Humans 300 Male 300 Middle Aged human male adult 278 Female 264 female 260 Adult 224 article 224 controlled study 184 priority journal 168 aged 152 Aged 150 middle aged 150 major clinical study 106 clinical article 84 Adolescent 76 Argentina 66 adolescent 56 Article 54 Young Adult 44 human cell 40 human tissue 40 Child 38 Animals 36 Aged, 80 and over 34 child 34 physiology 34 genetics 32