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Biomedical subjects

N Moreau

Publications and source records attributed to N Moreau.

At least 55 records · Page 3Linked to original sources
PubMed1986

Association of nucleoplasmin with transcription products as revealed by immunolocalization in the amphibian oocyte.

The oocyte nucleus of Pleurodeles waltlii contains a major 32,000-mol-wt acidic protein which is called nucleoplasmin. Rabbit antibodies were raised against total nuclear proteins from Pleurodeles oocytes. Affinity-purified antibodies directed against nucleoplasmin were prepared using antigens bound to nitrocellulose paper. The specificity of the antibody was controlled on two-dimensional electrophoretic gels of nuclear proteins. The intranuclear distribution of nucleoplasmin was analyzed by indirect immunofluorescence and the immunogold technique in light and electron microscopy. The antibody was tested on a spread of the nuclear content prepared in the presence of calcium, on the nuclear content spread in the presence of phalloidin so that an actin network appeared, and on a spread of nuclei from oocytes previously treated by actinomycin D. In all cases, nucleoplasmin appeared to be localized on the lampbrush loops, i.e., on the sites of transcription and, more specifically, on the ribonucleoprotein (RNP) particles; this protein was also associated with the RNP particles of the nuclear sap (free or inserted in the actin network). Nucleoplasmin was localized on large RNP particles that appeared when transcription was blocked. We never found this protein on the chromosome axis. These results suggest that nucleoplasmin may play a role in transcriptional activity.

Animals↗
PubMed1986

[Female karyotype and male phenotype: XX men. Apropos of 2 cases].

Males with a female karyotype are of special interest because they bear potential information on male determining factors leading to a masculine development in spite of a normal female chromosome constitution. We present 2 XX males, the clinical features correspond closely to many of those described in De La Chapelle's series of 46,XX males: reduced body height, infertility with small testicles, marked seminiferous tubular atrophy and azoospermia, slightly decreased testosterone level in serum and increased FSH and LH levels. Four main classes of theories concerning the etiology of XX males are presented, while mosaicism appears very unlikely in most cases, autosomal gene mutation, deletion or inactivation of X-chromosomal genes, X-Y interchange remain possible. The etiology of XX maleness may well be heterogeneous.

Adult↗
PubMed1985

About the specificity of photoinduced affinity labeling of Escherichia coli ribosomes by dihydrorosaramicin, a macrolide related to erythromycin.

Photoactivation of the [3H]dihydrorosaramicin chromophore at a wavelength above 300 nm allows the covalent attachment of the macrolide antibiotic to the bacterial ribosome. Bidimensional electrophoresis shows that the radioactivity is mainly associated with proteins L1, L5, L6, L15, L18, L19, S1, S3, S4, S5 and S9. When photoincorporation of the drug is conducted in the presence of puromycin as effector of [3H]dihydrorosaramicin-binding sites, a decrease in the labeling of most proteins is observed, except for L18 and L19, which are radiolabeled to a larger extent. These results allow us to speculate that L18 and L19 belong to the high-affinity binding site of rosaramicin antibiotic.

Affinity Labels↗
PubMed1985

Cross-resistance to nalidixic acid, trimethoprim, and chloramphenicol associated with alterations in outer membrane proteins of Klebsiella, Enterobacter, and Serratia.

We studied in vitro mutants of Klebsiella, Enterobacter, and Serratia cross-resistant to nalidixic acid, trimethoprim, and chloramphenicol that were similar to mutants found in vivo. The sole mechanism for this type of resistance appeared to be a reduction in permeability of the cell envelope. The mutants had significantly lower rates of uptake of glucose and chloramphenicol, but binding of chloramphenicol to ribosomes was normal. In addition, the amounts of dihydrofolate reductase were similar in both wild-type and cross-resistant mutants of Klebsiella. Examination of the bacterial outer membrane revealed that the amount of at least one major protein, with a molecular size of approximately 40 kilodaltons, was decreased in the mutants. Therefore the resistance seemed likely to be due to the reduction in quantity of these outer membrane proteins, possibly porins, in the mutant bacteria.

Anti-Bacterial Agents↗
PubMed1984

Antibiotic uptake by bacteria as measured by partition in polymer aqueous phase systems.

Polyethyleneglycol/dextran and polyethyleneglycol/salt two-phase systems are used to measure the entry of antibiotics into Escherichia coli and Staphylococcus aureus cells. Aminoglycosides, macrolides, a quinolone, and a cycline were assayed. The method is simple and rapid and eliminates the problems encountered with filters, especially nonspecific binding; it allows rapid uptake kinetics to be measured.

Anti-Bacterial Agents↗
PubMed1984

Effect of P and A site substrates on the binding of a macrolide to ribosomes. Analysis of the puromycin-induced stimulation.

The puromycin-induced stimulation of [3H]dihydrorosaramicin binding is due to a twofold increase in affinity of the macrolide antibiotic, with no change in the number of binding sites. Conversely, the binding of [3H]puromycin (A site) is stimulated by rosaramicin. The synergistic effect observed between the two antibiotics can be explained by a conformational change with positive effect, which occurs at the level of their binding sites. Various effectors of [3H]dihydrorosaramicin binding have been tested. Adenosine and dimethyladenosine stimulate the binding; phenylalanine, uridine and gougerotin (A site) have no effect whereas AMP, ADP, ATP, GTP, puromycin 5'-phosphate and lincomycin (P site) are inhibitors. These results point to the importance of the purine moiety in the stimulatory effect and of the phosphate function in reversing this effect. It is concluded that rosaramicin binds to the ribosomal P site and that the synergism observed between rosaramicin and puromycin may be related to interactions between the A and P sites.

Adenosine Triphosphate↗
PubMed1984

Comparison of fortimicins with other aminoglycosides and effects on bacterial ribosome and protein synthesis.

Fortimicins are bicyclic aminoglycoside antibiotics that contain a fortamine moiety instead of the deoxystreptamine found in other aminoglysides. Fortimicin A had a bactericidal effect on Escherichia coli and Staphylococcus epidermidis and was found to inhibit protein synthesis in vivo. In vitro, fortimicin A inhibited polyuridylic acid-directed phenylalanine polymerization and induced misreading, as shown by leucine incorporation. In contrast, fortimicin B had no effect on either polymerization or misreading. In assays programmed with natural mRNA, only a weak polymerization inhibition effect was observed with fortimicin A, whereas a strong stimulation was seen in the presence of fortimicin B. Both fortimicins A and B inhibited dissociation of 70S ribosomes into their subunits and neither was able to displace [3H]dihydrostreptomycin, [3H]tobramycin, or [3H]gentamicin from their respective binding sites on the 70S particle.

Aminoglycosides↗
PubMed1984

[Photochemical affinity labeling of the macrolide binding site on the 70S E. coli ribosome].

Photoactivation of the alpha, beta-unsaturated ketone-epoxide system of [3H] dihydrorosaramycin at a wavelength above 300 nm allows the covalent attachment of the antibiotic to its receptor site. The radioactivity is mainly associated to proteins L1, L5, L6, S1; as a consequence, the binding site of this type of drug could be located at the peptidyltransferase center and in between both subunits.

Affinity Labels↗
PubMed1983

Kinetic studies of aminoglycoside acetyltransferase and phosphotransferase from Staphylococcus aureus RPAL. Relationship between the two activities.

In the Staphylococcus aureus strain harbouring the plasmid RPAL, the resistance to aminoglycoside antibiotics results from two inactivating reactions catalyzed by a 6'-N-aminoglycoside acetyltransferase and a 2"-O-amino-glycoside phosphotransferase. These enzymes are copurified with a constant ratio between the two activities, the purification process consisting in affinity chromatography, native electrophoresis and gel exclusion chromatography. The kinetic mechanisms of each activity have been determined from studies of initial velocities, as well as product and dead-end inhibitions. Both activities follow a random rapid equilibrium mechanism. The substrates and cofactors of one reaction have been tested as effectors of the other reaction. No interaction between the two activities has been observed. However, the GTP cofactor of phosphotransferase protects, at weak concentrations, the acetyltransferase against thermal inactivation, which suggests that the two activities may be associated.

Acetyltransferases↗
PubMed1983

Role of the 1-amino group in aminocyclitol antibiotics: synthesis of 1-deaminogentamicin C2.

The synthesis of 1-deaminogentamicin C2 described here, uses 3,2',6',3"-tetrakis-N-tert-butoxycarbonylgentamicin C2 (2) as intermediate. N-Formylation of 2 followed by per-O-acetylation and dehydration furnished the isocyanide 5. Radical-induced deamination of the latter using tri-n-butylstannane and removal of the protecting groups afforded the target 1-deaminogentamicin C2 (7). Its in vitro antibacterial activity is less than that of the parent gentamicin C2. The behaviour of 7 towards aminoglycoside-inactivating enzymes was also examined; interestingly, it was found to be neither substrate nor inhibitor for such enzymes. These results strongly suggest that the substitution pattern of the 1-position determines the biological properties of the aminoglycoside antibiotics.

Gentamicins↗
PubMed1983

[Familial pericentric inversion of chromosome 10. 2 new cases].

Two cases of pericentric inversion involving a chromosome no. 10 are reported in infertile men. Using R-, G-, and C-banding techniques, the inversions were identified as inv(10)(p15q11) and inv(10)(p11q21). A similar chromosome was found in a parent of one of the probands. The literature on similar cases is reviewed briefly and the relationship between pericentric inversion and sterility are discussed.

Adult↗
PubMed1982

Mechanism of action of a 16-membered macrolide. Characteristics of dihydrorosaramicin binding to Escherichia coli ribosome and the effects of some competitors.

The macrolide [3H]dihydrorosaramicin binds specifically to 50S and 70S bacterial ribosomal particles. We have studied the influence of salts, pH and additives on the interaction and found that the optimum requirement for salts was 10 mM trs-HCl (pH 7.6), 6 mM MgCl2, 60 mM NH4Cl, and that beta-mercaptoethanol which reacts on rosaramicin and its dihydro derivative cannot be used. The parameters of the binding were not dependent on the technique used, i.e. equilibrium dialysis, ethanol precipitation or two-phase partitioning. In our search for effectors of this binding, we have found that it is inhibited by other macrolides, little effected by tobramycin and chloramphenicol and enhanced by puromycin.

Anti-Bacterial Agents↗