Harman Denham
Department of Medicine, University of Nebraska College of Medicine, Nebraska Medical Center, Omaha, 68198-4635, USA.
Ann N Y Acad Sci. 2006 May;1067:10-21. doi: 10.1196/annals.1354.003.
Aging is the progressive accumulation of diverse, deleterious changes with time that increase the chance of disease and death. The basic chemical process underlying aging was first advanced by the free radical theory of aging (FRTA) in 1954: the reaction of active free radicals, normally produced in the organisms, with cellular constituents initiates the changes associated with aging. The involvement of free radicals in aging is related to their key role in the origin and evolution of life. Aging changes are commonly attributed to development, genetic defects, the environment, disease, and an inborn aging process (IAP). The latter produces aging changes at an exponentially increasing rate with age, becoming the major risk factor for disease and death for humans after the age of 28 years in the developed countries. In them the IAP limits human average life expectancy at birth (ALE-B)--a rough measure of the healthy life span--to about 85 years; few reach 100 years and only one is known to have lived to 122 years. In these countries, improvements in living conditions (ILC) have gradually raised ALE-Bs to 76-79 years, 6-9 years less than the limit imposed by aging, with no change in the maximum life span (MLS). The extensive studies based on the FRTA hold promise that ALE-B and the MLS can be extended, the ALE-B possibly by a few years, and the MLS somewhat less.
衰老指的是随着时间推移，各种有害变化不断累积，从而增加患病和死亡几率的过程。1954年，自由基衰老理论（FRTA）首次提出了衰老背后的基本化学过程：生物体中正常产生的活性自由基与细胞成分发生反应，引发与衰老相关的变化。自由基与衰老的关联与其在生命起源和进化中的关键作用有关。衰老变化通常归因于发育、遗传缺陷、环境、疾病以及内在衰老过程（IAP）。后者随着年龄增长以指数级速度产生衰老变化，在发达国家，它成为28岁之后人类患病和死亡的主要风险因素。在这些国家，IAP将人类出生时的平均预期寿命（ALE-B，这是衡量健康寿命的一个粗略指标）限制在约85岁；很少有人能活到100岁，已知只有一人活到了122岁。在这些国家，生活条件的改善（ILC）已逐渐将ALE-B提高到76至79岁，比衰老所设定的限制少6至9岁，而最长寿命（MLS）没有变化。基于FRTA的广泛研究表明，ALE-B和MLS有望得到延长，ALE-B可能延长数年，而MLS的延长幅度则稍小一些。
