bio aging final common aging mech.txt

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bio aging final common aging mech.txt
2012-12-12 15:15:45
bio aging final common mechanism

bio aging final common aging mechanism
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  1. Pre-WWII Gerontology
    Weismann and Pearl thought single cause to aging: Weismann was disposable soma, Pearl was metabolic rate
  2. Post-WWII Gerontology
    • molecular basis for several theories
    • 1. Harman's: free radical theory - STOCHASTIC INTRAcellular
    • 2. Bjorksten's: Cros-linkage theory - STOCHASTIC, INterCELLULAR
    • 3. Hayflick: cell senescence theory - Systemic INTRAcellular
    • 4. Nathan Shock: integrative theory - Systemic, INterCELLULAR
  3. Rober Arking view
    multiple molecular events contribute to aging, none more than others
  4. Rajindar Sohal
    SIngle molecular event more important than others related to aging: Free radical production by mitochondria
  5. Qualitative model
    Describes HOW each level of complexity is integrated, but does NOT measure physiological values
  6. Quantitative model
    • Estimates rates of damage and repair, and simulates how altering these parameters affect mortality rates
    • such as Kirkwood's: free radical damage and antioxidant defenses
    • Show greater predictive value vs. qualitative: hypothesis is testable, and computer simulations including mitochondrial DNA damage rates are giving GOOD estimates of species lifespan
  7. Ultimate aging mechanism
    • must take evolutionary strategies into account
    • Will Hamilton: senescence is adaptive, if first senescent pop had lower mortality rates…nat. selection favored senescence in some instances
    • Peter Medawar: senescense is non-adaptive, mortality rates can't be distinguished b/w each other, so no nat. selection
    • George Williams: antagonistic pleiotropy model explains adaptive features of senescence early in life, then NON-adaptive features later
  8. Proximal mechanism of aging
    • offer immediate biochemical explanations for WHY aging occurs
    • 1. INcreasing damage rates: predictions of STOCHASTIC models
    • 2. DEcreasing repair rates: predictions of SYSTEMIC models
    • 3. STOCHASTIC can provide clues about SOURCES of age-related damage
    • 4. Systemic models useful for offering INTERVENTION strategies to keeping age-related damage to a minimum