The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
The question of whether aging - the process that converts fit adults into frailer adults with a progressively increased risk of illness, injury, and death - is under genetic control is ambiguous, and its answer depends on what one means by aging. Natural selection can select for genes that retard aging, but only in species and niches where the value of prolonged survival outweighs its costs. Although the form aging takes can be affected by variations at many genetic loci the number of loci that moderate the pace of synchronized decay may be far smaller.
A review of biochemical mechanisms underlying the known approaches to extension of lifespan and/or slowing down of ageing suggests that they all modify balances between generation of active oxygen and carbonyl species and the mechanisms that protect from their damaging effects or repair their consequences. A likely common target of the geroprotector effects of antioxidants, melatonin, and antidiabetic biguanides is the mitochondrial respiratory chain.
We hypothesize that many ailments are attributable to dysfunctions of autonomic balance. The autonomic system is a primitive, highly-adaptive response system that allows differential allocation of biologic effort under varying conditions. The autonomic system, however, can execute a response that is inappropriate for the system stressor due to evolutionary displacement. Evolutionary displacement is a situation in which a trait that evolved as an adaptive response to certain conditions now faces a new set of conditions.
Dramatically extending the human lifespan seems increasingly possible. Many bioethicists object that life-extension will have Malthusian consequences as new Methuselahs accumulate, generation by generation. I argue for a Life-Years Response to the Malthusian Objection. If even a minority of each generation chooses life-extension, denying it to them deprives them of many years of extra life, and their total extra life-years are likely to exceed the total life-years of a majority who do not want life-extension.
The search for effective treatments that prevent oxidative stress associated with premature ageing and neurodegenerative diseases is an important area of neurochemical research. As age- and disease-related oxidative stress is frequently associated with mitochondrial dysfunction, amphiphilic antioxidant agents of high stability and selectivity that target these organelles can provide on-site protection.
Many opinions and ideas about aging exist. Biological theories have taken hold of the popular and scientific imagination as potential answers to a "cure" for aging. However, it is not clear what exactly is being cured or whether aging could be classified as a disease. Some scientists are convinced that aging will be biologically alterable and that the human lifespan will be vastly extendable.
International Journal of Radiation Oncology, Biology, Physics
PURPOSE: We investigated the effects of fractionated radiation treatments on the life spans of athymic rats bearing intracerebral brain tumors. METHODS AND MATERIALS: U-251 MG or U-87 MG human glioblastoma cells were implanted into the brains of athymic rats, and the resulting tumors were irradiated once daily with various doses of ionizing radiation for 5 consecutive days or for 10 days with a 2-day break after Day 5. RESULTS: Five daily doses of 1 and 1.5 Gy, and 10 doses of 0.75 and 1 Gy, cured some U-251 MG tumors.
Recent studies confirm that dietary methionine restriction increases both mean and maximal lifespan in rats and mice, achieving "aging retardant" effects very similar to those of caloric restriction, including a suppression of mitochondrial superoxide generation. Although voluntary caloric restriction is never likely to gain much popularity as a pro-longevity strategy for humans, it may be more feasible to achieve moderate methionine restriction, in light of the fact that vegan diets tend to be relatively low in this amino acid.
Some researchers in the field of ageing claim that significant extension of the human lifespan will be possible in the near future. While many of these researchers have assumed that the community will welcome this technology, there has been very little research on community attitudes to life extension. This paper presents the results of an in-depth qualitative study of community attitudes to life extension across age groups and religious boundaries.
Autophagy, which is a process of self eating, has gained interest in the past decade due to its both beneficial and controversial roles in various biological phenomena. The discovery of autophagy genes (ATG) in yeast has led to focused research designed to elucidate the mechanism and regulation of this process. The role of autophagy in a variety of biological phenomena, including human disease, is still the subject of debate. However, recent findings suggest that autophagy is a highly regulated process with both beneficial and negative effects.