Biomedical subjects

J Catalin

Publications and source records attributed to J Catalin.

57 records · Page 4Linked to original sources

PubMedDate not supplied

UDP-glucuronosyltransferase activity toward digitoxigenin monodigitoxoside in human liver microsomes.

The properties of UDP-glucuronosyltransferase (UDPGT) toward digitoxigenin-monodigitoxoside (DT1) have been studied in human liver microsomes. The enzyme activity determined in nonactivated microsomes was very low (20 pmol/min/mg protein) compared with previously published values in rats (104 pmol/min/mg protein) or mice (379 pmol/min/mg protein) DT1-UDPGT activity was increased (180 to 220% of control activity) by Lubrol PX, Triton X-100, or (3-[3-cholamidopropyl]dimethylammonio)-1-propane sulfonic acid. The rate of DT1 glucuronidation determined for 29 different human liver microsomes was variable (18 to 87 pmol/min/mg protein). The KM found was approximately 4.5 microM. DT1-UDPGT activity was tentatively correlated with other known UDPGT activities. No significant correlations were found between DT1 and p-nitrophenol or 4-hydroxybiphenyl UDPGT activities. On the other hand, a strong correlation (r = 0.64, p < 0.05) was observed between DT1-UDPGT activity and digoxigenin-monodigitoxoside (DG1, another cardiac glycoside) glucuronidation rate.

Adolescent↗

PubMedDate not supplied

[In vitro metabolism of zidovudine in man].

The metabolism of zidovudine (AZT) and its modulating factors have been studied in human liver microsomes. In a first step, we demonstrated the involvement of UDP-glucoronosyltransferase (UDPGT) 2 form in AZT glucuronidation. In a second step, in order to predict drug interactions, we screened the effect of 52 drugs, representative of 17 different therapeutic classes, on AZT glucuronidation. We demonstrated that about twenty molecules glucuronidated or not are able to inhibit AZT glucuronidation. Finally, the NADPH-dependent reductive metabolism of AZT which produced a toxic metabolite, 3'-amino-3'-deoxythymidine (AMT) has been studied. Our studies demonstrated that AMT was formed only under anaerobic conditions and that its formation is catalysed by the NADPH-cytochrome P450 reductase.

Drug Interactions↗

PubMedDate not supplied

Determination of clonazepam ("Rivotril" or "Ro 5-4023") in plasma by gas chromatography using an internal standard.

A method has been developed for gas-chromatographic determination of clonazepam ("Rivotril" or "Ro 5-4023") in plasma, using methyl-clonazepam ("Ro 4082") as an internal standard. Following extraction of the benzodiazepines and hydrolysis, the benzophenones are analyzed by gas-chromatography, using a glass column filled with 3% OV 225 on Gas Chrom Q and a 63Ni electron-capture detector. The technique has good selectivity. The limit of sensitivity is less than 1 ng/ml of plasma. Using this method the plasma kinetics of clonazepam may be studied in man and the correlations between plasma levels and therapeutic activity investigated. It is also available for toxicological analysis, as well as pharmacovigilance purpose. The same internal standard and a similar method can also be used for the determination of flunitrazpem ("Rohypnol" or "Ro 5-4200") and its major metabolite (N-desmethyl-flunitrazepam) in plasma.

Administration, Oral↗