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Biomedical subjects

D Bonnet

Publications and source records attributed to D Bonnet.

At least 271 records · Page 15Linked to original sources
PubMed1985

[Bone involvement in histiocytosis X in adults. 11 cases].

The authors report 11 cases of bone lesions associated with histiocytosis X in adults, with a total of 25 bone sites: 22 were detected on X-rays and 3 were detected on scintigraphy when the corresponding X-rays were normal. They stress the high incidence of cranio-facial involvement, predominantly in the maxillae, with premature localised loosening of the teeth. They recommend X-rays in the staging of histiocytosis X and reserve scintigraphy for the cases with normal or doubtful X-rays. The bone lesions do not affect the prognosis of histiocytosis X, which depends on the associated visceral lesions. It generally has a favourable outcome and requires careful treatment: limited to a localised procedure for the purposes of histological diagnosis or to control the local underlying visceral risk or the functional complications. Bone lesions do not usually participate in the decision to treat histiocytosis X by chemotherapy.

Adult↗
PubMed1984

Interaction of anilinonaphtyl labeled spectrin with fatty acids and phospholipids: a fluorescence study.

Anilinonaphtyl labeled spectrin exhibits a fluorescence emission spectrum characteristic of a highly hydrophobic environment. Quenching of the fluorescence intensity by nitroxide analogs of fatty acids of affinity 10(4) M-1 reveals that the sites of interaction of fatty acids lie very close to the anilinonaphtyl groups. Similar experiments performed with a nitroxide analog of phosphatidylserine yield a 30% quenching of fluorescence while the same phosphatidylcholine analog has essentially no effect. The changes in the fluorescence emission spectrum exhibited in the presence of sonicated phosphatidylserine vesicles further outline the specificity of interaction towards phosphatidylserine, with one spectrin binding site per about 750 exposed phospholipids. Moreover, they suggest a penetration of the anilinonaphtyl group into the lipid bilayer.

Fatty Acids↗
PubMed1984

[Changes in HBs antigen and anti-HBs antibody in 77 patients with acute B-virus hepatitis].

Serum HBs antigen (HBs Ag) and anti-HBs antibody (anti-HBs), as determined by radioimmuno-assay or ELISA methods, were studied in a group of 77 patients with acute icterogenic viral hepatitis over a period of at least three months and correlated to the evolution of the disease either to return to good health or to a chronic state. The cumulative rate of patients in whom HBs Ag had disappeared (n = 53) was a linear function of time during the first sixteen weeks. Correlation seemed even stronger in the subgroup of patients restored to good health before the third month. Time of HBs Ag disappearance ranged from 5 days to 5 months in common forms of hepatitis. There was no evident correlation between the time of disappearance and the normalization of ALAT levels. Among the four cases of chronic persistent hepatitis, three had no detectable antigenemia six months later. Development of anti-HBs preceded the loss of HBs Ag in one case, was simultaneous or posterior to it in all other cases; the absence of any serologic HBV marker could last up to 4 months. No chronological link was found between seroconversion and normalization of ALAT levels. The correlation between time and HBs Ag disappearance from the blood could be specific for a given group of patients placed under specific conditions; its determination might help in understanding the factors that influence the course of the disease.

Acute Disease↗
PubMed1982

The histidines of the bacterial ribosome: a tritium exchange study.

The accessibility of histidines in the E. coli 30S subunits was assessed by exchange of C-2 histidine protons with tritiated water at 37 degrees C. The absence of exchange at acidic pH allowed the separation and identification of individual proteins without loss of histidine labelling. Only the two ribosomal proteins S5 and S6 exhibited significant exchange. No gross change of accessibility was detected in the 70S ribosome couples.

Chemical Phenomena↗
PubMed1980

Characterization of Mg2+-induced conformational change in the 50S ribosomal subunit by differential hydrogen exchange.

The technique of differential hydrogen exchange allows detection of a conformational change in the 50S subunit of Escherichia coli ribosome when the magnesium concentration is lowered in a range where ribosomal activity is fully preserved. This change is characterized by a seventy-fold acceleration of about thirty labile hydrogens in the case of a Mg2+ jump from 10 mM to 2 mM. The small number of hydrogens involved can explain the difficulty in detecting this change by other methods.

Escherichia coli↗
PubMed1980

Photo-induced affinity labeling of Escherichia coli ribosomes by chloramphenicol.

In order to obtain more information about the binding site for chloramphenicol (D-threo diastereoisomer) on the bacterial ribosome, photo-affinity labeling experiments of this receptor have been performed with [3H]chloramphenicol itself. Control experiments show that this drug can be split photochemically by ultraviolet irradiation, whereas the ribosome is not modified structurally or functionally by such a treatment. When photolysis of a mixture of chloramphenicol and ribosomes is performed under critical conditions, some proteins like L1, L11, S3 and S4 are radiolabeled. L11, S3 and S4 are radiolabeled specifically as demonstrated by photo-incorporation experiments with isotopically diluted [3H]chloramphenicol or by comparison of the results obtained here with reversible experiments performed by the isotopic dilution method. When the D-erythro diastereoisomer of chloramphenicol is photo-incorporated into the bacterial ribosome, proteins are radiolabeled only in a non-specific way. These results show that this material could be used as an efficient scavenger. When finally D-threo [3H]chloramphenicol is photo-incorporated in the presence of a large amount of the D-erythro diastereoisomer, the radiolabeling pattern obtained for the proteins is quite different from that expected: while L11 is still labeled fairly extensively, L27 is the most radiolabeled protein found.

Affinity Labels↗
PubMed1977

Plasmid-mediated pristinamycin resistance. PAC IIA: a new enzyme which modifies pristinamycin IIA.

A wild strain of Staphylococcus aureus which inactivates a wide variety of antibiotics has been found to inactivate pristinamycin IIA, an antistaphylococcal antibiotic. This phenomenon has been demonstrated to be plasmid mediated. The plasmid directs the biosynthesis of an acetyltransferase which is able to O-acetylate the drug. We propose to call the new enzyme PAC (IIA): Pristinamycin acetyltransferase.

Acetyltransferases↗