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1.
Diabetologia ; 49(5): 958-61, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16538488

RESUMO

AIMS/HYPOTHESIS: The association between IL4R and type 1 diabetes has been tested in many studies in recent years, with contradictory results. The aim of this study was to re-evaluate the genetic association in type 1 diabetic nuclear families of mixed European background. SUBJECTS, MATERIALS AND METHODS: We genotyped six non-synonymous single-nucleotide polymorphisms (SNPs) of the IL4R gene in 830 nuclear families as specified above, including a French Canadian subset. RESULTS: No association between type 1 diabetes and any SNP or haplotype was found by the transmission disequilibrium test. CONCLUSIONS/INTERPRETATION: Previous positive reports may be due to population stratification as, according to HapMap data, allele frequencies in the IL4R region vary considerably by ethnicity.


Assuntos
Diabetes Mellitus Tipo 1/genética , Polimorfismo de Nucleotídeo Único , Receptores de Interleucina-4/genética , Canadá , Diabetes Mellitus Tipo 1/imunologia , Feminino , França/etnologia , Genótipo , Humanos , Desequilíbrio de Ligação , Masculino , Núcleo Familiar , População Branca
2.
J Med Genet ; 43(2): 129-32, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16014697

RESUMO

BACKGROUND: The 2',5'-oligoadenylate synthetase genes (OAS1, OAS2, and OAS3) map to human chromosome 12q24 and encode a family of enzymes pivotal to innate antiviral defence. Recently, the minor allele of an OAS1 single nucleotide polymorphism (SNP) that alters splicing (rs10774671) was found to be associated with increased enzymatic activity and, in a case-sibling control study, with type 1 diabetes (T1D). METHODS: We have confirmed this T1D association in 784 nuclear families (two parents and at least one affected offspring) by the transmission disequilibrium test (TDT; G:A = 386:329, p = 0.033). However, because of linkage disequilibrium within OAS1 and with the other two OAS genes, functional attribution of the association to this SNP cannot be assumed. To help answer this question, we also genotyped two non-synonymous SNPs in OAS1 exons 3 and 7. RESULTS: All three SNPs showed significant transmission distortion. Three of the eight possible haplotypes accounted for 98.4% of parental chromosomes and two of them carried the non-predisposing A allele at rs10774671. Parents heterozygous for these two haplotypes showed significant transmission distortion (p = 0.009) despite being homozygous at rs10774671. CONCLUSIONS: We confirm the T1D association with rs10774671, but we conclude that it cannot be attributed (solely) to the splicing variant rs10774671. A serine/glycine substitution in OAS1 exon 3 is more likely a functional variant.


Assuntos
2',5'-Oligoadenilato Sintetase/genética , Diabetes Mellitus Tipo 1/genética , Haplótipos/genética , Família Multigênica/genética , Polimorfismo Genético/genética , Splicing de RNA/genética , Adolescente , Predisposição Genética para Doença , Humanos , Desequilíbrio de Ligação
4.
Res Microbiol ; 151(7): 563-74, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11037134

RESUMO

Escherichia coli O115:F165 strains are associated with septicaemia in young pigs and possess at least two types of fimbriae. F165(1) fimbriae belong to the P fimbrial family and F165(2) fimbriae belong to the S fimbrial family. Regulatory regions of foo (F165(1)) and fot (F165(2)) fimbrial gene clusters from wild-type strain 4787 were sequenced and characterised. Expression of F165(1) and F165(2) fimbrial genes was analysed by using lacZ and/or luxAB as reporter genes under the control of the native fimbrial promoters. Differential expression of fimbrial genes was observed. Global regulatory mechanisms such as catabolite repression, leucine-responsive regulatory protein (Lrp), methylation and DNA supercoiling were demonstrated to influence foo and fot expression. foo and fot expression was optimal at 37 degrees C and under aerobic conditions. Expression of foo was higher on minimal medium, whereas fot expression was higher on complex Luria-Bertani medium. This could reflect an in vivo differential expression.


Assuntos
Antígenos de Bactérias , Proteínas de Bactérias/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Proteínas de Fímbrias , Fímbrias Bacterianas/genética , Regulação Bacteriana da Expressão Gênica , Genes Reguladores , Sequência de Aminoácidos , Animais , Bacteriemia/microbiologia , Bacteriemia/veterinária , Proteínas de Bactérias/metabolismo , Sequência de Bases , DNA Super-Helicoidal , Escherichia coli/patogenicidade , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Genes Reporter , Dados de Sequência Molecular , Óperon , Regiões Promotoras Genéticas , Suínos , Doenças dos Suínos/microbiologia , Virulência
5.
Can J Microbiol ; 46(12): 1101-7, 2000 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11142399

RESUMO

Escherichia coli O115:F165 strains are associated with septicaemia in young pigs and synthesize fimbriae involved in virulence, designated as F165(1). F165(1) fimbriae belong to the P fimbrial family and are encoded by the foo gene cluster. The foo regulatory region of strain 5131 possesses characteristics similar to that of members of the P regulatory family, including papI and papB homologues, and two GATC sites separated by 102 bp, targets of differential Dam methylation. In wild-type strains, the synthesis of F165(1) is repressed by leucine and the fimbriae undergo phase variation. Immunofluorescence staining showed that phase variation of F165(1) results in a majority of cells (98%) in the ON phase, in contrast with phase variation of other members of this regulatory family, for which the majority of the cells are in the OFF state. Using a translational fusion in strain 5131 between phoA and fooA, encoding for the major structural subunit of F165(1), it was shown that leucine inhibits the OFF to ON switch and modulates the basal transcription of the foo operon.


Assuntos
Antígenos de Bactérias , Proteínas de Bactérias/biossíntese , Proteínas de Escherichia coli , Escherichia coli/genética , Escherichia coli/patogenicidade , Proteínas de Fímbrias , Fímbrias Bacterianas/metabolismo , Óperon , Sequências Reguladoras de Ácido Nucleico , Alanina/farmacologia , Animais , Bacteriemia/microbiologia , Bacteriemia/veterinária , Proteínas de Bactérias/genética , Sequência de Bases , Escherichia coli/fisiologia , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Regulação Bacteriana da Expressão Gênica , Leucina/farmacologia , Dados de Sequência Molecular , Fenótipo , Suínos , Doenças dos Suínos/microbiologia , Virulência
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