How long is the human life-span?

Article Abstract:

There are two competing theories regarding the human life-span. One holds that biological limits exist that begin to be felt around the age of 85. The other claims that there are no such limits. Some scientists in the first group think death due to old age arises from frailty of the body, observing that even minor insults to the body, such as the flu or a fall, often lead to death in older people. Others believe that diseases such as osteoporosis (a decrease in bone density) or atherosclerosis (accumulation of deposits in the blood vessels) are the prime causes of death in the elderly and that the development of these illnesses can be delayed or prevented, thereby extending the life span. It is theorized by the latter group that if the major causes of death in the aging, such as heart disease, cancer and diabetes, were eliminated, people would tend to live well past the age of 85. While the records of people over the age of 85 in the United States are not accurate enough for such study, records in Sweden are extremely accurate and can be used to examine the life expectancy for people over 85. Studies have shown that the death rates in this age group have dropped dramatically in the last 50 years because more diseases can now be treated. A study with fruit flies, as an animal model for aging, shows that very old fruit flies do not grow biologically frail. Other studies in humans examined the idea of genetic determination of the age of death by using a registry of identical twins born between 1870 and 1890 and the age of death of the two twins if they died due to natural causes, at around the same age. Using a computerized model, the age of senescence was calculated to be around 110 years old, not 85. The expected length of the human life span will affect policies for care and treatment of the aging. The question arises whether money should be made available for the care and treatment of a population older than 85. (Consumer Summary produced by Reliance Medical Information, Inc.)

Aging, Research, Models, Longevity, Gerontology, Age factors in disease, Disease age factors

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Vitamin C gets a little respect

Article Abstract:

The role of vitamin C in preventing or curing disease is controversial. However, recent research has supported the importance of vitamin C. This vitamin is an antioxidant that reduces compounds which cause the oxidation of molecules in the body, including lipids, proteins and DNA, before they cause damage to cells. Compounds such as cigarette smoke and smog cause oxidation of molecules. A conference on the effects of vitamin C was recently held. Data were presented that support the importance of vitamin C, not as a anticancer drug, as previously claimed, but as an agent which reduces the toxicity of some other drugs used in cancer treatment, including adriamycin and interleukin-2. Data were also presented showing that vitamin C may prevent atherosclerosis, or hardening of the arteries. Oxidation of low-density lipoproteins increases the development of plaque, and vitamin C may prevent this oxidation. Clinical trials will begin testing the role of antioxidants in preventing atherosclerosis. Other research has shown that antioxidants may inhibit the reproduction of the human immunodeficiency virus (HIV). Thus, further research and clinical trials in humans are needed to determine if indeed vitamin C has metabolic benefits. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Antioxidants, Antioxidants (Nutrients), Atherosclerosis, Vitamin C

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A shared strategy for virulence

Article Abstract:

Microbiologists presented papers on the type III secretion system at a May 1996 meeting of the American Society for Microbiology. The system, discovered in 1991, has been acquired by a broad range of pathogenic bacteria. It enables them to deliver damaging proteins directly into host cells.

Infection, Genetic aspects, Bacteria, Pathogenic, Pathogenic bacteria

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