The complexity of global change and its effects on insects.

Global change includes multiple overlapping and interacting drivers: 1) climate change, 2) land use change, 3) novel chemicals, and 4) the increased global transport of organisms. Recent studies have documented the complex and counterintuitive effects of these drivers on the behavior, life histories, distributions, and abundances of insects. This complexity arises from the indeterminacy of indirect, non-additive and combined effects. While there is wide consensus that global change is reorganizing communities, the available data are limited. As the pace of anthropogenic changes outstrips our ability to document its impacts, ongoing change may lead to increasingly unpredictable outcomes. This complexity and uncertainty argue for renewed efforts to address the fundamental drivers of global change

Fluoropolymer coated Dacron or polytetrafluoroethylene for femoropopliteal bypass grafting: a multicentre trial

This trial was designed to compare graft patency between expanded polytetrafluoroethylene (PTFE) and fluoro­polymer coated Dacron for femoropopliteal bypass in patients in whom saphenous vein was unavailable. Methods: A multicentre prospective trial randomized 129 patients (74 men, 55 women) who underwent femoropopliteal bypass using either a PTFE or fluoropolymer coated Dacron graft. The indication for operation was disabling claudication in 68 (52.7%) and critical limb ischaemia in 61 (47.3%) patients. Distal anastomosis was above the knee in 76 (58.9%) and below the knee in 53 (41.1%) patients. Results: Primary patency at 6, 12 and 24 months was 71%, 56% and 47% for PTFE and 50%, 36% and 36% for fluoropolymer coated Dacron (P = 0.002), respectively. Secondary patency at 6, 12 and 24 months was 77%, 60% and 48% for PTFE and 66%, 49% and 46% for fluoropolymer coated Dacron (P = 0.13), respectively. The superior primary patency of PTFE over fluoropolymer coated Dacron was most evident in patients with poor prognostic indicators for graft survival: critical limb ischaemia (P = 0.001); below-knee anastomosis (P = 0.01); and smaller (6 mm) diameter grafts (P = 0.002). Graft thrombosis developed in the first month in 22 of 61 (36%) patients receiving fluoropolymer coated grafts compared to six of 68 (8.8%) patients receiving PTFE, which accounts for the difference in primary patency. Successful thrombectomy in 10 of the 22 fluoropolymer coated grafts resulted in similar secondary patency. Conclusion: Polytetrafluoroethylene has superior primary patency and similar secondary patency to fluoropolymer coated Dacron. These results support the preferential use of PTFE in patients with critical limb ischaemia, especially when a below-knee distal anastomosis and smaller diameter graft is required.A. Richardson, P. Tomlinson, R. Bell, C. Fisher, M. Condous, R. Ventura, A. Scott, D. Stary, R. Allen, E. Lippey, M. Appleberg, A. Chao, R. Fitridge, G. Frydman, S. Hazelton, B. King, P. Middleton, P. Pai, I. Thomson, B. Beiles, A. Gray-Wheale and R. Lan