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[
1974]
The free-living nematode, Caenorhaditis briggsae, is being used in our laboratory to study the complex events associated with biological aging. Our approach to this problem involved first the defining of parameters characterizing senescence in this animal, and then evaluating the effects on these aging signs of a drug reported to have a modifying effect on some aspects of the aging processes. Reference in this report to this preparation, Gerovital H3 (2% procaine hydrochloride, 0.16% benzoic acid, 0.14% potassium metabisulfite, buffered to pH 3.3 from Rom-Amer Pharmaceuticals, Ltd., Beverly Hills, California) is by its active ingredient, "Procaine".
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[
1980]
The use of nematodes as models to study aging is currently attracting wide interest among developmental biologists. The trend is clearly indicated by the large numbers of recent papers on nematode aging cited in these volumes. Because of the rapidly expanding interest in free-living nematodes, a large amount of data has accumulated on all aspects of the biology of these organisms. Certainly there is no other group of multicellular organisms about which so much is known. The question arises, Why the nematode and not another small metazoan chosen as a model? This question was considered in detail in other reviews, and only the principal advantages need be summarized here. Briefly, these include a short life span (about 25 days for Caenorhabditis briggsae), small size, ease of maintainance in axenic or monoxenic culture, the relatively small number of cells that are differentiated into nervous, digestive, reproductive, and muscular systems, and, most important, the rapidly expanding body of information which is now available on the genetics, nutrition, development, and physiology of several species of free-living nematodes. Another critical question often asked by biomedical researchers is the relevance of nematode aging to human senescence. As knowledge of molecular biology grew it rapidly became apparent that certain basic cellular processes proceed along similar paths of all living things. This chapter refers to a number of observations related to the biology and physiology of nematode aging that appear to parallel events associated with mammalian aging.
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[
Worm Breeder's Gazette,
1983]
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[
Nematologica,
1971]
Caenorhabditis briggsae was used as a model to study aging of a metazoan under gnotobiotic conditions. At higher temperatures nematodes were shorter-lived and had a shorter generation time. Nematodes moved more slowly as they aged. Physiologic aging was marked by a decreased ability to withstand osmotic stress, a possible increase in the body's internal solute concentration, and increased sensitivity to formaldehyde. These results suggest that the ability to osmoregulate and the permeability of the body wall are altered during senescence. The interchordal hypodermis, as well as the chordal hypodermis, contained fairly abundant structures having biosynthetic activity. During aging mitochondria of the hypodermis degenerated, some areas of the thin hypodermal band thickened and lysosome-like bodies formed in the interchordal hypodermis. Changes in osmoregulatory and excretory mechanisms are probably associated with deterioration of hypodermis organelles.
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[
1983]
The advantages of the free-living nematode Caenrohabditis elegans as a model for pharmacologic, toxicant and anthelmintic testing have become apparent to many companies, and the application of this organism as a primary screen for test compounds or toxic agents has expanded rapidly. It is appropriate to briefly summarize some of this nematode's qualities, to invoke an appreciation of this elegant system. As true of many invertebrate test organisms, C. elegans is small (about 1 mm X 40 u at maturity) and has a short life cycle: reproduction starts on day 3-4, ceases by day 14 and by day 25 it dies. Thus, for aging studies, all the symptoms of senescence are compressed into a short time period. In addition, this nematode has a small, fixed number of cells (about 830 at maturity) and differentiated organ systems: nervous, excretory, muscular, digestive and reproductive. The preceding characteristics are not unique in invertebrate model systems and their enumeration fails to explain the increasing popularity of C. elegans as a test organism. To understand this phenomenon several additional facts must be emphasized. First, the selection of C. elegans for detailed studies on the genetic control and regulation of behavior and developmental processes has fostered a wealth of knowledge on its neuroanatomy, cell lineages, biochemistry and behavior. There is now undoubtedly more accumulated knowledge on C. elegans than on any other multicellular creature. It is also the largest metazoan which can be continuously cultured on a chemically defined medium, and though most studies have proceeded on undefined media or in monoxenic culture (utilizing a bacterium as a food source), this property can be exploited for precise nutritional studies. In regard to aging studies, the question of relevance of aging in the nematode to that in mammals has been answered in respect to some parameters which characterize senescence in humans, and further study will define other features of aging which are common to all metazoa. In practical terms, this means that test which require 24-36 months to rear an aged rat for evaluation of a pharmaceutical, can potentially be accomplished in 21 days using the nematode. The paper emphasizes that the use of the C. elegans system as a primary screen for candidate compounds to intervene in the aging process can save time, effort and money, while
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[
Advances in the Biosciences,
1987]
Data supporting the use of nematodes as a preliminary screen for pharmaceuticals effective in retarding certain degenerative events associated with mammalian aging is presented. Among the criteria are 1. certain indices of cellular aging in nematodes are relevant to mammals; 2. the nematode system produces results in weeks as compared to one to two years for laboratory rats; and 3. the overall cost of nematode research is but a fraction of that required for mammalian studies with similar goals.
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[
Age,
1983]
Vitamin E at 200 ug/ml significantly extended the mean lifespan and extended maximum lifespan of the nematode Caenorhabditis elegans when supplied early in the prereproductive stage. At this concentration, vitamin E increased growth, but did not affect fecundity or the length of the reproductive period. The vitamin E effect was not passed from the parents to the progeny. Evaluations of the effects of vitamin E on lipofuscin accumulation were inconclusive. The results are compared to previous studies on C. briggsae and Turbatrix aceti.