RESUMEN
Massive hemorrhage from arterial access in patients receiving anticoagulation and antiplatelet therapy is a rare but potentially devastating complication. The authors present a patient who developed a large retroperitoneal and anterior abdominal wall hemorrhage following an unintentional and unrecognized arterial injury during an endovascular procedure. Reversal of anticoagulation in patients who have undergone stent-assisted coil embolization of intracranial aneurysms is an undesirable approach due to the risk of thromboembolism; rather, transcatheter embolization of the bleeding source should be considered.
RESUMEN
The Candida albicans ALS (agglutinin-like sequence) gene family encodes eight cell-surface glycoproteins, some of which function in adhesion to host surfaces. ALS genes have a central tandem repeat-encoding domain comprised entirely of head-to-tail copies of a conserved 108-bp sequence. The number of copies of the tandemly repeated sequence varies between C. albicans strains and often between alleles within the same strain. Because ALS alleles can encode different-sized proteins that may have different functional characteristics, defining the range of allelic variability is important. Genomic DNA from C. albicans strains representing the major genetic clades was PCR amplified to determine the number of tandemly repeated sequence copies within the ALS5 and ALS6 central domain. ALS5 alleles had 2-10 tandem repeat sequence copies (mean=4.82 copies) while ALS6 alleles had 2-8 copies (mean=4.00 copies). Despite this variability, tandem repeat copy number was stable in C. albicans strains passaged for 3000 generations. Prevalent alleles and allelic distributions varied among the clades for ALS5 and ALS6. Overall, ALS6 exhibited less variability than ALS5. ALS5 deletions can occur naturally in C. albicans via direct repeats flanking the ALS5 locus. Deletion of both ALS5 alleles was associated particularly with clades III and SA. ALS5 exhibited allelic polymorphisms in the coding region 5' of the tandem repeats; some alleles resembled ALS1, suggesting recombination between these contiguous loci. Natural deletion of ALS5 and the sequence variation within its coding region suggest relaxed selective pressure on this locus, and that Als5p function may be dispensable in C. albicans or redundant within the Als family.
Asunto(s)
Candida albicans/genética , Moléculas de Adhesión Celular/genética , Proteínas Fúngicas/genética , Glicoproteínas de Membrana/genética , Alelos , Secuencia de Bases , Southern Blotting , Candida albicans/crecimiento & desarrollo , ADN de Hongos/química , ADN de Hongos/genética , Europa (Continente) , Eliminación de Gen , Dosificación de Gen , Frecuencia de los Genes , Variación Genética , Genoma Fúngico , Geografía , Datos de Secuencia Molecular , América del Norte , Análisis de Secuencia de ADN , Sudáfrica , América del Sur , Especificidad de la Especie , Secuencias Repetidas en TándemRESUMEN
Candida albicans strain SC5314 contains two ALS3 alleles, which differ in sequence with respect to the number of copies of the 108 bp tandem repeat sequence within the central domain of the coding region. One allele (ALS3(12)) has 12 tandem repeat copies while the other (ALS3(9)) has 9 copies. Wild-type C. albicans (ALS3(12)/ALS3(9)) and those containing various ALS3 alleles (ALS3(12)/als3Delta(9), als3Delta(12)/ALS3(9) and als3Delta(12)/als3Delta(9)) were assayed for adhesion to monolayers of cultured vascular endothelial and pharyngeal epithelial cells. These assays showed obvious adhesive function for the larger Als3p protein, compared to a minor contribution to adhesion from the smaller protein. These functional differences in strain SC5314 prompted examination of ALS3 allelic diversity across the five major genetic clades of C. albicans. This analysis focused on the number of copies of the tandem repeat sequence within the central domain of the coding region and showed a range of alleles encoding from 6 to 19 tandem repeat copies. Clades differed with respect to prevalent ALS3 alleles and allele distribution, but were similar for the mean number of tandem repeat copies per ALS3 allele. Analysis of allelic pairing showed clade differences and the tendency for C. albicans strains to encode one longer and one shorter ALS3 allele. The allelic variability observed for ALS3 and its functional consequences observed in strain SC5314 highlight the importance of understanding ALS allelic diversity in order to draw accurate conclusions about Als protein function.