A 530kb YAC contig tightly linked to the Friedreich ataxia locus contains five CpG clusters and a new highly polymorphic microsatellite

Friedreich ataxia (FA) is a severe autosomal recessive neurodegenerative disease. The defective gene has been previously assigned to chromosome 9q13-q21 by demonstration of tight linkage to the two independent loci D9S15 and D9S5. Linkage data indicate that FRDA is at less than 1 c M from both markers. Previous physical mapping has shown that probes defining D9S15 (MCT112) and D9S5 (26P) are less than 260kb apart and are surrounded by at least six CpG clusters within 450 kb, which might indicate the presence of “candidate” genes for FA. We isolated and characterized a 530 kb YAC (yeast artificial chromosome) contig that contains five of the CpG clusters. The YACs were used to search for new polymorphic markers needed to map FRDA precisely with respect to the cloned segment. In particular, we found a (CA) n microsatellite polymorphism, GS4, that detects 13 alleles with a PIC value of 0.83 and allows the definition of haplotypes extending over 310kb when used in combination with polymorphic markers at D9S5 and D9S15.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47632/1/439_2004_Article_BF00219179.pd

Origin and quantification of circulating DNA in mice with human colorectal cancer xenografts

Although circulating DNA (ctDNA) could be an attractive tool for early cancer detection, diagnosis, prognosis, monitoring or prediction of response to therapies, knowledge on its origin, form and rate of release is poor and often contradictory. Here, we describe an experimental system to systematically examine these aspects. Nude mice were xenografted with human HT29 or SW620 colorectal carcinoma (CRC) cells and ctDNA was analyzed by Q–PCR with highly specific and sensitive primer sets at different times post-graft. We could discriminate ctDNA from normal (murine) cells and from mutated and non-mutated tumor (human) cells by using species-specific KRAS or PSAT1 primers and by assessing the presence of the BRAF V600E mutation. The concentration of human (mutated and non-mutated) ctDNA increased significantly with tumor growth. Conversely, and differently from previous studies, low, constant level of mouse ctDNA was observed, thus facilitating the study of mutated and non-mutated tumor derived ctDNA. Finally, analysis of ctDNA fragmentation confirmed the predominance of low-size fragments among tumor ctDNA from mice with bigger tumors. Higher ctDNA fragmentation was also observed in plasma samples from three metastatic CRC patients in comparison to healthy individuals. Our data confirm the predominance of mononucleosome-derived fragments in plasma from xenografted animals and, as a consequence, of apoptosis as a source of ctDNA, in particular for tumor-derived ctDNA. Altogether, our results suggest that ctDNA features vary during CRC tumor development and our experimental system might be a useful tool to follow such variations

A worldwide survey on incidence, management and prognosis of oesophageal fistula formation following atrial fibrillation catheter ablation: The POTTER-AF study.

AIMS Oesophageal fistula represents a rare but dreadful complication of atrial fibrillation catheter ablation. Data on its incidence, management and outcome are sparse. METHODS AND RESULTS This international multicenter registry investigates the characteristics of oesophageal fistulae after treatment of atrial fibrillation by catheter ablation. A total of 553,729 catheter ablation procedures (radiofrequency: 62.9%, cryoballoon: 36.2%, other modalities: 0.9%) were performed at 214 centers in 35 countries. In 78 centers 138 patients (0.025%, radiofrequency: 0.038%, cryoballoon: 0.0015% (p<0.0001)) were diagnosed with an oesophageal fistula. Periprocedural data were available for 118 patients (85.5%). Following catheter ablation, the median time to symptoms and the median time to diagnosis were 18 (7.75, 25; range: 0-60) days and 21 (15, 29.5; range: 2-63) days, respectively. The median time from symptom onset to oesophageal fistula diagnosis was 3 (1, 9; range: 0-42) days. The most common initial symptom was fever (59.3%). The diagnosis was established by chest computed tomography in 80.2% of patients. Oesophageal surgery was performed in 47.4% and direct endoscopic treatment in 19.8%, and conservative treatment in 32.8% of patients. The overall mortality was 65.8%. Mortality following surgical (51.9%) or endoscopic treatment (56.5%) was significantly lower as compared to conservative management (89.5%) (odds ratio 7.463 (2.414, 23.072) p<0.001). CONCLUSIONS Oesophageal fistula after catheter ablation of atrial fibrillation is rare and occurs mostly with the use of radiofrequency energy rather than cryoenergy. Mortality without surgical or endoscopic intervention is exceedingly high

Hemodynamical consequences and tolerance of sustained ventricular tachycardia.

AimsFactors underlying clinical tolerance and hemodynamic consequences of monomorphic sustained ventricular tachycardia (VT) need to be clarified.MethodsIntra-arterial pressures (IAP) during VT were collected in patients admitted for VT ablation and correlated to clinical, ECG and baseline echocardiographical parameters.Results114 VTs from 58 patients were included (median 67 years old, 81% ischemic heart disease, median left ventricular ejection fraction 30%). 61 VTs were untolerated needing immediate termination (54%). VT tolerance was tightly linked to the evolution of IAPs. Faster VT rates (pConclusionThis study helps to explain the large variability in clinical tolerance during VT, which is clearly related to IAP. VT tolerance may be linked to resynchronization therapy, VT rate, baseline QRS duration and location of myocardial infarction