RESUMEN
OBJECTIVES: Data concerning an association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and ischemic stroke (IS) remain inconsistent. Results of some studies suggest that DD genotype may be a risk factor for small vessel disease (SVD) stroke. Here, we investigated whether this polymorphism is associated with IS of different etiologies in a Polish population. SUBJECTS AND METHODS: Ischemic stroke etiology was established according to the TOAST criteria. We studied 92 stroke patients with large vessel disease and their 184 matched controls; 96 stroke patients with SVD and 192 controls; 180 patients with cardioembolic stroke (CE) and 180 controls. ACE I/D polymorphism was determined using the polymerase chain reaction method. RESULTS: The distribution of ACE genotypes and alleles was essentially the same in all analyzed IS subtypes and their matched controls. CONCLUSIONS: We failed to find an association between ACE polymorphism and etiological subtypes of IS in a Polish population.
Asunto(s)
Isquemia Encefálica/enzimología , Isquemia Encefálica/genética , Peptidil-Dipeptidasa A/genética , Polimorfismo Genético/genética , Accidente Cerebrovascular/enzimología , Accidente Cerebrovascular/genética , Anciano , Isquemia Encefálica/fisiopatología , Análisis Mutacional de ADN , Femenino , Eliminación de Gen , Frecuencia de los Genes , Marcadores Genéticos/genética , Predisposición Genética a la Enfermedad/genética , Pruebas Genéticas , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Mutación/genética , Polonia , Accidente Cerebrovascular/fisiopatologíaRESUMEN
Genomic scans of clones isolated from long-term stab cultures of Escherichia coli K-12 showed the loss of two large segments of the genome, with each lost segment being approximately 20 kb long. A detailed analysis of one of the deletions, located between 5.4 and 5.9 min, revealed that similar deletions had arisen in several other stab cultures. All deletions of this type exhibited a right terminus ending precisely at an IS5A element and a left terminus that varied over an approximately 5-kb range but was bordered in all but two cases by sequences belonging to the preferred consensus target sequence for IS5, YTAR. The ubiquity of such deletions in independent stab cultures and the increase in their frequency over time argue that they have a selective advantage. It is speculated that the loss of the crl locus is responsible for the selective advantage of the deletions.
Asunto(s)
Escherichia coli/genética , Elementos Transponibles de ADN , Escherichia coli/crecimiento & desarrollo , Reordenamiento Génico , Genoma Bacteriano , Hibridación de Ácido NucleicoRESUMEN
Estimates of the rate and frequency distribution of deleterious effects were obtained for the first time by direct scoring and characterization of individual mutations. This was achieved by applying tetrad analysis to a large number of yeast clones. The genomic rate of spontaneous mutation deleterious to a basic fitness-related trait, that of growth rate, was U = 1.1 x 10(-3) per diploid cell division. Extrapolated to the fruit fly and humans, the per generation rate would be 0.074 and 0.92, respectively. This is likely to be an underestimate because single mutations with selection coefficients s < 0.01 could not be detected. The distribution of s > or = 0.01 was studied both for spontaneous and induced mutations. The latter were induced by ethyl methanesulfonate (EMS) or resulted from defective mismatch repair. Lethal changes accounted for approximately 30-40% of the scored mutations. The mean s of nonlethal mutations was fairly high, but most frequently its value was between 0.01 and 0.05. Although the rate and distribution of very small effects could not be determined, the joint share of such mutations in decreasing average fitness was probably no larger than approximately 1%.
