PubMed Health⌕ Search

Biomedical subjects

G Poirier

Publications and source records attributed to G Poirier.

50 records · Page 3Linked to original sources
PubMed1985

Non-histone chromosomal protein acceptors for poly(ADP)-ribose in phorbol-12-myristate-13-acetate treated mouse embryo fibroblasts (C3H10T1/2).

The tumor promoter phorbol-12-myristate-13-acetate (PMA) increases the level of poly ADP-ribosylation of chromosomal proteins in mouse embryo fibroblasts C3H10T1/2. The poly ADP-ribosylated nuclear proteins fall into the following molecular weight classes: 40, 48, 61, 77, 92, 158, 200 kd. Preincubation with catalase reduced the poly ADP-ribose (ADPR) substitution of all these proteins essentially to control levels. Western blot analysis with antibody directed against ADPR transferase indicates that the major acceptors are ADP-ribose transferase (116 kd) itself and its proteolytic degradation products of 20-25, 45 and 72-95 kd. Poly ADP-ribosylation of these proteins is suppressed by cycloheximide, 3-aminobenzamide, antipain and catalase. The latter three inhibitors possess anti-promotional activities in certain in vitro cell culture systems. Auto-poly ADP-ribosylation of ADPR transferase and its proteolytic cleavage as well as the poly ADP-ribosylation of other chromosomal proteins may play a role in the modulation of gene expression by PMA.

Animals↗
PubMed1982

Modulation of pancreatic muscarinic receptors by weaning.

We have investigated the effects of early and delayed weaning on the development of the rat pancreatic muscarinic receptors. Weaning after 12, 14 and 16 complete days resulted in significantly increased concentrations of muscarinic receptors. Milk feeding, as the exclusive source of food, from day 12 to 23, 25 or 28, was associated with slight non significant decreases in receptor concentration. In both instances, early or delayed weaning, the apparent KDs of (3H-QNB binding were not affected. It is suggested that early solid food intake can modulate rapidly the pancreatic muscarinic receptor population while exclusive milk feeding does not seem to influence the dynamic of the muscarinic receptor population.

Amylases↗
PubMed1977

Purification of plasma membrane fractions from the bovine pars intermedia and neurohypophyseal lobe and properties of associated adenylate cyclase.

A procedure for the isolation of plasma-membrane-enriched fractions from bovine 'pars intermedia' and neurohypophysis is described. Various fractions are isolated by differential centrifugation and discontinuous sucrose density gradients. The plasma-membrane-enriched fractions have a density in sucrose of 1.14 and 1.16 and the yields are 1.8 mg and 1.5 mg per gram of tissue for the pars intermedia and neural lobe, respectively. The fractions are characterized by electron microscopy and enzymatic assays. The plasma membrane fractions are mainly vesicular in nature and are free of nuclei, mitochondria, and microsomes when examined by electron microscopy. 5'-Nucleotidase (EC 3.1.3.5) and Mg2+-(Na+ + K+)-ATPase (EC 3.6.1.3) activities are concentrated in the plasma-membrane-enriched fraction. Also, adenylate cyclase (EC 4.61.1) shows a 5 to 10-fold purification in the isolated membrane fraction. NaF (10mM) gives a two to three-fold stimulation of enzymatic activity in all fractions studied The yields of adenylate cyclase, 5'-nucleotidase, and Mg2+-(Na+ +K+)-ATPase are about 6% in the membrane fraction.

Adenosine Triphosphatases↗
PubMed1977

[For a clinical approach to impulsion phobias].

Having first recalled the problems involved in classifying impulsion phobias, (problems which have been experienced in the course of all the work done on this subject), the authors report, from a strictly clinical viewpoint, on a series of studies of patients whose problems are very different but who all show the symptoms of impulsion phobia. They next setout a phenomenological approach to the problem, with emphasis on the products of the patient's imagination, his passive fascination with the image of a terrifying act constituting the object of the phobia, the external world in relation to the subject, and the ambiguity of dependance on others which is mirrored by aggressiveness. Lastly, the subject's entire existence is put symbolically at stake, and the phobia is seen to spring from his narcissistic relationship with the external world at a deeper level than that of any oedipian relationships. The first stage in the treatment is, indeed, to build up this narcissistic relationship, and later treatment will be varied according to the patient's fundamental needs.

Adult↗
PubMed1972

Binding of thyrotropin-releasing hormone to plasma membranes of bovine anterior pituitary gland (hormone receptor-adenylate cyclase-equilibrium constant-( 3 H)thyrotropin).

An assay for the binding of [(3)H]thyrotropin-releasing hormone ([(3)H]TRH) is described. Plasma membranes isolated from bovine anterior pituitary gland bind about 600 femtomoles of this hormone per mg of protein, as compared to 15 femtomoles per mg of protein in the total adenohypophyseal homogenate (40-fold purification). The equilibrium constant of membrane receptor-[(3)H]TRH binding at 0 degrees C is 4.3 x 10(7) L.M(-1), or a half-maximal binding of this hormone at 23 nM. The binding is time-dependent; addition of unlabeled hormone induces dissociation of the receptor-[(3)H]TRH complex with a half-life of 14 min. The binding of TRH is not altered by 10 muM melanocyte-stimulating hormone-release inhibiting hormone, lysine-vasopressin, adrenocorticotropin, growth hormone, prolactin, luteinizing hormone, insulin, glucagon, L-thyroxine, or L-triiodothyronine. K(+) and Mg(++) increase formation of the receptor-TRH complex at optimal concentrations of 5-25 mM and 0.5-2.5 mM, respectively, with inhibition at higher concentrations. Ca(++) inhibits binding of TRH at all concentrations tested.

Animals↗
PubMedDate not supplied

Anti-beta 2-microglobulin monoclonal antibodies mediate a delay in HIV1 cytopathic effect on MT4 cells.

We attempted to select monoclonal antibodies (mAb) which reacted with T-cell surface molecules and were able to interfere with the human immunodeficiency virus type 1 (HIV1) replicative cycle in the MT4 T-leukaemic cell line. In comparison with OKT4A, an anti-CD4 mAb, only one mAb, HC11.151.1, was found to significantly delay HIV-induced cytopathic effect on MT4 cells among the 15 mAb tested which reacted with MT4 cell surface antigens. Biochemical and immunological characterization of HC11.151.1 demonstrated its specificity for beta 2-microglobulin (beta 2m), the light chain of human leukocyte antigen (HLA) class I molecules. Other beta 2m-specific mAb were tested in order to assess whether this effect represented an intrinsic capacity of HC11.151.1 or whether it was a common feature shared by all anti-beta 2m mAb. Three (B1.1G6, B2.62.2 and BBM1) of the four anti-beta 2m mAb demonstrated the same protective effect, whereas C21.48A, which was devoid of a functional effect, was directed towards a beta 2m epitope involved in binding to the HLA class I heavy chain molecule. The physiological relevance of this observation is discussed.

Antibodies, Monoclonal↗
PubMedDate not supplied

Sources of nitrate exposure in residents of rural areas in Quebec, Canada.

Nitrate exposure was investigated in a group of 187 people using well water and living in four areas of rural Quebec (Canada) with intensive agricultural activities. Nitrate intake was evaluated using a 24-h dietary recall and a food frequency questionnaire, in conjunction with a validated food database and measurements of nitrate concentrations in private wells. The total internal dose was estimated by means of the 24-h urinary nitrate excretion, while taking into account risk factors for endogenous nitrate formation. Mean (geometric) 24-h urinary nitrate excretion was 16.9 mg N for the 100 people with low groundwater contamination (mean nitrate concentration=0.18 mg N/l) and 23.3 mg N in the 87 individuals with moderate groundwater contamination (mean nitrate concentration=7.1 mg N/l). A multivariate analysis revealed that dietary nitrate intake during the last 24 h was the principal source of exposure, followed by water intake during the last 24 h. The Quetelet index was also a significant predictor of urinary excretion. The total predictive model explained only 29% of the variability in urinary nitrate excretion (R2=0.286). Neither the inflammatory status as indicated by elevated C reactive protein, the presence of Helicobacter pylori antibodies nor the occurrence of diarrhea during the last 24 h prior to urine collection were associated with urinary nitrate excretion. In conclusion, food and to a lesser extent water contribute to nitrate exposure in this rural setting with moderate water contamination. Better predictors of endogenous nitrate production are needed to improve our ability to model nitrate body burden and estimate associated health risks.

Adult↗