生科永新编译报导: 科学家知道在Alzheimer (AD) 患者 脑子中amyloid β (Aβ) 肽是淀粉样蛋白amyloid 的主要成分。Aβ 肽可能是有38 到43个氨基酸长, 其主要种类有40 或42个氨基酸，称为Aβ40或者 Aβ42。已有实验结果表明, Aβ42是引发AD的主要原因，但是, Aβ42与 淀粉样蛋白沉淀的必然关系 (absolute requirement) 从未在整体动物 (in-vivo) 身上被证明。不同于早先调控淀粉样蛋白前体蛋白的动物模型，McGowan 等 (Neuron, Vol 47, 191-199, 21 July 2005) 培养了专一表达Aβ40或者 Aβ42的老鼠，结果直接证明了Aβ42 确实是引起淀粉样蛋白沉淀的主要因素，而不是Aβ40。

For two decades scientists have known that the amyloid β (Aβ) peptide is the principal component of amyloid plaques found in Alzheimer’s disease (AD) brain. The Aβ peptide can be from 38 to 43 amino acids in length, with the predominant species being 40 or 42 amino acids. Considerablecircumstantial evidence suggests that Aβ42 is the initiating molecule in AD pathogenesis. However, the absolute requirement for Aβ42 for amyloid deposition has never been demonstrated in vivo. Unlike previous models in which overexpression of the amyloid precursor protein results in amyloid plaque formation, have produced mice that overexpress only Aβ40 or Aβ42 and prove that Aβ42 is critical for the formation of amyloid deposits in vivo.