Is the Hayflick limit an absolute limit for the human lifespan?


by Bararontok
Tags: absolute, hayflick, human, lifespan, limit
Bararontok
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#1
Oct13-13, 06:28 AM
P: 298
Is the Hayflick limit an absolute limit for the human lifespan or is it just the average limit of the human lifespan just like there are average heights and weights? Based on the maximum number of times the cells divide which is 50 according to Hayflick's experiments, how can the maximum theoretical lifespan of humans be calculated?

A possible way to estimate lifespan as quoted from Wikipedia:

"It has also been observed that the VO2max value (a measure of the volume of oxygen flow to the cardiac muscle) decreases as a function of age. Therefore, the maximum lifespan of an individual can be determined by calculating when his or her VO2max value drops below the basal metabolic rate necessary to sustain life ---approximately 3 ml per kg per minute. Noakes (p. 84) notes that, on the basis of this hypothesis, athletes with a VO2max value between 50 and 60 at age 20 can be expected "to live for 100 to 125 years, provided they maintained their physical activity so that their rate of decline in VO2max remained constant.

A theoretical study suggested the maximum human lifespan to be around 126 years using a modified stretched exponential function for human survival curves."


The scientific paper that the Wikipedia entry came from:

http://link.springer.com/article/10....522-008-9156-4

Does the value of 126 years estimated by this scientific paper match the maximum theoretical lifespan that can be calculated using the Hayflick limit?
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jarekd
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#2
Oct13-13, 08:08 AM
P: 111
Hayflick limit requires lack of telomeraze, which was discovered a few years later. It is expressed for example in stem cells (used to repair tissues), making them virtually immortal ... however, there is also e.g. degradation of genetic material - stem cells have better mechanisms to prevent DNA damages, but are close to create extremely dangerous cancer stem cells.
Bararontok
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#3
Oct13-13, 09:06 AM
P: 298
Additionally, this quote from a Wikipedia article:

http://en.wikipedia.org/wiki/Maximum_Lifespan

"Most living species have at least one upper limit on the number of times cells can divide. This is called the Hayflick limit, although number of cell divisions does not strictly control lifespan (non-dividing cells and dividing cells lived over 120 years in the oldest known human)."

States that the Hayflick limit is not the only factor determining the lifespan of living organisms.

jarekd
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#4
Oct13-13, 09:53 AM
P: 111

Is the Hayflick limit an absolute limit for the human lifespan?


Here is a list of longest living organism, starting with 80000 years: http://en.wikipedia.org/wiki/List_of...ving_organisms
In prokaryotes mitosis can go infinite number of times, meiosis in higher organisms - the main problem are mutations, but some cells doesn't care - I wouldn't be surprised if Henrietta Lack's cells would be still dividing in thousands of years ...
Bararontok
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#5
Oct13-13, 10:06 AM
P: 298
That is fascinating, some of the life forms on that list and Henrietta Lack's cancer cells have even achieved immortality.
Ygggdrasil
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#6
Oct13-13, 12:11 PM
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Here's a recent review article that attempts to explain the major biological and biochemical factors underlying aging:

Aging is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases. Aging research has experienced an unprecedented advance over recent years, particularly with the discovery that the rate of aging is controlled, at least to some extent, by genetic pathways and biochemical processes conserved in evolution. This Review enumerates nine tentative hallmarks that represent common denominators of aging in different organisms, with special emphasis on mammalian aging. These hallmarks are: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. A major challenge is to dissect the interconnectedness between the candidate hallmarks and their relative contributions to aging, with the final goal of identifying pharmaceutical targets to improve human health during aging, with minimal side effects.
López-Otín et al. 2013 The Hallmarks of Aging. Cell 153: 1194. doi:10.1016/j.cell.2013.05.039
Bararontok
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#7
Oct29-13, 10:22 AM
P: 298
Quote Quote by Ygggdrasil View Post
Here's a recent review article that attempts to explain the major biological and biochemical factors underlying aging:

Aging is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. This deterioration is the primary risk factor for major human pathologies, including cancer, diabetes, cardiovascular disorders, and neurodegenerative diseases. Aging research has experienced an unprecedented advance over recent years, particularly with the discovery that the rate of aging is controlled, at least to some extent, by genetic pathways and biochemical processes conserved in evolution. This Review enumerates nine tentative hallmarks that represent common denominators of aging in different organisms, with special emphasis on mammalian aging. These hallmarks are: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. A major challenge is to dissect the interconnectedness between the candidate hallmarks and their relative contributions to aging, with the final goal of identifying pharmaceutical targets to improve human health during aging, with minimal side effects.
López-Otín et al. 2013 The Hallmarks of Aging. Cell 153: 1194. doi:10.1016/j.cell.2013.05.039
Interesting, additionally there is also this publication from the following source:

http://www.sciencedirect.com/science...14482784711323

Which proves that carnosine can increase the Hayflick limit of human diploid fibroblasts, the cells responsible for various vital functions in the human body such as:

1.) Synthesis of the extracellular matrix and collagen

2.) Forms the structural framework (stroma) for tissues

3.) Plays a critical role in wound healing

4.) Are the most common cells of connective tissue


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