Aging Research Center Home Page

All Previous Aging Related Articles

On-line Medical Dictionary

National Library of Medicine's PubMed directory of MEDLINE citations.

Recent Papers

1.5 7th August 1997



Mech Ageing Dev 1997 Jul;97(1):15-34

P53 synthesis and phosphorylation in the aging diet-restricted rat following retinoic acid administration.

Pipkin JL, Hinson WG, James SJ, Lyn-Cook LE, Duffy PH, Feuers RJ, Shaddock JG, Aly KB, Hart RW, Casciano DA

Division of Genetic Toxicology, National Center for Toxicological Research, Jefferson, AR 72079-9502, USA.

Multiple doses of retinoic acid (RA) were administered intraperitoneally to three groups of male Fischer 344 rats over a 36 h period. The p53 isoforms from bone marrow nuclei in these three groups of rats were analyzed over time by two-dimensional polyacrylamide gel electrophoresis (PAGE) and fluorography for the incorporation of [35S]methionine (p53-synthesis) and [32P]phosphate (p53-phosphorylation). Two groups of rats, young (3.5 months) ad libitum (Y/AL) and old (28 months) ad libitum (O/AL), had free access to Purina rat chow; a third group of old (28 months) diet-restricted rats (O/DR) were maintained on a restricted caloric intake (60% of the AL diet) from 3 months of age. After 36 h of RA dosing, the PAGE patterns of p53 synthesis and phosphorylation in Y/AL and O/DR rats were very similar. In both groups, an increase in complexity was observed with labeling of additional isotypes possessing more acidic isoelectric values. In contrast, the O/AL animals showed a pattern of p53 isoform synthesis and phosphorylation that was considerably less complex and lacked the pronounced shift to more acidic forms following RA dosing. The p53 isoforms of O/AL rats as recognized by wild type (wt) Pab 246 antibody, were also much less dramatic in their increase to more acidic forms. Two-dimensional phospho-tryptic maps of Y/AL and O/DR rats were also very similar, both exhibiting two additional minor 32P-labeled fragments after RA dosing. The maps of O/AL rats did not show the two additional fragments following RA administration. After RA dosing, cyclin protein inhibitors (p16, p21, p27) revealed robust labeling with their respective antibodies in Y/AL and O/DR rats as analyzed by Western blotting. The O/AL animals showed marginally detectable antibody recognition of the cyclin inhibitors after RA dosing. Taken together, these data suggest that the biosynthesis and phosphorylation of p53 isoforms and the expression of cyclin dependent kinase inhibitor proteins is not significantly different between Y/AL and O/DR rats. Further, these results confirm and extend our previous observations that chronic diet-restriction attenuates the age related decline in the metabolic activity of nuclear protein products.

J Clin Endocrinol Metab 1997 Jul;82(7):2093-2096

Dehydroepiandrosterone sulfate: a biomarker of primate aging slowed by calorie restriction.

Lane MA, Ingram DK, Ball SS, Roth GS

Gerontology Research Center, Nathan W. Shock Laboratories, National Institutes of Health, Johns Hopkins University Bayview Campus, Baltimore, Maryland 21224, USA.

The adrenal steroids, dehydroepiandrosterone (DHEA) and its sulfate (DHEAS), have attracted attention for their possible antiaging effects. DHEAS levels in humans decline markedly with age, suggesting the potential importance of this parameter as a biomarker of aging. Here we report that, as seen in humans, male and female rhesus monkeys exhibit a steady, age-related decline in serum DHEAS. This decline meets several criteria for a biomarker of aging, including cross-sectional and longitudinal linear decreases with age and significant stability of individual differences over time. In addition, the proportional age-related loss of DHEAS in rhesus monkeys is over twice the rate of decline observed in humans. Most important is the finding that, in rhesus monkeys, calorie restriction, which extends life span and retards aging in laboratory rodents, slows the postmaturational decline in serum DHEAS levels. This represents the first evidence that this nutritional intervention has the potential to alter aspects of postmaturational aging in a long-lived species.

Proc Natl Acad Sci U S A 1997 Jul 8;94(14):7537-7542

Potentially predictive and manipulable blood serum correlates of aging in the healthy human male: progressive decreases in bioavailable testosterone, dehydroepiandrosterone sulfate, and the ratio of insulin-like growth factor 1 to growth hormone.

Morley JE, Kaiser F, Raum WJ, Perry HM 3rd, Flood JF, Jensen J, Silver AJ, Roberts E

Geriatric Research Education and Clinic Center, Veterans Administration Medical Center, St. Louis, MO 63106, USA.

A cross-sectional survey was made in 56 exceptionally healthy males, ranging in age from 20 to 84 years. Measurements were made of selected steroidal components and peptidic hormones in blood serum, and cognitive and physical tests were performed. Of those blood serum variables that gave highly significant negative correlations with age (r > -0.6), bioavailable testosterone (BT), dehydroepiandrosterone sulfate (DHEAS), and the ratio of insulin-like growth factor 1 (IGF-1) to growth hormone (GH) showed a stepwise pattern of age-related changes most closely resembling those of the age steps themselves. Of these, BT correlated best with significantly age-correlated cognitive and physical measures. Because DHEAS correlated well with BT and considerably less well than BT with the cognitive and physical measures, it seems likely that BT and/or substances to which BT gives rise in tissues play a more direct role in whatever processes are rate-limiting in the functions measured and that DHEAS relates more indirectly to these functions. The high correlation of IGF-1/GH with age, its relatively low correlation with BT, and the patterns of correlations of IGF-1/GH and BT with significantly age-correlated cognitive and physical measures suggest that the GH-IGF-1 axis and BT play independent roles in affecting these functions. Serial determinations made after oral ingestion of pregnenolone and data from the literature suggest there is interdependence of steroid metabolic systems with those operational in control of interrelations in the GH-IGF-1 axis. Longitudinal concurrent measurements of serum levels of BT, DHEAS, and IGF-1/GH together with detailed studies of their correlations with age-correlated functional measures may be useful in detecting early age-related dysregulations and may be helpful in devising ameliorative approaches.

Drugs Aging 1997 Jul;11(1):1-6

Immunosenescence revisited. Does it have any clinical significance?

Voets AJ, Tulner LR, Ligthart GJ

Section of Geriatrics, Free University Hospital, Amsterdam, The Netherlands.

Immunosenescence refers to the influence of aging on the immune system. Numerous problems are encountered in studying this topic, the main one being the influence of concomitant disease. Despite the great efforts that have been devoted to research in this field, the results of studies performed to date have not been convincing and, until now, no sound scientific evidence has emerged to show that immunosenescence is clinically significant. The only possible exceptions to this are the discovery of a selective defect in cell-mediated immunity and the reactivation of varicella zoster virus. Therefore, many more, and better designed, studies will have to be conducted before the full clinical impact of immunosenescence can be delineated.

J Am Geriatr Soc 1997 Jul;45(7):813-817

Glucose metabolism in older adults: a study including subjects more than 80 years of age.

Garcia GV, Freeman RV, Supiano MA, Smith MJ, Galecki AT, Halter JB

Department of Internal Medicine, University of Michigan, Ann Arbor, USA.

OBJECTIVE: This study was undertaken to understand the dynamics of glucose metabolism in healthy non-diabetic subjects older than age 80 (old-old) compared with subjects aged 61 to 79 (young-old), as well as to compare healthy older subjects with impaired glucose tolerance (IGT) with older subjects with normal glucose tolerance (NGT). DESIGN: A cross sectional, observational study. SETTING: A university hospital clinical research center. PARTICIPANTS: There were 28 community-dwelling adults, 10 older than age 80 and 18 aged 61 to 79. Thirteen of these people had NGT and 15 had IGT. Subjects were not taking any medication that interfered with glucose tolerance. MEASUREMENTS: Status of glucose tolerance was determined by an oral glucose tolerance test categorized as NGT or IGT according to WHO criteria. Insulin sensitivity (SI) and glucose effectiveness (SG) were assessed using a tolbutamide-assisted intravenous glucose tolerance test (IVGTT). The data were analyzed using the Minmod modeling program. Glucose tolerance (K(g)) and the acute insulin response to glucose (AIRg) were calculated from the IVGTT. RESULTS: There were no significant differences between the young-old and old-old in body mass index or in plasma glucose, insulin, or C-peptide levels in the fasting state or during the OGTT. Values for K(g), SI, SG, and AIRg from the IVGTT were similar in the two age groups. When the subjects were classified by glucose tolerance status, the subjects with NGT had age, gender, and body mass index similar to the subjects with IGT. Older people with IGT had a lower K(g) and tended to have higher fasting glucose and similar fasting insulin compared with people with NGT. IGT subjects had lower SI and tended to have lower SG. The AIRg in IGT subjects tended to be low rather than high when compared with older people with NGT. CONCLUSION: Otherwise healthy adults more than 80 years of age have measures of glucose metabolism similar to people aged 61 to 79. The presence of IGT in older adults is associated with insulin resistance, regardless of patient age. We hypothesize that the lack of pancreatic islet compensation for insulin resistance may contribute to impaired glucose tolerance in older adults.



An internal ARC road map

Back to Home Page.

Recent Books


Bio tool box

Upcoming Events

Biotech Companies

Bill Board - Research Opportunities, Calls For Research and News