ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Large individual differences in the clinical response to morphine therapy have been known for a long time by clinicians. The recent advances in genomic research encourage the search for pharmacogenetic causes of that variability. As a measure of central opioid effects, pupil diameters were assessed every 20 min for 18 h after administration of morphine or its active metabolite morphine-6-glucuronide (M6G) in a two-way crossover study. The opioid effects were compared between six subjects with a single-nucleotide polymorphism (SNP) A118G in the μ-opioid receptor gene (five heterozygous, one homozygous) and six control subjects. Non-parametric pharmacokinetic-pharmacodynamic modelling was employed to identify the influence of the A118G SNP on the concentration–response relationship of M6G and morphine, which was described by a sigmoidEmaxmodel. As a measure of potency, the EC50of the pupil constrictory effects of M6G was 714±197 nmol/l in wild-type and 1475±424 nmol/l in heterozygous carriers of the A118G SNP. In the homozygous carrier of the SNP, it had an EC50of 3140 nmol/l. In addition, the dose–response relationship was flatter in the A118G carriers than in control subjects (shape factor of the sigmoidEmaxmodel: γ = 3.3±1.2, 1.7±0.5 and 1.6 for wild-type, heterozygous and the homozygous A118G carriers, respectively). In contrast, the concentration–response relationship of morphine was not affected by this specific SNP. The A118G SNP in the μ-receptor gene significantly reduces the potency of M6G in humans.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

3′-Phosphoadenosine 5′-phosphosulfate (PAPS) is the sulfate donor cosubstrate for all sulfotransferase (SULT) enzymes. SULTs catalyze the sulfate conjugation of many endogenous and exogenous compounds, including drugs and other xenobiotics. In humans, PAPS is synthesized from adenosine 5′-triphosphate (ATP) and inorganic sulfate (SO2−4) by two isoforms, PAPSS1 and PAPSS2. Rare mutations that inactivate PAPSS2 are associated with human spondyloepimetaphyseal dysplasia and murine brachymorphism. To determine whether more common genetic polymorphisms that do not completely inactivate the enzyme might be one factor responsible for individual differences in sulfate conjugation, we previously cloned the human PAPSS2 gene. In the present studies, we ‘resequenced’ all twelvePAPSS2exons and splice junctions, as well as approximately 500 bp of the 5′-flanking region, using 90 Polymorphism Discovery Resource (PDR) DNA samples from the Coriell Cell Repository. Twenty-two single nucleotide polymorphisms (SNPs) were observed, including four nonsynonymous coding region SNPs (cSNPs) that altered the following amino acids: Glu10Lys, Met281Leu,Val291Met and Arg432Lys. We also observed four insertions/deletions, including one sample that was homozygous for an 81-bp deletion in the 5′-flanking region 286 bp upstream from the site of transcription initiation. Transient expression studies showed that two of the nonsynonymous cSNPS, those that resulted in Glu10Lys and Val291Met alterations in encoded amino acids, showed significant decreases in levels of PAPSS activity. In the case of Glu10Lys, decreased activity was paralleled by a decrease in immunoreactive protein, while the Val291Met allozyme displayed a significant decrease in affinity for both ATP and Na2SO4when compared to ‘wild-type’ enzyme, but without a significant alteration in level of immunoreactive protein. It will now be possible to test the hypothesis that these common, functionally significantPAPSS2genetic polymorphisms might contribute to variations in sulfate conjugationin vivo.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Cholecystokinin (CCK) and gastrin (G) and their receptors (CCK1 and CCK2) are involved in multiple physiological functions. Notably, CCK1R plays a role in the regulation of food intake whereas both CCK1R and CCK2R play a role in the regulation of pancreatic endocrine function. CCK1R and CCK2R may therefore serve as pharmacological targets in diabetes and obesity and genes encoding these receptors may be candidate genes in the pathogenesis of the diseases. In this study, we used single nucleotide polymorphism analysis and allele specific amplification for mutation screening of the CCK2 receptor gene and family linkage study. Mutated receptors were constructed, expressed in COS-7 cells for analysis of their binding and functional properties. V125I-CCK2 receptor variant was found in 2 out of 18 type 2 diabetes mellitus families tested. V125I mutation co-segregated in those 2 initial families, but further association studies showed that this mutation was not associated with diabetes or early age at diagnosis of the disease. V125I-CCK2 receptor high affinity sites exhibited a 2-fold enhanced binding affinity for CCK which was correlated to a slightly increased potency in coupling to inositol phosphate production. Since CCK2 receptor is expressed in pancreatic glucagon-producing cells in humans and is involved in secretion of glucagon, an increase of binding affinity of the mutated CCK2 receptor could enhance glucagon secretion in patients bearing V125I mutation. We also characterized a mutant of the CCK1 receptor which was previously identified in an obese patient. This mutant, V365I-CCK1, demonstrated a decreased level of expression (26%) and efficacy (25%) to stimulate inositol phosphates. It can therefore be expected that in humans bearing V365I mutation, decreases in CCK1 receptor expression and coupling efficiency may affect CCK-induced regulation of satiety. Polymorphism or mutations in the CCK receptors may be involved in type 2 diabetes mellitus and obesity. However, further studies are necessary to precisely evaluate this role in humans.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Recent data indicate that NAD(P)H: quinone oxidoreductase 1 (NQO1) is important in the activation of mitomycin C. A polymorphism in human NQO1 (609C>T) is associated with diminished NQO1 activity. The purpose of our study was to determine the effect of the 609C>T polymorphism on tumor NQO1 activity and overall survival in patients with disseminated peritoneal cancer receiving intraperitoneal mitomycin C therapy. Patients with disseminated peritoneal cancer of gastrointestinal or other origin were eligible. Following aggressive surgical debulking, patients were administered a 2-h heated (40.5°C) intraperitoneal perfusion with mitomycin C. NQO1 activity was determined in tumor tissue obtained during surgery and patients were genotyped for the NQO1 C609T polymorphism using a polymerase chain reaction-based method. The major response variable monitored during the trial was overall survival. Of the 117 patients genotyped for the NQO1 609C>T polymorphism, 67% were wild-type (WT), 31% were heterozygous (HE), and 2% were homozygous mutant (HM). In tumor tissue, the mean NQO1 activities from WT (n= 14) and HE (n= 5) patients were 794±603 and 70±133.1 nmol/min/mg protein respectively (P= 0.006). Significant differences in survival between WT versus HE/HM genotypes were noted in optimally debulked patients (R0/R1) (43.6+ months, median not yet reached versus 23 months respectively,P= 0.037) and in patients with peritoneal carcinomatosis of colonic origin (18.2 versus 11.5 months respectively,P= 0.050). These data indicate that the NQO1 609C>T polymorphism results in significantly reduced tumor NQO1 activity and reduced survival in subsets of patients receiving intraperitoneal hyperthermic mitomycin C therapy.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

SixNAT2single-nucleotide polymorphisms (SNPs) were analysed in 105 unrelated Ngawbe and 136 unrelated Embera Amerindians (482 chromosomes) by SNP-specific polymerase chain reaction analysis. 282C>T was the most common synonymous mutation, while 857G>A was the most frequent nonsynonymous inactivating exchange. The allelic frequency of theNAT2*5series (containing the 341T>C exchange) was 2.4% and 9.9% for Ngawbe and Embera, respectively, five- to 20-times lower than that in Caucasians. TheNAT2*6series (590G>A) showed allelic frequencies of 0% and 3.7%, eight- to 30-times lower than in Caucasians. On the other hand, theNAT2*7series, characterized by mutation 857G>A, had allelic frequencies (23.3% and 22.8%) that were 10–20-times higher in Amerindians than in Caucasians. Amerindians are characterized by decreased genetic diversity because they display a low number of mutated alleles (four and five for Ngawbe and Embera, respectively) that are present at low proportions (27.6% and 39%), reduced genotypic variability (seven out of 15 and 12 out of 21 possible genotypes) and low heterozygosity (40% and 55.1%) at theNAT2locus. The NAT2 phenotype was evaluated with caffeine in a subset of 72 Embera. There were no disagreements between genotype and phenotype among rapid and slow acetylators (13/72, 18%). We conclude that, in the Embera, the analysis of three inactivating mutations was sufficient in predicting the phenotype in more than 99.5% of these subjects.NAT2would appear to be of a selectively neutral character given that there is no evidence of adaptation to the prevailing ecology in Amerindians.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Familial adenomatous polyposis (FAP) exhibits a variable phenotype even in carriers of the same adenomatous polyposis coli germline mutation. Xenobiotic-metabolizing enzymes such asN-acetyltransferases (NATs) and glutathioneS-transferases (GSTs) were reported to modify the individual risk for colorectal cancer. We examined whether the polymorphisms of the NAT2, GSTM1, and GSTT1 enzymes affect age at diagnosis of first colorectal adenomas or extracolonic manifestations in 411 FAP patients. Neither age at diagnosis of colorectal adenomas nor occurrence of extra-intestinal tumors differed significantly between genotypes at the NAT2 and GSTM1 loci, whereas GSTT1 polymorphism showed an uncertain association with extra-intestinal manifestations. Combinations of supposed at risk genotypes of the three enzymes showed no significant differences either. Thus, NAT2, GSTM1, or GSTT1 are unlikely to modify the disease phenotype in FAP patients.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Pharmacogenomics offers the potential to define metabolic pathways and to provide increased knowledge of drug actions. We studied relative levels of gene expression in the rat using a microarray with 8448 rat UniGenes (1928 known genes, 6520 unknown ESTs) in the liver and kidney as a function of time of day and then of feeding regime, which are common variables in preclinical pharmacogenomic studies. We identified 597 genes, including several key metabolic pathways, whose relative expression levels are significantly affected by time of day: expression of some was further modified by feeding state. These would have sparked interest in a pharmacogenomic study. Our study demonstrates that two common variables in pharmacogenomic studies can have dramatic effects on gene expression. This study provides investigators with baseline information for both kidney and liver with respect to ‘normal’ changes in gene expression influenced by time of day and feeding state. It also identifies 18 new genes that should be investigated for a role in circadian rhythms in peripheral tissues.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Our previous studies suggested that bothCOMTandGSTgenotypes might modify individual breast cancer risk. Here, we extended the studies to examine the potential combined effect of these genotypes in susceptibility to breast cancer. Our study population consisted of 483 Finnish breast cancer cases and 482 population control subjects. The odds ratios (ORs) and (95%) confidence intervals (CIs) were calculated by unconditional logistic regression adjusting for known or suspected confounding factors. No significant increase in the overall breast cancer risk was seen for any combinations of the studied genotypes. However, a substantially increased risk of breast cancer was seen for women who had used hormone replacement therapy (HRT) and simultaneously carried theCOMT-Lallele containing genotypes and either theGSTP1Ile/Ile genotype (OR 4.10, 95% CI 1.24–13.6) or theGSTT1null genotype (OR 4.19, 95% CI 1.30–13.5). These associations appeared to be mainly attributable to long-term users of HRT; the respective ORs were 7.00 (95% CI 1.21–40.6) and 8.36 (95% CI 1.44–49.0) among the users of HRT of more than 30 months. In addition, the combination ofCOMT-Lallele containing genotypes with theGSTM1null genotype posed a remarkably increased risk (OR 9.10, 95% CI 1.84–45.0) of breast cancer in this study group. These results suggest that the use of HRT could substantially increase the risk of breast cancer among women with specific combinations of the at-risk genotypes ofCOMTandGSTgenes.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Risk factors for patients developing visual disturbances in association with proton pump inhibitors are unknown. As omeprazole is substantially metabolized by polymorphic CYP2C19, we retrospectively identified and genotyped patients who experienced this adverse reaction. Among 29 patients, we found two poor metabolizers (PMs) of CYP2C19. The PM genotype does not appear to be a risk factor for omeprazole-associated visual disorders.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID