ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The cystic fibrosis membrane conductance regulator can be activated through β2-adrenoceptor (β2AR) stimulation. We tested the hypothesis that coding sequence polymorphisms in the β2AR gene contribute to the disease state in patients with cystic fibrosis. The Arg16Gly, Gln27Glu, and Thr164Ile β2AR polymorphisms were studied by specific polymerase chain reaction and restriction fragment length polymorphism analysis in 126 cystic fibrosis patients. Forced expiratory volume in 1 s was significantly (P<0.05) reduced in cystic fibrosis patients carrying the Gly16allele in either homozygous or heterozygous form (Gly16Gly + Arg16Gly) compared to patients homozygous for the Arg16allele (60.3 ± 3.5% versus 75.7 ± 4.9% predicted). Similarly, forced vital capacity and flows at lower lung volumes were significantly (P<0.05 andP<0.01) lower in cystic fibrosis patients carrying the Gly16allele. In addition, the Gly16allele was associated with a greater 5 year decline in pulmonary function (P<0.01). Bronchodilator responses to albuterol were not significantly different between the groups. The Thr164Ile variant was found in four patients; these patients had markedly reduced pulmonary function. Isoproterenol-stimulated cyclic AMP formation was significantly blunted in cystic fibrosis patients carrying either the Gly16allele or Thr164Ile genotype compared to cystic fibrosis patients homozygous for the respective Arg16alleles. These data provide the first evidence suggesting that polymorphisms of the β2AR gene contribute to clinical severity and disease progression in cystic fibrosis.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

CYP3A4 is involved in the metabolism of endogenous steroids, and an allelic variant,CYP3A4*1B, consisting of an A to G polymorphism within the 5′-flanking region termed the nifedipine-specific response element (NFSE) has been associated with high grade and advanced stage of prostate cancers. Because steroid hormone exposure is known to influence breast and ovarian cancer risk, we conducted case–control studies to assess the relationship betweenCYP3A4*1Band risk of breast or ovarian cancer.CYP3A4NFSE genotype was determined in 951 breast cancer cases and 500 controls frequency matched for age and 488 ovarian cancer cases and 276 controls of similar age distribution. Case–control analyses and comparisons of genotype distributions were conducted by unconditional logistic regression. In addition, the functional significance of theCYP3A4*1Bpolymorphism was assessed by analysis ofCYP3A4-reporter gene constructs transiently transfected into liver-derived cell lines and primary cultures of well-differentiated rat hepatocytes. The GG genotype was rare in all groups (0–0.4%). There was no risk of cancer associated with the AG/GG genotypes combined, with an OR (95% CI) of 0.86 (0.54–1.33) for breast cancer (P= 0.5), and 1.51 (0.80–2.89) for ovarian cancer (P= 0.2). Analysis ofCYP3A4-luciferase constructs showed thatCYP3A4*1Bdid not consistently affect reporter gene activity. Our data suggest that theCYP3A4*1Bpolymorphism is not associated with risk of breast or ovarian cancer. In support of this negative finding, in-vitro functional studies indicate that NFSE genotype is not a critical factor in the transcriptional activity of theCYP3A45′-flanking region, and is thus unlikely to modulate CYP3A4-mediated metabolism of steroids.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

In the present study, we report the first systematic investigation of polymorphism in the humanCYP4B1gene. Using a strategy based on single-strand conformation polymorphism analysis of PCR products (PCR–SSCP), we analyzed the twelve exons of the gene, as well as their 5′- and 3′- proximal flanking sequences, in DNA samples from 190 French Caucasians. In addition to the wild-typeCYP4B1* allele (CYP4B1*1), four variants, namelyCYP4B1*2, *3, *4and *5, were characterized. TheCYP4B1*3, *4and *5 alleles encode missense mutations Arg173Trp, Ser322Gly and Met331Ile, respectively. The fourth variant,CYP4B1*2, harbors three missense mutations (Met331Ile, Arg340Cys and Arg375Cys) and a double nucleotide deletion (AT881-882del) that causes a frameshift and premature stop codon in the second third of the coding sequence of the gene. This latter mutation can be assumed to lead to the synthesis of a severely truncated protein and, therefore, probably contributes to interindividual variability of CYP4B1 expression and enzymatic activity. In order to investigate the extent of theCYP4B1*2allele in a large population, a rapid genotyping test, based on restriction analysis of PCR products, was developed and applied to 2082 French Caucasians. Forty-two subjects were found homozygous for the AT881-882 deletion, which suggests that about 2% of individuals should be unable to develop metabolic reactions mediated by CYP4B1. Given the relatively high frequency and the functional consequences of theCYP4B1*2allele, associations betweenCYP4B1polymorphism and certain pathological processes should be considered.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Black Africans show lower rates of CYP2D6- and CYP2C19-dependent drug metabolism compared to Caucasians of the same apparent genotype. To determine if environmental factors are responsible for this difference, the genotypes and phenotypes of CYP2D6 and CYP2C19 among Ethiopians living in Sweden (n= 70) were assessed and compared to our previously published data from Ethiopians living in Ethiopia (n= 114) and Swedish Caucasians (n= 134). There was no significant difference inCYP2C19genotype or phenotype as assessed by mephenytoin between Ethiopians in Sweden or in Ethiopia. However, Swedes were significantly more rapid for CYP2C19 activity than both Ethiopian groups (P<0.01). A comparison of the debrisoquine MR among individuals of the sameCYP2D6genotype revealed that Swedes exhibited the highest rate of debrisoquine metabolism, followed by Ethiopians in Sweden and Ethiopians in Ethiopia. The difference between the Ethiopian groups was significant (P<0.02 using a univariate test ANOVA) and amounted to approximately 50% of the magnitude of the MR difference between Swedes and Ethiopians in Ethiopia. It is tempting to speculate that inhibitory dietary factors may explain the differences seen between the two Ethiopian groups and that these components in the past might have contributed to dietary stress-mediated selection of duplicated and multiduplicated activeCYP2D6genes, as frequently seen in Ethiopians. In conclusion, the results indicate a significant influence of environmental factors as an explanation for the difference in capacity for CYP2D6, but not CYP2C19 metabolism between Caucasians and Black Africans. Additional factors remain to be elucidated to fully explain the interethnic differences in CYP2D6 activity.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ArylamineN-acetyltransferase (NAT) polymorphism in humans has been associated with variation in susceptibility to drug toxicity and cancer. In mice, three NAT isoenzymes are encoded byNat1,Nat2andNat3genes. OnlyNat2has been shown previously to be polymorphic, a single nucleotide substitution causing the slow acetylator phenotype in the A/J strain. We sequenced theNatgenes from inbred (CBA and 129/Ola), outbred (PO and TO) and wild-derived inbred (Mus spretusandMus musculus castaneus) mouse strains and report polymorphism in all threeNatgenes ofM. spretusand inNat2andNat3genes ofM. m. castaneus. Enzymatic activity assays using liver homogenates demonstrated thatM. m. castaneusis a ‘fast’ andM. spretusa ‘slow’ acetylator. Western blot analysis indicated that hepatic NAT2 protein is less abundant inM. spretusthanM. m. castaneus. The new allozymes were expressed in a mammalian cell line and NAT enzymatic activity was measured with a series of substrates. NAT1 and NAT2 isoenzymes ofM. m. castaneusexhibited a higher rate of acetylation, compared with those ofM. spretus. Activity of the NAT3 allozymes was hardly detectable, although theNat3gene does appear to be transcribed, since mRNA was detected by RT–PCR in the spleen. Additional polymorphisms, useful forNat-related genetic studies, have been identified between BALB/c, C57Bl/6J, A/J, 129/Ola, CBA, PO, TO,M. m. castaneusandM. spretusstrains in four microsatellite repeats located close to theNatgenes.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The completion of the Human Genome Project and the development of high-throughput polymorphism identification methods have allowed researchers to carry out full genetic analyses of many clinically relevant genes. However, few studies have combined genetic analysis within vitrophenotyping to better understand the relationship between genetic variation and protein function. Many transporters in the kidney are thought to play key roles in defense against a variety of foreign substances. The goal of this study was to understand the relationship between variation in a gene encoding a major renal xenobiotic transporter, OCT2, and transporter function. We report a comprehensive genetic analysis and functional characterization of variants of OCT2. Twenty-eight variable sites in theOCT2gene were identified in a collection of 247 ethnically diverse DNA samples. Eight caused non-synonymous amino acid changes, of which four were present at⩾1% in an ethnic population. All four of these altered transporter function assayed inXenopus laevisoocytes. Analysis of nucleotide diversity (π) revealed a higher prevalence of synonymous (π = 22.4×10−4) versus non-synonymous (π = 2.1×10−4) changes in OCT2 than in other genes. In addition, the non-synonymous sites had a significant tendency to exhibit more skewed allele frequencies (more negative Tajima'sD-values) compared to synonymous sites. The population-genetic analysis, together with the functional characterization, suggests that selection has acted against amino acid changes in OCT2. This selection may be due to a necessary role of OCT2 in the renal elimination of endogenous amines or xenobiotics, including environmental toxins, neurotoxic amines and therapeutic drugs.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Impaired platelet-derived nitric oxide (NO) contributes to acute coronary syndromes by enhancing platelet recruitment and thrombus formation. Polymorphic variants of the endothelial NO synthase (eNOS) gene have been associated with cardiovascular diseases. To examine whether eNOS variants affect platelet-derived NO and platelet function, and to assess the effects of estradiol on platelet function, we studied platelets from 47 healthy caucasians who were genotyped for eNOS polymorphisms in the promoter region (T−786C), in intron 4, and in exon 7 (Glu298Asp). Platelet aggregation, platelet-derived NO and superoxide production were measured in control samples and samples pretreated with 17-α-estradiol (10 nmol/l). The occurrence of variants in the promoter region (P= 0.002) or in exon 7 (P= 0.007), but not in intron 4 (P>0.05), were associated with lower levels of platelet-derived NO. An increased (P= 0.047) release of superoxide was observed with platelets from subjects with the variant in the promoter region, but not with other eNOS genetic variants. The eNOS gene polymorphisms did not affect ADP-induced platelet aggregation (P>0.05). However, estradiol significantly increased platelet aggregation (P= 0.004), and platelet-derived superoxide (P= 0.047) in individuals homozygous for the variant in exon 7, but not in subject with other genotypes. These data demonstrate that the eNOS variants in the promoter region and in exon 7 decrease platelet-derived NO and that estradiol significantly increases platelet aggregation in homozygous for the variant in exon 7 but not in subjects with other genotypes, suggesting that eNOS variants may influence the thrombotic response.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The objective was to evaluate the effects of the apolipoprotein E (ApoE) genotype and gender on the response to donepezil treatment in Alzheimer's disease. ApoE genotyping was performed on 117 patients with mild to moderate Alzheimer's disease who were included in a 36-week open label trial of donepezil therapy. Of these 117 patients, who constituted the intent-to-treat population (ITT), 80 completed the trial, and constituted the evaluable population. Patients were treated blindly in relation to ApoE genotype. Outcome measures were Alzheimer's disease Assessment Scale-Cognitive Component (ADAS-Cog), the Mini Mental State Examination, Instrumental Activities of Daily Living, and the Caregiver-rated Clinical Global Impression of Change. ITT analysis did not reveal significant differences between the responses of &epsis;4− and &epsis;4+ carriers according to the ADAS-Cog (P= 0.28). No differences were found either between the responses of men and women (P= 0.81), and there was no significant interaction between genotype and gender (P= 0.09). Other outcome measures all exhibited similar patterns of change to those seen using the ADAS-Cog. Consequently, these results do not support the hypothesis that the ApoE phenotype and gender are predictors of the response to donepezil in Alzheimer's disease patients.

ISSN:0960-314X    

出版商:OVID    

年代:2002

数据来源: OVID