Life extension
From Wikipedia, the free encyclopedia
Life extension science, also known as anti-aging medicine, experimental gerontology, and biomedical gerontology, is the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan. Some researchers in this area, and "life extensionists" or "longevists" (those who wish to achieve longer lives themselves), believe that future breakthroughs in tissue rejuvenation with stem cells, molecular repair, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans (agerasia[1]) through complete rejuvenation to a healthy youthful condition. |
| http://tinyurl.com/for-longer-life |
The sale of putative anti-aging products such as nutrition, physical fitness, skin care, hormone replacements, vitamins, supplements and herbs is a lucrative global industry, with the US market generating about $50 billion of revenue each year.[2] Medical experts state that the use of such products has not been shown
to affect the aging process, and many claims of anti-aging medicine advocates have been roundly criticized by medical experts, including the American Medical Association. However, it has not been shown that the goal of indefinite human lifespans itself is necessarily unfeasible; some animals such as lobsters and certain jellyfish do not die of old age, and an award was offered to anyone who could prove life extensionist Aubrey de Grey's hopes were 'unworthy of learned debate'; nobody won the prize.[7] Bioethicists question the ethical ramifications of life extension.
Average and maximum lifespans
Main article: Senescence
Average lifespan in a population is lowered by infant and child mortality, which are frequently linked to infectious diseases or nutrition problems. Later in life, vulnerability to accidents and age-related chronic disease such as cancer or cardiovascular disease play an increasing role in mortality. Extension of expected lifespan can often be achieved by access to improved medical care, vaccinations, good diet, exercise and avoidance of hazards such as smoking.
Maximum lifespan is determined by the rate of aging for a species inherent in its genes and by environmental factors. One widely recognized method of extending maximum lifespan in organisms such as nematodes is calorie restriction. Another technique used evolutionary pressure such as breeding from only older members.
Theoretically, extension of maximum lifespan could be achieved by reducing the rate of aging damage, by periodic replacement of damaged tissues, or by molecular repair or rejuvenation of deteriorated cells and tissues and the enhancement of telomerase enzyme activity. Future research will be geared towards telomere repair strategies.
Current anti-aging strategies and issues
See also: Ageing#Prevention and reversal
Diets and supplements
Much life extension research focuses on nutrition—diets or supplements—as a means to extend lifespan, although few of these have been systematically tested for significant longevity effects. The many diets promoted by anti-aging advocates are often contradictory. A dietary pattern with some support from scientific research is caloric restriction.[8]The free-radical theory of aging suggests that antioxidant supplements, such as Vitamin C, Vitamin E, Q10, lipoic acid, carnosine, and N-acetylcysteine, might extend human life. However, combined evidence from several clinical trials suggest that β-Carotene supplements and high doses of Vitamin E increase mortality rates.[10] Other substances proposed to extend lifespan include oxytocin, insulin, human chorionic gonadotropin (hCG), and erythropoietin (EPO). Resveratrol is a sirtuin stimulant that appears to extend lifespan in simple organisms such as nematodes[11] and short-lived fish.[12]
Some supplements, including the minerals selenium[13] or zinc[14] have been reported to extend the lifespan of rats and mice, though none have been proven to do so in humans, and significant toxic effects were observed. Metformin[16] may also extend life span in mice. Interestingly there is a tea called Jiaogulan that has been dubbed "China's Immortality Herb".
Hormone treatments
The anti-aging industry offers several hormone therapies. Some of these have been criticized for possible dangers to the patient and a lack of proven effect. For example, the American Medical Association has been critical of some anti-aging hormone therapies.Even if some recent clinical studies have shown that low-dose GH treatment for adults with GH deficiency changes the body composition by increasing muscle mass, decreasing fat mass, increasing bone density and muscle strength, improves cardiovascular parameters (i.e. decrease of LDL cholesterol), and affects the quality of life without significant side effects.[17] The evidence for use of growth hormone as an anti-aging therapy is mixed and based on animal studies. An early study suggested that supplementation of mice with growth hormone increased average life expectancy.[20] Additional animal experiments have suggested that growth hormone may generally act to shorten maximum lifespan; knockout mice lacking the receptor for growth hormone live especially long.[21] Furthermore, mouse models lacking the insulin-like growth factor also live especially long and have low levels of growth hormone.[21]]
Insulinlike growth factor (IGF-1) restriction
People suffering from rare condition known as Laron syndrome have mutation in the gene that makes the receptor for growth hormone. Its theorised that that mutation may hold a key to life extension.Dr. Longo said that some level of IGF-1 was necessary to protect against heart disease, but that lowering the level might be beneficial. A drug that does this is already on the market for treatment of acromegaly, a thickening of the bones caused by excessive growth hormone. “Our underlying hypothesis is that this drug would prolong life span,” Dr. Longo said. He said he was not taking the drug, called pegvisomant or Somavert, which is very hard to obtain.
Consumer motivations for using anti-aging products
Research by Sobh and Martin (2011) suggests that people buy anti-aging products to obtain a hoped-for self (e.g., keeping a youthful skin) or to avoid a feared-self (e.g., looking old). The research shows that when consumers pursue a hoped-for self, it is expectations of success that most strongly drive their motivation to use the product. The research also shows why doing badly when trying to avoid a feared self is more motivating than doing well. Interestingly, when product use is seen to fail it is more motivating than success when consumers seek to avoid a feared-self.[22]Proposed strategies of life extension
Nanotechnology
Future advances in nanomedicine could give rise to life extension through the repair of many processes thought to be responsible for aging. K. Eric Drexler, one of the founders of nanotechnology, postulated cell repair machines, including ones operating within cells and utilizing as yet hypothetical molecular computers, in his 1986 book Engines of Creation. Raymond Kurzweil, a futurist and transhumanist, stated in his book The Singularity Is Near that he believes that advanced medical nanorobotics could completely remedy the effects of aging by 2030.[23]Cloning and body part replacement
Some life extensionists suggest that therapeutic cloning and stem cell research could one day provide a way to generate cells, body parts, or even entire bodies (generally referred to as reproductive cloning) that would be genetically identical to a prospective patient. Recently, the US Department of Defense initiated a program to research the possibility of growing human body parts on mice.[24] Complex biological structures, such as mammalian joints and limbs, have not yet been replicated. Dog and primate brain transplantation experiments were conducted in the mid-20th century but failed due to rejection and the inability to restore nerve connections. As of 2006, the implantation of bio-engineered bladders grown from patients' own cells has proven to be a viable treatment for bladder disease.[25] Proponents of body part replacement and cloning contend that the required biotechnologies are likely to appear earlier than other life-extension technologies.The use of human stem cells, particularly embryonic stem cells, is controversial. Opponents' objections generally are based on interpretations of religious teachings or ethical considerations. Proponents of stem cell research point out that cells are routinely formed and destroyed in a variety of contexts. Use of stem cells taken from the umbilical cord or parts of the adult body may not provoke controversy.[26]
The controversies over cloning are similar, except general public opinion in most countries stands in opposition to reproductive cloning. Some proponents of therapeutic cloning predict the production of whole bodies, lacking consciousness, for eventual brain transplantation.
Cryonics
Main article: Cryonics
Many cryonicists do not believe that legal death is "real death" because stoppage of heartbeat and breathing—the usual medical criteria for legal death—occur before biological death of cells and tissues of the body. Even at room temperature, cells may take hours to die and days to decompose. Although neurological damage occurs within 4–6 minutes of cardiac arrest, the irreversible neurodegenerative processes do not manifest for hours.[27] Cryonicists state that rapid cooling and cardio-pulmonary support applied immediately after certification of death can preserve cells and tissues for long-term preservation at cryogenic temperatures. People, particularly children, have survived up to an hour without heartbeat after submersion in ice water. In one case, full recovery was reported after 45 minutes underwater.[28] To facilitate rapid preservation of cells and tissue, cryonics "standby teams" are available to wait by the bedside of patients who are to be cryopreserved to apply cooling and cardio-pulmonary support as soon as possible after declaration of death.[29]
No mammal has been successfully cryopreserved and brought back to life, and resuscitation from cryonics is not possible with current science. Some scientists still support the idea based on their expectations of the capabilities of future science.[30]
Strategies for Engineered Negligible Senescence (SENS)
Main article: Strategies for Engineered Negligible Senescence
Genetic modification
Gene therapy, in which artificial genes are integrated with an organism to replace mutated or otherwise deficient genes, has been proposed as a future strategy to prevent aging.[33]Targeting catalase to the mitochondria resulted in a 20% lifespan increase in transgenic mice, and improved performance in AAV therapeutically infected mice.[35]Fooling genes
In The Selfish Gene, Richard Dawkins describes an approach to life-extension that involves "fooling genes" into thinking the body is young.[36] Dawkins attributes inspiration for this idea to Peter Medawar. The basic idea is that our bodies are composed of genes that activate throughout our lifetimes, some when we are young, and others when we are older. Presumably, these genes are activated by environmental factors, and the changes caused by these genes activating can be lethal. It is a statistical certainty that we possess more lethal genes that activate in later life than in early life. Therefore, to extend life, we should be able to prevent these genes from switching on, and we should be able to do so by "identifying changes in the internal chemical environment of a body that take place during aging... and by simulating the superficial chemical properties of a young body".[37]History of life extension and the life extension movement
In 1970, the American Aging Association was formed under the impetus of Denham Harman, originator of the free radical theory of aging. Harman wanted an organization of biogerontologists that was devoted to research and to the sharing of information among scientists interested in extending human lifespan.In 1976, futurists Joel Kurtzman and Philip Gordon wrote No More Dying. The Conquest Of Aging And The Extension Of Human Life, (ISBN 0-440-36247-4) the first popular book on research to extend human lifespan. Subsequently, Kurtzman was invited to testify before the House Select Committee on Aging, chaired by Claude Pepper of Florida, to discuss the impact of life extension on the Social Security system.
Saul Kent published The Life Extension Revolution (ISBN 0-688-03580-9) in 1980 and created a nutraceutical firm called the Life Extension Foundation, a non-profit organization that promotes dietary supplements. The Life Extension Foundation publishes a periodical called Life Extension Magazine. The 1982 bestselling book Life Extension: A Practical Scientific Approach (ISBN 0-446-51229-X) by Durk Pearson and Sandy Shaw further popularized the phrase "life extension".
In 1983, Roy Walford, a life-extensionist and gerontologist, published a popular book called Maximum Lifespan. In 1988, Walford and his student Richard Weindruch summarized their research into the ability of calorie restriction to extend the lifespan of rodents in The Retardation of Aging and Disease by Dietary Restriction (ISBN 0-398-05496-7). It had been known since the work of Clive McCay in the 1930s that calorie restriction can extend the maximum lifespan of rodents. But it was the work of Walford and Weindruch that gave detailed scientific grounding to that knowledge.
Walford's personal interest in life extension motivated his scientific work and he practiced calorie restriction himself. Walford died at the age of 80 from complications caused by amyotrophic lateral sclerosis.
Money generated by the non-profit Life Extension Foundation allowed Saul Kent to finance the Alcor Life Extension Foundation, the world's largest cryonics organization. The cryonics movement had been launched in 1962 by Robert Ettinger's book, The Prospect of Immortality. In the 1960s, Saul Kent had been a co-founder of the Cryonics Society of New York. Alcor gained national prominence when baseball star Ted Williams was cryonically preserved by Alcor in 2002 and a family dispute arose as to whether Williams had really wanted to be cryopreserved.
Regulatory and legal struggles between the Food and Drug Administration (FDA) and the Life Extension Foundation included seizure of merchandise and court action. In 1991, Saul Kent and Bill Faloon, the principals of the Foundation, were jailed. The LEF accused the FDA of perpetrating a "Holocaust" and "seeking gestapo-like power" through its regulation of drugs and marketing claims.[38]
In 1992, the American Academy of Anti-Aging Medicine (A4M) was formed to create what it considered an anti-aging medical specialty distinct from geriatrics, and to hold trade shows for physicians interested in anti-aging medicine. The American Board of Medical Specialties recognizes neither anti-aging medicine nor the A4M's professional standing.[39]
Aging as a disease
Most mainstream medical organizations and practitioners do not consider aging to be a disease. David Sinclair says: "I don't see aging as a disease, but as a collection of quite predictable diseases caused by the deterioration of the body".[48] The two main arguments used are that aging is both inevitable and universal while diseases are not.[49] However not everyone agrees. Harry R. Moody, Director of Academic Affairs for AARP, notes that what is normal and what is disease strongly depends on a historical context.[50] David Gems, Assistant Director of the Institute of Healthy Ageing, strongly argues that aging should be viewed as a disease.[51] In response to the universality of aging, David Gems notes that it is as misleading as arguing that Basenji are not dogs because they do not bark.[52] Because of the universality of aging he calls it a 'special sort of disease'. Robert M. Perlman, coined the terms ‘aging syndrome’ and ‘disease complex’ in 1954 to describe aging.[53]The discussion whether aging should be viewed as a disease or not has important implications. It would stimulate pharmaceutical companies to develop life extension therapies and in the United States of America, it would also increase the regulation of the anti-aging market by the FDA. Anti-aging now falls under the regulations for cosmetic medicine which are less tight than those for drugs.[52]
source : http://en.wikipedia.org/wiki/Life_extension
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