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Biomedical subjects

R Laumonier

Publications and source records attributed to R Laumonier.

At least 19 recordsLinked to original sources
PubMed1985

[Experimental colonic cancers].

An experimental model of colonic cancer can be obtained in rodents by administration of 1-2 Dimethylhydrazine. It produces constant, reproducible lesions, ranging from simple anomalies of secretion to invasive cancers, which are identical to those observed in man. It should be noted that the rats and mice used in these experiments do not present spontaneous colonic tumours. This model has contributed to the substitution of the polyp-cancer sequence by the dysplasia-cancer sequence. All of steps of malignant transformation of the mucosa can be followed by histochemistry of the mucins, by ultrastructural examination of the basement membrane and by labeling of the sub-epithelial connective tissue with hyaluronectin. In man, it is possible to define high risk lesions prior to the appearance of polyps.

1,2-Dimethylhydrazine↗
PubMed1984

[Diagnosis of tumor recurrence within the breast after tumor removal for cancer, followed or not by radiotherapy. Apropos of 23 cases].

The diagnostic value of mammography was evaluated retrospectively in 23 recurrent carcinomas in patients previously treated by partial mastectomy with or without adjuvant radiotherapy. Mammography established accurate diagnosis in 11 of the 23 patients. Mammography should always be performed in addition to clinical and cytological examinations and results must be evaluated jointly. Confrontation of these three investigations may be inconclusive as a result of changes produced by radiotherapy or surgery. The authors recall the necessity of surgical control of any nodular lesion developed in the area of the initial operation, particularly during the first three years.

Biopsy, Needle↗
PubMed1984

[Benign mammographic stellar images. Apropos of 15 cases].

15 stellar types breast lesions were reviewed and classified according their etiology (fibrosing adenosis, dysplasia, dystrophy, radial scar of Aschoff, fat necrosis). Radio-anatomical confrontation allowed to understand the images given by the varying appearances of the connective skeleton surrounded by adipose lobules. The authors study the diagnosis of the stellar breast lesions and recall the determinant role of connective tissue in the genesis of mammographic stellar images.

Adult↗
PubMed1981

Preneoplastic changes in epithelium and mesenchyme in colon of rats treated with 1,2-dimethylhydrazine.

Twenty-eight rats were given weekly injections of 1,2-dimethylhydrazine (DMH) for periods of 1-10 weeks. The preneoplastic changes occurring in the descending colon were monitored by transmission electron microscopy. Marked uniformity was observed in the time period of lesion development in the colon induced by the carcinogen especially at the epithelialstromal junction in preneoplastic lesions. Little changes were observed after 3 weeks treatment with the DMH. The greatest changes occurred after 6 weeks treatment, resulting in epithelium and mesenchyme. It has been confirmed that 3 weeks treatment with DMH is subcarcinogenic, whereas 10 weeks treatment results in a high incidence of tumors. These findings are compatible with the hypothesis that a carcinogen may act by inducing alterations in a small number of enterocytes and that colonic tumors arise through stepwise evolutional changes in these cells.

1,2-Dimethylhydrazine↗
PubMed1980

Brain glycoprotein in tumours of the nervous system.

We studied various tumours of the nervous system by the immunofluorescence technique using an anti-brain specific alpha 2 glycoprotein antiserum (anti-NSA3 antiserum). We found the antigen in 24/27 astrocytomas and 4/4 oligodendrogliomas but in none of the 8 meningiomas tested. There was an identity between the astrocytoma/oligodendroglioma antigen and that of normal brain as shown by the immunoprecipitation technique. By the immunofluorescence technique using inhibition of the antiserum we demonstrated that the tumour antigen is devoid of some specific nervous system determinants present in normal brain.

Antigens, Neoplasm↗
PubMed1980

1-2 Dimethylhydrazine induced colonic tumours in rats.

1-2 dimethylhydrazine was injected subcutaneously on a weekly basis of 15 mg/kg, during periods ranging from one to twenty-eight weeks into five hundred Wistar rats. Glandular-mucin depletion appears as early as the second injection (sulfomucins disappear). From the sixth week, one observes dysplasia; if the animals are allowed to survive for a longer period all will develop colonic carcinomas, which were found mainly in the left colon. This dysplasia, which is first mild, then moderate, is finally severe in rat mucosa or in the area of polyps. Dysplastic polyps become less frequent when carcinomas increase in number and in size. The average length of survival after cessation of the exposure is inversely proportional to the total dose administered. The glandular mucin depletion-dysplasia-carcinoma sequence characterizes the types of formation of 1-2 DMH induced colonic carcinomas. One of the striking features is the early appearance of this sequence.

Animals↗
PubMed1979

An antigen associated with mesenchyme in human tumours that cross-reacts with brain glycoprotein.

Anti-NSA3 antiserum was found to react with many kinds of benign and malignant tumours, as well as foetal skin and intestinal extracts. The corresponding antigens isolated from nervous tissue, benign breast adenoma, and a fibrosarcoma were compared. Immunoprecipitation cannot distinguish between these antigens, and their amino-acid contents were comparable. However, immuno-absorption identified an antigenic determinant that was confined to nervous tissue. Indirect immunofluorescence further confirmed the validity of the concept of a nervous form vs a mesenchymal form of the antigen. Furthermore, immunofluorescence enabled the localization of the antigen found in non-nervous tissue to mesenchyme (mesenchyme-associated antigen: MAA), whether the mesenchymal tissue be normal (foetal organs), tumoral (fibrosarcoma) or reactional (connective-tissue stroma of epithelial tumours).

Amino Acids↗
PubMed1979

[Transitional tumours of urinary bladder (author's transl)].

An overall survey of the transitional epithelium of the bladder and its carcinomas. This study is based upon the recent literature, in particular the considerable contribution of scanner electron microscopy. a) The transitional epithelium has the reputation of having a simple structure and even behaviour. In fact, it is complex with highly specialised surface cells. It has marked powers of regeneration after aggressions of various types. b) Tumours of the transitional epithelium are defined in relation to rupture of the basal lamina. Invasive carcinomas are classified according to their histological stage of penetration, their pure or partially metaplasic type and their degree defined according to the criteria of Broders. There exists a correlation between these three types of evaluation. Non-invasive carcinomas are either papillary--putting into question the reality of benign bladder papilloma--or flat mucosal and then often associated closely or at a distance with an invasive carcinoma. c) Abnormal regeneration, dysplasia or hyperplasia as a result of aggressions of different types or developing in isolation represent a high risk histologically, implying the need for careful follow-up and surveillance. d) Histopathological study of urothelial or transitional tumours is simple in operative specimens but difficult in biopsies. It requires close cooperation between surgeons and pathologists to ensure correct orientation of the fragments.

Carcinoma in Situ↗
PubMed1978

[Mesenchyme-associated antigen: a new immunochemical marker of human tumors].

An antiserum raised in Rabbits against brain glycoprotein precipitated an identical antigen in faetal dermis and intestine extracts, and also in non nervous tumors (breast adenocarcinomas and adenofibromas, ovarian cystadenoma, gastric and colonic adenocarcinomas, hepatomas, malignant melanomas, rhabdomvosarcoma, fibrosarcomas). By the indirect immunofluorescence technique, this antigen was always found associated with the mesenchymal proliferation, either malignant (fibrosarcoma) or reactive (fibrous stroma reaction of carcinomas).

Animals↗
PubMed1978

[Disappearance of the gliofibrillar protein (GFA) during the cultivation of glioblastoma cells].

Absence of GFA in established cell lines from glioblastomas promped us to look for this protein from the first replication of malignant cells in vitro and in following subcultrues. Our results show that GFA disappeared during the first twelve replications, often before the fifth replication. No correlation was observed with a morphological transformation of the cells.

Antigens, Neoplasm↗
PubMed1978

[Stages of carcinogenesis of experimental colonic tumors induced with 1-2 dimethylhydrazine].

The authors poisoned 500 female Wistar rats with a dialy dose of 15 mg/kg, The total dose ranged from 15 mg/kg to 420 mg/kg, according to the group. The animals were either killed when the dose defined for each group and been reached, or allowed to live. In a first series of 6 groups (120 animals), the following facts were noted: tumours deeveloped in all animals left alive, after 28 weeks (total dose of 1/2 D.M.H. = 420 MG/KG). Changes in the mucosa were seen from the 40th day on with, in the descending colon, a punctate abnormality involving two or three glandular tubes, in general at the summit of the folds. This abnormality consisted of basophilia of the upper part of the tubes, with a loss of mucus secretion. All transitional stages were seen between this lesion, hyperplasia of the apex of the tubes, the formation of "polyp seeds" and the appearance of polyps. Carcinomas most frequently developed in polyps but sometimes in flat mucosa. In the ascending colon, changes in mucosecretion were seen after a similar time delay at the base of the glandular crypts.

Animals↗
PubMed1978

[Ultrastructure study of the preneoplastic colon (carcinogenesis with 1,2-dimethylhydrazine)].

100 Wistar rats, belonging to a series of 500 animals, were treated with increasing doses and for increasing periods of time with 1,2-dimethylhydrazine. A previous study has shown that tumors begin to appear only after the 19th week. Before this period there are abnormalities of mucin secretion (by the 2nd week), and then there are dysplasic lesions (after the 4th week). The ultrastructure study, done before the 19th week ("pretumor" phase) confirms some previous observations (increase in the zone of mitosis, secretory changes, mutation producing effects). These features are reminiscent of the histochemical characteristics of the human foetal colon. They show an epitheliomesenchymatous disorganisation unrelated to inflammation. There are abnormally early changes in the vasculature, there is loss of the (epithelial) coat, there is dissociation of the basal membrane and abnormal connections between it and the epithelial cells, collagen and fibroblasts; all this represents a disorganisation of the regeneration system of the colon mucosa. This loss of equilibrium between the parenchyma and the mesenchyma may represent a factor favoring excessive and disorganised growth of the mucosa.

Adenocarcinoma↗