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Age (1978-1999)

J C Carlson, R Bharadwaj, A Bartke
Growth hormone (GH) stimulates metabolic activity. The purpose of this study was to examine whether it is involved in the aging process by increasing oxidative stress. Inorganic peroxides and lipid peroxides were measured in kidney and liver samples in dwarf mice that are deficient in GH, prolactin and thyrotropin and in transgenic mice that produce high levels of GH. In normal male mice, there was an increase in inorganic peroxides in the kidney with age. Levels were lower in old male dwarfs when compared with normal male mice of similar age...
October 1999: Age (1978-1999)
K Kuether, R Arking
It has been demonstrated in several animal models that a brief non-lethal application of high temperature is capable of inducing an increased longevity. It is also known that an even briefer exposure to a non-lethal elevated temperature enables some organisms to subsequently survive what would normally be a lethal exposure to high temperature. Our long-lived La strain is significantly resistant to oxidative stress due to an enhanced expression of certain antioxidant defense genes and enzyme activities. We collected survival data on 12, 463 adults of normal-lived and long-lived strains of Drosophila melanogaster in order to determine if animals selected for extended longevity also had an enhanced resistance to heat shock, and whether they exhibited thermotolerance as well...
October 1999: Age (1978-1999)
H J Palmer, C T Tuzon, K E Paulson
Loss of proliferative capacity is common in many tissue types during aging. We have shown that mitogenic signaling through the epidermal growth factor (EGF) receptor declines in hepatocytes from old rats. Specifically, we showed that in old hepatocytes there is a decrease in autophosphorylation of EGF receptor at Tyr-1173. This results in loss of recruitment of the adapter protein Shc to the membrane and decreased ERK MAP kinase pathway activation. Because EGF receptor signaling also requires intracellular generation of H202, we next questioned whether altering the intracellular GSH/thiol concentration may also affect the age-dependent decline in EGF receptor signaling...
October 1999: Age (1978-1999)
D Busbee, R Barhoumi, R C Burghardt, C Gauntt, B McAnalley, H R McDaniel
A complex glyconutritional (GN) mixture of mono-, di-and polysaccharides was investigated to assess its capacity to protect two different types of rodent cells, rat hepatocytes and mouse splenocytes, from depletion of glutathione by a sulfhydryl-reactive mycotoxin, patulin, or by coxsackievirus B3 (CVB3) infection, respectively. Rat hepatocytes were treated with the GN mixture in vitro or received carrier medium only prior to treatment with patulin. When treated with the GN mixture prior to patulin exposure hepatocytes demonstrated protection against depletion of intracellular reduced glutathione (GSH)...
October 1999: Age (1978-1999)
C Gauntt, D Busbee, H J Wood, S Reyna, R Barhoumi, R Burghardt, W McAnalley, H R McDaniel
Challenge of adolescent male CD-1 mice with a coxsackievirus B3 (CVB3) strain (CVB3m) induces mild to severe destruction of pancreatic acinar cells, but causes no deaths and does not induce hyperglycemia. A weekly parenteral (intraperitoneal) administration of a glyconutritional mixture (Ambrotose® to virus-challenged mice was assessed to determine if there were any benefits to recovery over an eight month period. Virus-challenged mice showed a significant weight loss over the initial five weeks of the experiment, but injection of Ambrotose® to similar virus-challenged mice restored the total body weight to levels found in normal mice...
October 1999: Age (1978-1999)
C F McDaniel
No abstract text is available yet for this article.
October 1999: Age (1978-1999)
C Bertoni-Freddari, P Fattoretti, U Caselli, T Casoli, G Di Stefano, S Algeri
A computer-assisted morphometric study has been carried out on the synaptic ultrastructural features in the hippocampus of 14-month old (DR14) and 27-month old (DR27) dietary restricted (-50% lipids and -35% carbohydrates) rats. Age-matched controls were maintained on an ad libitum (AL) feeding schedule. Synaptic numeric density (Nv), surface density (Sv) and average area (S) were the parameters measured. In old AL vs. adult AL animals, Nv decreased to a not significant extent, while S increased and Sv decreased significantly...
July 1999: Age (1978-1999)
S Doubal, P Klemera
The full exploitation of information contained in mortality curves offers a tool for direct verification of theories of aging. We have analyzed the behavior of mortality curves for middle and high age groups and have proposed a mathematical model of mortality correlated with the rate of aging. The model offers an explanation for the mutual relationships between mortality curves and suggests potential methodologies for determining experimental modification of the rate of aging. The applicability of this theory is demonstrated by analysis of the changes in mortality as it is influenced by dietary antioxidants or by a calorie restricted diet...
July 1999: Age (1978-1999)
K Takubo, K Nakamura, N Izumiyama, M Sawabe, T Arai, Y Esaki, Y Tanaka, K Mafune, M Fujiwara, M Kammori, K Sasajima
Progressive telomere shortening with aging was studied using normal esophageal mucosal specimens from 177 human subjects aged between 0 and 102 years (yrs). We observed age-related shortening of the telomere, at a rate of 60 base pairs (bp) per year (yr). The mean telomere length of 12 neonates was 15.2 kilobase pairs (kbp) and that of 2 centenarians was 9.3 kbp. Mean (±SD) telomere lengths were 14.9±1.3, 14.0±1.8, 10.1±3.7, 10.4±3.3 and 9.5±3.1 kbp for the age groups less than 2 yrs, 2-20 yrs, 21-60 yrs, 61-80 yrs and 81-102 yrs, respectively...
July 1999: Age (1978-1999)
M A Shammas, R J Shmookler Reis
Genetic recombination is the creation of new gene combinations in a cell or gamete, which differ from those of progenitor cells or parental gametes. In eukaryotes, recombination may occur at mitosis or meiosis. Mitotic recombination plays an indispensable role in DNA repair, which presumably directed its early evolution; the multiplicity of recombination genes and pathways may be best understood in this context, although they have acquired important additional functions in generating diversity, both somatically (increasing the immune repertoire) and in germ line (facilitating evolution)...
April 1999: Age (1978-1999)
K Hubbard, H L Ozer
Model systems implementing various approaches to immortalize cells have led toward further understanding of replicative senescence and carcinogenesis. Human diploid cells have a limited life span, termed replicative senescence. Because cells are terminally growth arrested during replicative senescence, it has been suggested that it acts as a tumor suppression mechanism as tumor cells exhibit an indefinite life span and are immortal. The generation of immortal cells lines, by the introduction of SV40 and human papillomavirus (HPV) sequences into cells, has provided invaluable tools to dissect the mechanisms of immortalization...
April 1999: Age (1978-1999)
J K Cowell
Telomeres lie at the ends of human chromosomes and contain long tandem repeats of a simple nucleotide sequence. Because DNA replication cannot proceed to the very end of chromosomes, copies of these repeats are lost at each cell division. If the telomeres shorten below a critical length, the cells will eventually die as a result of genomic instability. Aging cells usually avoid death by entering senescence before the critical telomere length is reached. Malignantly transformed, immortal cells overcome senescence but they must still avoid the final, critical shortening of telomeres to survive...
April 1999: Age (1978-1999)
I M Hadshiew, M S Eller, B A Gilchrest
Multiple pathways are involved in accurate synthesis and distribution of DNA during replication, repair and maintenance of genomic integrity. An increased error rate, abovethe spontaneous mutation baseline, has been implicated in carcinogenesis and aging. Moreover, cytogenetic abnormalities are increased in Down's, Edwards', Patau's, and Klinefelter's syndromes with increasing maternal age, and in Marfan's and Apert's syndromes with paternal age. In response to DNA damage, multiple overlapping systems of DNA repair have evolved, preferentially repairing the transcribed strand within transcriptionally-active regions of the genome...
April 1999: Age (1978-1999)
J R Tunstead, P J Hornsby
p21(WAF1/CIP1/SDI1) was originally described as a protein expressed at high levels in senescent human fibroblasts. We have studied the expression of p21 in adrenocortical cells, p21 is not expressed under most circumstances in the intact adrenal gland in vivo, except when the gland is damaged. When human and bovine adrenocortical cells are isolated and placed in both short-term and long-term culture, p21 levels are much higher. These levels did not show a large increase when the cells senesce after long-term proliferation...
April 1999: Age (1978-1999)
T J Gould
The present review provides an overview of age-related changes in cerebellar β-adrenergic function, associated motor learning, causal agents and possible treatments. Norepinephrine acts as a neuromodulator of Purkinje cell activity. With aging, however, the ability of norepinephrine to modulate Purkinje cell activity and specifically GABAergic inhibition of Purkinje cell activity is decreased. This age-associated deficit in cerebellar noradrenergic function correlates with deficits in acquisition of a motor learning task...
January 1999: Age (1978-1999)
B Shukitt-Hale
Decrements in motor and cognitive function occur in aging, possibly due to oxidative stress-induced damage to the brain. Declines in antioxidant defense mechanisms have been postulated as a causative factor in these age-related decrements, however a clear link between oxidative stress (OS) and behavioral changes in aging has yet to be established. This review shows that age-validated psychomotor and cognitive tests are sensitive to behavioral deficits under different models of OS, including: 1) decreasing OS protection by depleting glutathione and then increasing the OS with dopamine; 2) 100% oxygen exposure; and 3) radiation...
January 1999: Age (1978-1999)
G M Rose
Neurotrophic factors are now recognized to play important roles in the normal function of the mature central nervous system. This knowledge has motivated experiments to evaluate the potential benefits of administering neurotrophic factors to the aged brain. This article provides a review of studies to date that have determined the behavioral effects of such treatments. Nerve growth factor (NGF) administration appears to reliably enhance learning and memory in aged rats, while glial-derived neurotrophic factor (GDNF) causes some improvement in motor function...
January 1999: Age (1978-1999)
E C Feleder, H A Peredo, V E Mendizábal, E Adler-Graschinsky
The aim of the present work was to evaluate, in the rat isolated mesenteric bed, whether increasing age is associated with alterations in the ATP sensitive K(+) channels functionality. Moreover, studies were performed in order to evaluate the effects of aging on the synthesis of vascular prostanoids as well as on its possible contribution to the pressor responses of this vascular bed. Male Wistar rats of 3 month (adults) and 24 month (aged) were used. Although no differences were found among adult and aged rats in pressor responses to 2-30 nmol noradrenaline and to 40-160 nmol KCl, the relaxant responses to the K(+) channel opener, 10(-6) M cromakalim, were significantly diminished in the aged group compared to the adults...
October 1998: Age (1978-1999)
D A Troyer, J T Venkatraman, G Fernandes
Aging is accompanied by a steady increase in the incidence of spontaneous tumors and a decline in immune function. Calorie restriction (CR) or supplementation with ω-3 fats prolongs life span, suppresses tumorigenesis, and ameliorates immune function in a variety of experimental models. We suggest that decreased oxidant stress and upregulation of apoptosis mediate the effects of calorie restriction on immunity and longevity. CR prolongs life span in several animal models and our studies have examined the effects of CR on the immune system and on tumorigenesis...
October 1998: Age (1978-1999)
M A Pahlavani
The decline in immunologic function with age is associated with an increase in susceptibility to infections and the occurrence of autoimmune diseases and cancers. Hence, the restoration of immunologic function is expected to have a beneficial effect in reducing pathology and maintaining a healthy condition in advanced age. A number of therapeutic strategies have been employed to intervene in the aging immune system. This article reviews the effect of dietary restriction (DR), dehydroepiandrosterone (DHEA) treatment, melatonin (MLT) therapy, and exercise on modulating the immune responses and retarding/reducing immunosenescence...
October 1998: Age (1978-1999)
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