Biomedical subjects

R Rivière

Publications and source records attributed to R Rivière.

At least 19 recordsLinked to original sources

PubMed2001

Immunoassays for the detection of nicergoline and its metabolites in human plasma.

In order to determine nicergoline pharmacokinetics after oral administration to humans, we have developed two radioimmunoassays, one directed against nicergoline and the other directed against known nicergoline metabolites. The assays were validated according to the recommendations of international regulatory agencies and their limits of quantification were 40 and 10 pg/ml, respectively. In order to further validate the methods, a chromatographic separation of immunoreactive entities was performed with samples from healthy volunteers who were given 15 mg of Sermion (nicergoline orally administered). Chromatographic determination of assay specificity showed that the metabolite radioimmunoassay recognised known nicergoline metabolites but also a new metabolite. Using the antibodies directed against nicergoline, we were unable to detect nicergoline in the human plasma. This suggests that nicergoline is absent in the circulation because of complete metabolism through its first-pass effect.

Adrenergic alpha-Antagonists↗

PubMed1992

[The pharmacokinetics of dihydroergocristine after intravenous and oral administration in rats].

The pharmacokinetic properties of dihydroergocristine (DHEC, CAS 17479-19-5) were investigated in rats using a specific radioimmunoassay technique specific for non-metabolized drugs. DHEC, administered intravenously at the dose of 6 mg/kg, showed a plasma profile conforming to an open two-compartment pharmacokinetic model with a long terminal half-life (t1/2 = 13.6 h). DHEC kinetics after oral administration (6 mg/kg) showed two peaks. The first peak (C = 37 micrograms/l) occurred at the first collection point (0.5 h) indicating a quick absorption of the drug. The second peak (C = 34 micrograms/l) occurred at 2 h and may be considered an indication of an enterohepatic cycle. A long terminal half-life (t1/2 = 18.1 h) was observed. An extensive biotransformation of DHEC was indicated by an almost complete absence of unchanged drug in the urine and a high systemic clearance (2.65 l.h-1 x kg-1). A large volume of distribution (52 l.kg-1) was calculated.

Administration, Oral↗

PubMed1989

Metabolism of dihydroergotamine by a cytochrome P-450 similar to that involved in the metabolism of macrolide antibiotics.

1. Previous studies have shown that the macrolide antibiotics, such as oleandomycin and erythromycin, enhance their own transformation into a stable metabolite-cytochrome P-450 complex, thus impairing monooxygenase activity. This cytochrome P-450 induced by macrolides is similar to the major form induced in rats by pregnenolone-16 alpha-carbonitrile (PCN) (III A1 isozyme). 2. The cytochrome P-450 isozyme induced in rats by PCN or macrolide antibiotics bound dihydroergotamine (DHE) with high affinity and was also capable of metabolizing the drug. However, phenobarbital administration enhanced the metabolism of DHE to a greater extent than would be expected from the levels of the PB-PCNE isoenzyme, indicating that other cytochrome P-450 proteins may also be involved in DHE metabolism. 3. DHE metabolism was inhibited by macrolide antibiotics both ex vivo and in vitro. The metabolite-cytochrome P-450 complex formed by the antibiotics impairs the metabolism of DHE, so that when the complex is dissociated the metabolic activity is restored. These findings explain the observed clinical interactions between macrolides and other drugs, and such an approach may prove useful in their prediction.

Animals↗

PubMed1985

[Bacterial contamination of the air in different operating rooms].

Bacteria air samples were taken in the operating rooms, with no people present, to specify the level of air contamination and suggest bacteriological standards for different operating rooms. In the first step of this study, for 5 months the air contamination mean value of operating rooms, ventilated at 15 changes/hour was 18.5 Cfu/m3 +/- 1.9. In the second part of the study, during two years, 1 381 air samples were taken in 8 different operating rooms. The mean values of air contamination range from 1.4 Cfu/m3 in a Charnley isolator system to 121 Cfu/m3 in an operating room ventilated at 7.5 changes per hour. As a general rule, the airborne contamination is more significant in the oldest operating rooms than in the new one with filtrated air. The variations observed between 1981 and 1982 are explained by technical modifications of the system or progress in control of operating room conditions. Measurements of the bacterial contamination of the air give useful informations, but it is however better to ensure that the specifications for volume air supply and positive air pressure in the operating theatres are being fulfilled. The airborne bacterial concentration in a modern ventilated operating room should not exceed 30 Cfu/m3.

Air Microbiology↗

PubMed1982

[Pain and inflammation of the foot in metabolic osteopathies : new causes of algodystrophy (author's transl)].

Three observations of patients with algodystrophia of the foot are reported. Biologic disorders suggestive of osteomalacia were found in two patients who recovered after receiving vitamin D. Cushing disease was diagnosed in the remaining patient ; again algodystrophia disappeared after specific therapy was given. The few similar cases published in the medical literature are reviewed. Attention is drawn to their misleading nature. Most published cases occurred with osteomalacia or endocrinic osteopathy. Such conditions should be looked for in all patients with apparently primary algodystrophia of a lower limb.

Aged↗

PubMed1978

[Nutritional value of fish flours made in laboratory from fishes of the Nosy-Bé area].

Several types of fish meals (principally from no commercializable Carangues) are made in a laboratory. They are tested for general composition, amino-acid composition, vitamin and mineral compositions. Two fish meals from Carangues are very interesting: they are white muscle meal (rich in proteins of good quality, poor in lipids and slightly rich in minerals) and the meal from fish without head and guts (not so rich in proteins but slightly richer in minerals). These fish meals have a variable interest regarding mineral and vitamin contents. All of them have a lack of methionin and cystin which is comparable to the defficiency mentioned in other fish meals by various authors.

Amino Acids↗

PubMed1978