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Chen J, Astle CM, Harrison DE.Chen J, et al.J Gerontol A Biol Sci Med Sci. 1998 Sep;53(5):B330-7; discussion B338-9. doi: 10.1093/gerona/53a.5.b330.J Gerontol A Biol Sci Med Sci. 1998.PMID: 9754130