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Biomedical subjects

J Rondelet

Publications and source records attributed to J Rondelet.

At least 19 recordsLinked to original sources
PubMed1984

Quantitative correlation between the metabolism and the mutagenic activity of N-nitrosopyrrolidine.

The metabolism of N-nitrosopyrrolidine (NPyrr) via alpha-hydroxylation is modified by pretreatments of the animals with compounds which affect the microsomal level of cytochrome P-450 and by addition, in vitro, of 2-diethylaminoethyl-2,2-diphenyl valerate hydrochloride (SKF 525-A), an inhibitor of cytochrome P-450. This phenomenon is due exclusively to the induction or the inhibition of the enzymatic activity involved in the microsomal metabolism. After preincubation in liquid medium, the mutagenic activity of NPyrr towards the Salmonella typhimurium strain TA 1530 is similarly modified by these effectors. A similar effect is not observed when using the plate incorporation method. The mutagenic intermediate is formed by the microsomal fraction. The presence of the S. typhimurium strain TA 1530 decrease the transformation of NPyrr into its ultimate metabolite (1,4-butanediol); there is a relationship between the formation of 1,4-butanediol and the mutagenic activity of NPyrr. The S. typhimurium strain TA 1530 is able to partially transform 4-hydroxybutanal, the first identifiable microsomal metabolite of NPyrr, into its ultimate metabolite (1,4-butanediol).

Animals↗
PubMed1983

Pharmacokinetics of disopyramide in patients with chronic renal failure.

The pharmacokinetics study of a single oral dose of 200 mg of disopyramide was performed in 22 normal control subjects and 33 patients with chronic renal failure (CRF). The latter were subdivided into 3 groups of 11 patients each as a function of the gravity of renal insufficiency. With the exception of maximum concentration (C max), which was only slightly modified, and of the apparent distribution volume which remained unchanged, all the other pharmacokinetic blood parameters (t max, concentration at 24th hour, elimination constant (ke h-1), elimination half-life, area under the curve and plasma clearance) were significantly modified in the CRF group; in particular, the elimination half-life was significantly increased (for 22 cases of CRF with mean plasma creatinine greater than 250 microM at 16.3 hours compared to 8.0 hours in controls). The urinary elimination of disopyramide was studied in 14 renal insufficiency patients and in 6 controls. The decreased rate of urinary excretion of disopyramide and its monodealkylated derivative (NMD), during the first 24 hours, was directly related to the severity of renal insufficiency. The ratio of urinary NMD/(disopyramide + NMD) was unchanged in CRF patients as compared to the controls. The results suggest that the dosage of disopyramide should be decreased when plasma creatinine values are greater than 250 microM, and creatinine clearance is less than 30 ml/min. The dose for a 70 kg subject would be 100 mg, administered every 12 hours.

Adolescent↗
PubMed1981

Mutagenicity of n-nitrosodiethanolamine and its acetyl derivatives.

The mutagenicity of N-nitrosodiethanolamine and its mono- and di-acetyl derivatives was tested in the S. typhimurium test system, in cytogenetic studies and in the micronucleus test. N-nitrosodiethanolamine had no mutagenic effects towards several strains of S. typhimurium either in the absence or in the presence of metabolic activating systems. Its diacetyl derivative exerted mutagenic effects towards the S. typhimurium strains TA1530 and TA100. Neither compound increased significantly the nubmer of chromosomal aberrations or of micronuclei in mice.

Animals↗
PubMed1977

[Virginiamycin resistance in staphylococci (author's transl)].

Virginiamycin M factor transformation into an o-acetyl derivative has been observed in a particular Staphylococcus strain, naturally resistant to virginiamycin (Vr). It could not be detected in induced strains nor in sensitive ones. Turbidimetric studies with the naturally resistant strain showed that increasing concentration of the antibiotic had a progressive prolongation effect on the lag phase, without change in the growth rate. The prolonged lag phase could be reduced or eliminated by using an inoculum of cells previously "adapted" to M factor or virginiamycin. Preadapted cells had an increased acetylating power. Acridine dye treated cells showed a decreased o-acetyl derivative formation. This all suggested that virginiamycin resistance in the particular Vr strain was effectively connected with o-acetylation of the M factor.

Acetylation↗
PubMed1976

Microbial acetylation of M factor of virginiamycin.

The M component of virginiamycin was found to be modified by whole cells or cell-free enzyme preparations of a Staphylococcus aureus strain. It was shown that this reaction proceeds by enzymatic acetylation of the secondary alcoholic function of the molecule, followed by a rapid chemical degradation of the O-acetylated product.

Acetylation↗
PubMedDate not supplied

Pharmacokinetic study of pyridinol carbamate in chronic renal insufficiency.

The pharmacokinetics of Pyridinol carbamate (PDC) were studied over a 48 hour period in 14 patients with Chronic Renal Failure (C.R.F.) and in 10 normal controls. Following a single oral dose of 1 gm of PDC, the serum was assayed for PDC and M1 (monodemethylated PDC, the 1st metabolite) and the urine for PDC: M1, and M2 (second metabolite). The C max of PDC was found to be increased in the patients with C.R.F. when compared with the controls (21.8 +/- 5.26 micrograms VS 18.28 +/- 4.58 micrograms) but the half-life was unchanged (6.56 +/- 3.93 h VS 5.86 +/- 1.5 h). There was no difference between the C max of M1 of the patients and that of the controls (7.04 +/- 1.5 micrograms VS 6.49 +/- 0.84 micrograms), but there was an increase in the half-life (21.28 +/- 15.86 h VS 11.78 +/- 5.86) and of the area under curve (319.8 +/- 170.8 micrograms VS 182.6 +/- 78.5 micrograms ml-1 h). The overall excretion of PDC, M2 and particularly of M1 was found to be decreased and a higher concentration of PDC was noted in the urine of C.R.F. group. A correlation between the concentration of M2 and the severity of C.R.F. was observed, in that lower concentration or the absence of M2 in the 1st 6 hour urine sample appeared to be directly related to the severity of renal failure. Current evidence suggests that the N-demethylation of PDC remains normal in CRF and that there is enhanced transformation of M1 to ;M2.

Adult↗
PubMedDate not supplied

Mutagenicity and alpha-hydroxylation of N-nitrosopyrrolidine and N-nitrosopiperidine: a possible correlation.

N-Nitrosopyrrolidine (NPyrr) and N-nitrosopiperidine (NPip) are carcinogenic and mutagenic cyclic nitrosamines. Their biotransformation by rat liver post-mitochondrial fraction into 1,4-butanediol and 1,5-pentanediol, respectively, is evaluated by determining these ultimate metabolites with a sensitive and suitable method. Their mutagenic activity towards the Salmonella typhimurium strain TA 1530 was simultaneously observed. A relationship exists between their metabolism and their mutagenicity. alpha-Hydroxylation is probably the critical metabolic metabolism of cyclic nitrosamines.

Animals↗