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Biomedical subjects

Bruce A Carnes

Publications and source records attributed to Bruce A Carnes.

5 recordsLinked to original sources
PubMed2003

Biological evidence for limits to the duration of life.

Projections of duration of life for humans based on mathematical models have led some researchers to claim that there is no lower limit to death rates or upper limit to life expectancy, and that a life expectancy of 100 will be achieved in the 21st century. To assess the biological plausibility of these claims, we examined temporal aspects of biological phenomena in three mammalian species. Our examination revealed that: (1) physiological declines associated with reproduction consistently occur at ages that are less than one-third of the median age at death, (2) physiological parameters associated with aging in humans lose eighty percent of their functional capacity by age 80, and (3) young versus old individuals can be distinguished by the pathologies detected at death. The biological evidence suggests that organisms operate under warranty periods that limit the duration of life of individuals and the life expectancy of populations. We use these findings to discuss the issue of limits to the duration of life and the validity of mathematical models used to forecast human longevity.

Age Factors↗
PubMed2003

Mortality of atomic bomb survivors predicted from laboratory animals.

Exposure, pathology and mortality data for mice, dogs and humans were examined to determine whether accurate interspecies predictions of radiation-induced mortality could be achieved. The analyses revealed that (1) days of life lost per unit dose can be estimated for a species even without information on radiation effects in that species, and (2) accurate predictions of age-specific radiation-induced mortality in beagles and the atomic bomb survivors can be obtained from a dose-response model for comparably exposed mice. These findings illustrate the value of comparative mortality analyses and the relevance of animal data to the study of human health effects.

Age Factors↗
PubMed2002

Position statement on human aging.

A large number of products are currently being sold by antiaging entrepreneurs who claim that it is now possible to slow, stop, or reverse human aging. The business of what has become known as antiaging medicine has grown in recent years in the United States and abroad into a multimillion-dollar industry. The products being sold have no scientifically demonstrated efficacy, in some cases they may be harmful, and those selling them often misrepresent the science upon which they are based. In the position statement that follows, 52 researchers in the field of aging have collaborated to inform the public of the distinction between the pseudoscientific antiaging industry, and the genuine science of aging that has progressed rapidly in recent years.

Aged↗
PubMed2002

Pathology effects at radiation doses below those causing increased mortality.

Mortality data from experiments conducted at the Argonne National Laboratory (ANL) on the long-term effects of external whole-body irradiation on B6CF(1) mice were used to investigate radiation-induced effects at intermediate doses of (60)Co gamma rays or fission-spectrum neutrons either delivered as a single exposure or protracted over 60 once-weekly exposures. Kaplan-Meier analyses were used to identify the lowest dose in the ANL data (within radiation quality, pattern of exposure, and sex) at which radiation-induced mortality caused by primary tumors could be detected (approximately 1-2 Gy for gamma rays and 10-15 cGy for neutrons). Doses at and below these levels were then examined for radiation-induced shifts in the spectrum of pathology detected at death. To do this, specific pathology events were pooled into larger assemblages based on whether they were cancer, cardiovascular disease or non-neoplastic diseases detected within the lungs and pleura, liver and biliary tract, reproductive organs, or urinary tract. Cancer and cardiovascular disease were further subdivided into categories based on whether they caused death, contributed to death, or were simply observed at death. Counts of how often events falling within each of these combined pathology categories occurred within a mouse were then used as predictor variables in logistic regression to determine whether irradiated mice could be distinguished from control mice. Increased pathology burdens were detected in irradiated mice at doses lower than those causing detectable shifts in mortality-22 cGy for gamma rays and 2 cGy for neutrons. These findings suggest that (1) models based on mortality data alone may underestimate radiation effects, (2) radiation may have adverse health consequences (i.e. elevated health risks) even when mortality risks are not detected, and (3) radiation-induced pathologies other than cancer do occur, and they involve multiple organ systems.

Animals↗