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Old Animals (old + animals)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

Comparing methods for analysing mortality profiles in zooarchaeological and palaeontological samples

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2005
T. E. Steele
Abstract In this study, I examine three methods that are currently used for comparing mortality profiles from zooarchaeological and palaeontological samples: (1) histograms with 10% of life-span age classes; (2) boxplots showing tooth crown height medians; and (3) triangular plots of the proportions of young, prime and old animals. I assess the advantages and disadvantages of each method using data collected on two samples of Northern Yellowstone elk (Cervus elaphus nelsoni) with known, or cementum annuli-determined, ages at death. One sample was hunted by wolves (n,=,96), and the other was hunted by recent humans using rifles (n,=,226). I tested each method with the known or cementum annuli age distributions and with age estimation techniques appropriate for archaeological assemblages. Histograms are best used when the relationship between dental eruption/attrition and age is well established so that individuals can be confidently assigned into 10% of life-span groups, and when more than 30 or 40 individuals are present in the assemblage. Boxplots employ raw crown heights, thus removing the error introduced by assigning specimens to age classes, and therefore they allow the analysis of species where the relationship between dental eruption/attrition and age is unknown. Confidence intervals around the medians allow samples to be statistically compared. Triangular plots are easy to use and allow multiple samples and species to be considered simultaneously, but samples cannot be statistically compared. Modified triangular plots bootstrap samples to provide 95% confidence ellipses, allowing for statistical comparisons between samples. When possible, samples should be examined using multiple methods to increase confidence in the results. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Diminished contraction-induced intracellular signaling towards mitochondrial biogenesis in aged skeletal muscle

AGING CELL, Issue 4 2009
Vladimir Ljubicic
Summary The intent of this study was to determine whether aging affects signaling pathways involved in mitochondrial biogenesis in response to a single bout of contractile activity. Acute stimulation (1 Hz, 5 min) of the tibialis anterior (TA) resulted in a greater rate of fatigue in old (36 month), compared to young (6 month) F344XBN rats, which was associated with reduced ATP synthesis and a lower mitochondrial volume. To investigate fiber type-specific signaling, the TA was sectioned into red (RTA) and white (WTA) portions, possessing two- to 2.5-fold differences in mitochondrial content. The expression and contraction-mediated phosphorylation of p38, MKK3/6, CaMKII and AMPK, were assessed. Kinase protein expression tended to be higher in fiber sections with lower mitochondrial content, such as the WTA, relative to the RTA muscle, and this was exaggerated in tissues from senescent, compared to young animals. At rest, kinase activation was generally similar between young and old animals, despite the age-related variations in mitochondrial volume. In response to contractile activity, age did not influence the signaling of these kinases in the high-oxidative RTA muscle. However, in the low-oxidative WTA muscle, contraction-induced kinase activation was attenuated in old animals, despite the greater metabolic stress imposed by contractile activity in this muscle. Thus, the reduction of contraction-evoked kinase phosphorylation in muscle from old animals is fiber type-specific, and depends on factors which are, in part, independent of the metabolic milieu within the contracting fibers. These findings imply that the downstream consequences of kinase signaling are reduced in aging muscle. [source]

Circadian and age-related changes in stress responsiveness of the adrenal cortex and erythrocyte antioxidant enzymes in female rhesus monkeys

JOURNAL OF MEDICAL PRIMATOLOGY, Issue 5 2008
Nadezhda D. Goncharova
Abstract Background, The objective of this study was to evaluate the role of the adrenal cortex in the regulation of antioxidant enzyme defense and to characterize this regulation in different age periods. Methods, Five young and five old female rhesus monkeys were subjected to 2 hours squeeze cage restraint stress at 0900 or 1500 hours. Plasma levels of corticosteroids and activities of erythrocyte antioxidant enzymes were measured before the stress and 30, 60, 120, 240 minutes after beginning of the stress. Results, Young monkeys showed a circadian rhythm in stress responsiveness as measured by corticosteroids and glutathione reductase. The rhythm was attenuated in old animals. Age-related changes in the overall level of response to the afternoon stress were also seen in the corticosteroid and glutathione reductase measures. Conclusions, The study demonstrated that corticosteroids play an essential role in the regulation of antioxidant enzyme defense in stress conditions and that the reliability of their regulation decreases with age. [source]

The age-related decrease in CNS remyelination efficiency is caused by an impairment of both oligodendrocyte progenitor recruitment and differentiation

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 2 2002
C. Zhao
Developing strategies to reverse the age-associated decline in CNS remyelination requires the identification of how the regenerative process is impaired. We have addressed whether remyelination becomes slower because of an impairment of recruitment of oligodendrocyte progenitors (OPs) or, an impairment of OP differentiation into remyelinating oligodendrocytes. The OP response during remyelination of focal, toxin-induced CNS demyelination in young and old rats was compared by in situ hybridization using probes to PGDF-,R, and the OP transcription factor, MyT1. The expression patterns for both OP markers are very similar and reveal a delay in the colonization of the demyelinated focus with OPs in the old animals compared to young. By comparing the mRNA expression pattern MyT1 with that of the myelin proteins MBP and Gtx, we have found that in the old animals there is also a delay in OP differentiation, which increases with longer survival times. These results indicate that the age-associated decrease in remyelination efficiency occurs because of an impairment of OP recruitment and their subsequent differentiation into remyelinating oligodendrocytes, and that strategies aimed at ameliorating the age-associated decline in remyelination efficiency will therefore need to promote both components of the regenerative process. [source]

Evaluation of Baccharis trimera and Davilla rugosa in tests for adaptogen activity

PHYTOTHERAPY RESEARCH, Issue 6 2007
Fúlvio Rieli Mendes
Abstract Baccharis trimera (Asteraceae) and Davilla rugosa (Dilleniaceae) are used popularly as tonics, aphrodisiacs and for stomach ailments, among other uses. Hydroalcohol extracts of the aerial parts of both plants were investigated with regard to their chemical constitution and their pharmacological activity in tests that evaluate adaptogen activity. Alkaloids, flavonoids, saponins, polyphenols/tannins and coumarins were identified in both extracts, while lignans were found only in the extract of Davilla rugosa. This extract presented also a marked antioxidant activity and exerted a moderate antiulcer effect in rats submitted to cold immobilization stress. It did not, however, inhibit the increase in the levels of ACTH and corticosterone induced by stress. Moreover, the Davilla rugosa did not improve the physical performance of mice submitted to forced exercise and the learning time of old rats in the T-maze, neither did it reduce the blood viscosity of the old animals. Conversely, the Baccharis trimera extract only presented a moderate antioxidant activity, without any positive effect on the other tests. These results point to the absence of an adaptogen activity of Baccharis trimera, with some effects that could be related to such an activity as regards the Davilla rugosa. Copyright © 2007 John Wiley & Sons, Ltd. [source]