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SRT1720, a sirtuin1-activator, and metformin (MET), an antidiabetic drug, confer health and life-span benefits when administered individually. It is unclear whether combination of the two compounds could lead to additional benefits. Groups of 56-week-old C57BL/6J male mice were fed a high-fat diet (HFD) alone or supplemented with either SRT1720 (2 g/kg food), a high dose of MET (1% wt/wt food), or a combination of both. Animals were monitored for survival, body weight, food consumption, body composition, and rotarod performance. Mice treated with MET alone did not have improved longevity, and life span was dramatically reduced by combination of MET with SRT1720. Although all groups of animals were consuming similar amounts of food, mice on MET or MET + SRT1720 showed a sharp reduction in body weight. SRT1720 + MET mice also had lower percent body fat combined with better performance on the rotarod compared to controls. These data suggest that co-treatment of SRT1720 with MET is detrimental to survival at the doses used and, therefore, risk-benefits of combining life-span-extending drugs especially in older populations needs to be systematically evaluated.

In the last two decades, great strides were made in our ability to extend the life span of model organisms through dietary and other manipulations. Survival curves provide evidence of altered aging processes but are uninformative on what lead to that increase in life span. Longitudinal assessments of health and function during intervention studies could help in the identification of predictive biomarkers for health and survival. Comparable biomarkers of healthspan are necessary to effectively translate interventions into human clinical trials. Gait speed is a well-established predictive biomarker of healthspan in humans for risk of disability, health outcomes and mortality, and is relatively simple to assess noninvasively in rodents. In this study, we assessed and compared gait speed in males from two species (mice and humans), from young adulthood to advanced old age. Although gait speed decreases nonlinearly with age in both species, the underlying drivers of this change in gait speed were different, with humans exhibiting a shortened step length, and mice displaying a decrease in cadence. Future longitudinal and interventional studies in mice should examine the predictive value of longitudinal declines in gait speed for health and survival.

The nutrient sensing protein, SIRT1 influences aging and nutritional interventions such as caloric restriction in animals, however, the role of SIRT1 in human aging remains unclear. Here, the role of SIRT1 single-nucleotide polymorphisms (SNPs) and serum-induced SIRT1 protein expression (a novel assay that detects circulating factors that influence SIRT1 expression in vitro) were studied in the Concord Health and Ageing in Men Project (CHAMP), a prospective cohort of community dwelling men aged 70 years and older. Serum-induced SIRT1 expression was not associated with age or mortality, however participants within the lowest quintile were less likely to be frail (odds ratio (OR) 0.34, 95% confidence interval (CI) 0.17–0.69, N = 1,309). Serum-induced SIRT1 expression was associated with some markers of body composition and nutrition (height, weight, body fat and lean % mass, albumin, and cholesterol) but not disease. SIRT1 SNPs rs2273773, rs3740051, and rs3758391 showed no association with age, frailty, or mortality but were associated with weight, height, body fat and lean, and albumin levels. There were some weak associations between SIRT1 SNPs and arthritis, heart attack, deafness, and cognitive impairment. There was no association between SIRT1 SNPs and the serum-induced SIRT1 assay. SIRT1 SNPs and serum-induced SIRT1 expression in older men may be more closely associated with nutrition and body composition than aging and age-related conditions. NHMRC 512364, Sydney Medical School Foundation, Ageing and Alzheimers Research

Calorie restriction (CR) retards aging and extends mean and maximal life span in most species tested (1 ). However, whether prolonged CR increases life span in long-lived species (such as primates) is still controversial. Although two independent studies addressing the effects of CR in monkeys have shown different outcomes on life span, both converge into the fact that CR delays the onset and impact of age-related diseases (,3). In humans, the evidence of 2beneficial effects of CR derives from observational stud-ies in longer-lived population in Okinawa, Japan () and 4from individuals who self-impose CR (,6). In the lat5 -ter, severe food restriction causes several metabolic and molecular changes associated with CR in animals that protect against age-related pathologies, including changes in markers for type 2 diabetes, hypertension, cardiovas-cular disease, cancer, and dementia (). However, only a 7limited number of people have the discipline to follow the duration and severity of the CR regimen that is required for optimal benefits. In light of this, it became an impor-tant research objective to assess the feasibility, safety, and health-related outcomes of prolonged CR in a well-con-trolled human clinical trial.In this edition of the

This article investigates the effect on the mouse frailty index (FI), of factors known to influence lifespan and healthspan in mice: strain (short-lived DBA/2J mice vs long-lived C57BL/6J mice), calorie restriction (CR), and resveratrol treatment. The mouse FI, based on deficit accumulation, was recently validated in C57BL/6J mice by Whitehead JC, Hildebrand BA, Sun M, et al. (A clinical frailty index in aging mice: comparisons with frailty index data in humans. J Gerontol A Biol Sci Med Sci. 2014;69:621-632) and shares many characteristics of the human FI. FI scores were measured in male and female aged (18 months) ad-libitum fed and CR DBA/2J and C57BL/6J mice, as well as male aged (24 months) C57BL/6J mice ad-libitum fed with or without resveratrol (100 mg/kg/day) in the diet for 6 months. Mean scores of two raters were used, and the raters had excellent inter-rater reliability (ICC = 0.88, 95% CI [0.80, 0.92]). Furthermore, the interventions of CR and resveratrol were associated with a significant reduction in FI scores in C57BL/6J mice, compared to age-matched controls. The short-lived DBA/2J mice also had slightly higher FI scores than the C57BL/6J mice, for the male calorie-restricted groups (DBA/2J FI = 0.16±0.03, C57BL/6J FI = 0.11±0.03, p = .01). This study uses the mouse FI developed by Whitehead JC, Hildebrand BA, Sun M, et al. (A clinical frailty index in aging mice: comparisons with frailty index data in humans. J Gerontol A Biol Sci Med Sci. 2014;69:621-632) in a different mouse colony and shows that this tool can be applied to quantify the effect of dietary and pharmaceutical interventions on frailty.

Imbalance between proliferation and cell death accounts for several age-linked diseases. Aging, calorie restriction (CR), and fat source are all factors that may influence apoptotic signaling in liver, an organ that plays a central metabolic role in the organism. Here, we have studied the combined effect of these factors on a number of apoptosis regulators and effectors. For this purpose, animals were fed diets containing different fat sources (lard, soybean oil, or fish oil) under CR for 6 or 18 months. An age-linked increase in the mitochondrial apoptotic pathway was detected with CR, including a decrease in Bcl-2/Bax ratio, an enhanced release of cytochrome c to the cytosol and higher caspase-9 activity. However, these changes were not fully transmitted to the effectors apoptosis-inducing factor and caspase-3. CR (which abated aging-related inflammatory responses) and dietary fat altered the activities of caspases-8, -9, and -3. Apoptotic index (DNA fragmentation) and mean nuclear area were increased in aged animals with the exception of calorie-restricted mice fed a lard-based fat source. These results suggest possible protective changes in hepatic homeostasis with aging in the calorie-restricted lard group.

N the seminal 1935 publication, McCay and colleagues (1) reported that calorie restriction increased lifespan of white rats. Their primary hypothesis was that “a slow rate of growth results in an increased lifespan.” In order to slow the rate of growth, the food provided to the rats was down-titrated to maintain slow growth and a low body weight, whereas the control rats had unlimited access to food. This work has been cited over 1,300 times and has led to the dogma that calorie restriction is the most robust interven-tion to delay ageing. The conclusion has been replicated across taxa (2), and there are health benefits—if not longev-ity extension—seen in humans (3) and nonhuman primates (4). The relationship between calorie intake and ageing has led to important insights into the molecular switches (tar-get of rapamycin, sirtuins, insulin/IGF-1/growth hormone, 5′ adenosine monophosphate-activated protein kinase) that interface between dietary intake and those cellular pro-cesses (mitochondrial function, autophagy, DNA repair, oxidative stress) that influence the rate of ageing (5).Albert Einstein has been attributed with the comment that “everything should be as simple as it can be, but not simpler.” Is it too simple to conclude that just a reduction in energy intake delays ageing? Indeed there now are bur-geoning numbers of studies that show there is considerable complexity in the effects of various nutritional interventions on ageing. For example, there have been many attempts to compare the effects of calorie restriction against reduction of various components of the diet such as the macronutri-ents (fat, carbohydrates, and protein). One of the very first of these studies was undertaken by McCay who in 1928 reported a study where trout were fed many diets differing in micro- and macronutrient content. They found that those trout that lived the longest were fed the low-protein diets (6). Subsequent studies on protein restriction have reported mixed results but generally concluded that it is energy restriction rather than specific macronutrients that impact on ageing (7).However, one complication of only manipulating the ratio of protein to other nutrients in diets is that some animals use compensatory feeding when the balance of nutrients in their food is not optimal. The protein content of food is par -ticularly influential in driving energy intake and appetite. In a response called “protein leverage,” animals including humans tend to overconsume calories when presented with a low-protein diet, and vice versa (8,9). Therefore, simply reducing the amount of protein in the diet may not have any impact on protein intake if animals have adequate access to food—they will simply increase their total food until they achieve their protein target. Therefore, it is important that studies carefully measure and report food intake, particu-larly in ad libitum-fed animals.One approach that has been utilized to deconvolute the complex interactions between macronutrient intake and ageing is the geometric framework. This analytical method allows for the examination of the independent and inter-active effects of multiple nutritional components (energy, fat, carbohydrate, protein) on outcome data such as ageing (8,10,11). When this geometric framework method was applied to nutritional experiments in

We analyzed ultrastructural changes and markers of fission/fusion in hepatocyte mitochondria from mice submitted to 40% calorie restriction (CR) for 6 months versus ad-libitum-fed controls. To study the effects of dietary fat under CR, animals were separated into three CR groups with soybean oil (also in controls), fish oil, and lard. CR induced differential changes in hepatocyte and mitochondrial size, in the volume fraction occupied by mitochondria, and in the number of mitochondria per hepatocyte. The number of cristae per mitochondrion was significantly higher in all CR groups compared with controls. Proteins related to mitochondrial fission (Fis1 and Drp1) increased with CR, but no changes were detected in proteins involved in mitochondrial fusion (Mfn1, Mfn2, and OPA1). Although many of these changes could be attributed to CR regardless of dietary fat, changing membrane lipid composition by different fat sources did modulate the effects of CR on hepatocyte mitochondria., This work was supported by NIH grant 1R01AG028125-01A1 (to J.J.R., P.N., and J.M.V.), Ministerio de Economía y Competitividad BFU2011-23578 (to J.M.V.), Junta de Andalucía Proyectos de Excelencia grant P09-CVI-4887 (to J.M.V.), Junta de Andalucía Proyectos Internacionales grant (to J.M.V.), and BIO-276 (Junta de Andalucía and the University of Córdoba, to J.M.V.). H.K. was funded by a predoctoral fellowship of the Agencia Española de Cooperación Internacional al Desarrollo and BIO-276. J.A.L.D. was funded by a predoctoral fellowship of the Spanish Ministerio de Educación and BIO-276.

We investigated the effect of age-related pseudocapillarization of the liver sinusoidal endothelium on the hepatic disposition of acetaminophen. The multiple indicator dilution technique assessed the hepatic disposition of tracer (14)C-acetaminophen and reference markers in isolated perfused livers of young (n = 11) and old (n = 12) rats. Electron microscopy confirmed defenestration of the sinusoidal endothelium in old rats compared with young rats. Acetaminophen recovery following a single pass through the liver was significantly increased in old rats (0.64 ± 0.04, old; 0.59 ± 0.05, young; p < .05). In old age, there was significant reduction of the intercompartmental rate constant k(1) (0.34 ± 0.10 s(-1), old; 0.61 ± 0.38 s(-1), young; p < .05) and the permeability-surface area product for the transfer of acetaminophen across the sinusoidal endothelium (0.034 ± 0.006 mL/s/g, old; 0.048 ± 0.014 mL/s/g, young; p < .005). There was no difference in k(3), the measure of sequestration of acetaminophen that reflects enzyme activity. Age-related pseudocapillarization of the liver sinusoid resulted in increased acetaminophen recovery and decreased transfer of acetaminophen into the liver.

Nuclear factor E2–related factor-2 (Nrf2) transcription factor is one of the main regulators of intracellular redox balance and a sensor of oxidative and electrophilic stress. Low Nrf2 activity is usually associated with carcinogenesis, but Nrf2 is also considered as an oncogene because it increases survival of transformed cells. Because intracellular redox balance alterations are involved in both senescence and tumorigenesis, we investigated the impact of Nrf2 genetic deletion on cellular immortalization and life span of murine embryonic fibroblasts. We report that Nrf2 genetic deletion promotes immortalization due to an early loss of p53-dependent gene expression. However, compared with control cells, immortalized Nrf2−/− murine embryonic fibroblasts exhibited decreased growth, lower cyclin E levels, and impaired expression of NQO1 and cytochrome b5 reductase. Moreover, SirT1 was also significantly reduced in immortalized Nrf2−/− murine embryonic fibroblasts, and these cells exhibited shorter life span. Our results underscore the dual role of Nrf2 in protection against carcinogenesis and in the delay of cellular aging.