Analysis of thiopurine S-methyltransferase phenotype-genotype in a Tunisian population with Crohn's disease.

This study was conducted to investigate the thiopurine S-methyltransferase TPMT activity distribution and gene mutations in Tunisian population with positive diagnostic for Crohn's disease. TPMT activity was measured in Tunisian population (n = 88) by a high performance liquid chromatography assay. Polymerase chain reaction-based methods were used to determine the frequency of TPMT mutant alleles TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C. TPMT activity was normally distributed, ranging from 4.58 to 35.27 nmol/(h ml) RBC with a mean of 18.67 ± 7.10 nmol/(h ml) RBC. Seven TPMT*3A heterozygotes and one TPMT*3C homozygote were found in 88 patients, with allele frequencies of 0.039 and 1.13, respectively. TPMT*3A and the TPMT*3C, which cause the largest decrease in enzyme activity, were both variant alleles detected in the Tunisian population.

Relationships between pharmacokinetic parameters of carbamazepine and therapeutic response in patients with bipolar disease.

This study aimed to assess the relationship between plasma levels of carbamazepine and its active metabolite 10,11-epoxide-carbamazepine, and the therapeutic response in patients with bipolar disease. Thirteen patients were kept on a fixed individual dose of carbamazepine for 19 weeks under psychiatric care. Steady-state plasma concentrations of carbamazepine and its metabolite 10,11-epoxide-carbamazepine were measured at weeks 4, 12, and 20 by HPLC essay. Simultaneously, the psychopathologic state was assessed using the Brief Psychiatric rating scale (BPRS). Upon correlational analysis, mean BPRS scores did not correlate with the plasma levels of carbamazepine, whereas both mean plasma levels of 10, 11-epoxide-carbamazepine concentrations and 10,11-epoxide-carbamazepine to plasma carbamazepine ratio were closely correlated with mean values of BPRS scores (r = 0.80, p =10(-4), r= -0.89, p =10(-3) respectively). Optimum therapeutic response was observed among patients who had a plasma metabolite level of 1.4 µg/mL and a plasma carbamazepine concentrations of 7 µg/mL simultaneously. These results suggest that both plasma carbamazepine and 10,11-epoxide-carbamazepine levels must be fixed to achieve optimum therapeutic response. In order to reach these conditions, inhibitor drugs (such as valproic acid) or inductor drugs (such as phenobarbital) of epoxyde-hydrolase might be coadministered with the carbamazepine in order to adapt the plasma level of 10,11-epoxide-carbamazepine.

Role of CYP1A2 polymorphisms in breast cancer risk in women.

Cytochrome P4501A2 (CYP1A2) is a key enzyme in the etiology of breast cancer (BC). It is involved in breast carcinogen activation [aromatic (AAs) and heterocyclic amines (HAs), polycyclic aromatic hydrocarbons (PAHs)], in the production of beneficial oestrogen [2-hydroxyestrone (2-OHE1)] and in converting arachidonic acid (AAc) to epoxyeicosatrienoic acids (EETs), which have anti-inflammatory properties. Within a hospital-based case-control study, the effect of functional CYP1A2 variants [-3860G/A (rs2069514), -2467T/delT (rs3569413), -163C/A (rs762551)] and their interactions with environmental factors in BC risk was investigated. The study population included 125 BC cases and 43 non-cancer controls. Genotyping was performed in RT-PCR using Taqman assays. The gene-environment interaction was appraised using a case-only study design. We found that the -3860A variant, independently from environmental factors, as well as by interacting with fried foods (p=0.025) and indoor exposure to pollutants (p=0.050), reduced the risk of BC (p=0.025), whereas its interaction with coffee (p=0.045) increased the BC risk. This is the first study indicating that the -3860A variant, by decreasing CYP1A2 activity, modifies BC risk by interacting with environmental factors, thereby supporting the hypothesis that reduced CYP1A2 activity contributes to BC risk in different ways, for example, it may be protective by reducing the activation of pro-carcinogens such as AAs, HAs and PAHs, but would increase risk by reducing the beneficial formation of 2-OHE1 and EETs.