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According to FDA regulations, a combination drug is not efficacious unless each component contributes to the claimed effects. For a univariate endpoint, this implies that the combination at specific doses must be superior to each of its components at the same doses. More demanding is the property of synergy, in which the effect of the combination must be superior to the effect expected based on those of its components. If it is equal to those effects, it is additive, and if it is inferior, it is antagonistic. We give regions in the combination dose plane where these concepts are well defined. If the effect of the combination is greater than the greatest effect achievable by any of its components it is therapeutically synergistic. A combination can be antagonistic, yet its components can still contribute to the claimed effects. If it is additive, synergistic or therapeutically synergistic, its components must contribute to the claimed effects. We relate these concepts and provide designs and sequential procedures for determining whether a combination is therapeutically synergistic, synergistic, additive, antagonistic and contributing or antagonistic and non-contributing. 相似文献
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DI Timokhin AV Istomin TS Shushkova TG Voronel' IG Mikha?lov 《Canadian Metallurgical Quarterly》1997,(2):19-21
Based on generalization and analysis of instructions and guidelines for therapeutical and prophylactic diets of workers, ways of its optimization were proposed, by using bifide-containing acid dairy products as a preventive agent against possible occupational diseases caused by occupational factors. 相似文献
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SL Barker MJ McNicholas D Kader P Abdon T Adalberth D McGurty DI Rowley CM Walker 《Canadian Metallurgical Quarterly》1998,43(6):400-403
A cohort of 39 patients (28 male, 11 female) that had undergone total meniscectomy as adolescents (mean age 16 years) underwent FISP 3D Magnetic Resonance Imaging at a mean follow up of 30 years. The presence of meniscal tissue was assessed by two independent observers blinded to the operation details. The volume of any meniscal tissue present was calculated. A posterior horn remnant was seen in 57% of medial and 45% of lateral meniscectomy cases. The mean volume of an operated medial meniscal remnant was 0.29 mL compared with a mean volume of 1.15 mL for an intact medial meniscus. The mean volume of an operated lateral meniscal remnant was 0.30 mL compared with 1.07 mL for an intact lateral meniscus. We have shown that the incidence of incomplete excision of the posterior horn is more common after total medial meniscectomy, and that at a mean follow up of 30 years there is no convincing in vivo MRI evidence of long-term meniscal regeneration. 相似文献
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Arterial bypass grafting for occlusive disease is still considered the gold standard in the treatment of arterial occlusive disease. However, less invasive methods are available for select patients. Percutaneous balloon angioplasty has been shown to be effective in focal iliac artery stenosis, with patency rates of 50% to 90% at 5 years. Patency rates for femoropopliteal lesions are generally less than 50% at 2 years. Complications seen with balloon angioplasty often can be treated with arterial stents. Stents can be categorized into balloon-expandable, which provide a rigid scaffold to support the artery, self-expanding, which exert radial force to resist external compression, and thermal expanding stents, which allow for the use of a smaller introducer sheath. Another treatment option is atherectomy, in which the offending lesion is removed instead of fracturing and dilating the lumen. Although overall initial results of atherectomy have not been favorable, short lesions with eccentric atheroma or intimal hyperplasia, such as those seen in dialysis access fistulas or vein graft stenoses, may respond well. 相似文献