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Objectives: LMNA mutations lead to a wide spectrum of disorders now called laminopathies. Due to large cohorts to investigate, mutational screening must be performed using an extremely sensitive and specific scanning method., Design and Methods: High Resolution Melting (HRM) analysis was developed for LMNA mutation detection. A cohort of 64 patients with dilated cardiomyopathy was prospectively screened using both HRM and DHPLC methodologies., Results: All gene variants detected by DHPLC or by direct sequencing were also readily identified as abnormal by HRM analysis. Mutations were identified in 7 patients (approximately 11%). Complete molecular LMNA investigation was completed two times faster and cheaper than using DHPLC strategy., Conclusions: HRM analysis represents an inexpensive, highly sensitive and high-throughput method to identify LMNA genetic variants. The discovery of novel LMNA mutations will provide new insights into the pathophysiology of dilated cardiomyopathy and in all other laminopathies.

Objectives: SCN5A mutations lead to a wide spectrum of cardiovascular disorders. Due to large cohorts to investigate and the large gene size, mutational screening must be performed using an extremely sensitive and specific scanning method., Design and Methods: High Resolution Melting (HRM) analysis was developed for SCN5A mutation detection using control DNAs and DNAs carrying previously identified gene variants. A cohort of 40 patients was further screened. To evaluate HRM sensitivity, this cohort was also screened using an optimized DHPLC methodology., Results: All gene variants detected by DHPLC were also readily identified as abnormal by HRM analysis. Mutations were identified for 5 patients. Complete molecular SCN5A investigation was completed two times faster and cheaper than using DHPLC strategy., Conclusions: HRM analysis represents an inexpensive, highly sensitive and high-throughput method to allow identification of SCN5A gene variants. Identification of more SCN5A mutations could provide new insights into the pathophysiology of SCN5A-linked diseases syndromes.

In addition to DNA damage, exposure to irradiation involves the plasma membrane in the early phases of gamma-ray-induced cell death. The involvement of raft microdomains following gamma-radiation derives essentially from the role of ceramide as a critical component leading to apoptosis. It is demonstrated here that gamma-irradiation of a radiosensitive human head and neck squamous carcinoma cell line (SCC61) results in the triggering of raft coalescence to larger membrane platforms associated with the externalization of an acid sphingomyelinase (A-SMase), leading to ceramide release in raft, 30 min postirradiation. For the first time, we show that this structural rearrangement is defective in the radioresistant SQ20B cells and associated with the lack of A-SMase activation and translocation, a result which could explain in part their resistance to apoptosis following ionizing radiation. Moreover, we show that SQ20B are protected against radiation injury through a fivefold upper level of endogenous glutathione compared to SCC61. Overcoming the endogenous antioxidant defenses of SQ20B through either H(2)O(2) treatment or GSH depletion triggers A-SMase activation and translocation, raft coalescence, and apoptosis. On the contrary, ROS scavengers abolished these events in radiosensitive SCC61 cells. Translation of this concept to tumor biology suggests that manipulation of rafts through redox equilibrium may provide opportunities for radiosensitization of tumor cells.