transition stages have been described due to the lack of any known aetiology, the question of nosology remains open: should the different forms be separated or identified simply as two pathological forms?