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Biomedical subjects

M Pierre

Publications and source records attributed to M Pierre.

At least 73 records · Page 4Linked to original sources
PubMed1988

Induction of type II 5'-deiodinase activity by cyclic adenosine 3', 5'-monophosphate in cultured rat astroglial cells.

Cultured astroglial cells were found to contain a type II 5'-deiodinase (5'D) activity which was increased by 10(-3) M (Bu)2cAMP but not by 2 X 10(-3) M n-butyrate. 8-Bromo-cAMP (8-Br-cAMP) (10(-3) M) also increased this enzyme activity. Cycloheximide (2 micrograms/ml) inhibited the 8-Br-cAMP effect on 5'D activity. Forskolin (10(-5) M), cholera toxin (5 micrograms/ml), 10(-5) M isoproterenol, and 3 X 10(-6) M norephinephrine also increased the 5'D activity of astroglial cells. After a 4-h incubation these agents or cAMP analogs had maximal effect, and enzyme activities were 6- to 14-fold above control value. The stimulatory effects of isoproterenol and norepinephrine were almost completely reversed after 8 h incubation. The induction of 5'D activity by isoproterenol or norepinephrine was inhibited by the beta-adrenergic antagonist alprenolol (5 X 10(-6) M). The effect of norepinephrine was not significantly affected by the alpha 1-adrenergic antagonist, prazosin (10(-5) M). Thus, 5'D activity is controlled by agents increasing cAMP in astroglial cells, and in particular by the neurotransmitter, norephinephrine, via a beta-adrenergic mechanism.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1987

[Recourse to amniocentesis after the age of 38. Factors related to access to medical care].

Antenatal screening by amniocentesis was not much used in Haute-Normandie (France) in 1981. This study compared 59 women aged 38 and over who did benefit from this test with a control sample of 71 women who delivered in the same region at the same time and who were not screened. The use of the screening was linked to the socio-professional category of the woman, to her professional activity, to her nationality, to where she studied, to her parity, and the quality of her obstetrical care. The information that the women who were screened had about trisomy 21 and its screening was far higher in those who were screened. Regression analysis indicates that there are 3 factors that play an important role: whether the specialist or the general practitioner offered the screening test and the socio-professional category of the woman. Amniocentesis could be used much more efficiently if the population was better informed and if the medical corps made a special effort as well as providing more screening facilities.

Adult↗
PubMed1986

Activation of S6 kinase activity in astrocytes by insulin, somatomedin C and TPA.

Treatment of cultured astrocytes from 2-day-old rat cerebral hemispheres with insulin or somatomedin C (IGF1) promoted a rapid activation of a cytosolic protein kinase which phosphorylates ribosomal protein S6. Phosphorylation of substrates currently used for protein kinase assays (histone H2B and phosvitin) was not stimulated. Neither the cyclic AMP-dependent protein kinase activity nor that of protein kinase C was modified. Treatment of these astrocytes with TPA also promoted a rapid increase in S6 kinase activity in the cytosolic fraction. Simultaneously, protein kinase C disappeared from the cytosol. Neither cyclic AMP-dependent protein kinase activity nor phosvitin kinase activity was modified. The effects of insulin, IGF1 and TPA were also observed in the presence of cycloheximide. Cycloheximide also potentiated their effects. These data indicate that S6 kinase activity in astrocytes is promoted from a pre-existing molecule via the tyrosine kinase-insulin receptor and suggest that protein kinase C is implicated in the process.

Animals↗
PubMed1986

Properties of neurofilament protein kinase.

Neurofilament (NF) protein kinase, partially purified from NF preparations [Toru-Delbauffe & Pierre (1983) FEBS Lett. 162, 230-234], was found to be distinct from both the casein kinase present in NFs and the cyclic AMP-dependent protein kinase which is able to phosphorylate NFs. NF-kinase phosphorylated the three NF protein components. The amount of phosphate incorporated per molecule was higher for NF 200 than for NF 145 and NF 68. Other proteins present in the NF preparations were also used as NF-kinase substrates. Two of them might correspond to the myelin basic proteins with Mr values of 18,000 and 21,000. Four other substrates in the NF preparation were not identified (respective Mr values 53,000, 55,000, 65,000 and greater than 300,000). NF kinase also phosphorylated two additional brain-cell cytoskeletal elements: GFAp and vimentin. Casein, histones and phosvitin, currently used as substrates for protein kinase assays, were very poor phosphate acceptors. Half-maximal NF-kinase activity was obtained at an NF protein concentration of about 0.25 mg/ml in heated, salt-washed, NF preparations. The specific activity was about 5 pmol of 32P incorporated/min per microgram of NF kinase preparation protein. ATP was a phospho-group donor (Km 8 X 10(-5) M), but GTP was not. NF-kinase activity remained stable at 65 degrees C for more than 1 h. The enzyme was not degraded by storage at -20 degrees C for several months in a buffer containing 50% (w/v) sucrose. Maximal activity was obtained with 5 mM-Mg2+ (Mg2+ could be replaced by Co2+); Zn2+ and Cu2+ inhibited the reaction. NF-kinase was not dependent on cyclic AMP, cyclic GMP, Ca2+ or Ca2+ plus dioleoylglycerol and phosphatidylserine.

Animals↗
PubMed1985

Autophosphorylation of the insulin receptor in rat adipocytes is modulated by thyroid hormone status.

The effect of thyroid status on the in vitro autophosphorylation of the insulin receptors was studied in triton-solubilized adipocyte plasma membranes obtained from normal and thyroidectomized rats. Thyroidectomy results in an increase (two to three times) of the in vitro insulin-dependent phosphorylation of the insulin beta-subunit receptor. Phosphorylation occurred on tyrosine residues. In vivo injection of triiodothyronine to thyroidectomized rats restored plasma membranes autophosphorylation of the beta-subunit to the values obtained for control euthyroid rats. This effect was independent of the number and affinity of the insulin receptors, which were not modified regardless of thyroid status.

Adipose Tissue↗
PubMed1985

Biological parameters in Japanese quail genetically selected for resistance or sensitivity to an acute hypoxic survival.

Various biological parameters were measured in two strains of Japanese quail selected for their resistance (Ls+) or susceptibility (Ls-) to an acute normobaric hypoxic challenge. Adults of these two strains showed very little or no significant differences concerning body weights, carbon dioxide emission, photoperiodic (L----D and D----L) respiratory reactions, cloacal temperatures, heart rates and ECG QRSII amplitudes, red blood cell data, hemoglobin electrophoresis, and plasma corticosterone (before and after an hypoxic challenge). Enzymatic capacities of phosphofructo-and pyruvate kinases, of glucose-6-phosphatase, lactico- and malate-dehydrogenases, measured in brains and hearts, showed but few statistically significant differences. Changing societal contacts did not suppress the differences of acute hypoxic survival between the two strains. Several statistically significant differences which concern reproduction and eggs, and especially egg laying and egg water vapor conductance were noted between the two strains.

Animals↗
PubMed1984

Indirect SOS induction is promoted by ultraviolet light-damaged miniF and requires the miniF lynA locus.

Indirect prophage induction is produced by transfer to recipients of u.v.-damaged F plasmid (95 kb). We tested whether the SOS signal can be produced by miniF, a 9.3 kb restriction fragment, coding for the replication and segregation functions of plasmid F. We used lambda miniF, a hybrid phage-plasmid. u.v.-irradiated lambda miniF induced prophages phi 80 or lambda and sfiA, a chromosomal SOS gene, in more than 50% of the infected cells. The maximal inducing dose produced about 0.5 pyrimidine dimers per kb and left 1% of lambda miniF survivors. Thus, the SOS signal produced by u.v.-damaged lambda miniF was almost as potent as that resulting from direct u.v.-irradiation of the lysogens. The u.v.-damaged vector lambda, devoid of miniF, failed to promote SOS induction. In contrast, efficient induction was observed when u.v.-damaged lambda miniF infected a lambda immune host, in which replication and expression of the phage genome were repressed. When replication and expression of the miniF genome was repressed by Hfr incompatibility, SOS induction was largely prevented. All these facts indicate that, in the hybrid lambda-miniF, it is the u.v.-damaged miniF that generates an SOS signal. To locate on the miniF genome the loci that are involved in the production of the SOS signal, we isolated deletions spanning all the miniF restriction fragments. We characterized six mutant phenotypes (Par+, Rep-, Fid-, Par-2, Par-1 and SOS-) related to four functions; partition, copy number, replication and SOS induction. A locus, we call lynA, 800 bp long, located by deletion mapping between the two origins of replication oriP and oriS is required for the production of an inducing signal. We postulate that indirect SOS induction by u.v.-damaged miniF results from the disturbance of the lynA function that may be involved in the co-segregation of F plasmid with the host chromosome.

Bacteriophage lambda↗
PubMed1983

A rat brain protein kinase phosphorylating specifically neurofilaments.

Protein kinase activities associated with neurofilament (cAMP, cGMP, Ca2+-independent) were almost completely extracted by 0.8 M KC1. Two activities were separated by either sucrose gradient ultracentrifugation of phosphocellulose chromatography. One of them phosphorylates specifically neurofilament proteins and preferentially the triplet (200 kDa, 145 kDa and 68 kDa) but neither casein nor type IIA histone. The second activity was identified as casein kinase I and does not catalyze the phosphorylation of neurofilament protein.

Animals↗
PubMed1983

Multisite phosphorylation of tau proteins from rat brain.

tau proteins from adult and young rat brains were phosphorylated in vitro by protein kinases present in microtubule preparations. Several phosphates were incorporated in each molecular species of this group of proteins. Cyclic AMP dependent protein kinases and casein kinase (type I) phosphorylated tau proteins on different sites. These observations indicate that tau proteins are an example of multisite phosphorylation.

Adenosine Triphosphate↗
PubMed1983

Prophage phi 80 is induced in Escherichia coli K12 recA430.

In contrast to prophage lambda, wild-type prophage phi 80 was induced by UV-irradiation or thymine deprivation in recA430 mutants of E. coli K12. There was no induction of prophage phi 80 in two recombination-deficient mutants recA13 and recA99. Phage phi 80ind3, a non-inducible derivative in a rec+ was not induced in a recA430 lysogen. Two other lambdoid prophages were tested for UV-induction in recA430 lysogens: in common with lambda prophage, 434 was not induced whereas prophage 21 was induced in 1% of the cells. Induction of RecA430 protein synthesis was 30% of that observed in recA+ bacteria at 30 min of post-irradiation incubation, indicating that LexA repressor had been cleaved by RecA430 protease. In lexA1 recA430 and lexA1 recA+ bacteria, RecA protein synthesis was not amplified, yet, prophage phi 80 was fully induced. If phi 80cI repressor is inactivated by cleavage by RecA430 protease as is LexA repressor, RecA430 protease can inactivate all the molecules of phi 80cI repressor, its basal level being high enough in a recA430 lysogen. In such a lysogen, a fraction only of 21cI and LexA repressors are cleaved but no molecules of either lambda cI or 434cI repressor. We postulate that RecA430 protein has an altered pattern of recognition of repressor molecules and a cleavage efficiency which is more efficient the more remote is the repressor conformation from that of lambda repressor.

Bacterial Proteins↗
PubMed1982

Heterogeneity of microtubule-associated proteins and brain development.

Developmental changes in the composition of brain microtubule-associated proteins have been studied in three species: the rat and the mouse, which are characterized by post-natal brain development, and the guinea-pig, whose brain is mature at birth. 1. At an adult stage, and whatever the species, two major microtubule-associated proteins, which have been referred to MAP2 and tau, have been identified by polyacrylamide gel electrophoresis. Rat tau is composed of four closely spaced bands; mouse tau contains only three components with one of them being present in higher proportion than the others; adult guinea-pig tau is essentially present as a single band. 2. Microtubule-associated proteins were also prepared at different stages of brain development. In the three species only two bands were seen in the tau region at immature stages of development (fast tau and slow tau). However adult tau factors progressively replace the young entities. In contrast, only small changes were seen in the proportion of MAP2. 3. Peptide mapping analysis of the purified tau entities confirmed that the four adult rat proteins are very similar. In contrast, peptide mapping of the two young rat tau proteins were very different from each other and from those of the adult ones. Peptide mappings of young and adult MAP2 were only slightly different. 4. The activities of young tau proteins and young MAP2 in promoting pure tubulin assembly were much lower than those of the adult ones. Young fast tau and young slow tau were purified and both show to be active in promoting pure tubulin polymerization. 5. These data demonstrate the existence of two types of heterogeneity of microtubule-associated proteins: plurality of protein species at every stage of brain development and changes in composition and activity dependent on development.

Animals↗
PubMed1982

Purification and characterization of the cytoplasmic casein kinase I from rat liver.

Two cyclic nucleotide-independent protein kinases, which preferentially utilize casein and phosvitin as substrates, exist in rat liver. In contrast to cytosol the "light' form of these enzymes was predominant in the "microsomal extract'. This form (30 000-40 000 daltons, casein kinase I) was separated from the "heavy' form (130 000 daltons, casein kinase II) by gel filtration. This enzyme was then purified by successive chromatography on carboxymethyl-Sephadex, phosvitin-Sepharose and hydroxyapatite. The activity of the purified enzyme was 2000-3000-fold the casein kinase activity of the cytosol. It had a s20,w of approx. 3 S as determined on sucrose density gradient. After iodination or incubation with [gamma- 32P]ATP, it was analyzed on polyacrylamide gel in the presence of sodium dodecyl sulfate (SDS) and appeared to be composed of a single polypeptide (36 000 +/- 1000 daltons) which self-phosphorylated. In contrast to casein kinase II, casein kinase I preferentially utilized ATP over GTP. The Km value for ATP was determined to be 14 micro M. The Km value for phosvitin was 0.17 mg/ml. Casein kinase I phosphorylated sites different from those of casein kinase II (as shown with ribosomes or SV40 T antigen). Casein kinase I was further characterized by studying its thermal stability. The half-life at 37 degree C was 6 min and 1 min 30 s at 54 degree C. In the presence of two substrates (ATP and phosvitin), the half-life at 54 degree C increased from 1 min 30 s to 4 min. Hemin strongly increased the rate of inactivation of the casein kinase I at 37 degree C in the absence or presence of the substrates. N-ethylmaleimide also inactivated casein kinase I. Phosvitin, though not ATP, protected the enzyme. This observation may indicate that thiols are involved at the binding site of the enzyme for the protein substrate.

Animals↗