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Biomedical subjects

M Royer

Publications and source records attributed to M Royer.

At least 37 records · Page 2Linked to original sources
PubMed1991

Cholinergic inositol phosphate formation in striatal neurons is mediated by distinct mechanisms.

In murine striatal neurons devoid of functional synapses (6 days in vitro) the cholinergic agonists carbachol and arecoline evoked dose-dependent inositol phosphate (InsP) responses with mean log EC50s of -4.1 +/- 0.5 and -4.48 +/- 0.1, respectively. Carbachol (1 mM) and arecoline (1 mM) responses were insensitive to tetrodotoxin, a voltage-sensitive Na+ channel blocker, and were blocked by pirenzepine with relatively low affinity (logIC50 = -5.9 +/- 0.3 for the carbachol response and logIC50 = -5.8 +/- 0.3 for the arecoline response). After synaptogenesis (13 days in vitro) the maximal carbachol effect doubled whereas the arecoline response remained unchanged. This additional effect was sensitive to tetrodotoxin and the voltage-dependent Ca2+ channel blocker, omega-conotoxin. The tetrodotoxin-sensitive carbachol response was blocked by lower concentrations of pirenzepine than the tetrodotoxin-insensitive carbachol response. More than 75% of the InsP response evoked by low concentrations of muscarine (1 and 10 microM) was sensitive to tetrodotoxin whereas only 38% of the InsP response stimulated by 1 mM of muscarine could be blocked by tetrodotoxin. These results suggest that there are at least two different mechanisms (depending on the stage of development), activated most probably by two different muscarinic receptors responsible for the carbachol-induced InsP formation in striatal neurons.

Animals↗
PubMed1991

Functional domains of HIV-1 gag-polyprotein expressed in baculovirus-infected cells.

Seven recombinants of AcNPV harboring various forms of complete or truncated gag gene from HIV-1 were constructed to determine which functional domains of the gag polyprotein are implicated in its self-assembly and cellular localization. The p6 carboxy-terminal portion of the p15 NCgag domain appeared to be dispensable for assembly, budding, and release of gag particles by insect cells. However, all the morphopoietic information was not entirely confined to the p9 NC domain, as N-myristylation could compensate for p15 NC deletion in gag assembly and the budding process. The two consensus karyophilic signals situated in the p17 MAgag domain were inefficient for targeting nonmyristylated forms of gag polyprotein to the nucleus when the p6 NC domain was deleted. In the presence of p6, or with a third, baculovirus-specific, karyophilic signal added at its N-terminus, gag particles relocated in the nucleus. These data suggested that p6 played a critical role in the conformation of gag polyprotein.

Amino Acid Sequence↗
PubMed1991

Partial Purification and Characterization of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase Large Subunit epsilonN-Methyltransferase.

The large subunit (LS) of tobacco (Nicotiana rustica) ribulose-1,5-bisphosphate carboxylase/oxygenase (ribulose-P(2) carboxylase) contains a trimethyllysyl residue at position 14, whereas this position is unmodified in spinach ribulose-P(2) carboxylase. A protein fraction was isolated from tobacco chloroplasts by rate-zonal centrifugation and anion-exchange fast protein liquid chromatography that catalyzed transfer of methyl groups from S-adenosyl-[methyl-(3)H]-l-methionine to spinach ribulose-P(2) carboxylase. (3)H-Methyl groups incorporated into spinach ribulose-P(2) carboxylase were alkaline stable but could be removed by limited tryptic proteolysis. Reverse-phase high-performance liquid chromatography of the tryptic peptides released after proteolysis showed that the penultimate N-terminal peptide from the LS of spinach ribulose-P(2) carboxylase contained the site of methylation, which was identified as lysine-14. Thus, the methyltransferase activity can be attributed to S-adenosylmethionine:ribulose-P(2) carboxylase LS (lysine) ;N-methyltransferase, a previously undescribed chloroplast enzyme. The partially purified enzyme was specific for ribulose-P(2) carboxylase and exhibited apparent K(m) values of 10 micromolar for S-adenosyl-l-methionine and 18 micromolar for ribulose-P(2) carboxylase, a V(max) of 700 picomoles CH(3) groups transferred per minute per milligram protein, and a broad pH optimum from 8.5 to 10.0. S-Adenosylmethionine:ribulose-P(2) carboxylase LS (lysine)(epsilon)N-methyltransferase was capable of incorporating 24 (3)H-methyl groups per spinach ribulose-P(2) carboxylase holoenzyme, forming 1 mole of trimethyllysine per mole of ribulose-P(2) carboxylase LS, but was inactive on ribulose-P(2) carboxylases that contain a trimethyllysyl residue at position 14 in the LS. The enzyme did not distinguish between activated (Mg(2+) and CO(2)) and unactivated forms of ribulose-P(2) carboxylase as substrates. However, complexes of activated ribulose-P(2) carboxylase with the reaction-intermediate analogue 2'-carboxy-d-arabinitol-1,5-bisphosphate, or unactivated spinach ribulose-P(2) carboxylase with ribulose-1,5-bisphosphate, were poor substrates for tobacco LS (epsilon)N-methyltransferase.

Journal Article↗
PubMed1990

MoMuLV-derived self-inactivating retroviral vectors possessing multiple cloning sites and expressing the resistance to either G418 or hygromycin B.

To facilitate cloning procedures in recombinant murine leukemia virus-derived retroviruses, we have constructed vectors that both carry a polylinker with multiple restriction sites and express resistance to either G418 or hygromycin B. Our vectors are self-inactivating retroviruses that suppress interferences between LTR enhancers and internal promoters and avoid transcriptional stimulation of host cell genes. They can also be used as expression vectors in direct transfection assays, since no translation initiation codon lies between the 5' LTR and the cloning polylinker.

Base Sequence↗
PubMed1978

[Contribution to the etiologic diagnosis of hypertrichosis and hirsutism of functional origin in women during active genital life by statistical study of observations (author's transl)].

After a recall of the etiologies of hypertrichosis and hirsutism, a method of diagnosis limited to functional pathological cases, was established. Having 31 complete case reports of functional hirsutism or hypertrichosis in women whose diagnosis--ovarian dystrophy or corticosuprarenal hyperplasia--was confirmed, the authors established a decision procedure based on the confrontation of two criteria obtained with a discriminant analysis program. These criteria included a clinical examination (intensity and localization of pilosity) and the effect of dexamethasone blockade on two plasmatic steroids, i. e., 17-hydroxyprogesterone and testosterone. The proposed diagnosis was furnished with a confidence index. 43 new cases confirmed the consistency between the clinical diagnosis and the automatic diagnosis.

Female↗
PubMed1975

Study of indirect methods for measuring hepatic blood flow in the isolated perfused dog liver.

This study was undertaken to assess the reliability of the constant infusion clearance and extraction technique (CIT) and the single injection clearance method (SIT), to measure hepatic perfusate flow at different levels of liver function. In the 36 isolated perfused dog livers, hepatic perfusate flow(HPF) was monitored by a direct method (DM), and the HPF was simultaneously measured with an indirect method (IM) utilizing bromosulphophthalein BSP) as indicator (20 SIT and 16 SIT). In 16 experiments, absolute ethanol (750 mM) and sodium taurocholate (600 muM) were seperately utilized to impair BSP metabolism. By comparison with DM, in the experiments with an extraction ratio(ER) of BSP lower than 10%, the error of the IM (ml/min) was for the CIT 154.57 +/- 46.55 and for the SIT 107.25 +/- 34.20. This error was significantly greater than in the experiments with an ER greater than 10% (CIT 15.70 +/- 3.88, SIT 8.20 +/- 1.38) p less than 0.01. In the studies with ER less than 10%, no difference was found in the error detected with the SIT (107 +/- 34.20) and CIT measurements (154.37 +/- 46.55); in the experiments with an ER greater than 10%, the error with the CIT (15.70 +/- 3.88) was greater than the one attained with the SIT (8.20 +/- 1.38, p less than 0.10 greater than 0.05). It is concluded that both methods are reliable techniques, for measuring HPF in livers with normal or near normal clearance capacity, but even in these ideal experimental conditions the values for HPF are inacurate when the liver clearance function is moderate or severly impaired.

Animals↗
PubMed1975

Incorporation of ALA-14C in circulating bilirubin and hemoglobin heme of hepatectomized dogs.

After intravenous injection of delta amino-levulinic acid-14C (ALA-14C) (50 muCi) in hepatectomized dogs, bilirubin-14C reaches a peak after 3-6 hours and then slowly falls. During this time radioactivity of hemoglobin heme is much lower and rises sluggishly. Bilirubin specific activity is several hundred times that of hemoglobin heme. Incorporation of isotope is also much greater for bilirubin. This difference between bilirubin-14C and hemoglobin heme-14C provides evidence that bilirubin is produced outside the liver by a mechanism other than breakdown of hemoglobin. In intact dogs with cannulated common duct, intravenous injection of ALA-14C produces similar results but the rise of bilirubin-14C produced in 9 hours in the hepatectomized dogs is about 12% of the total blood bilirubin-14C of non hepatectomized animals with cannulated common duct. If we include bile bilirubin-14C produced in the same time by intact animals with cannulated common duct, nonhemoglobin bile production is only 4.2% of the total.

Aminolevulinic Acid↗