Search PubMed⌕ Search

Biomedical subjects

A Croué

Publications and source records attributed to A Croué.

9 recordsLinked to original sources
PubMed1996

Effect of stereotactic implantation of biodegradable 5-fluorouracil-loaded microspheres in healthy and C6 glioma-bearing rats.

OBJECTIVE: Poly(lactic acid-co-glycolic acid) (PLAGA) microspheres are promising systems for interstitial chemotherapy of brain tumors. They can be readily implanted by stereotaxy and are biocompatible with the brain, in which they are totally biodegraded within 2 months. 5-Fluorouracil (5-FU) was selected for encapsulation, because this hydrophilic and antimetabolic drug is not directly neurotoxic and does not readily cross the blood-brain barrier. Also, its anticancer activity may be improved by sustained administration. Furthermore, it is a potent radiosensitizer. METHODS: To study their fate and toxicity, two types of 5-FU-loaded PLAGA microspheres were implanted in healthy rats by stereotaxy. One type presented a fast in vitro release profile (FR), and the second exhibited a slow in vitro release pattern (SR) (100% of the encapsulated 5-FU is released within 72 hours and 18 days, respectively). Periodically, rats were killed for microscopic examination. The efficacy of these microspheres on rat glioma was then evaluated. Seven days after stereotactic implantation of C6 malignant glioma cells in the brain, the rats were treated by intratumoral injection of 5-FU solution, blank microspheres, or 5-FU-loaded microspheres (FR and SR types). The mortality of these treated groups was compared by the log-rank test with that of an untreated group. RESULTS: After implantation of two types of 5-FU-loaded PLAGA microspheres, no sign of clinical or histological toxicity was observed. Entrapped 5-FU crystals were observed until Days 12 and 20 postimplantation within FR and SR microspheres, respectively, which suggests a longer releasing period in vivo than in vitro. In the therapeutic evaluation, only intratumoral implantation of SR-type 5-FU-loaded microspheres significantly decreased the mortality (P = 0.017). CONCLUSION: 5-FU-loaded PLAGA microspheres were implanted in rat brains without evident toxicity. Histological examination suggested a longer sustained delivery period in vivo than in vitro. Intratumoral implantation of SR-type 5-FU-loaded microspheres decreased the mortality of C6 tumor-bearing rats. This effect can be related to the local and the sustained delivery of the drug, because 5-FU administered systemically is ineffective against brain tumors.

Animals↗
PubMed1995

[Overexpression of protein p53 and Barrett esophagus. A frequent and early event in the course of carcinogenesis].

OBJECTIVES AND METHODS: In Barrett's oesophagus, the risk of malignancy is evaluated histologically with the presence of dysplasia. The abnormal expression of p53 protein could represent a useful new marker. The aim of this study was evaluate the abnormal expression of p53 protein in a series of 52 oesophagectomy specimens with Barrett's oesophagus, either non-dysplastic (n = 3), dysplastic (n = 8), or malignant (n = 41). The immunohistochemical study was made on deparaffinized sections with the monoclonal anti-p53 antibody DO7. RESULTS: The 3 non-dysplastic cases were p53 negative; 1 case of low-grade dysplasia in 5 was positive, as were the 3 cases of high grade dysplasia and 33 of 41 cancers (80%), including 13 superficial cancers in 14 (93%) and 20 invasive cancers in 27 (74%). A common feature was the presence of rare p53 positive crypts in low grade dysplastic areas and non-dysplastic specialized mucosa that surrounded high grade dysplasia and cancers. CONCLUSIONS: Our results confirm the high frequency of the abnormal expression of p53 protein in cancer developed in Barrett's oesophagus. This expression is a consequence of alterations of the TP53 gene, and has an important role in the carcinogenesis of Barrett's mucosa; it is likely to represent an early event. Prospective studies are needed to evaluate its interest in the surveillance of patients with Barrett's oesophagus.

Barrett Esophagus↗
PubMed1994

Fate and biocompatibility of three types of microspheres implanted into the brain.

The implantation of polymer devices in the brain that release neuroactive drugs locally and in a controlled manner is gaining increasing interest. The fates and tissue reactions of poly(epsilon-caprolactone), ethylcellulose, and polystyrene microspheres, prepared by the solvent evaporation method, radiosterilized by gamma-irradiation, and stereotactically implanted in rat brain have been studied by routine staining and immunohistochemistry. During the first few days after implantation, a nonspecific astrocytic brain tissue reaction was observed along with a macrophagous-microglial cell reaction typically found following any damage in the central nervous system, except in the presence of certain foreign body giant cells. Nine months into the experiment, microspheres appeared to be engulfed by histiocytic cells. The microsphere cluster was surrounded by a sheath composed of collagen and astrocytic cells. No necrosis was observed, suggesting the absence of toxicity. In some animals, however, an hydrocephalus developed as a result of obstruction of the medial ventricle by some microspheres.

Animals↗
PubMed1994

A lymph node interdigitating reticulum cell sarcoma.

A 20-year-old woman presented with bilateral cervical, supraclavicular, and mediastinal lymphadenopathy. A nodal biopsy specimen showed a diffuse malignant proliferation of large pleomorphic cells. The ultrastructural features and the antigen phenotype (expression of HLA-DR, CD68, alpha 1-antichymotrypsin, and S100 protein and inconstant reactivity for CD11c, CD15, and peanut agglutinin) were consistent with a derivation from interdigitating reticulum cells. Despite intensive combination chemotherapy with autologous bone marrow transplantation and local irradiation, the patient relapsed in the initial sites of the disease. A review of 12 previous reports of interdigitating reticulum cell sarcomas showed that most of these rare tumors behaved aggressively and were unresponsive to classic intensive chemotherapeutic regimens.

Adult↗
PubMed1993

["Tufted angioma". A benign vascular tumor to differentiate with Kaposi sarcoma].

Among recently characterized vascular tumors, tufted angioma or angioblastoma is a benign acquired slowly progressive cutaneous tumor, which most commonly arises in the neck and upper trunk in children and young adults. This case report emphasizes the clinical and histological features of tufted angioma. Light microscopic examination reveals numerous lobules of closely packed capillaries scattered throughout the dermis. Vascular lumina are difficult to define. There are no atypical cells. Familiarity with tufted angioma should prevent this lesion from being misdiagnosed as malignant vascular tumor arising in young persons, especially Kaposi's sarcoma.

Adolescent↗
PubMed1992

[Why and how to grade renal carcinomas?].

The prognosis of renal cell carcinomas has been a controversial subject for pathologists for a long time. At the present time, in addition to stage, the nuclear grade defined by Führman represents an essential element in the prognostic assessment. A renal cell carcinoma can be easily characterized by its stage and its grade, defining a precise prognosis. Specific entities such as tubulopapillary tumors, oncocytomas and chromophobe cell carcinomas must also be graded until the results of complementary studies become available allowing a better assessment of their autonomy among renal cell carcinomas.

Adenocarcinoma↗
PubMed1992

[Is it useful to isolate a chromophobe cell variant among carcinomas of the kidney?].

Chromophobe cell carcinoma is a little known variety of renal cell carcinoma representing 7 to 9% of all renal tumors. This tumor is confused with either clear cell carcinoma (clear subvariety) or oncocytoma (eosinophilic subvariety). Until ultrastructural and prospective studies of the prognosis of this tumor become available, it already seems important to perform colloidal iron staining to establish the differential diagnosis between oncocytoma and chromophobe cell carcinoma.

Adenoma, Chromophobe↗
PubMed1992

[Nephrogenic nephroma].

Nephrogenic nephroma was individualized by A. Pagès in 1980 as a rare renal neoplasia that mainly occurs in adolescents and adults and presents a benign outcome. The tumor is composed of very small tubular, papillary, and glomeruloid structures. Immunohistochemistry and electron microscopy show that the tumor is a proliferation of primitive epithelial cells that mimic the embryonal nephron. This neoplastic entity has often been confused with a nephroblastoma, although it is a benign tumor that is cured by simple resection. Further studies are needed to define its exact incidence and its histogenesis.

Adolescent↗