ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

We aimed to develop a microarray genotyping system for multiplex analysis of a panel of single nucleotide polymorphisms (SNPs) in genes encoding proteins involved in blood pressure regulation, and to apply this system in a pilot study demonstrating its feasibility in the pharmacogenetics of hypertension. A panel of 74 SNPs in 25 genes involved in blood pressure regulation was selected from the SNP databases, and genotyped in DNA samples of 97 hypertensive patients. The patients had been randomized to double-blind treatment with either the angiotensin II type 1 receptor blocker irbesartan or the β1-adrenergic receptor blocker atenolol. Genotyping was performed using a microarray based DNA polymerase assisted ‘minisequencing’ single nucleotide primer extension assay with fluorescence detection. The observed genotypes were related to the blood pressure reduction using stepwise multiple regression analysis. The allele frequencies of the selected SNPs were determined in the Swedish population. The established microarray-based genotyping system was validated and allowed unequivocal multiplex genotyping of the panel of 74 SNPs in every patient. Almost 7200 SNP genotypes were generated in the study. Profiles of four or five SNP-genotypes that may be useful as predictors of blood pressure reduction after antihypertensive treatment were identified. Our results highlight the potential of microarray-based technology for SNP genotyping in pharmacogenetics.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The aim of this study was to identify the extent of genetic variability in breast cancer resistance protein (BCRP) in humans. We first analysed the sequence of BCRP cDNA from human livers and from human intestines phenotyped for expression of intestinal BCRP. We then determined the frequency of all known coding single nucleotide polymorphisms (cSNPs) using DNA from individuals representing 11 different ethnic populations. Nine SNPs including four non-synonymous and three synonymous cSNPs and two intronic SNPs were identified. Of the missense mutations, exon 2 SNP (G34A) resulted in a V12M change; exon 5 SNP (C421A) resulted in a Q141K substitution; exon 6 SNP (A616C) resulted in an I206L amino acid substitution; and exon 15 SNP (A1768T) resulted in a N590Y change in the BCRP protein. The two most frequent polymorphisms identified in the human population studied were the G34A and C421A transitions. There was marked variation in BCRP genotypes and allele frequencies in the different populations. BCRP mRNA was phenotyped in human small bowel intestinal samples by real-time polymerase chain reaction and BCRP protein was analysed on immunoblots of tissue from the same individuals. There was a 78-fold variation in expression of BCRP mRNA and significant variation in BCRP protein expression in human intestine. Expression of intestinal BCRP mRNA and protein was not different between persons expressing the common Gln141allele compared to the Lys141allele. Thus, common natural allelic variants of BCRP have been identified, and did not influence interindividual variation in expression of BCRP mRNA in human intestine, but remain to be tested for their effect on BCRP function.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To test the hypothesis that analyses of drug targets for polymorphism will help to establish gene-based information for the treatment of cancer patients, we investigated the functional single-nucleotide polymorphisms in the human cytidine deaminase (HCDA) gene. The cDNAs from 52 leukaemia/lymphoma samples and 169 control blood samples were direct-sequenced and analysed for the polymorphisms. Three different polymorphisms (A79C, G208A and T435C) were identified in the coding region of theHCDAgene and displayed allelic frequencies of 20.1%, 4.3% and 70.1%, respectively. No association with susceptibility to disease was observed. A novel polymorphism, G208A produced an alanine to threonine substitution (A70T) within the conserved catalytic domain. By introduction of the polymorphicHCDAgenes into the yeast CDA-null mutants, the HCDA-70T showed 40% and 32% activity of prototype for cytidine and ara-C substrates, respectively (P<0.01). The ara-C IC50value of the yeast transformants carrying HCDA-70T was 757±33 μmol and was significantly lower (P<0.01) than that of prototype (941±58 μmol). This study demonstrated a population characterized with 208A genotype forHCDA, which potentially leads one more sensitive to ara-C treatment than prototype. Accumulation of polymorphisms in the genes responsible for drug metabolism and determination of polymorphism-induced biological variations could provide the additional therapeutic strategies in risk-stratified protocols for the treatment of childhood malignancies.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

CYP2D6 is involved in theO-demethylation metabolic pathway of venlafaxine in humans. In this study, we investigated whether this isozyme is stereoselective. Plasma samples from seven CYP2D6 extensive metabolizers (EMs) and five CYP2D6 poor metabolizers (PMs), collected during a period without and with coadministration of quinidine, were analysed. Subjects were administered venlafaxine hydrochloride 18.75 mg orally every 12 h for 48 h on two occasions (1 week apart); once alone and once during the concomitant administration of quinidine sulphate every 12 h. Blood and urine samples were collected under steady-state conditions over one dosing interval (12 h). The present results show that, although CYP2D6 catalyses theO-demethylation of both enantiomers of venlafaxine, it displays a marked stereoselectivity towards the (R)-enantiomer. The oral clearance of (R)-venlafaxine was found to be nine-fold higher in EMs compared to PMs [median (range) 173 (29–611) l/h versus 20 (16–24) l/h,P<0.005], while it was two-fold higher for (S)-venlafaxine [73 (32–130) l/h versus 37 (21–44) l/h,P<0.05]. In EMs, quinidine decreased (R)- and (S)-venlafaxine oral clearance by 12-fold (P<0.05) and four-fold (P<0.05), respectively. In contrast, quinidine did not have any effects on renal clearance of (R)-venlafaxine [4 (2–10) l/h for venlafaxine alone versus 5 (0.6–7) l/h for venlafaxine + quinidine] and of (S)-venlafaxine [4 (1–7) l/h for venlafaxine alone versus 3 (0.4–6) l/h for venlafaxine + quinidine]. The coadministration of quinidine to EMs resulted in an almost complete inhibition of the partial metabolic clearance of (R)-venlafaxine toO-demethylated metabolites [127 (10–493) l/h down to 1 (0.1–3) l/h,P<0.05], while a seven-fold reduction was measured for (S)-venlafaxine [47 (14–94) l/h versus 7 (1–19) l/h,P<0.05]. In PMs, coadministration of quinidine did not significantly change oral clearance and partial metabolic clearance of (R)- and (S)-venlafaxine to its various metabolites. In contrast, data obtained on the partial metabolic clearance of (R)- and (S)-venlafaxine toN-demethylated metabolites, a reaction which is mediated by CYP3A4, suggest a lack of stereoselectivity of this enzyme.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Human dihydrodiol dehydrogenase (DD) catalyses the oxidation oftrans-dihydrodiols of polycyclic aromatic hydrocarbons and the reduction of several ketone-containing drugs. About 40-fold interindividual difference in DD activities has been noted. Recently, we found that transcriptional factors, hepatocyte nuclear factor (HNF)-1α, HNF-4α and HNF-4γ were essential for the expression of DD4 mRNA, which is a major form of DDs. Thus, to clarify a possible mechanism(s) underlying the interindividual difference in DD activities, we investigated the sequences of genes and the expression levels of mRNA for DD4 and HNFs in human livers. We found no clear relationship between the genotypes ofDD4andHNFgenes and the expression levels of DD4 mRNA in the subjects. The expression level of DD4 mRNA significantly correlated with that of HNF-1α, HNF-4α or HNF-4γ. These results suggest that the expression level of DD4 mRNA is cooperatively regulated by the amounts of HNF-1α, HNF-4α and HNF-4γ.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

This study was carried out to characterize the distribution of NAT2 allelic variants among a sample of three African populations. We determined the frequencies of major NAT2 allele clusters (NAT2*5, *6, *7and*14) using PCR/restriction fragment length polymorphism and sequencing techniques. The genotypes predict slow acetylator phenotypes of 49, 38 and 52% among Tanzanians, Venda and Zimbabweans, respectively. The most common genotype wasNAT2*4/*5. NAT2*5was the most common allele whileNAT2*7was the least common. A new allele with two base changes occurring together, 481C>T and 590G>A, is reported. The frequency of the occurrence of the combination 481C>T and 590G>A, was found to be 9% (30/326), 7% (14/192) and 8% (18/234) among Zimbabweans, Venda and Tanzanians, respectively. The allele has been namedNAT2*6E. Among Africans, the change 481C>T is not only associated with 341C>T (i.e. theNAT2*5allele cluster) as in other populations, but also with 590G>A on the same allele.

ISSN:0960-314X    

出版商:OVID    

年代:2003

数据来源: OVID