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Biomedical subjects

R Hooghe

Publications and source records attributed to R Hooghe.

At least 37 records · Page 2Linked to original sources
PubMed1989

Inhibition of peroxisomal beta-oxidation and brain development in rats.

Thioridazine, an inhibitor of peroxisomal beta-oxidation, was administered orally to nursing rats during the period of maximal myelination in the pups (8-21 days postnatally). Under the experimental conditions, thioridazine causes accumulation of C24 and C26 fatty acids in pup brain lipids, an effect we consider to be a typical consequence of inhibited peroxisomal beta-oxidation. In the corpus callosum of treated pups, the relationship between axon diameter and myelin sheath thickness is altered compared with matched controls. Thioridazine also induces undernourishment effects in 21 day-old rats. Body and brain weight are severely reduced. Liver peroxisomes show a starvation-type metabolism. Undernourishment is known to influence myelination in developing rat brain. However, known consequences of undernourishment, such as decreased myelin concentration in whole brain, decreased percentage of myelinated fibers, and decreased granule-to-Purkinje cell ratio are not present.

Animals↗
PubMed1989

Evidence of recombinant ecotropic provirus integration in thymic lymphomas induced by direct or indirect radiation effects.

Several investigators described the occurrence of ecotropic recombinant proviruses in the DNA of in-vivo or in-vitro propagated radio-induced lymphomas, but such proviruses were never detected in primary tumors. To assess their biological significance in the tumorigenic process, we reinvestigated the presence of new proviruses chiefly in primary radio-induced tumors and in models of radioleukemogenesis which could give additional support for their role. Such models included thymic lymphomas originating after (i) graft of non-irradiated thymuses in thymectomized irradiated mice and (ii) the injection of a B-ecotropic retrovirus (T1223/B) in association with a subleukemogenic dose of irradiation. We report for the first time that new ecotropic proviral sequences are encountered in a significant number (30%) of primary lymphomas induced directly by irradiation or indirectly in non-irradiated thymuses grafted in irradiated hosts. The existence of a 3.5-kbp Kpn1 restriction fragment with ecotropic sequences in the digested DNA of these tumor cells indicates that these new sequences belong to an ecotropic provirus recombinant in the gag-pol region. We observed that most of the primary radio-induced tumors in which novel recombinant provirus could be detected, displayed the integration at a single or at a few sites, demonstrating their clonality with respect to viral integration. The same was observed in thymic lymphomas arising after T1223/B virus injection and irradiation and in in-vivo or in-vitro propagated tumors. Altogether, these data bring the first evidence of the integration of ecotropic recombinant proviral genomes in a significant number of primary radiation induced thymic lymphomas and of their possible role in view of their frequent occurrence in grafted thymomas.

Animals↗
PubMed1989

Variable stimulation of adenylate cyclase activity by vasoactive intestinal-like peptides and beta-adrenergic agonists in murine T cell lymphomas of immature, helper, and cytotoxic types.

We examined several cultured murine T cell lymphomas, induced by a radiation leukemia virus MuRadLV, including cell lines derived from immature T cells (5 clones of the BL/VL3 cell line), antigen-specific T helper cells (5 lines of the TL2 series), and one T cytotoxic cell line (NS8). With one exception (the TL2-9 cell line), these cells showed common characteristics: 1) an efficient adenylate cyclase system; 2) increased cyclic AMP production in response to at least one type of neurotransmitter, i.e., to the catecholamine isoproterenol and/or the neuropeptide VIP; 3) on the basis of adenylate cyclase stimulation, beta-adrenoceptors were of the beta 2 subtype and VIP receptors were of a "helodermin-preferring" subtype previously encountered in a human T lymphoblast cell line. Although we analyzed only a limited number of cell lines, it appeared that the immature T BL/VL3 clones responded to peptides of the VIP family with higher potency and efficacy than T helper and T cytotoxic cells. The membranes from the specific TL2-9 helper cell line were without adenylate cyclase activity in the presence of Gpp[NH]p, NaF, and GTP alone or GTP in the presence of isoproterenol or VIP. They produced cyclic AMP in the presence of Mn2+ and forskolin only, suggesting a defect in Gs as in S49 cyc- mouse lymphosarcoma cells. This was further demonstrated by the absence of cholera toxin-stimulated ADP-ribosylation in TL2-9 membranes.

Adenylyl Cyclases↗
PubMed1989

Failure to detect immune deficiency in rats after prenatal or early postnatal irradiation.

We have looked for medium-term sequelae in the immune system of rats that had been X-irradiated (0-2 Gy whole-body irradiation) during prenatal or early postnatal life. At an age of 8 weeks the histology of the spleen was normal, and so was the distribution of B and T lymphocytes. The serum immunoglobulin levels were not significantly altered, even when the different isotypes were considered. At an age of 10 weeks, the rats were immunized with a T-dependent or a T-independent dinitrophenylated-carrier antigen. Normal levels of specific antibodies were generated in all groups of animals injected with the T-independent antigen. The T-dependent response, in contrast, was higher in animals irradiated between day 6 and day 20 of gestation (but not in rats irradiated early after birth). This increase, however, was significant only for the IgM and IgG1 responses of some irradiated groups. Thus no medium-term immunodeficiency could be documented with the methods used. The alteration in a T-dependent response, however, points to a radiosensitive T regulatory mechanism.

Animals↗
PubMed1988

Prolactin cell subpopulations separated on discontinuous Percoll gradient: an immunocytochemical, biochemical, and physiological characterization.

A single-step procedure was devised to separate PRL cells from the rat anterior pituitary gland. After dissociation, cells were centrifuged on a Percoll gradient. Three layers were recovered. The composition of the different layers was evaluated using immunocytochemistry (with antisera to the six pituitary hormones), and in situ hybridization [with DNA complementary to PRL or to GH messenger RNA (mRNA)]. Both methods yielded identical values. PRL cells were recovered in the lower density layer (layer 1) with a good yield (that is 81% of the total PRL cells of the initial cell suspension) and in addition, markedly enriched (indeed 85% of the cells in layer 1 stained for PRL). A second layer (layer 2: intermediate density) contained most of the remaining PRL cells which were, however, heavily contaminated mainly by GH cells and cells that did not stain for any of the known pituitary hormones. A third layer (layer 3: higher density) was enriched in GH cells to 93% (representing, however, only 10% of the initial pituitary GH cells). In addition, PRL and GH were measured by RIA in culture medium and in cell lysates. Hormone biosynthesis was monitored by polyacrylamide gel electrophoresis and autoradiography after culture in the presence of [35S]methionine. These experiments confirmed that layer 1 was enriched in cells containing, and producing, PRL and depleted from GH cells. Cells in layer 2 contained and produced more GH than PRL. PRL cells from layer 1 responded to dopamine and to vasoactive intestinal polypeptide in the same way as PRL cells in the unseparated pituitary cell population. In contrast PRL cells in layer 2 had a lower basal secretion rate but a higher response to vasoactive intestinal polypeptide. Unless this represents a paracrine effect of non-PRL cells, PRL cells in layer 2 exhibit different properties and may therefore form a distinct subpopulation of PRL cells.

Animals↗
PubMed1986

Phenotype of thymic lymphomas in the mouse.

The MP2 cell line was established from a murine leukemia virus-induced thymic lymphoma. Half of the cells were consistently L3T4 positive and less than 5% of the cells were Lyt-2 positive. Single cell cloning on the basis of the presence or absence of Lyt-2 allowed the isolation of four clones with stable phenotypes: (1) Lyt-2-, L3T4-; (2) Lyt-2+, L3T4+; (3) Lyt-2-, L3T4+; (4) Lyt2+, L3T4-. These data are discussed in relation to tumour cell heterogeneity and to normal T-cell differentiation pathways.

Animals↗
PubMed1986

[Prenatal irradiation of the rat with very weak doses of X-rays: lesions of the white matter].

The depth of the cingulum bundle, a myelinated substructure of the corpus callosum was found to represent a sensitive indicator of exposure to X-irradiation in utero at dose levels as low as 20 cGy. In such conditions, the origin of the anatomical damage is probably to be found in a disordered sequence of morphogenetic events rather than in mitotic cell death processes.

Animals↗
PubMed1983

Characterisation of Concanavalin A-binding glycoproteins from mouse splenic leukocytes by two-dimensional electrophoresis: preferential binding of incompletely glycosylated forms of H-2 antigen to the lectin.

Concanavalin A (Con A)section-binding proteins from mouse spleen leukocytes were characterised by two-dimensional electrophoresis of material precipitated, by Con A plus anti-Con A, from lysates of biosynthetically-labelled cells. Although most cell surface (iodinatable) proteins are known to bind Con A, some of the major Con A-binding proteins detected by immunoprecipitation, after a four-hour biosynthetic labelling period, are not iodinatable and are probably intracellular. Thus the major biosynthetically labelled Con A-binding species are: (i) a non-iodinatable, high molecular weight glycoprotein (C-145); (ii) intracellular precursors of secretory immunoglobulins (IgM and, probably, IgA); (iii) immature (not fully-sialylated) forms of H-2 D and K antigens; and (iv) Ia antigens. In the case of the H-2 antigens, (and possibly of other cell surface proteins) the selection of immature forms by Con A is not due to lack of biosynthetic labelling of mature products, but to preferential binding of Con A to incompletely glycosylated molecules.

Animals↗
PubMed1979

Cellular basis of regulation of expression of idiotype. II. Immunity to anti-MOPC-460 idiotype antibodies increases the level of anti-trinitrophenyl antibodies bearing 460 idiotypes.

The antibody response of BALB/c mice to trinitrophenyl (TNP)-levan or TNP-Nocardia water-soluble mitogen (NWSM) includes a small but significant fraction of antibodies which share idiotypes (Id) with the dinitrophenyl (DNP)- and TNP-binding myeloma protein MOPC-460. Active immunization of BALB/c mice with MOPC-460 or passive administration of anti-460-Id antibodies suppresses the 460-Id+ component of the anti-TNP response. By contrast, active immunization of BALB/c with anti-460-Id antibodies or passive administration of BALB/c anti-[anti-460-Id] antibodies leads to an enhanced 460-Id+ component in the anti-TNP antibodies produced in response to TNP-levan or TNP-NWSM. This enhanced 460-Id+ response appears to be a result of the elimination of suppressor T lymphocytes specific for the 460-Id as T lymphocytes from such mice are unable to suppress the in vitro 460-Id+ response to TNP-NWSM whereas normal T cells are suppressive. These results indicate that suppressor cells specific for 460-Id normally regulate the activation of precursors of cells capable of secreting 460-Id+ anti-TNP antibodies.

Animals↗
PubMed1978

The mode of interaction with macrophages of two ordered synthetic polypeptides which differ in their thymus dependency.

The mode of interaction with macrophages of two ordered synthetic polypeptides (Tyr-Tyr-Glu-Glu)-poly(DLAla)--poly(Lys), (T-T-G-G)-A--L, and (Tyr-Glu-Tyr-Glu)-poly(DLAla)--poly(Lys), (T-G-T-G)-A--L, which differ in their requirements for T-B cell co-operation in the process of antibody production, was compared. The binding of the two radiolabelled antigens to the surface of peritoneal adherent cells, their uptake by the cells and the rate of their degradation were investigated. Macrophages were found to be capable of degrading both poly-peptides with the same efficiency. (T-G-T-G)-A--L, the antigen which is less T-dependent, was bound to macrophage surfaces more readily than (T-T-G-G)-A--L, the T-dependent antigen, however, its uptake by the cells was found to be lower. Thus, (T-G-T-G)-A--L remains for a longer period in the form of a membrane bound polyvalent antigen.

Animals↗
PubMed1975

Hairy cell leukemia: functional, immunologic, kinetic, and ultrastructural characterization.

A diagnosis of hairy cell leukemia was made by optic microscopy, phase-contrast microscopy, electron microscopy, scanning microscopy, and histochemistry of the abnormal blood cells. In vivo these cells were found to have a half-time in the blood of approximately 150 hr. In vitro they had the capacity to adhere firmly to plastic, making it possible to obtain a pure population of hairy cells. Neither T-rosette formation nor phytohemagglutinin (PHA) transformation could be demonstrated in these cells. On the other hand, the presence of immunoglobulins on the surface of the hairy cells (HC) by immunofluorescence, and the synthesis and secretion by these cells of IgM type lambda-chains shown by radioimmunodiffusion, were in favor of their B-type lymphocyte origin. Similarities to chronic lymphocytic leukemia were apparent.

Bone Marrow↗