The need for multiple time points in aging studies

Age-dependent changes in myocardial matrix metalloproteinase/tissue inhibitor of metalloproteinase profiles and fibroblast function

“…Linear regressions were performed to determine relationships between groups, using age as the independent variable. Changes that occurred with aging were divided into four types: (1) changes that continually progressed in the same direction from the young to MA to old groups; (2) changes that occurred from the young to MA group and then remained stable in the old group; (3) changes that occurred only in the old group; and (4) changes that occurred in one direction in MA and then reversed direction in the old group [32].…”

“…The changes in MMP levels between MA and old groups indicate a change in myocardial ECM composition, while LV mass is still maintained. The use of three time points allowed nonlinear changes to be assessed and the rate of change to be determined [32]. Interestingly, changes in total MMP levels from the pooled fractions mirrored changes in the soluble but not insoluble fraction.…”

Early and Simultaneous Emergence of Multiple Hippocampal Biomarkers of Aging Is Mediated by Ca2+-Induced Ca2+Release

“…Although there is wide recognition of the value of examining intermediate age points in biological aging research (Miller and Nadon, 2000;Coleman et al, 2004), the age of first appearance has not been determined with high resolution for most brain biomarkers. Nevertheless, age-of-onset data can provide important insights into the sequence and potential mechanistic interactions of multiple age-dependent processes.…”

Microglia, Calcification and Neurodegenerative Diseases

“…This reduced vulnerability may be related to several factors: for example, age-associated variations in the relative abundance of glutamate receptors and pre-synaptic alterations of glutamate release may explain, at least in part, an increased resistance to excitotoxicity in the hippocampus (Mullany et al, 1996, Nicolle et al, 1996. This effect is compatible with the increased vulnerability to excitotoxicity observed in the oldest animals (Brouillet et al, 1993), since some of the factors responsible for injury resistance may follow a biphasic pattern, with a progressive increase until reaching maturity followed by a subsequent decrease (Coleman et al, 1990). Many authors have also described biphasic variations in several parameters during aging, with an opposite tendency before and after middle age (Villa et al, 1994).…”