The plasma metabolome is associated with preservation of physiological function following lifelong aerobic exercise in mice

Declines in physiological function with aging are strongly linked to age-related diseases. Lifelong voluntary aerobic exercise (LVAE) preserves physiological function with aging, possibly by increasing cellular quality control processes, but the circulating molecular transducers mediating these processes are incompletely understood. The plasma metabolome may predict biological aging and is impacted by a single bout of aerobic exercise. Here, we conducted an ancillary analysis using plasma samples, and physiological function data, from previously reported studies of LVAE in male C57BL/6N mice randomized to LVAE (wheel running) or sedentary (SED) (n = 8-9/group) to determine if LVAE alters the plasma metabolome and whether these changes correlated with preservation of physiological function with LVAE. Physical function (grip strength, coordination, and endurance) was assessed at 3 and 18 months of age; vascular endothelial function and the plasma metabolome were assessed at 19 months. Physical function was preserved (%decline; mean ± SEM) with LVAE vs SED (all p < 0.05)-grip strength, 0.4 ± 1.7% vs 12 ± 4.0%; coordination, 10 ± 4% vs 73 ± 10%; endurance, 1 ± 15% vs 61 ± 5%. Vascular endothelial function with LVAE (88.2 ± 2.0%) was higher than SED (79.1 ± 2.5%; p = 0.03) and similar to the young controls (91.4 ± 2.9%). Fifteen metabolites were different with LVAE compared to SED (FDR < 0.05) and correlated with the preservation of physiological function. Plasma spermidine, a polyamine that increases cellular quality control (e.g., autophagy), correlated with all assessed physiological indices. Autophagy (LC3A/B abundance) was higher in LVAE skeletal muscle compared to SED (p < 0.01) and inversely correlated with plasma spermidine (r =  - 0.5297; p = 0.054). These findings provide novel insight into the circulating molecular transducers by which LVAE may preserve physiological function with aging.

Role of the circulating milieu in age-related arterial dysfunction: a novel ex vivo approach

The circulating milieu, bioactive molecules in the bloodstream, is altered with aging and interfaces constantly with the vasculature. This anatomic juxtaposition suggests that circulating factors may actively modulate arterial function. Here, we developed a novel, translational experimental model that allows for direct interrogation of the influence of the circulating milieu on age-related arterial dysfunction (aortic stiffening and endothelial dysfunction). To do so, we exposed young and old mouse arteries to serum from young and old mice and young and midlife/older (ML/O) adult humans. We found that old mouse and ML/O adult human, but not young, serum stiffened young mouse aortic rings, assessed via elastic modulus (mouse and human serum, P = 0.003 vs. young serum control), and impaired carotid artery endothelial function, assessed by endothelium-dependent dilation (EDD) (mouse serum, P < 0.001; human serum, P = 0.006 vs. young serum control). Furthermore, young mouse and human, but not old, serum reduced aortic elastic modulus (mouse serum, P = 0.009; human serum, P < 0.001 vs. old/MLO serum control) and improved EDD (mouse and human serum, P = 0.015 vs. old/MLO serum control) in old arteries. In human serum-exposed arteries, in vivo arterial function assessed in the human donors correlated with circulating milieu-modulated arterial function in young mouse arteries (aortic stiffness, r = 0.634, P = 0.005; endothelial function, r = 0.609, P = 0.004) and old mouse arteries (aortic stiffness, r = 0.664, P = 0.001; endothelial function, r = 0.637, P = 0.003). This study establishes novel experimental approaches for directly assessing the effects of the circulating milieu on arterial function and implicates changes in the circulating milieu as a mechanism of in vivo arterial aging.NEW & NOTEWORTHY Changes in the circulating milieu with advancing age may be a mechanism underlying age-related arterial dysfunction. Ex vivo exposure of young mouse arteries to the circulating milieu from old mice or midlife/older adults impairs arterial function whereas exposure of old mouse arteries to the circulating milieu from young mice or young adults improves arterial function. These findings establish that the circulating milieu directly influences arterial function with aging.

Intermittent supplementation with fisetin improves arterial function in old mice by decreasing cellular senescence

Cellular senescence and the senescence-associated secretory phenotype (SASP) contribute to age-related arterial dysfunction, in part, by promoting oxidative stress and inflammation, which reduce the bioavailability of the vasodilatory molecule nitric oxide (NO). In the present study, we assessed the efficacy of fisetin, a natural compound, as a senolytic to reduce vascular cell senescence and SASP factors and improve arterial function in old mice. We found that fisetin decreased cellular senescence in human endothelial cell culture. In old mice, vascular cell senescence and SASP-related inflammation were lower 1 week after the final dose of oral intermittent (1 week on-2 weeks off-1 weeks on dosing) fisetin supplementation. Old fisetin-supplemented mice had higher endothelial function. Leveraging old p16-3MR mice, a transgenic model allowing genetic clearance of p16INK4A -positive senescent cells, we found that ex vivo removal of senescent cells from arteries isolated from vehicle- but not fisetin-treated mice increased endothelium-dependent dilation, demonstrating that fisetin improved endothelial function through senolysis. Enhanced endothelial function with fisetin was mediated by increased NO bioavailability and reduced cellular- and mitochondrial-related oxidative stress. Arterial stiffness was lower in fisetin-treated mice. Ex vivo genetic senolysis in aorta rings from p16-3MR mice did not further reduce mechanical wall stiffness in fisetin-treated mice, demonstrating lower arterial stiffness after fisetin was due to senolysis. Lower arterial stiffness with fisetin was accompanied by favorable arterial wall remodeling. The findings from this study identify fisetin as promising therapy for clinical translation to target excess cell senescence to treat age-related arterial dysfunction.

Protective effects of apigenin on the brain transcriptome with aging

Brain aging is associated with reduced cognitive function that increases the risk for dementia. Apigenin is a bioactive plant compound that inhibits cellular aging processes and could protect against age-related cognitive dysfunction, but its mechanisms of action in the brain have not been comprehensively studied. We characterized brain transcriptome changes in young and old mice treated with apigenin in drinking water. We observed improved learning/memory in old treated mice, and our transcriptome analyses indicated that differentially expressed genes with aging and apigenin were primarily related to immune responses, inflammation, and cytokine regulation. Moreover, we found that genes/transcripts that were increased in old vs. young mice but downregulated with apigenin treatment in old animals were associated with immune activation/inflammation, whereas transcripts that were reduced with aging but increased with apigenin were related neuronal function and signaling. We also found that these transcriptome differences with aging and apigenin treatment were driven in part by glial cells. To follow up on these in vivo transcriptome findings, we studied aged astrocytes in vitro, and we found that apigenin reduced markers of inflammation and cellular senescence in these cells. Collectively, our data suggest that apigenin may protect against age-related cognitive dysfunction by suppressing neuro-inflammatory processes.

Effects of regular exercise on vascular function with aging: Does sex matter?

Vascular aging, featuring endothelial dysfunction and large elastic artery stiffening, is a major risk factor for the development of age-associated cardiovascular diseases (CVDs). Vascular aging is largely mediated by an excessive production of reactive oxygen species (ROS) and increased inflammation leading to reduced bioavailability of the vasodilatory molecule nitric oxide and remodeling of the arterial wall. Other cellular mechanisms (i.e., mitochondrial dysfunction, impaired stress response, deregulated nutrient sensing, cellular senescence), termed "hallmarks" or "pillars" of aging, may also contribute to vascular aging. Gonadal aging, which largely impacts women but also impacts some men, modulates the vascular aging process. Regular physical activity, including both aerobic and resistance exercise, is a first-line strategy for reducing CVD risk with aging. Although exercise is an effective intervention to counter vascular aging, there is considerable variation in the vascular response to exercise training with aging. Aerobic exercise improves large elastic artery stiffening in both middle-aged/older men and women and enhances endothelial function in middle-aged/older men by reducing oxidative stress and inflammation and preserving nitric oxide bioavailability; however, similar aerobic exercise training improvements are not consistently observed in estrogen-deficient postmenopausal women. Sex differences in adaptations to exercise may be related to gonadal aging and declines in estrogen in women that influence cellular-molecular mechanisms, disconnecting favorable signaling in the vasculature induced by exercise training. The present review will summarize the current state of knowledge on vascular adaptations to regular aerobic and resistance exercise with aging, the underlying mechanisms involved, and the moderating role of biological sex.

Cellular Senescence Contributes to Large Elastic Artery Stiffening and Endothelial Dysfunction With Aging: Amelioration With Senolytic Treatment

BACKGROUND

Here, we assessed the role of cellular senescence and the senescence associated secretory phenotype (SASP) in age-related aortic stiffening and endothelial dysfunction.

METHODS

We studied young (6-8 mo) and old (27-29 mo) p16-3MR mice, which allows for genetic-based clearance of senescent cells with ganciclovir (GCV). We also treated old C57BL/6N mice with the senolytic ABT-263.

RESULTS

In old mice, GCV reduced aortic stiffness assessed by aortic pulse wave velocity (PWV; 477±10 vs. 382±7 cm/s, P<0.05) to young levels (old-GCV vs. young-vehicle, P=0.35); ABT-263 also reduced aortic PWV in old mice (446±9 to 356±11 cm/s, P<0.05). Aortic adventitial collagen was reduced by GCV (P<0.05) and ABT-263 (P=0.12) in old mice. To show an effect of the circulating SASP, we demonstrated that plasma exposure from Old-vehicle p16-3MR mice, but not from Old-GCV mice, induced aortic stiffening assessed ex vivo (elastic modulus; P<0.05). Plasma proteomics implicated glycolysis in circulating SASP-mediated aortic stiffening. In old p16-3MR mice, GCV increased endothelial function assessed via peak carotid artery endothelium-dependent dilation (EDD; Old-GCV, 94±1% vs. Old-vehicle, 84±2%, P<0.05) to young levels (Old-GCV vs. young-vehicle, P=0.98), and EDD was higher in old C57BL/6N mice treated with ABT-263 vs. vehicle (96±1% vs. 82±3%, P<0.05). Improvements in endothelial function were mediated by increased nitric oxide (NO) bioavailability (P<0.05) and reduced oxidative stress (P<0.05). Circulating SASP factors related to NO signaling were associated with greater NO-mediated EDD following senescent cell clearance.

CONCLUSIONS

Cellular senescence and the SASP contribute to vascular aging and senolytics hold promise for improving age-related vascular function.

Anthracycline chemotherapy, vascular dysfunction and cognitive impairment: burgeoning topics and future directions

Anthracyclines, chemotherapeutic agents used to treat common forms of cancer, increase cardiovascular (CV) complications, thereby necessitating research regarding interventions to improve the health of cancer survivors. Vascular dysfunction, which is induced by anthracycline chemotherapy, is an established antecedent to overt CV diseases. Potential treatment options for ameliorating vascular dysfunction have largely been understudied. Furthermore, patients treated with anthracyclines have impaired cognitive function and vascular dysfunction is an independent risk factor for the development of mild cognitive impairment. Here, we will focus on: anthracycline chemotherapy associated CV diseases risk; how targeting mechanisms underlying vascular dysfunction may be a means to improve both CV and cognitive health; and research gaps and potential future directions for the field of cardio-oncology.

The effect of conjugated linoleic acids on inflammation, oxidative stress, body composition and physical performance: a comprehensive review of putative molecular mechanisms

Conjugated linoleic acids (CLAs) are polyunsaturated fatty acids primarily found in dairy products and ruminant animal products such as beef, lamb, and butter. Supplementation of CLAs has recently become popular among athletes due to the variety of health-promoting effects, including improvements in physical performance. Preclinical and some clinical studies have shown that CLAs can reduce inflammation and oxidative stress and favorably modulate body composition and physical performance; however, the results of previously published clinical trials are mixed. Here, we performed a comprehensive review of previously published clinical trials that assessed the role of CLAs in modulating inflammation, oxidative stress, body composition, and select indices of physical performance, emphasizing the molecular mechanisms governing these changes. The findings of our review demonstrate that the effect of supplementation with CLAs on inflammation and oxidative stress is controversial, but this supplement can decrease body fat mass and increase physical performance. Future well-designed randomized clinical trials are warranted to determine the effectiveness of (1) specific doses of CLAs; (2) different dosing durations of CLAs; (3) various CLA isomers, and the exact molecular mechanisms by which CLAs positively influence oxidative stress, inflammation, body composition, and physical performance.

Female C57BL/6N mice are a viable model of aortic aging in women

The aorta stiffens with aging in both men and women, which predicts cardiovascular mortality. Aortic wall structural and extracellular matrix (ECM) remodeling, induced in part by chronic low-grade inflammation, contribute to aortic stiffening. Male mice are an established model of aortic aging. However, there is little information regarding whether female mice are an appropriate model of aortic aging in women, which we aimed to elucidate in the present study. We assessed two strains of mice and found that in C57BL/6N mice, in vivo aortic stiffness (pulse wave velocity, PWV) was higher with aging in both sexes, whereas in B6D2F1 mice, PWV was higher in old vs. young male mice, but not in old vs. young female mice. Because the age-related stiffening that occurs in men and women was reflected in male and female C57BL/6N mice, we examined mechanisms of stiffening in this strain. In both sexes, aortic modulus of elasticity (pin myography) was lower in old mice, occurred in conjunction with and was related to higher plasma levels of the elastin-degrading enzyme matrix metalloproteinase-9 (MMP-9), and was accompanied by higher numbers of aortic elastin breaks and higher abundance of adventitial collagen-1. Plasma levels of the inflammatory cytokines interferon-γ, interleukin 6 and monocyte chemoattractant protein-1 were higher in both sexes of old mice. In conclusion, female C57BL/6N mice exhibit aortic stiffening, reduced modulus of elasticity, and structural/ECM remodeling, and associated increases in MMP-9 and systemic inflammation with aging, and thus are an appropriate model of aortic aging in women.

Aging, aerobic exercise, and cardiovascular health: Barriers, alternative strategies and future directions

Age-associated cardiovascular (CV) dysfunction, namely arterial dysfunction, is a key antecedent to the development of CV disease (CVD). Arterial dysfunction with aging is characterized by impaired vascular endothelial function and stiffening of the large elastic arteries, each of which is an independent predictor of CVD. These processes are largely mediated by an excess production of reactive oxygen species (ROS) and an increase in chronic, low-grade inflammation that ultimately leads to a reduction in bioavailability of the vasodilatory molecule nitric oxide. Additionally, there are other fundamental aging mechanisms that may contribute to excessive ROS and inflammation termed the "hallmarks of aging"; these additional mechanisms of arterial dysfunction may represent therapeutic targets for improving CV health with aging. Aerobic exercise is the most well-known and effective intervention to prevent and treat the effects of aging on CV dysfunction. However, the majority of mid-life and older (ML/O) adults do not meet recommended exercise guidelines due to traditional barriers to aerobic exercise, such as reduced leisure time, motivation, or access to fitness facilities. Therefore, it is a biomedical research priority to develop and implement time- and resource-efficient alternative strategies to aerobic exercise to reduce the burden of CVD in ML/O adults. Alternative strategies that mimic or are inspired by aerobic exercise, that target pathways specific to the fundamental mechanisms of aging, represent a promising approach to accomplish this goal.

A bench to bedside perspective on anthracycline chemotherapy-mediated cardiovascular dysfunction: challenges and opportunities. A symposium review

Cardiovascular diseases (CVD) are the leading cause of death worldwide and the risk of developing CVD is markedly increased following anthracycline chemotherapy treatment. Anthracyclines are an essential component of the cancer treatment regimen used for common forms of cancer in male and female children, adolescents, young adults, and older adults. Increased CVD risk with anthracyclines occurs, in part, due to vascular dysfunction-impaired endothelial function and arterial stiffening. These features of vascular dysfunction also play a major role in other common disorders observed following anthracycline treatment, including chronic kidney disease, dementia, and exercise intolerance. However, the mechanisms by which anthracycline chemotherapy induces and sustains vascular dysfunction are incompletely understood. This budding area of biomedical research is termed cardio-oncology, which presents the unique opportunity for collaboration between physicians and basic scientists. This symposium, presented at Experimental Biology 2022, provided a timely update on this important biomedical research topic. The speakers presented observations made at levels from cells to mice to humans treated with anthracycline chemotherapeutic agents using an array of translational research approaches. The speaker panel included a diverse mix of female and male investigators and unique insight from a cardio-oncology physician-scientist. Particular emphasis was placed on challenges and opportunities in this field as well as mechanisms that could be viewed as therapeutic targets leading to novel treatment strategies.

Initiation of 3,3-dimethyl-1-butanol at midlife prevents endothelial dysfunction and attenuates in vivo aortic stiffening with ageing in mice

Vascular dysfunction: develops progressively with ageing; increases the risk of cardiovascular diseases (CVD); and is characterized by endothelial dysfunction and arterial stiffening, which are primarily mediated by superoxide-driven oxidative stress and consequently reduced nitric oxide (NO) bioavailability and arterial structural changes. Interventions initiated before vascular dysfunction manifests may have more promise for reducing CVD risk than interventions targeting established dysfunction. Gut microbiome-derived trimethylamine N-oxide (TMAO) induces vascular dysfunction, is associated with higher CV risk, and can be suppressed by 3,3-dimethyl-1-butanol (DMB). We investigated whether DMB supplementation could prevent age-related vascular dysfunction in C57BL/6N mice when initiated prior to development of dysfunction. Mice received drinking water with 1% DMB or normal drinking water (control) from midlife (18 months) until being studied at 21, 24 or 27 months of age, and were compared to young adult (5 month) mice. Endothelial function [carotid artery endothelium-dependent dilatation (EDD) to acetylcholine; pressure myography] progressively declined with age in control mice, which was fully prevented by DMB via higher NO-mediated EDD and lower superoxide-related suppression of EDD (normalization of EDD with the superoxide dismutase mimetic TEMPOL). In vivo aortic stiffness (pulse wave velocity) increased progressively with age in controls, but DMB attenuated stiffening by ∼ 70%, probably due to preservation of endothelial function, as DMB did not affect aortic intrinsic mechanical (structural) stiffness (stress-strain testing) nor adventitial abundance of the arterial structural protein collagen. Our findings indicate that long-term DMB supplementation prevents/attenuates age-related vascular dysfunction, and therefore has potential for translation to humans for reducing CV risk with ageing. KEY POINTS: Vascular dysfunction, characterized by endothelial dysfunction and arterial stiffening, develops progressively with ageing and increases the risk of cardiovascular diseases (CVD). Interventions aimed at preventing the development of CV risk factors have more potential for preventing CVD relative to those aimed at reversing established dysfunction. The gut microbiome-derived metabolite trimethylamine N-oxide (TMAO) induces vascular dysfunction, is associated with higher CV risk and can be suppressed by supplementation with 3,3-dimethyl-1-butanol (DMB). In mice, DMB prevented the development of endothelial dysfunction and delayed and attenuated in vivo arterial stiffening with ageing when supplementation was initiated in midlife, prior to the development of dysfunction. DMB supplementation or other TMAO-suppressing interventions have potential for translation to humans for reducing CV risk with ageing.

Promoting healthy cardiovascular aging: emerging topics

The development of age-related cardiovascular (CV) dysfunction increases the risk of CV disease as well as other chronic age-associated disorders, including chronic kidney disease, and Alzheimer's disease and related dementias. Major manifestations of age-associated CV dysfunction that increase disease risk are vascular dysfunction, primarily vascular endothelial dysfunction and arterial stiffening, and elevated systolic blood pressure. Declines in nitric oxide bioavailability secondary to increased oxidative stress and inflammation are established mechanisms of CV dysfunction with aging. Moreover, fundamental mechanisms of aging, termed the "hallmarks of aging" extend to the CV system and, as such, may be considered "hallmarks of CV aging". These mechanisms represent viable therapeutic targets for treating CV dysfunction with aging. Healthy lifestyle behaviors, such as regular aerobic exercise and certain dietary patterns, are considered "first-line" strategies to prevent and/or treat age-associated CV dysfunction. Despite the well-established benefits of these strategies, many older adults do not meet the recommended guidelines for exercise or consume a healthy diet. Therefore, it is important to establish alternative and/or complementary evidence-based approaches to prevent or reverse age-related CV dysfunction. Targeting fundamental mechanisms of CV aging with interventions such as time-efficient exercise training, food-derived molecules, termed nutraceuticals, or select synthetic pharmacological agents represents a promising approach. In the present review, we will highlight emerging topics in the field of healthy CV aging with a specific focus on how exercise, nutrition/dietary patterns, nutraceuticals and select synthetic pharmacological compounds may promote healthy CV aging, in part, by targeting the hallmarks of CV aging.

Senolysis induced by 25-hydroxycholesterol targets CRYAB in multiple cell types

Cellular senescence is a driver of many age-related pathologies. There is an active search for pharmaceuticals termed senolytics that can mitigate or remove senescent cells in vivo by targeting genes that promote the survival of senescent cells. We utilized single-cell RNA sequencing to identify CRYAB as a robust senescence-induced gene and potential target for senolysis. Using chemical inhibitor screening for CRYAB disruption, we identified 25-hydroxycholesterol (25HC), an endogenous metabolite of cholesterol biosynthesis, as a potent senolytic. We then validated 25HC as a senolytic in mouse and human cells in culture and in vivo in mouse skeletal muscle. Thus, 25HC represents a potential class of senolytics, which may be useful in combating diseases or physiologies in which cellular senescence is a key driver.

Comparison of the Gauntlet Test With Standard Laboratory Measures of Aerobic Fitness

ABSTRACT

Burnsed-Torres, ML, Wichmann, TK, Clayton, ZS, and Hahn, ME. Comparison of the Gauntlet test with standard laboratory measures of aerobic fitness. J Strength Cond Res 36(2): 386-391, 2022-The purpose of this study was to validate whether the Gauntlet test (GT) can accurately estimate individual aerobic endurance performance compared with standard laboratory-based physiological tests. The GT required athletes to complete 5 maximal effort running stages, with a 1-minute break between each stage, with the goal of achieving the best overall time. Eighteen men (n = 9) and women (n = 9) (age, 23.5 ± 4.13 years; body mass index, 23.1 ± 7.62 kg·m-2; 5k time, 22 ± 7 minutes; 10k time, 47 ± 15 minutes; V̇o2max, 52.3 ± 8 ml·kg-1·min-1) completed a lactate threshold test and V̇o2max test (laboratory measures). Four to 14 days later, subjects completed the GT on an outdoor track. Blood lactate (bLa), V̇o2max, and heart rate (HR) were recorded during the laboratory session. Blood lactate, HR, stage completion time, and overall completion time were recorded during the GT. Linear regression correlation analyses revealed a significant inverse association between V̇o2max (mL·kg-1·min-1) and GT completion time (r = -0.88, P < 0.0001). In addition, there were significant correlations between V̇o2max maximum HR and GT maximum HR (r = 0.89, P < 0.0001) and V̇o2max 3-minute post bLa and GT 3-minute post bLa (r = 0.63, P = 0.0029). Sex-specific analysis showed significant inverse associations between female and male GT completion time and V̇o2max (r = -0.70, P = 0.0352; r = -0.94, P < 0.0002). Bland-Altman plots were used to evaluate concordance between GT completion time, V̇o2max, maximum HR, and 3-minute post bLa. Results suggest the GT is a valid assessment to accurately estimate aerobic endurance performance similar to standard laboratory methods.

Lifelong physical activity attenuates age- and Western-style diet-related declines in physical function and adverse changes in skeletal muscle mass and inflammation

It is unknown if consumption of a Western diet (WD; high-fat/sucrose), versus a non-WD (healthy diet), accelerates declines in physical function over the adult lifespan, and whether regular voluntary activity attenuates age- and WD-associated declines in function. Accordingly, we studied 4 cohorts of mice that consumed either normal chow [NC] or WD with or without access (sedentary, Sed) to voluntary wheel running [VWR] beginning at 3 mo of age. We assessed coordination, grip strength and endurance every 6 mo throughout life, and measured skeletal muscle mass and inflammation at 3 pre-determined ages (6-7, 13-14 and 19-20 mo). Age-related declines (% change 3-18 mo) in physical function were accelerated in WD-Sed versus NC-Sed (coordination: +47 ± 5%; grip strength: +18 ± 2%; endurance: +32 ± 5%; all p < 0.05). VWR attenuated declines in physical function within diet group (coordination: -31 ± 3% with WD-VWR; -18 ± 2% with NC-VWR; grip strength: -26 ± 2% with WD-VWR; -24 ± 2% with NC-VWR; endurance: -48 ± 4% with WD-VWR; -23 ± 6% with NC-VWR; all p < 0.05). Skeletal muscle mass loss and pro-inflammatory cytokine abundance were exacerbated by WD throughout life (mass: NC-Sed [-]7-28%, WD-Sed [-]17-40%; inflammation: NC-Sed [+]40-65%, WD-Sed [+]40-84%, all p < 0.05 versus NC-Sed), and attenuated by VWR (mass: NC-VWR, [-]0-10%, WD-VWR [-]0-10%; inflammation: NC-VWR [+]0-30%, WD-VWR [+]0-42%, all p < 0.05 versus diet-matched Sed group). Our results depict the temporal impairment of physical function over the lifespan in mice, acceleration of dysfunction with WD, the protective effects of voluntary exercise, and the potential associations with skeletal muscle mass and inflammation.

A positive effect of egg consumption on macular pigment and healthy vision: a systematic review and meta-analysis of clinical trials

Increasing macular pigment optical density (MPOD) as a result of increased macular concentration of lutein and zeaxanthin may reduce the risk of age-related macular degeneration (AMD). The aim of the present study was to determine whether the consumption of eggs, a rich source of dietary lutein and zeaxanthin, influences MPOD and serum lutein. In this systematic review and meta-analysis we searched PubMed, Scopus, and ISI Web of Science up to July 2020, for relevant randomized clinical trials. Using a random-effects model, pooled weighted mean differences, and standard deviations (SDs) for each outcome were obtained. The quality of the eligible studies was assessed by the Cochrane Collaboration's tool. A meta-analysis of five trials (296 participants) revealed that egg consumption significantly increased MPOD (weighted mean differences (WMD): +0.037; 95% CI: 0.004, 0.069; P = 0.027) and serum lutein (WMD: +0.150 μmol L̂-1; 95% CI: 0.037, 0.263; P = 0.009). Subgroup analyses showed that egg consumption: (a) had a larger effect on MPOD in studies with a parallel design; and (b) increased serum lutein to a greater extent in a healthy population. We did not detect any heterogeneity between studies. Daily egg consumption has beneficial effects on MPOD and serum lutein is inversely associated with reduced AMD progression. Further clinical trials are required to confirm the results of this study. © 2021 Society of Chemical Industry.

Effect of enteral immunomodulatory nutrition formula on mortality and critical care parameters in critically ill patients: A systematic review with meta-analysis

BACKGROUND

Enteral immunomodulatory nutrition is recommended as an adjuvant therapy for patients in intensive care units (ICU), but its effectiveness is incompletely understood.

AIM

The aim of this review was to examine the effect of a commonly used immunomodulatory formula-omega-3 fatty acids, γ-linolenic acid, and antioxidants-on clinical outcomes and mortality risk in critically ill patients.

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

METHOD

PubMed, Scopus, and Institute for Scientific Information (ISI) Web of Knowledge databases were searched until 18 February 2021. RCTs that used the immunomodulatory formula in the ICU were included.

RESULTS

Ten RCTs (1166 participants) were included in the meta-analysis. The immunomodulatory formula reduced the duration of ICU stay weighted mean difference [(WMD): -2.97 days; 95%CI: -5.59, -0.35)], mechanical ventilation (WMD = -2.20 days, 95%CI: -4.29, -0.10), sequential organ failure assessment and multiple organ dysfunction scores (Hedge's g: -0.42 U/L; 95% CI: -0.74, -0.11), decreased 8-day overall mortality risk (RR = 0.74, 95% CI: 0.58, 0.91), and extended the ICU-free days (WMD: 4.06 days, 95% CI: 0.02, 8.09). The improvement in respiratory function and reduction in mortality risk was more in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Furthermore, the reduction in mechanical ventilation and mortality risk was more evident in older (>60 years) vs young adults.

CONCLUSION AND RELEVANCE TO CLINICAL PRACTICE

Taken together, the immunomodulatory formula may enhance clinical practice for critical care nurses, such that the prevalence and/or susceptibility to secondary conditions commonly encountered in the ICU (ie, ALI and ARDS) could be attenuated, ultimately allowing critical care nurses to focus their care on the primary reason for which a patient is in the ICU. The study protocol was registered in PROSPERO.

Anthracycline chemotherapy-mediated vascular dysfunction as a model of accelerated vascular aging

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and age is by far the greatest risk factor for developing CVD. Vascular dysfunction, including endothelial dysfunction and arterial stiffening, is responsible for much of the increase in CVD risk with aging. A key mechanism involved in vascular dysfunction with aging is oxidative stress, which reduces the bioavailability of nitric oxide (NO) and induces adverse changes to the extracellular matrix of the arterial wall (e.g., elastin fragmentation/degradation, collagen deposition) and an increase in advanced glycation end products, which form crosslinks in arterial wall structural proteins. Although vascular dysfunction and CVD are most prevalent in older adults, several conditions can "accelerate" these events at any age. One such factor is chemotherapy with anthracyclines, such as doxorubicin (DOXO), to combat common forms of cancer. Children, adolescents and young adults treated with these chemotherapeutic agents demonstrate impaired vascular function and an increased risk of future CVD development compared with healthy age-matched controls. Anthracycline treatment also worsens vascular dysfunction in mid-life (50-64 years of age) and older (65 and older) adults such that endothelial dysfunction and arterial stiffness are greater compared to age-matched controls. Collectively, these observations indicate that use of anthracycline chemotherapeutic agents induce a vascular aging-like phenotype and that the latter contributes to premature CVD in cancer survivors exposed to these agents. Here, we review the existing literature supporting these ideas, discuss potential mechanisms as well as interventions that may protect arteries from these adverse effects, identify research gaps and make recommendations for future research.

Apigenin restores endothelial function by ameliorating oxidative stress, reverses aortic stiffening, and mitigates vascular inflammation with aging

We assessed the efficacy of oral supplementation with the flavanoid apigenin on arterial function during aging and identified critical mechanisms of action. Young (6 mo) and old (27 mo) C57BL/6N mice (model of arterial aging) consumed drinking water containing vehicle (0.2% carboxymethylcellulose; 10 young and 7 old) or apigenin (0.5 mg/mL in vehicle; 10 young and 9 old) for 6 wk. In vehicle-treated animals, isolated carotid artery endothelium-dependent dilation (EDD), bioassay of endothelial function, was impaired in old versus young (70% ± 9% vs. 92% ± 1%, P < 0.0001) due to reduced nitric oxide (NO) bioavailability. Old mice had greater arterial reactive oxygen species (ROS) production and oxidative stress (higher nitrotyrosine) associated with greater nicotinamide adenine dinucleotide phosphate oxidase (oxidant enzyme) and lower superoxide dismutase 1 and 2 (antioxidant enzymes); ex vivo administration of Tempol (antioxidant) restored EDD to young levels, indicating ROS-mediated suppression of EDD. Old animals also had greater aortic stiffness as indicated by higher aortic pulse wave velocity (PWV, 434 ± 9 vs. 346 ± 5 cm/s, P < 0.0001) due to greater intrinsic aortic wall stiffness associated with lower elastin levels and higher collagen, advanced glycation end products (AGEs), and proinflammatory cytokine abundance. In old mice, apigenin restored EDD (96% ± 2%) by increasing NO bioavailability, normalized arterial ROS, oxidative stress, and antioxidant expression, and abolished ROS inhibition of EDD. Moreover, apigenin prevented foam cell formation in vitro (initiating step in atherosclerosis) and mitigated age-associated aortic stiffening (PWV 373 ± 5 cm/s) by normalizing aortic intrinsic wall stiffness, collagen, elastin, AGEs, and inflammation. Thus, apigenin is a promising therapeutic for arterial aging.NEW & NOTEWORTHY Our study provides novel evidence that oral apigenin supplementation can reverse two clinically important indicators of arterial dysfunction with age, namely, vascular endothelial dysfunction and large elastic artery stiffening, and prevents foam cell formation in an established cell culture model of early atherosclerosis. Importantly, our results provide extensive insight into the biological mechanisms of apigenin action, including increased nitric oxide bioavailability, normalization of age-related increases in arterial ROS production and oxidative stress, reversal of age-associated aortic intrinsic mechanical wall stiffening and adverse remodeling of the extracellular matrix, and suppression of vascular inflammation. Given that apigenin is commercially available as a dietary supplement in humans, these preclinical findings provide the experimental basis for future translational studies assessing the potential of apigenin to treat arterial dysfunction and reduce cardiovascular disease risk with aging.

Chronic ethanol consumption does not reduce true bone density in male Wistar rats

Osteoporosis is characterized by reduced bone mineral density (BMD) and increased bone fragility, which may be modified by lifestyle behaviors. In observational studies, chronic moderate ethanol consumption is associated with higher BMD, but results are inconsistent and underlying mechanisms are unknown. To understand the influence of chronic ethanol consumption on true bone density (Archimedes principal), bone mechanical properties (Young's Modulus of bend), and osteogenic gene expression, 12-month-old male Wistar rats were randomly assigned to a control group or ethanol intervention (20% ethanol in drinking water on alternate days) group for 13 weeks and tibiae and femurs were collected. Blood was collected to assess alcohol content and antioxidant enzyme activities. We hypothesized that chronic ethanol consumption would increase true bone density and mechanical properties and increase osteoblastic gene expression and serum antioxidant enzyme activity. Ethanol consumption did not influence femoral or tibial true bone density but did result in lower tibial Young's modulus of bend (p = 0.0002). However, there was no influence of ethanol on other measures of mechanical properties. Femoral pro-osteoclastic gene expression of Dkk1 was lower (p = 0.0006) and pro-osteoblastic gene expression of Ctnnb1 was higher (p = 0.02) with ethanol consumption. We observed no differences in circulating antioxidant activities between groups, other than a tendency for greater (p = 0.08) glutathione peroxidase in the ethanol group. Results showed chronic ethanol consumption did not influence true bone density, only modestly reduced tibial mechanical properties (lower Young's modulus of bend), and moderately impacted expression of genes within the femur known to regulate both osteoblast and osteoclast activities.

Gut Microbiome-Derived Metabolite Trimethylamine N-Oxide Induces Aortic Stiffening and Increases Systolic Blood Pressure With Aging in Mice and Humans

[Figure: see text].

Tumor Necrosis Factor Alpha-Mediated Inflammation and Remodeling of the Extracellular Matrix Underlies Aortic Stiffening Induced by the Common Chemotherapeutic Agent Doxorubicin

[Figure: see text].

Exercise intensity influences plasma and sweat amino acid concentrations: a crossover trial

BACKGROUND

The purpose of this study was to explore the relationship between concentrations of amino acid (AA) and related metabolites in plasma and sweat obtained before and after exercise performed at different intensities and therefore different rates of sweat loss.

METHODS

Ten subjects completed a maximally ramped exercise test and three 30-min submaximal (45/60/75% VO2max) exercise bouts. Blood samples were collected before/after the exercise bouts and sweat was collected from the forearm throughout. Samples were analyzed for concentrations of AA and related molecules.

RESULTS

Sweat AA excretion rate was higher during the 60% bout compared to the 45% bout but was similar in comparison to the 75% indicating a plateau in rates of sweat AA losses as sweat rate increased. Plasma concentrations of AAs, urea, ammonia, and other non-proteinogenic AAs were not significantly different between exercise bouts performed at 45 and 60%. Exercise at 75% tended to reduce concentrations of sweat amino acids with significantly depressed concentrations of glycine, lysine, serine, threonine, histidine, arginine, tryptophan, aspartate and ornithine.

CONCLUSIONS

Overall, this research suggests that increasing exercise intensity increases AA metabolism as demonstrated by reduced plasma AA concentrations and increased excretion through sweat glands, which is mediated by a mechanism yet to be identified.

Lifelong voluntary aerobic exercise prevents age- and Western diet- induced vascular dysfunction, mitochondrial oxidative stress and inflammation in mice

KEY POINTS

The results of the present study establish the temporal pattern of age-related vascular dysfunction across the adult lifespan in sedentary mice consuming a non-Western diet, and the underlying mechanisms The results demonstrate that consuming a Western diet accelerates and exacerbates vascular ageing across the lifespan in sedentary mice They also show that lifelong voluntary aerobic exercise has remarkable protective effects on vascular function throughout the lifespan, in the setting of ageing alone, as well as ageing compounded by Western diet consumption Overall, the results indicate that amelioration of mitochondrial oxidative stress and inflammation are key mechanisms underlying the voluntary aerobic exercise-associated preservation of vascular function across the lifespan in both the presence and absence of a Western dietary pattern ABSTRACT: Advancing age is the major risk factor for cardiovascular diseases, driven largely by vascular endothelial dysfunction (impaired endothelium-dependent dilatation, EDD) and aortic stiffening (increased aortic pulse wave velocity, aPWV). In humans, vascular ageing occurs in the presence of differences in diet and physical activity, but the interactive effects of these factors are unknown. We assessed carotid artery EDD and aPWV across the lifespan in mice consuming standard (normal) low-fat chow (NC) or a high-fat/high-sucrose Western diet (WD) in the absence (sedentary, SED) or presence (voluntary wheel running, VWR) of aerobic exercise. Ageing impaired nitric oxide-mediated EDD (peak EDD 88 ± 12% 6 months P = 0.003 vs. 59 ± 9% 27 months NC-SED), which was accelerated by WD (60 ± 18% 6 months WD-SED). In NC mice, aPWV increased 32% with age (423 ± 13 cm/s at 24 months P < 0.001 vs. 321 ± 12 cm/s at 6 months) and absolute values were an additional ∼10% higher at any age in WD mice (P = 0.042 vs. NC-SED). Increases in aPWV with age in NC and WD mice were associated with 30-65% increases in aortic intrinsic wall stiffness (6 vs. 19-27 months, P = 0.007). Lifelong aerobic exercise prevented age- and WD-related vascular dysfunction across the lifespan, and this protection appeared to be mediated by mitigation of vascular mitochondrial oxidative stress and inflammation. Our results depict the temporal impairment of vascular function over the lifespan in mice, acceleration and exacerbation of that dysfunction with WD consumption, the remarkable protective effects of voluntary aerobic exercise, and the underlying mechanisms.

Doxorubicin-Induced Oxidative Stress and Endothelial Dysfunction in Conduit Arteries Is Prevented by Mitochondrial-Specific Antioxidant Treatment

Background

Doxorubicin (DOXO) chemotherapy increases risk for cardiovascular disease in part by inducing endothelial dysfunction in conduit arteries. However, the mechanisms mediating DOXO-associated endothelial dysfunction in (intact) arteries and treatment strategies are not established.

Objectives

We tested the hypothesis that DOXO impairs endothelial function in conduit arteries via excessive mitochondrial reactive oxygen species (ROS) and that these effects could be prevented by treatment with a mitochondrial-targeted antioxidant (MitoQ).

Methods

Endothelial function (endothelium-dependent dilation [EDD] to acetylcholine) and vascular mitochondrial ROS were assessed 4 weeks following administration (10 mg/kg intraperitoneal injection) of DOXO. A separate cohort of mice received chronic (4 weeks) oral supplementation with MitoQ (drinking water) for 4 weeks following DOXO.

Results

EDD in isolated pressurized carotid arteries was 55% lower 4 weeks following DOXO (peak EDD, DOXO: 42 ± 7% vs. sham: 94 ± 3%; p = 0.006). Vascular mitochondrial ROS was 52% higher and manganese (mitochondrial) superoxide dismutase was 70% lower after DOXO versus sham (p = 0.0008). Endothelial function was rescued by administration of the mitochondrial-targeted antioxidant, MitoQ, to the perfusate. Exposure to plasma from DOXO-treated mice increased mitochondrial ROS in cultured endothelial cells. Analyses of plasma showed differences in oxidative stress-related metabolites and a marked reduction in vascular endothelial growth factor A in DOXO mice, and restoring vascular endothelial growth factor A to sham levels normalized mitochondrial ROS in endothelial cells incubated with plasma from DOXO mice. Oral MitoQ supplementation following DOXO prevented the reduction in EDD (97 ± 1%; p = 0.002 vs. DOXO alone) by ameliorating mitochondrial ROS suppression of EDD.

Conclusions

DOXO-induced endothelial dysfunction in conduit arteries is mediated by excessive mitochondrial ROS and ameliorated by mitochondrial-specific antioxidant treatment. Mitochondrial ROS is a viable therapeutic target for mitigating arterial dysfunction with DOXO.

Late-life voluntary wheel running reverses age-related aortic stiffness in mice: a translational model for studying mechanisms of exercise-mediated arterial de-stiffening

Aortic stiffening, assessed as pulse-wave velocity (PWV), increases with age and is an important antecedent to, and independent predictor of, cardiovascular diseases (CVD) and other clinical disorders of aging. Aerobic exercise promotes lower levels of aortic stiffness in older adults, but the underlying mechanisms are incompletely understood, largely due to inherent challenges of mechanistic studies of large elastic arteries in humans. Voluntary wheel running (VWR) is distinct among experimental animal exercise paradigms in that it allows investigation of the physiologic effects of aerobic training without potential confounding influences of aversive molecular signaling related to forced exercise. In this study, we investigated whether VWR in mice may be a suitable model for mechanistic studies (i.e., "reverse translation") of the beneficial effects of exercise on arterial stiffness in humans. We found that 10 weeks of VWR in old mice (~ 28 months) reversed age-related elevations in aortic PWV assessed in vivo (Old VWR: 369 ± 19 vs. old sedentary: 439 ± 20 cm/s, P < 0.05). The de-stiffening effects of VWR were accompanied by normalization of age-related increases in ex vivo mechanical stiffness of aortic segments and aortic accumulation of collagen-I and advanced glycation end products, as well as lower levels of aortic superoxide and nitrotyrosine. Our results suggest that late-life VWR in mice recapitulates the aortic de-stiffening effects of exercise in humans and indicates important mechanistic roles for decreased oxidative stress and extracellular matrix remodeling. Therefore, VWR is a suitable model for further study of the mechanisms underlying beneficial effects of exercise on arterial stiffness.

A diet containing high- versus low-daidzein does not affect bone density and osteogenic gene expression in the obese Zucker rat model

Phytoestrogens are nonsteroidal plant compounds with similar chemical structures to mammalian estrogen capable of mimicking the effect of estrogen in selective tissues. A diet rich in phytoestrogens is associated with a variety of health benefits including decreased risks for heart disease, breast cancer, and osteoporosis. Obesity has long thought to be associated with improved bone density due to increased mechanical loading, but recent literature suggests obesity may actually decrease bone health. Daidzein, a soy-derived phytoestrogen, has been shown to improve parameters of bone health in lean animal models of osteoporosis but has not been tested in obese animals. Following a one-week acclimation to a standard AIN-93G diet, 19 five-week-old female obese Zucker rats (OZR) were randomly assigned to a modified AIN-93G diet containing either high daidzein (HD, 0.121 g kg-1 feed) or low daidzein (LD, 0.01 g kg-1 feed). After 8 weeks, tibias and femurs were removed to assess true density (Archimedes principal), mechanical strength (three-point bending test), and femoral osteogenic gene expression. Serum was collected to assess osteocalcin and deoxypyridinoline. Our results indicated that there were no significant differences between the measures for tibial or femoral true density or mechanical strength for the rats in the HD and LD diet groups. Similarly, there were no significant differences in gene expressions related to osteogenic pathways, or serum biomarkers of bone formation and resorption. Overall, an increased dose of daidzein from soy protein supplementation does not elicit an improvement in markers of bone health in obese Zucker rats.

Biochemical, Anthropometric, and Physiological Responses to Carbohydrate-Restricted Diets Versus a Low-Fat Diet in Obese Adults: A Randomized Crossover Trial

Some research supports high-fat carbohydrate (CHO)-restricted diets for weight and fat loss and improvement of cardiovascular disease risk factors. To test this, a randomized crossover study was designed. Subjects (17 obese men and women [BMI: 30-38 kg/m²]) were fed three diets (supplying 1600 and 2200 kilocalories (kcal)/day for women and men, respectively) for 4 weeks, with each trial separated by 4-week washout periods. One CHO-restricted diet (10% CHO, 50% fat, and 40% protein content) was rich in plant foods and mushrooms, while the other CHO-restricted diet included more animal foods (10% CHO, 60% fat, and 30% protein content). The third diet was lower in fat and protein content (LF) and higher in CHOs (61% CHO, 21% fat, and 18% protein content). Body composition was assessed through hydrostatic weighing before and after each diet trial. Fasting blood samples were collected weekly for analysis of hormones and lipids. Data were analyzed through repeated measures analysis of variance with post hoc paired comparison t-tests. Weight and fat loss were similar (P > .05) among trials. Subjects lost lean mass (P < .05) during CHO-restricted trials, but not in the LF trial. Insulin concentrations decreased (P < .05) during the CHO-restricted trial and tended (P = .05) to decrease during the LF trial. Total cholesterol decreased (P < .05) for all trials; however, high-density lipoprotein cholesterol decreased (P < .05) and triacylglycerols were higher (P < .05) following the LF trial. Taken together, energy restriction regardless of diet composition promoted similar weight loss; however, CHO-restricted diets based on either plants/mushrooms or animal foods elicited a more beneficial lipid-altering effect in comparison with the LF diet.

Honey does not adversely impact blood lipids of adult men and women: a randomized cross-over trial

Consumption of added sugars in the US is estimated to be approximately 1.5 times recommended levels and has been linked to increased risk for developing chronic diseases. We hypothesized that relative to sugar, honey would reduce energy intake and improve serum lipid profiles. To test this, we assessed the short-term (1-week) and relatively long-term (1-month) effects of honey versus sucrose on changes in dietary intake and serum lipid concentrations. Thirty-seven apparently healthy subjects (21 males; 16 females) aged 24-57 years (BMI = 17.6-37.2 kg/m²) completed two 4-week trials in a randomized, cross-over design separated by ≥4-week washout. During each trial, subjects consumed either clover honey or sucrose providing 1.2 g/kg/day of carbohydrate under free-living conditions with instructions to avoid changing their habitual food intake. Serum triglyceride (TG) concentrations were elevated (P < .05) after 1 week for both trials but only remained elevated (P < .05) at the 4-week time-point during sucrose consumption. The elevation after 1 week during the honey trial was concurrent with a transient increase (P < .05) in body weight. No effects on serum concentrations of insulin, total cholesterol, low density lipoprotein-cholesterol, or high density lipoprotein-cholesterol were detected for either trial. Subjects consumed significantly less energy (P < .05), carbohydrate (P < .005), sugars (P < .05), and saturated fat (P < .05) during the honey trial. These data suggest that honey may serve as a favorable substitute for sucrose with regard to reduced energy intake, carbohydrate and sugars, without negatively influencing serum lipid concentrations.

LIFETIME EXERCISE ATTENUATES AGE- AND WESTERN DIET-RELATED DECLINES IN PHYSICAL FUNCTION IN MICE

Aging is associated with progressive declines in physical function. However, it is unknown if consumption of a western-style diet (WD; high-fat and sucrose, low fiber), compared with a non-WD (healthy diet), accelerates declines in physical function over the adult lifespan, and whether regular voluntary exercise attenuates age- and WD-associated declines in function. To determine this, we studied 4 cohorts of male C57BL/6 mice that consumed either normal chow [NC] or WD with or without access to voluntary running [VR] wheels beginning at 3 mo of age and assessed strength (grip strength normalized to body mass) and endurance (rota-rod distance) every 3 mo throughout life. WD decreased average lifespan by 30% (WD: 18.6±0.5 vs. NC: 26.7±0.8 mo); therefore, function was compared from 3-18 mo of age in all groups. Age-related declines (% change over 3-18 mo) in physical function were accelerated by WD (strength: WD -61.2±10.1%, NC -43.2±10.2%; endurance: WD -97.4±5.1%, NC -65.1±6.3%; all p<0.05 WD vs. NC). VR attenuated declines in physical function within the same diet group (strength: WDVR -34.7±5.1%, NCVR -18.6±5.2%; endurance: WDVR -48.5±5.2%, NCVR -41.4±4.7%; all p<0.05 versus same diet non-VR group). These unique data obtained from a lifelong study of aging in mice, indicate that: 1) consuming a WD reduces lifespan and accelerates age-related declines in physical function by 40-50% vs. a non-WD; regular voluntary exercise (wheel running) prevents this effect of WD on physical function; and 2) regular voluntary exercise also attenuates the age-associated decline in physical function by ~60-130% when consuming a healthy diet.

Heat therapy improves glucose tolerance and adipose tissue insulin signaling in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is associated with high rates of obesity and metabolic dysfunction. Repeated passive heat exposure (termed heat therapy) is a novel lifestyle intervention for improving health in obese women with PCOS. The purpose of this study was to examine changes in metabolic function in obese women with PCOS following heat therapy. Eighteen age- and BMI-matched obese women with PCOS (age: 27 ± 1 yr, BMI: 41.3 ± 1.1 kg/m^-2) were assigned to heat therapy (HT) or time control (CON). HT participants underwent 30 one-hour hot tub sessions over 8-10 wk, while CON participants completed all testing but did not undergo heat therapy. Before (Pre), at the mid-point (Mid), and following (Post) 8-10 wk of heat therapy, metabolic health was assessed using a 2-h oral glucose tolerance test, a subcutaneous abdominal fat biopsy (Pre-Post only), and other blood markers relating to metabolic function. HT participants exhibited improved fasting glucose (Pre: 105 ± 3, Post: 89 ± 5mg/dl; P = 0.001), glucose area under the curve (AUC) (Pre: 18,698 ± 1,045, Post: 16,987 ± 1,017 mg·dl^-1·min^-1; P = 0.028) and insulin AUC (Pre: 126,924 ± 11,730, Post: 91,233 ± 14,429 IU l^-1·min^-1; P = 0.012). Adipocyte insulin signaling (p-AKT at Ser-473 with 1.2 nM insulin) increased in HT (Pre: 0.29 ± 0.14, Post: 0.93 ± 0.29 AU; P = 0.021). Additionally, serum testosterone declined in HT participants (Pre: 51 ± 7, Post: 34 ± 4 ng/dl; P = 0.033). No parameters changed over time in CON, and no change in BMI was observed in either group. HT substantially improved metabolic risk profile in obese women with PCOS. HT also reduced androgen excess and may improve PCOS symptomology.

Snack selection influences glucose metabolism, antioxidant capacity and cholesterol in healthy overweight adults: A randomized parallel arm trial

Including carbohydrate/fructose-rich foods (predominantly fruit) in the diets of overweight individuals can improve chronic disease risk factors. We hypothesized dried plums (DP) would improve nutrient consumption, total antioxidant capacity (TAC), lipid and adipokine profiles, and would decrease adiposity and inflammation. To test this, we studied the effects of 8-weeks of twice-daily snacking of macronutrient-matched 100kcal servings of DP or refined carbohydrate-rich snack (low-fat muffins: LFM) on daily energy and nutrient consumption, and chronic disease risk factors in overweight adults. Body weight/composition, waist circumference, blood pressure, plasma glucose, insulin, c-peptide, lipids, TAC, adipokines and inflammation were measured at baseline and throughout the study. Postprandial glucose and insulin were assessed following assigned test foods at baseline and 8-weeks. Repeated measures ANOVAs were undertaken to examine group and time differences. Post-hoc independent and paired samples t-tests were conducted where necessary. DP increased (P<.05) overall intake of dietary fiber and potassium, and TAC, from baseline to 8-weeks. Baseline postprandial glycemia tended (P=.09) to be lower with DP versus LFM, while both groups had a decreased response after 8-weeks. Postprandial insulinemia was lower (P<.05) for DP at both time-points. No differences in body weight/composition, blood pressure, or fasting glucose, insulin, triglycerides, total cholesterol, HDL-C, inflammation or adipokines were detected. Low-density lipoprotein cholesterol (LDL-C) increased (P<.05) throughout the trial following LFM. Overall, DP lessened postprandial insulinemia, improved nutrient consumption and plasma TAC, and maintained plasma LDL-C compared to a macronutrient-matched refined carbohydrate snack, which could decrease chronic disease risk.

Correction: A diet containing high- versus low-daidzein does not affect bone density and osteogenic gene expression in the obese Zucker rat model

Correction for ‘A diet containing high- versus low-daidzein does not affect bone density and osteogenic gene expression in the obese Zucker rat model’ by Eric Rochester et al., Food Funct., 2019, 10, 6851–6857.

Short-term thermoneutral housing alters glucose metabolism and markers of adipose tissue browning in response to a high-fat diet in lean mice

Systemic insulin resistance and glucose intolerance occur with as little as 3 days of a high-fat diet (HFD) in mice and humans; the mechanisms that initiate acute insulin resistance are unknown. Most laboratories house mice at 22°C, which is below their thermoneutral temperature (~30°C). Cold stress has been shown to increase white adipose tissue (WAT) browning, alter lipid trafficking, and impair immune function, whereas energy intake and expenditure decrease with increasing ambient temperature; importantly, dysregulation of these parameters has been strongly linked to obesity-induced insulin resistance. Therefore, we compared acute changes in glucose metabolism and the metabolic phenotype in lean mice in response to a control diet or HFD housed at standard vivarium (22°C) and thermoneutral (30°C) temperatures. Glucose intolerance occurred following 1 or 5 days of HFD and was independent of housing temperature or adiposity; however, the reduction in tissue-specific glucose clearance with HFD diverged by temperature with reduced brown adipose tissue (BAT) glucose uptake at 22°C but reduced soleus glucose uptake at 30°C. Fasting glucose, food intake, and energy expenditure were significantly lower at 30°C, independent of diet. Additionally, markers of browning in both BAT and inguinal subcutaneous WAT, but not perigonadal epididymal WAT, decreased at 30°C. Together, we find housing temperature has a significant impact on the cellular pathways that regulate glucose tolerance in response to an acute HFD exposure. Thus, even short-term changes in housing temperature should be highly considered in interpretation of metabolic studies in mice.