Biomedical subjects

A Danguy

Publications and source records attributed to A Danguy.

At least 73 records · Page 4Linked to original sources

PubMed1994

Androgen status and expression of glycoconjugates and lectins in the epithelial cells of the mouse ventral prostate. A glycohistochemical approach.

We investigated histochemically the expression of glycans and endogenous sugar-binding proteins (endolectins) in the ventral prostate of normal and androgen-deprived mice. The avidin-biotin-peroxidase complex technique was used with a panel of biotinylated lectins and neoglycoproteins, respectively, on paraffin sections. Characteristic binding patterns depending upon the type of lectin were observed in the glandular epithelium and basement membranes. This report also initiates the histochemical study of endogenous glycan-binding proteins in this male-accessory sex organ. Remarkably, the endocrine status was found to affect the distribution of lectin-reactive determinants of glycoconjugates as well as endolectins. The histophysiological significance of these modifications in the glandular cells are discussed in the light of previous biochemical findings obtained mainly in humans and the rat.

Androgens↗

PubMed1994

Contribution of carbohydrate histochemistry to glycobiology.

The physiological importance of carbohydrate biology has gradually emerged from a lot of recent information on protein-carbohydrate and carbohydrate-carbohydrate interaction in normal and pathological conditions. After considering the conventional methods which allowed researchers to differentiate glycan-containing macromolecules from other complex compounds (nucleic acids, proteins), selected topics of intracellular and cellular organ architecture are focused upon in which the use of lectins and neoglycoproteins as histochemical reagents has opened new horizons for the localization of glycoconjugates in situ and the elucidation of their often still enigmatic functions. The authors hope to place into perspective that such glycohistochemical studies will strongly contribute to the progress in the dynamically growing field of glycobiology.

Animals↗

PubMed1993

Histochemical analysis of carbohydrate moieties and sugar-specific acceptors in the kidneys of the laboratory mouse and the golden spiny mouse (Acomys russatus).

The aims of this work were to histochemically compare the pattern of lectin binding and endolectin expression in different portions of nephrons of two rodent species producing either normal hyperosmotic urine (the laboratory mouse) or highly concentrated urine (Acomys russatus, the golden spiny mouse). A panel of biotinylated lectins and neoglycoproteins and the avidin-biotin-peroxidase complex technique were used on Bouin's fixed, paraffin-embedded sections. Various segments of the uriniferous tubule in both species showed differential affinity for labelled lectins and neoglycoproteins. Significant differences were also evident between comparable tubular segments in laboratory and golden spiny mouse kidneys. Whether the histochemical expression of sugar moieties of glycoconjugates as well as endolectins, thus both sides of presumed protein-carbohydrate interactions, may be correlated to the various glycoproteins which would include constituents of the glycocalyx and domains of a variety of transport enzymes deserves further studies.

Animals↗

PubMed1993

Reverse lectin histochemistry: design and application of glycoligands for detection of cell and tissue lectins.

Plant and invertebrate lectins are valuable cyto- and histological tools for the localization of defined carbohydrate determinants. The well-documented ubiquitous occurrence of sugar receptors encourages functional considerations. Undoubtedly, analysis of the presence of vertebrate lectins in tissues and cells is required to answer the pertinent and tempting question on the physiological relevance of protein (lectin)-carbohydrate recognition in situ. Carrier-immobilized glycoligands, derived from custom-made chemical synthesis, enable the visualization of respective binding sites. Histochemically inert proteins or synthetic polymers with appropriate functional groups are suitable carrier molecules for essential incorporation of ligand and label. The resulting neoglycoconjugates can track down tissue receptors that are neither impaired by fixation procedures nor blocked by endogenous high-affinity ligands. Lectins, especially the receptors of the tissue under investigation (endogenous lectins), and appropriately tailored immobilized glycoligands or lectin-specific antibodies (when available) are complementary tools to test the attractive hypothesis that diverse, functionally relevant glycobiological processes within or between cells are operative. Concomitant evaluation of both sides of lectin histochemistry, namely lectins as tools and lectins as functionally important molecules in situ, will indubitably render desired progress amenable in our often still fragmentary understanding of the importance of tissue lectin and glycoconjugate expression and its regulation.

Animals↗

PubMed1991

In vitro influence of gastrin, oestradiol and gonadotropin-releasing hormone on HCT-15 and LoVo human colorectal neoplastic cell proliferation.

We set up in vitro several human colorectal neoplastic cell lines that we labelled "hormone-sensitive" (HS) in comparison to the original cell lines which appeared to be rather "hormone-insensitive" (HI). We used LoVo and HCT-15 human colorectal neoplastic cell lines and studied the influence of 17 beta-oestradiol (E2), gastrin and two gonadotropin-releasing hormone (GnRH) analogues, HRF and buserelin, on the proliferation of the HS and HI variants of the LoVo and HCT-15 cell lines. Cell proliferation was evaluated by a colorimetric assay, the MTT test. Our results show that E2, gastrin, HRF and buserelin did not induce a significant stimulatory influence on the HI variants of the LoVo and HCT-15 cells, i.e. the cells that were cultured in a hormone-free 10% FCS-supplemented medium. In sharp contrast, the colorectal cells cultured for 30 passages in an E2 and/or gastrin + 1% FCS-supplemented medium showed a marked tropic response to E2, gastrin, HRF and buserelin. However, the HS variants of the HCT-15 cells appeared less sensitive to the two GnRH analogues than did the HS variants of the LoVo cells.

Cell Count↗

PubMed1991

Histochemical evaluation of application of biotinylated neoglycoproteins for the detection of endogenous sugar receptors in fish skin.

The physiological importance of recognitive protein-carbohydrate interactions is by no means restricted to mammals. Thus, the analysis of expression of sugar receptors in lower vertebrates is warranted, employing carrier-immobilized carbohydrate ligands. The present work initiates such a systematic glycohistochemical mapping of endogenous sugar receptor expression, focussing on fish epidermis. A battery of biotinylated neoglycoproteins exposing 11 different types of ligand structures, and the avidin-biotin-peroxidase complex (ABC) technique has been used to assess extent of binding on Bouin's solution-fixed paraffin-embedded specimens. The semi-quantitative evaluation disclosed both quantitative and qualitative site-associated differences in expression of endogenous lectins by the integument constituents. Moreover, a distinct expression of sugar receptors by two or three types of trunk myocytes was also observed. This study thus emphasized the feasibility of glycohistochemistry with neoglycoproteins, conducted in lower vertebrates. The approach used with carbohydrate constituents of cellular glycosubstances as ligands in search of specific receptors is proposed to be a powerful complementary tool in carbohydrate histochemistry to the monitoring of the carbohydrate structures by labelled plant or invertebrate lectins and a step to elucidate the functional significance of protein-carbohydrate interactions.

Animals↗

PubMed1990

Influence of smear preparation and fixatives on the DNA ploidy and the morphonuclear features of the MXT mammary tumor and normal tissues in the mouse.

We compared cytomorphonuclear parameters--related to DNA histogram and chromatin distribution--on MXT mouse mammary tumor and murine normal cells from fresh squash smears or from deparaffinized tissue smears fixed in several fluids. We used the SAMBA 200 cell image processor with software allowing for the discrimination of parameters computed on Feulgen-stained nuclei. The spectrophotometric results--assessed by integrated optical density values--indicate that the nuclei from deparaffinized tissue fixed in Bouin's fluid are around 50% less stained than those fixed in formalin or ethanol-formalin-acetic acid (EFA). The fresh smears of nuclei fixed in formalin contain a less well-defined and more homogeneous chromatin than after Bouin's or EFA fixation. This has led to the conclusion that morphonuclear parameter comparisons performed on tissues differently processed or from different origins present severe limitations.

Adenocarcinoma↗

PubMed1989

Influence of pituitary grafts or prolactin administrations on the hormone sensitivity of ovarian hormone-independent mouse mammary MXT tumors.

The sensitivity of MXT mouse mammary tumors to ovarian hormones was assessed by the following parameters: growth in vivo; presence or absence of estrogen receptors and progesterone receptors; and histological differentiation. A spontaneous evolution from hormone sensitivity (HS) to hormone independence (HI) was observed when the tumors underwent monthly transplantation onto intact recipient mice, with the tumors fulfilling the criteria of HI tumors after the 12th transplantation. In contrast, the tumors recovered most of the criteria of hormone sensitivity when pituitary isografts were placed under the kidney capsules of HI tumor-bearing animals or when these animals received daily administrations of prolactin over several months. Sensitivity to 17 beta-estradiol, progesterone, or prolactin was further assessed by actinomycin binding on the nucleus and thymidine labeling index, both measured by autoradiography. These technical approaches revealed that 17 beta-estradiol and prolactin stimulated the thymidine labeling index of both HI (despite the lack of detectable estrogen receptors) and HS MXT tumors whereas progesterone influenced only that of HS cancers. The three hormones significantly stimulated [3H]actinomycin D binding within HS tumors but not within HI ones. However, such "HI" tumors were characterized by increased actinomycin binding and thymidine labeling index in comparison with HS neoplasms. Thus, all the data presently reported strongly suggest that prolactin is able to restore the hormone-sensitive phenotype within so-called MXT hormone-independent tumors.

Adenocarcinoma↗

PubMed1989

Influence of fetal calf serum in combination with pharmacological doses of progesterone or estradiol on proliferation and cell cycle kinetics of cultured mammary cancer cells.

We describe an original method to monitor clonal cell density (hyperplasia) and the cell cycle kinetics of neoplastic cells simultaneously. We thus characterize the in vitro influence of two different types of fetal calf serum (FCS), defined as FCS-S and FCS-I, on the progesterone- or estradiol-induced effect on proliferation and cell cycle kinetic parameters of the MXT mouse and MCF-7 human mammary cancer cell lines. The two sera were treated with dextran-coated charcoal. The FCS-S serum showed a stimulatory influence on MXT and MCF-7 growth, whereas FCS-I was devoid of any clear-cut influence. The cells were cultured on glass coverslips, placed in Petri dishes containing either a control or a hormone-added medium, fixed for histology and submitted to the Feulgen reaction, which allows selective and quantitative (stoichiometric) staining of DNA. Proliferation and cell cycle kinetics were analyzed on the same sample of cells by means of the SAMBA 200 cell image processor. Our results show that steroid-mediated effects were dramatically modulated according to the type of serum used. Furthermore, they also show that pharmacological doses of progesterone or estradiol decrease MXT cell growth by at least two different mechanisms: the first is related to cell cycle kinetics, i.e. an inhibition of the cells into the S phase, while the second remains unknown but seems to be cell cycle independent. High dose estradiol, but not progesterone, induced the same inhibitory influence on the MCF-7 cells.

Animals↗

PubMed1989

Comparative lectin-binding patterns in the epidermis and dermal glands of Bufo bufo (L.) and Xenopus laevis (Daudin).

Bouin-fixed and paraffin-embedded sections from the dorsal skin of Bufo bufo and Xenopus Laevis were subjected to lectin histochemistry. A panel of biotinylated lectins (Con-A, PSA, LCA, UEA-I, DBA, SBA, SJA, RCA-I, BSL-I, WGA, s-WGA, PHA-E and PHA-L) and an avidin-biotin-peroxidase complex (ABC) showed a species-specific compartmentalization of saccharides to certain parts of the epidermis and glandular domains. Some marked histochemical differences between the two examined species adapted to fully aquatic (X. laevis) or semiterrestrial (B. bufo) environments may be relevant of a relationship existing between habitat selection and the glycosaminoglycans content of the skin. In addition the technique used in this paper may be applicable for further studies of the carbohydrate composition in various tissues of lower vertebrates.

Animals↗

PubMed1988

Detection of cell proliferation in pig testis and intestine sections using monoclonal anti-bromodeoxyuridine antibody and immunogold silver staining.

For the first time a monoclonal antibody against 5-bromodeoxyuridine was used to detect cell proliferation in pig testis and intestine sections. The influence of several parameters such as mode of injection, addition of thymidine biosynthesis inhibitor, tissue fixation, hydrolysis and revelation was examined. The technique of choice consisted in intravenously injecting the animals with 50 mg/kg BUdR added to 10 mg/kg FUdR 2 h before tissue collection and Bouin fixation; hydrolysis of sections was performed by HC1 4N: Ethanol 70 degrees (1:1 v/v); revelation of BUdR was made by a secondary antibody linked to colloidal gold particles, followed by a silver enhancement step. The data were superior when compared to those obtained by direct immunofluorescence and by the PAP technique. The described method is convenient and sensitive, provides an intense nuclear labelling without background and allows simultaneous examination of histology. The advantages over the technique using tritiated thymidine are particularly obvious when fast screening of numerous samples is required or when new experimental protocols are developing.

Animals↗

PubMed1988

Prevention of ovarian damage induced by cyclophosphamide in adult female mice by hormonal manipulations.

Doses of 10 or 20 mg cyclophosphamide/kg body weight were administered daily to mice for up to 20 days. This caused significant reductions in the incidence of prenatal (developing) follicles and significant increases in atretic (degenerating) follicles within the ovaries. Attempts to prevent cyclophosphamide-induced damage by simultaneous treatment with oestrogen alone, oestrogen plus progesterone, or danazol (a synthetic androgen) demonstrated that danazol effectively prevented the ovarian damage. The efficacy of danazol was considered to be due to its ability to inhibit LH/FSH secretion and, indirectly, the development of new ovarian follicles.

Animals↗

PubMed1988

Lectins in histochemistry. A survey.

The most pertinent works using lectin histochemistry at both light and electron microscopy were reviewed. The results and their eventual interpretation are summarized. The importance of lectins as a histochemical tool is mainly based upon the two following features: they possess a narrow specificity for various carbohydrate residues and they can be linked to different labels (fluorochrome, peroxidase, ferritin, colloidal gold) or be included in immunocytochemical techniques in order to be visualized at conventional, u.v. and electron microscopes. These have the advantage to preserve the cellular and tissular integrity. Various tissues and organs were investigated first as a descriptive manner and then under cell differentiation and ontogenetic points of view. Tissues from laboratory rodents and human were especially studied. Few works regarding other vertebrates have been published. However comparative studies could probably cast some lights regarding functions and phylogenetic evaluation. Finally, lectin histochemistry in pathology seems of great promise as indicated by the growing number of publications.

Animals↗

PubMed1987

Effect of ovariectomy, hypophysectomy and/or GnRH analog (HRF) administration on the cell proliferation of the MXT mouse hormone-dependent mammary tumor.

The MXT tumor is an experimental mammary neoplasm which is maintained by serial transplantation using B6D2F1 mice, and which contains significant amounts of estrogen and progesterone receptors. The aim of the present study is to examine the effects of ovariectomy (OVX) or ovariectomy plus hypophysectomy (OVX-HX) on both the macroscopic growth and the cell proliferation of this tumor. This cell proliferation was evaluated by means of in vivo tritiated thymidine autoradiography. In addition, we investigated the effects of a GnRH analog (Gonadorelin: HRF, 5-oxo-Pro-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-hydrochloride) on MTX tumor cell proliferation on 7 day-OVX and 5 day-HX (OVX-HX) mice. The uterine luminal epithelium was chosen to monitor the methodology. Our data clearly demonstrate that there is a delay in the growth of MXT tumors grafted into hypophysectomized animals and, to a lesser degree, ovariectomized animals. With respect to proliferation, castration induced a dramatic decrease of the thymidine labelling index (TLI) in the tissue used to monitor the methodology (the uterine luminal epithemium); in contrast, no cell proliferation was induced by hypophysectomy or HRF administration. In 4-week-old MXT tumors, ovariectomy also markedly decreased the TLI within a few days of its taking place. However hypophysectomy, performed on castrated animals, induced a significant and transient increase of cell proliferation in this neoplasm, an increase which lasted from the 2nd to the 5th day following the operation. The high basal level of MXT cell proliferation recorded in OVX-HX animals decreased dramatically after the administration of HRF between 12 and 48 h prior to the sacrifice of the animals. It is concluded that the HRF exerts a direct effect on the MXT tumor cells, and this HRF might be essential for their growth.

Animals↗

PubMed1987

In vitro studies of canine mammary tumors: influence of 17-beta-estradiol and progesterone on cell kinetics parameters.

Using an in vitro tritiated thymidine nuclear labeling followed by autoradiography, the effects of 17-beta-estradiol (E2) or progesterone (Pg) were studied in 30 canine mammary tumors that were incubated and hormonally stimulated in vitro. In 10 of these tumors, the synthetic (S) phase duration was also measured in absence or in presence of E2, by using a double labeling with tritiated thymidine. Our results demonstrate that E2, and, to a lesser degree, Pg can induce cell replication in both estrogen receptor-positive (ER+ PgR+) and estrogen receptor-negative (ER- PgR-) canine mammary tumors. The mitogenic effect of E2 may involve a shortening of the DNA S cell cycle phase. We have also found a significantly positive relationship between the estrogen and the progesterone receptor concentrations and the basal proliferation rate in these tumors, whereas no correlation was found between steroid receptor contents and the maximal level of stimulation achieved after E2 or Pg exposure.

Animals↗

PubMed1986

Morphology of MXT mouse mammary tumors. Correlation with growth characteristics and hormone sensitivity.

The transplantable MXT mouse mammary tumor has been a useful tool for studying endocrine mechanisms underlying mammary tumor growth. It is our experience, however, that this model is unstable during serial transplantation. This paper analyses this variability from the viewpoints of histology and estrogen receptor content and indicates that these parameters should always be checked before planning experimental work. It is advised that a more homogeneous material is needed and that this goal should be achieved by clonal selection before transplantation.

Animals↗

PubMed1986

Sensitivity of the hormone dependent MXT-mouse mammary carcinoma to estradiol during tumoral growth. An autoradiographic study.

The MXT transplantable mammary tumor is an ovarian sensitive carcinoma of the B6D2F1 mouse strain. The present work documents the mitogenic effect of a single near-physiological dose (pulse) of estradiol (E2) in castrated mice bearing MXT neoplasms 2-7 weeks after their inoculation. Histological sections of tumors and uteri (as control E2 target organs) were processed and nuclear thymidine labeling indices (TLI) were determined by autoradiography. Tumor estrogen receptors contents were evaluated in parallel. The results indicate that the MXT tumor keeps a constant sensitivity to E2 6 weeks after implantation.

Animals↗

PubMed1985

In vitro synergism between estrogens and cytotoxic agents.

Two lines of research intending to achieve synergism between cytotoxic agents and estrogens for breast cancer treatment are pursued in our laboratory. According to a screening procedure we select cytotoxic-linked estrogens which bind to estrogen receptors and thereby would be specifically concentrated into the tumor cells. A mesylate derivative of estrone has emerged from our investigations. This compound displays a very strong binding affinity for the receptors and inhibits the growth of the receptor-positive MCF-7 breast cancer cell line. The lack of growth inhibition in the receptor-negative line Evsa-T indicates that it is devoid of major non-specific cytotoxicity. We attempt to enhance the vulnerability of the tumor cells by producing an estrogen-induced modification of their chromatin. The in vitro exposure of isolated uterine nuclei to uterine cytosol preincubated with estradiol increases their ability to bind [3H]actinomycin D. Identical results are obtained with MXT mouse mammary tumors. Experiments are in progress to settle whether these changes are associated with enhanced cell killing.

Animals↗