As I was walking up the stair,
I met a man who wasn't there.
He wasn't there again today.
I wish, I wish he'd go away
--Author unknown
There are several species of spiders which eat their male mates after they copulate. Males willingly die. It is presumed that the extra time it takes the female spider to eat her sex partner insures more time for his sperm to fertilize the female, therefore making it more likely that his sperm fertilizes her eggs and passes on his genes. She is too distracted by eating him to have sex with another spider.
Death is part of the major, general scheme of life and apparently other species are much less concerned about death than we Homo sapiens are.
There is only so much we can do to minimize our death, one of which is to slow the way we age. So far we have not been very successful. A lot of people are thinking about it. I think quality of life is more important than how long we live. Death is not something we can stop; not death of self. Consciousness is ephemeral. It wouldn't survive us. And to many that is a frightening prospect.
The free radical theory of aging is one of the most popular scientific positions with regard to senescence. There are possibly many components to dying and that may only be one of them. It is suggested that the length of telemeres, the little tails on the end of our chromosomes get shorter and shorter and eventually we lose the ability to reproduce our chromosomes at which time death is certain. I'm not sure that is any more important than the ability to reproduce. The theory of free radical leakage from mitochondria is the likely culprit. The mitochondria is an organelle which lives in the cytoplasm around the nucleus whose function is chiefly the manufacturing of ATP, the energy or fuel for everything. - TheCrypt)
"...Mitochondria are elongated thread-like structures about the size of bacteria woven through our cells. Mitochondria are dubbed the power-plants of cells as they utilize over 80 per cent of the oxygen we breathe to produce 90 per cent of the energy required by our cells to function. This process transforms food calories into chemical energy, water, and carbon dioxide. The released chemical energy is then stored in the form of adenosine triphosphate (ATP). ATP is the universal currency of energy used by all living cells similar to petroleum which drives engines of automobiles. This process of burning food to make ATP is called oxidative phosphorylation." (Yam Cher Seng, "Age well the mitochondria way" - New Straits Times - January 13, 2004)
"Oxidative phosphorylation can only occur in mitochondria and without ATP, our body will not be able to move a muscle, to build, repair and renew damaged cell membranes and structures. ATP is also required for immune components to fight infection and the functioning of vital organs such as the heart, liver, kidneys and lungs." (ibid)
However not all the oxygen utilized by the mitochondria is completely transformed into water and the intermediates of oxygen (free radicals) are very damaging to cell structures. The cell is made up of several components which include the nucleus that stores our DNA, the mitochondria, the golgi and ribosomes, which are the manufacturing centers, and enzymes called lysosomes. Any defects or mutations in mitochondrial DNA lead to diseases, poor energy output and ill-health." (ibid)
When we hear anything about stem cells, we immediately think about the opposition to using stem cells for research, but we rarely hear that cancer is the disease of stem cells. When stem cells proliferate into aberrant cells which then give rise to more abberant stem cells; they differentiate as cancer cells. They don't die as cells are expected to die through programmed death called apoptosis when they are damaged cells and they become "caricatures" of cell renewal.
Of course stem cells have potential in the treatment of lethal genetic diseases. When cells are post-mitotic and have fully differentiated into cell types the offspring are normal cells. If not fully differentiated however they may become the target of carcinogenesis. Anotherwords, stem cells may either retain pluripotential differentiative competence and differentiate to lineage-specific mature normal cells or they may differentiate as incomplete cancer cells.
This is one of several theories of cancer genesis.
There is anectodal evidence that some cancers may sit dormant and never do anything until someone suffers another wound or medial invasion for treatment of something seemingly unrelated, like a broken hip and a tumor which has been pathologically benign then becomes a malignant tumor. This is controversial but I listened to a lecture yesterday by the chief of surgery at London Medical College University about how this may happen because it has happened. We don't yet know enough to know why this may happen in some cases and not in others. We do not know why compression from a mammogram can trigger cancer in some cases and we don't know why it does not in other instances. This same doctor swears by his research that radical mastectomy is not any more curative or effective than lumpectomy. Cancer appears to be a disease which may have many different etiologies.
We don't know why some people who smoke do not get cancer and some who never smoke do. It is always foolish to play Russian roulette with cigarettes however when the evidence is clear in many cases smoking has been implicated. About half the tumors in the kidney pelvis while malignant act as if benign and simple extirpation cures the cancer. We don't know why the 10 percent of patients with stomach cancer survive, but they do and no one would say it is luck; it must be something the body does to defeat the cancer in those who do survive and seem cured. With neuroblastoma, the most common tumor in children 40% of these children are cured by chemotherapy and the other 60% die and we dont' know why those who survive do survive the same therapy.
It is suspected that the reason for different cure rates and propensities for having cancer is many things because cancer is a series of many diseases. It is a disease of senescence but also affects children. Early diagnosis seems to offer the best hope for survival - before cancer has (spread) and early extirpation of the tumor before this happens is the best opportunity for a cure. There are exceptions, such as those diseases which are more common post-reproduction, and where in instances of acute disease the treatment is merely palliative, not curative.
Examples would be acute lymphatic leukemia, choriocarcinoma, testicular cancer, Hodgkin's disease, et al.
Often when treatment; chemotherapy or radiation is palliative, the success is also dependent on anti-imflamatory response and immune responses to the disease. Death is usually from infection.
In senescence, which is aging after reproduction - because there is no known benefit from evolution for survival after reproduction unless there is a significant benefit to reproduction to have older humans or other species survive past reproduction. I can anticipate some benefit if grandparents helping to care for children can be perceived through natural selection as also a benefit to reproduce - but I don't think that is the case, at least not so with any degree which would increase the frequency of selection.
To follow up on this, to minimalize senescence seems to be a potential in some species. We don't for example die immediately after copulating like some spiders and ants. We do live decades beyond the age of normal reproduction. Why is not known but it is surmised it is because of better medical magic. Treatments, medications, etc have improved and they have had an effect.
The longest life time expectancy seem to have been for Okinawa where the claim to long life indicates it is common for more Okinawans to live beyond the age of 100, that number being 34 per 1,000,000 which is higher geographical than elsewhere. However, the figures are very unreliable so we can't trust the claim. Unreliability seems to be the case where others have made similar claims and life expectancies and older age has been pretty much the same everywhere. Most of those who die early do so from infectious diseases and accidents and those who live longer and die post-reproduction do so from age related senescence; disease of the heart, strokes and cancer, the leading cause of death in old(er) aging. Nothing anyone does seems to have much of an effect on age related death.
Cancer is a disease of aging but none is immune and cancer can strike at any age, though some cancers affect the young more and there is an increase in the incidence rate for those who are older. Free radicals; oxygen leakage is accumulative and cells have their own way of dealing with this problem by dying. Programmed cell death is common as a method to eliminate damaged cells. When a cell refuses to die for the good of the host it can cluster and proliferate and is a serious health risk to the organism which it ultimately kills or is killed by chemotherapy, radiation or extirpation.
Cancer dates back to antiquity. The hard gray tissue extending from the tumor into normal tissues had a likeness to a crab, thus the Greek word for crab is cancer. And tumor is a mass which is either neoplastic, inflammatory, pathologic or physiologic. The word, "cancer" is a generic word for any malignant tumor. AND tumor is a generic term for any neoplasm.
A neoplasm is an incoordinate growth with the surrounding normal tissue which persists. We replace a lot of our cells everyday in a controlled manner to replace the cells which are lost to us. Neoplasms persist and increase their size, however benign tumors are slow growing neoplasms and generally innocuous, however they may not be if a benign slow growing tumor is located close to a vital organ where compressing it could endanger the host. An example would be meningiomas, which are slow growing tumors in the meninges, which is the covering of the brain and this might eventually cause death by the pressure and resultant atrophy and destruction of vital brain tissue.
Cells of malignant tumors however tend to grow uncontrollably. The nucleus of malignant cells are also pleomorphic which means they vary in size and in their shape. The nucleus may be either very large or very small but always abnormal from normal cells. The nucleus is atypical. Often the nucleus is larger. The chromatin is irregularly distributed in the nucleus. Malignant tumor cells proliferate and have a HIGH nucleus to to cytoplasm size. The nuceocytoplasmic ratio normally 1:3 or 1:4, whereas with a malignant tumor the cells are about 1:1.5.
Human cells (and the cells in other species) willingly die (called apoptosis) so other cells may live and life can sustain itself. However cancer cells are disobedient cells. They disobey their programming and they do not die. They choose life and by refusing to sacrifice themselves, to commit suicide, they consequently cause the death of the entire organism.
Life is programmed to sacrifice itself so others may live and genes may survive.
Hank Roth
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Today is Friday March 12, 2010
