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 |  Subject: Buying time  Wed Jul 17, 2013 11:58 pm | |
| Is ageing a process that we simply have to accept as a fact of life?
A philosopher would say yes. Many doctors would also agree: our cells eventually reach a point where they can no longer divide and either die or reach senescence, or retirement phase. Scientists believe in the Hayflick limit (named after molecular biologist Leonard Hayflick, who advanced the idea of limited somatic cell division), which says no one can live past about 120 years.
De Grey believes a person has already been born who will live to 1000.
These people might also say that ageing and dying are a good thing; that the world is already overcrowded, that we already cannot handle our ageing populations, that life must be finite to appreciate it, that all good things must come to an end.
Cartoon: Michael Mucci.
Cartoon: Michael Mucci. Photo: Michael Mucci
But an increasing number of people, including gerontologists, biologists, engineers and futurists, believe ageing is a disease, and one that can be cured. They believe ageing is not an immutable process, an inevitable ''dying of the light'', to quote poet Dylan Thomas, but one we can ''rage against'' through science, drugs and lifestyle changes.
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Since 1900, the average life expectancy has risen from 47.3 years to 78 years in the US, which is about a 60 per cent increase. It is not unlikely to believe that scientists will be able to prolong healthy living rather than just ''life''. Gerontologists and others in the field are not concerned with prolonging end-of-life stages, when we are at our weakest, unhealthiest point (when healthcare often steps in too late).
Today's search is for a longer and healthier life. It's about turning back our biological clocks to be younger for longer. They believe in the ''longevity dividend''; that is, the economic benefits of extending healthy lives, including savings on healthcare and entitlements, and an increase in contributions to society.
Long and short of it: Telomeres, on the ends of chromosomes preserve genetic information.
Long and short of it: Telomeres, on the ends of chromosomes preserve genetic information.
In today's popular scientific literature, many claim to have cures for ageing or ways to retard ageing. Some believe a kilojoule-restrictive diet can prolong lives. Oxford biogerontologist Aubrey de Grey, a leader of the anti-ageing movement, believes we can rejuvenate the body by repairing cellular and molecular damage. He believes that a person has already been born who will live to 1000.
In his book Fantastic Voyage: Live Long Enough to Live Forever, futurist Ray Kurzweil writes about the science behind radical life extension, and investigates everything from diet and exercise to hormone and gene therapy.
Some of these people are considered on the edge of accepted science. Kurzweil, for example, takes more than 250 supplements a day, while de Grey has arranged to have his head cryo-preserved after his death so he can be revived. On the other hand, scientists in Scotland recently used a 3D printer to replicate embryonic human stem cells. So who is to say what is outrageous?
The cure within
One of the most promising avenues of anti-ageing research comes from inside our own bodies: the telomere.
Derived from the Greek nouns telos (end) and meros (part), these ''end parts'' are at the tips of our chromosomes, serving as protective caps for preserving genetic information; think of them as acting like the plastic sheaths that prevent fraying at the ends of shoelaces. The telomeres are disposable buffers blocking the ends of the chromosomes. Without them, genomes would lose information after cell division. A cell's age can be measured by the length of its telomeres.
Telomeres also protect a cell's chromosomes from fusing with each other or rearranging (abnormalities that can lead to cancer). When cells divide, telomeres shorten. When telomeres reach their shortest point, cells stop dividing or die. These senescent cells, some believe, cause age-related diseases, make us wrinkle, and weaken our immune and other systems.
In 2009, the Nobel prize in physiology or medicine was awarded to Elizabeth Blackburn, Carol Greider and Jack Szostak for their 1984 discovery ''of how chromosomes are protected by telomeres and the enzyme telomerase''. Telomerase is a protein that stabilises telomeres when they get worn, or causes them to lengthen and aids cell division.
Three months later, a genetics team at the Longevity Genes Project, at the Institute for Ageing Research at the Albert Einstein College of Medicine in New York, discovered a correlation between living to 100 and inheriting a mutant gene that makes their telomerase-making system extra active and able to maintain telomere length more effectively. For the most part, these people were spared age-related diseases such as cardiovascular disease and diabetes, which cause the most deaths among elderly people.
In March this year, University of Copenhagen researchers mapped telomerase for the first time.
The telomerase switch
''The key to immortality is turning the telomerase gene from off to on,'' Dr Michael Fossel, Greta Blackburn and Dr Dave Woynarowski write in The Immortality Edge: Realize the Secrets of Your Telomeres for a Longer, Healthier Life (John Wiley & Sons, 2011).
Suppressing telomerase is already possible. Anti-telomerase drugs have been found to stop some cancers growing, putting them into senescence. The protein is present in almost 90 per cent of all cases, in effect helping cancer grow unchecked. (Cancer cells and reproductive cells are immortal - their telomeres do not shorten as the cell divides. This is why the disease is fatal.
The Immortality Edge authors believe that in the next 20 years there will be a drug therapy that will turn on the telomerase gene in healthy cells, thereby extending the telomere and reversing ageing. Aside from TA-65, a controversial, expensive supplement that is claimed to lengthen telomerase and costs up to $8000 a year, there have not been any solutions to finding this ''on'' switch to produce the protein that would lengthen our telomeres.
Besides, genetic factors account for only 30 per cent of what happens to us, according to the Human Genome Project. This means 70 per cent is environmental. So even if our telomere length is genetic, there's a lot we can do to protect our cells.
Say no to stress
Is there anything we can do to preserve or lengthen our telomeres? The short answer is yes, and some of us are already doing it. What telomere researchers have discovered is that many of the practices we know are healthy actually preserve telomeres, and other things we know are unhealthy wear our cells down.
Take stress, for example. We can see that it's bad for us - stressed people often look older. Evidence shows it on a cellular level, too. In Psychological and Metabolic Stress: A Recipe for Accelerated Cellular Aging?, published in 2009 in the journal Hormones, Dr Elissa Appel of the psychology department of the University of California, San Francisco, found that stress coupled with overeating ''appears to be conducive to several cell ageing mechanisms, mainly dampening telomerase and leading to telomere length shortening and cell senescence''. She also found that chronic stress may lead to ''immune cell senescence''; in other words, it will weaken our immune system, causing us to age faster.
In studies that Appel did with Nobel laureate Blackburn, they compared the mothers of children with chronic illness with mothers with healthy children. The mothers of the children with chronic illness had shorter telomeres and less telomerase. There was no genetic component, proving that our telomeres are indeed affected by stress.
The opposite is also true: alleviating stress strengthens our cells. Appel and Blackburn were involved in Tonya Jacobs' 2010 study published in Psychoneuroendocrinology, Intensive Meditation Training, Immune Cell Telomerase Activity, and Psychological Mediators. The study compared a group of people who meditated for three months to another similar group who had not and found that telomerase activity was significantly greater in retreat participants than in controls at the end of the retreat. They found that ''increases in perceived control and decreases in negative affectivity contributed to an increase in telomerase activity, with implications for telomere length and immune cell longevity''.
Blackburn, a professor in biology and physiology at the department of biochemistry and biophysics at the University of California, San Francisco, never thought she would be doing studies on meditation with psychologists, but her research on telomeres has her working across disciplines to see how her discovery affects all aspects of life.
… and yes to exercise
Telomere length has been linked to depression, anxiety, obesity, cancer and heart disease, so it probably will come as no surprise to find that exercise has a positive effect. In Physical Exercise Prevents Cellular Senescence in Circulating Leukocytes and in the Vessel Wall, published in Circulation (2009), Dr Christian Werner of the University of Hamburg and other colleagues compared young and middle-aged sedentary and fit men who ran more than 72 kilometres a week.
They didn't find much difference in the telomeres when comparing the sedentary and fit men in their 20s, which made sense, since the younger men hadn't lived so long that their cells would divide enough to show signs of ageing. But there was a significant difference in the telomere length of the men in their 50s: the sedentary older men had 40 per cent shorter telomeres than the fitter, older men. In fact, the telomeres of the older men who were runners were only 10 per cent shorter than the younger men. In the middle-aged runners, telomere loss was reduced by about 75 per cent.
When it comes to telomere length and diet, results are mixed. While a 2008 study Dietary Patterns, Food Groups, and Telomere Length in the Multi-Ethnic Study of Atherosclerosis, published in The American Journal of Clinical Nutrition, found that the intake of whole grains, fruit and vegetables, low-fat dairy, nuts or seeds, non-fried fish, coffee, refined grains, fried foods, red meat, sugar-sweetened soft drinks had no effect on telomeres. Eating processed meat, however, affected telomere length.
But another study in the same journal two years later, Associations Between Diet, Lifestyle Factors, and Telomere Length in Women, found that fibre, waist size and saturated fats all affected telomere length in older women. A 2012 study in Age found the Mediterranean diet reduced senescence-associated stress in endothelial cells. In other words, general diet recommendations for longevity correlate with longer telomeres. Drinking green tea, following the Mediterranean diet and lowering sugar have all been shown to protect our cells.
Will the secret to immortality be solved? Only time will tell. But science will probably provide the answer on how to cure more diseases and help us lengthen our healthy lives. Telomeres are just the first step.
Read more: http://www.smh.com.au/lifestyle/buying-time-20130712-2pudb.html#ixzz2ZMlRi3jS |
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