Echocardiographic assessment and percutaneous closure of multiple atrial septal defects

Percutaneous coronary intervention can be associated with distal embolization of thrombotic material causing myocardial necrosis and infarction. We discuss the role of intravascular imaging to guide the use of a distal protection device by describing the outcome of a young woman presenting with non-ST elevation myocardial infarction. Coronary angiography demonstrated an isolated minor stenosis in the proximal left anterior descending coronary artery with slight haziness beyond the lesion. Intravascular ultrasound confirmed an extensive thrombus overlying a bulky atherosclerotic plaque. A distal filter wire was therefore successfully used to reduce the risk of distal embolization. The use of intravascular ultrasound in patients presenting with acute coronary syndrome may reveal large thrombi that are difficult to image using conventional angiographic techniques. Intravascular ultrasound can therefore be used as a tool to select lesions requiring distal protection.     

Linkage mapping of the spinal muscular atrophy gene

Spinal muscular atrophy (SMA) is a common autosomal recessive disorder resulting in loss of motor neurons. We have performed linkage analysis on a panel of families using nine markers that are closely linked to the SMA gene. The highest lod score was obtained with the marker D5S351 (Z_max = 10.04 at = 0 excluding two unlinked families, and Z_max = 8.77 at = 0.007 with all families). One type III family did not show linkage to the 5q13 markers, and in one type I consanguineous family the affected individual did not show homozygosity except for the marker D5S435. Three recombinants were identified with the closest centromeric marker, D5S435, which position the gene telomeric of this marker. These recombinants will facilitate finer mapping of the location of the SMA gene. Lastly, two families provide strong evidence for a remarkable variability in presentation of the SMA phenotype, with the age at onset in one family varying from 17 months to 13 years.     

Sequence variations in small-subunit ribosomal RNAs of Hartmannella vermiformis and their phylogenetic implications

Evidence of associations between free-living amoebas and human disease has been increasing in recent years. Knowledge about phylogenetic relationships that may be important for the understanding of pathogenicity in the genera involved is very limited at present. Consequently, we have begun to study these relationships and report here on the phylogeny of Hartmannella vermiformis, a free-living amoeba that can harbor the etiologic agent of Legionnaires' disease. Our analysis is based on studies of small-subunit ribosomal RNA genes (srDNA). Nucleotide sequences were determined for nuclear srDNA from three strains of H. vermiformis isolated from the United Kingdom, Germany, and the United States. These sequences then were compared with a sequence previously obtained for a North American isolate by J. H. Gunderson and M. L. Sogin. The four genes are 1,840 bp long, with an average GC content of 49.6%. Sequence differences among the strains range are 0.38%-0.76%. Variation occurs at 19 positions and includes 2 single-base indels plus 14 monotypic and 3 ditypic single-base substitutions. Variation is limited to eight helix/loop structures according to a current model for srRNA secondary structure. Parsimony, distance, and bootstrap analyses used to examine phylogenetic relationships between the srDNA sequences of H. vermiformis and other eukaryotes indicated that Hartmannella sequences were most closely related to those of Acanthamoeba and the alga Cryptomonas. All ditypic sites were consistent with a separation between European and North American strains of Hartmannella, but results of other tests of this relationship were statistically inconclusive.