Biomedical subjects
E Didier
Publications and source records attributed to E Didier.
Major oncogenes and tumor suppressor genes involved in epithelial ovarian cancer (review).
Ovarian cancer remains the leading cause of death from gynecologic malignancy in Western countries. This cancer results from a succession of genetic alterations involving oncogenes and tumor suppressor genes which have a critical role in normal cell growth regulation. Mutations and/or overexpression of three oncogenes, HER-2/neu, c-myc and K-ras, and of the tumor suppressor gene p53, have frequently been observed in sporadic ovarian cancer. In the context of high risk families, the most frequently involved genes are BRCA1 and BRCA2. We review the function of these different proteins, the incidence of mutations in their genes in carcinogenesis and as potential prognostic factors in sporadic and hereditary ovarian cancer.
Rabbit intestinal xenograft model for human Encephalitozoon infections in mice.
BACKGROUND AND PURPOSE: The gastrointestinal tract is a common portal of entry for Encephalitozoon cuniculi, one of several microsporidial organisms emerging as opportunistic pathogens in immunocompromised humans. Although most human microsporidial pathogens can be propagated in vitro and in a variety of laboratory animals, an experimental animal system to specifically study intestinal uptake and systemic spread of these organisms does not exist. METHODS: Paired segments of near-term fetal rabbit small intestine were implanted subcutaneously into 25 athymic nude or 10 severe combined immune deficient mice. Five weeks after surgery, 65 xenografts were inoculated intraluminally with E. cuniculi (n = 14), E. intestinalis (n = 27), E. hellem (n = 20), or RK-13 cells (n = 2), or were left uninoculated (n = 2). RESULTS: Intestinal xenograft infection with E. cuniculi (n = 11), E. intestinalis (n = 17), and E. hellem (n = 18) was determined by light microscopy; control xenografts remained uninfected. Extraintestinal infection with E. cuniculi developed in host mouse brain, respiratory tract, spleen, salivary glands, and gastrointestinal tract (3 of 3 mice), and infection with E. intestinalis developed in the liver (8 of 15 mice). CONCLUSION: Intestinal xenografts provide a unique, sterile, and biologically relevant animal model system for studying host enterocyte/parasite interactions, mechanisms of microsporidial pathogenicity, antimicrosporidial chemotherapeutic agents, and immune effector mechanisms. This model provides evidence for persistent graft infection with three Encephalitozoon spp., and for intestinal spread of E. cuniculi and E. intestinalis from infected enterocytes in immunoincompetent mice.
Association of N-acetyllactosamine with tumor progression in human breast cancer: a study using a 16 kDa chick embryo lectin.
This study documents modifications in the expression and the cellular distribution of binding sites for a 16 kDa chick embryo lectin (CL16-BS) in breast cancer. This lectin binds preferentially to terminal and penultimate N-acetyllactosamine residues (Galbeta1-4GlcNAc). BS density and distribution, studied by lectin binding followed by indirect immunofluorescence, were compared in normal breast tissues and 45 invasive carcinomas (lobular and ductal). Increased number of fluorescent epithelial cells (ETC+) were observed in normal ducts adjacent to lobular carcinomas and in tumors from both types when compared to normal glands. In ductal carcinomas, a significant diminution of ETC+ percentage was observed in the highest anatomopathological SBR grades: 32.7% in grade III, 80.8% in grade II and 66.5% in grade I (p<0.001). For both lobular and ductal carcinomas, ETC+ percentages were also positively correlated with low versus high MSBR grades (p<0.002). The subcellular distribution of CL16-BS varied according to the tumor type and/or the histological grades. It was mostly membrane-associated in low SBR and MSBR grades (p<0.001 and p<0.01, respectively) and cytoplasm-associated in high grades (p<0.02 and p<0.05). Some of these parameters were also correlated with certain other clinicopathological factors, such as tumor size (p<0.02), high S-phase cell fraction (p<0.04 and p<0.03) and low density estrogen receptors (p<0.05). Diminution in CL16-BS density and cytoplasmic versus membrane localization may be considered as indicators of tumor progression but not of metastasis.
Effect of pantothenic acid and ascorbic acid supplementation on human skin wound healing process. A double-blind, prospective and randomized trial.
This study aimed at testing human skin wound healing improvement by a 21-day supplementation of 1.0 g ascorbic acid (AA) and 0.2 g pantothenic acid (PA). 49 patients undergoing surgery for tattoos, by the successive resections procedure, entered a double-blind, prospective and randomized study. Tests performed on both skin and scars determined: hydroxyproline concentrations, number of fibroblasts, trace element contents and mechanical properties. In the 18 supplemented patients, it was shown that in skin (day 8) Fe increased (p < 0.05) and Mn decreased (p < 0.05); in scars (day 21), Cu (p = 0.07) and Mn (p < 0.01) decreased, and Mg (p < 0.05) increased; the mechanical properties of scars in group A were significantly correlated to their contents in Fe, Cu and Zn, whereas no correlation was shown in group B. In blood, AA increased after surgery with supplementation, whereas it decreased in controls. Although no major improvement of the would healing process could be documented in this study, our results suggest that the benefit of AA and PA supplementation could be due to the variations of the trace elements, as they are correlated to mechanical properties of the scars.
[Study of an HIV positive, tropical origin population in a refugee center in France].
The study describes HIV positive refugee patients, who were seen over a 3 years period at COMEDE, a dispensary for foreign nationals. COMEDE offered a HIV test to every patient, and it followed up on the disease and its prevention. Out of 5,234 tests, 328 were positive (6.3%). Less than 5% of the patients refused the test. All the patients returned for the result; 88.4% were African and 11.3% Haitian. The mean age was 31.5 years. The male/female sex ratio was 1.28. In this study, 94.5% of the HIV patients were HIV1, 3% HIV2 and 2.5% carried both strains; 78% were asymptomatic, 7% had ARC and 12.5% had AIDS. The prevalence of tuberculosis was high (10.6%), especially for AIDS patients (65%); Treponematosis prevalence was 13% and toxoplasmosis was 62.8%; 40% had intestinal parasites. 36.4% of the women became pregnant during the study; 41% of the pregnancies were terminated, while 27% went full term. The proportion of missing patients after 6 months was high (57%) because of numerous factors which prevented them from returning. This study shows the importance of proposing a HIV test to this immigrant population, although follow-up is difficult, due to social and economic factors.
[Diarrhea due to microsporidia in a patient with AIDS].
A 26-year-old male AIDS patient with diarrhea of two-months evolution is reported here. The most relevant intestinal pathogens, including Cryptosporidium parvum, were ruled out by routine microbiological tests. Stool samples stained with an "oblong" Ziehl-Neelsen method (fucsin, 7 min instead of 3 min) allowed visualization of organisms resembling microsporidia. Both modified trichrome and calcofluor stains showed organisms compatible with Enterocytozoon bieneusi. Significant titer of antibodies (> or = 1/800) against 4 different microsporidial species were obtained from the serum of the patient by an ELISA test. Clinical improvement was observed after treatment with albendazole, 400 mg twice daily for 4 weeks, even though microsporidial spores were still detected in stool specimens. To our knowledge, this is the first microsporidial infection reported in Argentina.
Expression of the galactose-binding lectins during the formation of organ primordia in the chick embryo.
Early chick embryos contain two beta-galactoside-binding lectins of 16 kDa and 14 kDa. using several antisera to these proteins, we have studied lectin expression at embryonic stages when the segregation and early differentiation of organ primordia are taking place. With antisera to the 16 kDa lectin that display similar immunoreactivity in immunoblot analysis, we show that these antisera exhibit varying immunoreactivity in embryo sections. One antiserum reacts preferentially with a matrix form of lectin while another detects mainly a cellular form of this protein. During early development, galactoside-binding lectins of the matrix type are expressed in the vitelline membrane, the outer and inner limiting membranes of the neural tube, the surface of the notochord and the coelomic surface of the cardiac rudiments. The cellular form of the lectin occurs in the intracellular yolk of early embryos, in the primordial germ cells, the myocardium, in the early myotome, and in a cohort of cells which are presumed to belong to the neural crest. Our results indicate that, although all of the antisera recognize the intracellular lectin of the extraembryonic endoderm, some antisera to the 16 kDa lectin exhibit preferential reactivity with different lectin isoforms. The extracellular matrix form of lectin is transiently expressed during early development at the stages when the segregation of organ primordia is occurring. It's expression could be related to the acquisition of polarity in developing epithelia. Results also suggest that various versions of the same protein may perform distinct developmental roles in the embryo.
Different immunoreactivities of anti-soluble lactose lectin antisera to tissues from early chick embryos: a histochemical study.
The location of soluble lactose-binding proteins (S-lac lectins) has been studied by immunohistochemical methods during morphogenesis of the chick embryo, when segregation and early differentiation of organ primordia was occurring. Using a panel of polyclonal antisera raised to various purified lectin preparations, we observed striking differences in the antigenic properties of these antisera, indicating that diverse versions of the lectins may be expressed during development. The antisera referred to as anti-L-16, anti-M-16, anti-S-14 and anti-I-14 were respectively raised to native or denatured 16 kDa lectins from adult liver and embryonic muscle and to 14 kDa lectins from embryonic skin and adult intestine. Having determined the optimal immunohistochemical conditions in the preparation of embryo sections (fixation, embedding, sectioning) we show that anti-L-16, anti-S-14 and anti-I-14 mostly bind the lectins expressed at the cell surface, in the extracellular matrix and in some released secretion. As previously shown, anti-L-16 and anti-S-14 are also able to recognize the cytoplasmic form of some migrative lectin-rich cells (primitive streak, neural crest cells, germ cells). Anti-M-16 was bound exclusively to the cytoplasmic form of the 16 kDa lectin in the same cell lines as above and also in some others, such as in the notochord, the myotomal part of the somites, the pharyngeal endoderm and the cardiac muscle. These different antigenic properties may be applied to the accurate mapping of various lectin isoforms and evaluation of the respective contribution of their intra- and extracellular variants during development and differentiation.
Expression and distribution of carbohydrate sequences in chick germ cells: a comparative study with lectins and the NC-1/HNK-1 monoclonal antibody.
The expression of end-chain sugar residues and of oligosaccharidic sequences has been investigated in chick germ cells at critical stages during the migration, proliferation and sexual differentiation of these cells. Fluorescent lectins and indirect immunofluorescence studies using the NC-1/HNK-1 monoclonal antibody indicate a remarkable control of glycosylation during germ cell embryonal life. Besides a retained expression of glucose/mannose residues, it was found that alpha- and beta-galactose residues, N-acetyllactosamine and N-N' diacetylchitobiose sequences as well as the sulfated trisaccharidic NC-1 epitope were detectable in a stage-specific pattern. Present at a very high density in the cytoplasm and on the surface of the early germ cells at premigrative and migratory stages, the staining for these carbohydrate sequences gradually disappeared when the germ cells settled and proliferated in the developing gonadal primordia. The disaccharide Gal beta 1----3 Gal NAc was exclusively detected in migrating PGCs. In sexualized gonads, acetyllactosamine and/or diacetylchitobiose were similarly reexpressed in both oogonia and spermatogonia. Spermatogonia displayed beta-galactose residues and a high immunoreactivity with the NC1 Mab, indicating modulations in PGC glycosylations related to the acquisition of sexual phenotypes. In addition NC-1 was found to be expressed in the somatic component of the undifferentiated gonad and in the testis interstitial gland.
Effects of pantothenic acid on fibroblastic cell cultures.
To evaluate the effects of pantothenic acid during wound healing processes, fibroblastic cell cultures originating from foreskin were established and subcultured by trypsinization. PA (40 micrograms/ml) was added to the basal culture medium. The cell proliferation was estimated by cell count and determination of 3H-thymidine incorporation. The protein synthesis and secretion were determined by dosage in the cells and in the culture medium. When PA was added to the medium, a significant increase of cell proliferation and of 3H-thymidine incorporation was observed mainly during the first few days. PA also stimulated intracellular protein synthesis, but did not induce a release of proteins in the culture medium. The exact mechanism involved in this phenomenon remains unclear at this time.
Lectin activity and distribution of chicken lactose lectin I in the extracellular matrix of the chick developing kidney.
A lectin activity inhibitable by thiodigalactose, N-acetyllactosamine, lactulose, lactose and by an antibody raised against CLL I (chicken-lactose lectin I) has been investigated in the chick embryo developing kidney. At post-induction stages this activity was found in both mesonephros and metanephros. In immunofluorescence and immunoelectron microscopy, the extracellular distribution of CLL I was similar in the mesonephros and the metanephros. The lectin was never found intracellularly; cultured kidney cells did not express any endogenous lectin but were rich in lectin-receptor sites, which led to the hyphothesis that CLL I is not produced in situ but could be adsorbed on renal cells. Potential physiological roles for embryonic lectins are discussed.
Role of pantothenic and ascorbic acid in wound healing processes: in vitro study on fibroblasts.
In order to analyze the possible role of pantothenic acid (PA) and ascorbic acid (AA) in wound healing processes, the effects of these vitamins upon the growth of fibroblasts, obtained from human fetal skin or foreskin, were studied. Cell proliferation, protein synthesis and protein release were evaluated. The rate of cell growth remained identical when PA or AA were added to the culture medium. PA increased the basal incorporation of 14C proline into precipitated material while AA did not modify this action. However, when cultures were incubated with PA and AA, the release of intracellular protein into the culture medium increased. These results suggest that the combined use of these two vitamins might be of interest in postsurgical therapy and in wound healing.
Distribution of polyanionic sites in the developing gonads and the dorsal mesentery of the chick embryo.
The distribution of glycoconjugates was investigated in the embryonic trunk mesoderm used as a substrate by migrating primordial germ cells (PGCs) by means of ultrastructural cytochemistry. In both mesentery and developing gonads polyanionic sites were abundant in epithelial and mesenchymal cell coats, basal laminae, and extracellular matrices (ECM). In the latter, polyanions distributed on microfibrils and granules were associated with collagen fibers, forming an entangled network. No preferential association of this fibrillo-granular material with PGCs was observed, suggesting that polyanions present in ECM likely act by promoting inflation of the extracellular spaces rather than by providing mechanical guides for the moving cells.
Early sequential development in avian gonads. An ultrastructural study using selective glycogen labeling in the germ cells.
The early development of chick embryo gonads was studied by light and transmission electron microscopy and by cytochemical detection of glycogen in primordial germ cells (PGC's). The sequential events are presented from day 2 to day 5 (stages 14 to 27), together with the ultrastructural characteristics of the various cell populations. This study attempts to contribute data on the controversial origin of the avian gonadal medulla. It is shown that the main part of the primitive medulla arises from the association of the proliferating germinal epithelium (GE) and epithelioid cords (formed early from the condensed splanchnopleural mesenchyme); later deep cords, probably developed from the intermediate mesoderm mesenchyme, join the medulla. The process of mesenchymal condensation is described (cells aggregated by dense plaques and membrane anchorages, deposits of fibrillar extracellular material around the cords) together with ultrastructural changes in the GE basal lamina, which is progressively pushed back then disorganized. The study of the morphological relationships between the PGC's and the somatic cells has been facilitated by glycogen labeling in the former. Whereas the PGC's settled in the germinal epithelia do not display any junctional complex with the epithelial cells up to stage 26, those which are migrating through the dorsal mesentery and in the deep gonadal mesenchyme are associated to fibroblast-like somatic cells by dense plaques. The cytological characteristics of migrating PGC's (polymorphism, pseudopodia and filopodia, paucity of microfilaments, high alpha-glycogen particle content) have been described. In addition, the cell pattern in mesodermal tissues is thought well-suited to PGC invasion owing to a wide extracellular compartment, distributed in the mesenchyme and the early epithelium, and to discontinuities in the basal lamina.
Age-dependent control exerted by the somatic part of the gonad upon gonocyte proliferation in the chick embryo.
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[Germ cells of the bird embryo: early localization, migration and colonization of gonadal anlagen].
Several experimental and morphological papers are analyzed concerning germ cell origin, migration and proliferation within sexually undifferentiated gonads. The germ material which is first localized in both anterior and posterior halves of the unincubated blastoderm assembles in the anterior area only at the beginning of incubation. In gonads the germinal population does not depend on the initial quantity of germ cells in the early blastoderm: its value seems to be determined by the somatic cells of the gonadal stroma. During the migratory phase, it is suggested that regulated interactions occur between the glycoconjugates of the moving germ cells and the physico-chemical characteristics of the extracellular matrices acting as substrates for the movement.
[Somatic and germinal chimerism after the intracoelomic graft of quail splanchnic mesoderm to chick embryos].
The splanchnic mesoderm of the genital area can develop in coelomic graftings as soon as it is colonized by the primordial germ cells (stage 15 of H. and H.). Heterospecific associations between Chick and Quail embryos lead to the differentiation of gonads showing more or less pronounced somatic and germinal chimerisms.