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Biomedical subjects

N Antoine

Publications and source records attributed to N Antoine.

32 records · Page 2Linked to original sources
PubMed1992

Gene order comparisons for phylogenetic inference: evolution of the mitochondrial genome.

Detailed knowledge of gene maps or even complete nucleotide sequences for small genomes leads to the feasibility of evolutionary inference based on the macrostructure of entire genomes, rather than on the traditional comparison of homologous versions of a single gene in different organisms. The mathematical modeling of evolution at the genomic level, however, and the associated inferential apparatus are qualitatively different from the usual sequence comparison theory developed to study evolution at the level of individual gene sequences. We describe the construction of a database of 16 mitochondrial gene orders from fungi and other eukaryotes by using complete or nearly complete genomic sequences; propose a measure of gene order rearrangement based on the minimal set of chromosomal inversions, transpositions, insertions, and deletions necessary to convert the order in one genome to that of the other; report on algorithm design and the development of the DERANGE software for the calculation of this measure; and present the results of analyzing the mitochondrial data with the aid of this tool.

Biological Evolution↗
PubMed1989

Ultrastructural and cytochemical studies on extranucleolar bodies in rat oocytes at the preovulatory follicle stage.

At the antral follicle stage, the nucleolus is entirely composed of a homogeneous proteinic compact mass. This nucleolar compaction during oogenesis seems to be a general feature in mammalian oocytes. However, when oocyte maturation is induced by gonadotropin hormone (LH), oocytes enter into preovulatory stage. All the nucleoli are vacuolated and extranucleolar bodies appear in the germinal vesicle near the nucleolar mass. Based on the results obtained by ultrastructural cytochemical stainings, we postulate that these extranucleolar bodies originate from the nucleolar mass itself. The presence of the extranucleolar bodies could reflect the extrusion of nucleolar material, essentially ribonucleoproteins, into the ooplasm. This material could persist after fertilization in the pronuclei until the resumption of transcription at the early stage of embryogenesis.

Animals↗
PubMed1988

Ultrastructural cytochemistry of the nucleolus in rat oocytes at the end of the folliculogenesis.

Various ultrastructural changes occur during follicular growth in the rat oocyte nucleolus. The nucleolus, which has a reticulated fibrillogranular structure at the primordial and primary follicle stages, becomes entirely compact and is made up of a conspicuous and homogeneous mass at the antral follicle stage. In order to define the nature and the functions of this homogeneous mass, cytochemical methods allowing detection of nucleic acids, proteins and lipids were performed at the light microscopic and ultrastructural levels. The results obtained suggest that this nucleolar mass is probably composed of acid proteins which are not silver stained. This proteinaceous mass could be a special kind of nucleolar secretion providing material for meiotic resumption in the oocyte. Cytochemical researches now in progress should supply new information concerning the exact nature and the role of the nucleolar compact mass, which is the essential nucleolar component at the antral follicle stage and which really plays a role in the nucleolus in the first stages of embryogenesis.

Animals↗
PubMed1987

Evolution of the rat oocyte nucleolus during follicular growth.

The ultrastructural evolution of the nucleolus was followed during follicular growth by means of a silver staining procedure. The oocyte nucleolus in the primordial and primary follicles consists of strands of dense fibrillar silver-stained component and aggregates of granules which are devoid of silver grains. Small fibrillar centres are also recognized and appear to have less silver stainability. At the secondary follicle stage, a new nucleolar component appears in the reticulated oocyte nucleolus. This component is devoid of silver grains. During follicle growth, at the antral follicle stage, this new component seems to fuse and the nucleolus becomes constituted of a compact homogeneous mass which exhibits a vacuole at the end of the oocyte maturation. The results obtained suggest that this nucleolar mass is essentially made of proteins and particularly of acidic proteins.

Animals↗
PubMed1987

The occurrence of metals Al, Fe, Ni, Cu, Zn in the nuclei of animal cells: an ultrastructural, in situ, X-ray microanalytical study.

Cell nuclei may contain significant quantities of the metals Fe, Ni, Cu, Zn, since they are present in the nucleo-enzymes and/or nucleic acids. These metals have been detected by X-ray microanalysis in situ in dinoflagellates (Kearns et al). Aluminum was only detected in cell nuclei in cases of natural or provoked intoxication. We observed at the ultrastructural level, in situ, the presence of Al, Fe, Ni, Cu, Zn in nuclei of different types of non-intoxicated animal cells. Moreover, we measured the concentration of these metals in the nucleolus and chromatin and compared it with the concentration of P and S.

Aluminum↗
PubMed1986

[Nucleolar vacuoles observed in rat oocytes].

Recently Merveille and al (1984) using light microscope have observed intranucleolar cavities in rat ovocytes from large antral follicles. They have showed that the frequency of these vacuoles increases when follicular growth is stimulated by gonadotropins. In this paper, the ultrastructure of the nucleolar cavities has been studied. Two types of cavities are visible in these nucleoli: 1. nucleolar "interstices" present at the periphery of the nucleoli in remnants of the granular component and of the dense fibrillar components; 2. nucleolar "vacuoles" which are located in the homogeneous substance forming the greatest part of the nucleolus. The nucleolar vacuoli generally are clear-cut and spherical. The density of their content is similar to the nucleoplasm but they don't communicate to the nucleoplasm. By means of cytochemical to detect Ag-NOR proteins (Ploton and al [1983]) and basic proteins (Sheridan and Barnett [1984]), dense fibrillar component of the nucleolus but no basic proteins may be seen in the wall of the cavity. Moreover no evidence of relation between the presence of the vacuoles and the process of follicular atresia has been found.

Animals↗
PubMedDate not supplied

Chemotaxis-promoting and adhesion properties of human tonsillar follicular dendritic cell clusters.

Lymph follicles are globular and compact due to aggregation of lymphoid cells on follicular dendritic cells (FDC). To probe the mechanisms underlying this accumulation of cells, we analyse here the role played by FDCs in attracting and binding cells. FDCs prepared from human tonsils by mild separation techniques appeared in the form of clusters (FDC clusters), where, via cytoplasmic extensions, they enveloped lymphoid cells. Using Boyden's chambers, we demonstrated that these FDC clusters produced one or more chemoattractants capable of inducing chemotaxis of lymphoid cells. Supernatants of FDC cluster cultures also exerted a chemotaxis-promoting effect. FDC clusters induced true chemotaxis, not merely chemokinesis due to cell activation. They secreted a substance or substances that stuck to the substrate (a cellulose filter) and thus induced haptotaxis. B as well as T cells were attracted, but B cells apparently required the presence of T cells to respond fully to the chemoattractant(s). Subtypes of B cells (IgD+ and IgD-) and T cells (CD4+, CD8+, CD57+ AND CD57-) were tested and all were attracted. Since purified lymphoid cells did not induce these phenomena, FDCs were suspected to do so. FDCs have been shown to establish contact with lymphoid cells. Here we have determined that CD4+ T cells adhere in greater number to FDC clusters than do CD8+ T cells. We thus propose that FDCs specifically contribute to construction of lymph follicles by attracting and determining their cell composition.

CD4-Positive T-Lymphocytes↗
PubMedDate not supplied

The potent angioinhibin AGM-1470 stimulates normal but not human tumoral lymphocytes.

BACKGROUND: AGM-1470 is a newly synthesized molecule developed as an analog of the potent anti-angiogenic fumagillin. Its efficacy in restraining tumor growth in vivo and the absence of major side effects have already led to phase I clinical trials in patients with solid cancers. However, neither the exact mechanisms of action of AGM-1470 nor its effects on the host of normal cells have been extensively studied. Recently, we showed that AGM-1470 enhanced the proliferation of B lymphocytes in the presence of T cells. Since AGM-1470 could potentially be used in patients with lymphoma, it was urgent to test the effect of the molecule on the proliferation of tumor lymphocytes. METHODS: The possible effect of AGM-1470 on the proliferation of normal or tumor lymphocytes was evaluated by thymidine-incorporated assays. Normal T and B lymphocytes were purified from human tonsils. The tumor lymphocytes used in the study were Molt 3, Molt 4 and Jurkatt cell lines for the T lineage and Daudi and Radji cell lines for the B lineage. RESULTS: As shown previously, AGM-1470 stimulates the proliferation of normal B lymphocytes through an action on normal T cells. THe angioinhibin was ineffective ont eh proliferation of both T and B transformed cells. Moreover, in the presence of the drug, tumor T cells co-cultured with normal B lymphocytes did not induce any increase in B cell proliferation, as previously observed with normal T lymphocytes. Inversely, tumor B cells co-cultured with normal T lymphocytes were insensitive to the drug. CONCLUSIONS: Our results demonstrate that AGM-1470 is ineffective on lymphoid tumor cell proliferation and could potentially be safely administered to lymphoma patients.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

Ultrastructure of CD57+ cells isolated from human tonsils or blood.

The presence of CD4+, CD57+ T cells in the germinal centers has been reported by several authors. The CD57 antigen is also expressed by natural killer (NK) cells. We purified CD57+ cells from human tonsils and blood by microdissection, rosetting with sheep red blood cells and magnetic cell sorting (MACS) and examined the ultrastructural morphology of these cells. Clear differences were found in cell aspect: blood NK contained large granules which were not found in the tonsillar CD57+ cells. These latter appeared medium-sized and not fully activated. After immunolabeling, the tonsillar CD57+ cells were mainly found in the light zone of the germinal centers.

Antibodies, Monoclonal↗