ABSTRACT
Aneurysmal degeneration after peripheral angioplasty is a potentially serious complication. In this case, the patient underwent repeated angioplasty of a prior vein bypass graft utilizing a paclitaxel-coated balloon. He subsequently developed a progressive aneurysmal degeneration, threatening his bypass, which ultimately required an urgent exclusion with a covered stent. This case represents a rare complication of peripheral bypass graft related to percutaneous intervention as well as paclitaxel-coated devices and warns other practitioners of the increased scrutiny and caution one should exercise in the use of such interventions.
Subject(s)
Aneurysm/etiology , Angioplasty, Balloon/adverse effects , Angioplasty, Balloon/instrumentation , Cardiovascular Agents/administration & dosage , Coated Materials, Biocompatible , Graft Occlusion, Vascular/therapy , Paclitaxel/administration & dosage , Vascular Access Devices , Aged , Aneurysm/diagnostic imaging , Aneurysm/therapy , Graft Occlusion, Vascular/diagnostic imaging , Graft Occlusion, Vascular/etiology , Humans , Male , Peripheral Arterial Disease/diagnostic imaging , Peripheral Arterial Disease/surgery , Treatment Outcome , Vascular Grafting/adverse effectsABSTRACT
Mammalian antibody switch regions (â¼1500 bp) are composed of a series of closely neighboring G4-capable sequences. Whereas numerous structural and genome-wide analyses of roles for minimal G4s in transcriptional regulation have been reported, Long G4-capable regions (LG4s)-like those at antibody switch regions-remain virtually unexplored. Using a novel computational approach we have identified 301 LG4s in the human genome and find LG4s prone to mutation and significantly associated with chromosomal rearrangements in malignancy. Strikingly, 217 LG4s overlap annotated enhancers, and we find the promoters regulated by these enhancers markedly enriched in G4-capable sequences suggesting G4s facilitate promoter-enhancer interactions. Finally, and much to our surprise, we also find single-stranded loops of minimal G4s within individual LG4 loci are frequently highly complementary to one another with 178 LG4 loci averaging >35 internal loop:loop complements of >8 bp. As such, we hypothesized (then experimentally confirmed) that G4 loops within individual LG4 loci directly basepair with one another (similar to characterized stem-loop kissing interactions) forming a hitherto undescribed, higher-order, G4-based secondary structure we term a 'G4 Kiss or G4K'. In conclusion, LG4s adopt novel, higher-order, composite G4 structures directly contributing to the inherent instability, regulatory capacity, and maintenance of these conspicuous genomic regions.
