The ketone body ß-hydroxybutyrate shifts microglial metabolism and suppresses amyloid-ß oligomer-induced inflammation in human microglia.

Fatty acids are metabolized by ß-oxidation within the "mitochondrial ketogenic pathway" (MKP) to generate ß-hydroxybutyrate (BHB), a ketone body. BHB can be generated by most cells but largely by hepatocytes following exercise, fasting, or ketogenic diet consumption. BHB has been shown to modulate systemic and brain inflammation; however, its direct effects on microglia have been little studied. We investigated the impact of BHB on Aß oligomer (AßO)-stimulated human iPS-derived microglia (hiMG), a model relevant to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AßO with proinflammatory activation, which was mitigated by BHB at physiological concentrations of 0.1-2 mM. AßO stimulated glycolytic transcripts, suppressed genes in the ß-oxidation pathway, and induced over-expression of AD-relevant p46Shc, an endogenous inhibitor of thiolase, actions that are expected to suppress MKP. AßO also triggered mitochondrial Ca2+ increase, mitochondrial reactive oxygen species production, and activation of the mitochondrial permeability transition pore. BHB potently ameliorated all the above mitochondrial changes and rectified the MKP, resulting in reduced inflammasome activation and recovery of the phagocytotic function impaired by AßO. These results indicate that microglia MKP can be induced to modulate microglia immunometabolism, and that BHB can remedy "keto-deficiency" resulting from MKP suppression and shift microglia away from proinflammatory mitochondrial metabolism. These effects of BHB may contribute to the beneficial effects of ketogenic diet intervention in aged mice and in human subjects with mild AD.

Pre- and Postnatal Vitamin A Deficiency Impairs Motor Skills without a Consistent Effect on Trace Mineral Status in Young Mice.

Pregnant women and children are vulnerable to vitamin A deficiency (VAD), which is often compounded by concurrent deficiencies in other micronutrients, particularly iron and zinc, in developing countries. The study investigated the effects of early-life VAD on motor and cognitive development and trace mineral status in a mouse model. C57BL/6J dams were fed either a vitamin A-adequate (VR) or -deficient (VD) diet across two consecutive gestations and lactations. Offspring from both gestations (G1 and G2) continued the same diets until 6 or 9 weeks of age. Behavioral assays were conducted to evaluate motor coordination, grip strength, spatial cognition, and anxiety. Hepatic trace minerals were analyzed. A VD diet depleted hepatic retinoids and reduced plasma retinol across all ages and gestations. Retracted rear legs and abnormal gait were the most common clinical manifestations observed in VD offspring from both gestations at 9 weeks. Poor performance on the Rotarod test further confirmed their motor dysfunction. VAD didn't affect hemoglobin levels and had no consistent effect on hepatic trace mineral concentrations. These findings highlight the critical role of vitamin A in motor development. There was no clear evidence that VAD alters the risk of iron deficiency anemia or trace minerals.

Exploring the presence of bovine leukemia virus among breast cancer tumors in a rural state.

PURPOSE: The bovine leukemia virus (BLV) is a deltaretrovirus that causes malignant lymphoma and lymphosarcomas in cattle globally and has high prevalence among large scale U.S. dairy herds. Associations between presence of BLV DNA in human mammary tissue and human breast cancer incidence have been reported. We sought to estimate the prevalence of BLV DNA in breast cancer tissue samples in a rural state with an active dairy industry. METHODS: We purified genomic DNA from 56 fresh-frozen breast cancer tissue samples (51 tumor samples, 5 samples representing adjacent normal breast tissue) banked between 2016 and 2019. Using nested PCR assays, multiple BLV tax sequence primers and primers for the long terminal repeat (LTR) were used to detect BLV DNA in tissue samples and known positive control samples, including the permanently infected fetal lamb kidney cell line (FLK-BLV) and blood from BLV positive cattle. RESULTS: The median age of patients from which samples were obtained at the time of treatment was 60 (40-93) and all were female. Ninety percent of patients had invasive ductal carcinoma. The majority were poorly differentiated (60%). On PCR assay, none of the tumor samples tested positive for BLV DNA, despite having consistent signals in positive controls. CONCLUSION: We did not find BLV DNA in fresh-frozen breast cancer tumors from patients presenting to a hospital in Vermont. Our findings suggest a low prevalence of BLV in our patient population and a need to reevaluate the association between BLV and human breast cancer.

An Investigation into Equine Nutrition Knowledge and Educational Needs of Equine Veterinarians.

This study investigated equine nutrition knowledge and educational needs of licensed veterinarians in the United States who were exclusively or predominately equine practitioners. It found veterinarians regard their peers as an important resource of nutritional knowledge, ranking ahead of all other sources except a PhD equine nutritionist. Interestingly, only 21% of veterinarians felt good about their knowledge level in equine nutrition after graduating from veterinary school. Although veterinarians in this study reported equine nutrition to be an area of weakness, 75% had not pursued continuing education in the field of nutrition within the last year. Additionally, they devoted only 65 minutes per year on average to improving their knowledge of equine nutrition, yet the majority (82.2%) had been providing nutritional advice to clients. This study revealed that time spent practicing veterinary medicine increases (p < .001) a veterinarian's self-perceived knowledge level of equine nutrition, shifting from just below average after graduation from veterinary school to just above average at the time of this study. The majority (70%) of veterinarians in this study believe nutrition is very important in their practice philosophy, and 71% showed interest in taking online continuing education courses; thus, curriculum should be developed and offered in areas of need as identified by this study. These areas include insulin resistance, equine gastric ulcer syndrome, equine metabolic syndrome, performance horses, equine pituitary pars intermedia dysfunction, equine polysaccharide storage myopathy, and arthritis/joint pain, along with how to assess nutritional status during general wellness examinations.

Resolved images of a protostellar outflow driven by an extended disk wind.

Young stars are associated with prominent outflows of molecular gas. The ejection of gas is believed to remove angular momentum from the protostellar system, permitting young stars to grow by the accretion of material from the protostellar disk. The underlying mechanism for outflow ejection is not yet understood, but is believed to be closely linked to the protostellar disk. Various models have been proposed to explain the outflows, differing mainly in the region where acceleration of material takes place: close to the protostar itself ('X-wind', or stellar wind), in a larger region throughout the protostellar disk (disk wind), or at the interface between the two. Outflow launching regions have so far been probed only by indirect extrapolation because of observational limits. Here we report resolved images of carbon monoxide towards the outflow associated with the TMC1A protostellar system. These data show that gas is ejected from a region extending up to a radial distance of 25 astronomical units from the central protostar, and that angular momentum is removed from an extended region of the disk. This demonstrates that the outflowing gas is launched by an extended disk wind from a Keplerian disk.

Nonphagocytic Activation of NOX2 Is Implicated in Progressive Nonalcoholic Steatohepatitis During Aging.

BACKGROUND AND AIMS: Older patients with obesity/type II diabetes mellitus frequently present with advanced NASH. Whether this is due to specific molecular pathways that accelerate fibrosis during aging is unknown. Activation of the Src homology 2 domain-containing collagen-related (Shc) proteins and redox stress have been recognized in aging; however, their link to NASH has not been explored. APPROACH AND RESULTS: Shc expression increased in livers of older patients with NASH, as assessed by real time quantitative PCR (RT-qPCR) or western blots. Fibrosis, Shc expression, markers of senescence, and nicotinamide adenine dinucleotide phosphate, reduced form oxidases (NOXs) were studied in young/old mice on fast food diet (FFD). To inhibit Shc in old mice, lentiviral (LV)-short hairpin Shc versus control-LV were used during FFD. For hepatocyte-specific effects, floxed (fl/fl) Shc mice on FFD were injected with adeno-associated virus 8-thyroxine-binding globulin-Cre-recombinase versus control. Fibrosis was accelerated in older mice on FFD, and Shc inhibition by LV in older mice or hepatocyte-specific deletion resulted in significantly improved inflammation, reduction in senescence markers in older mice, lipid peroxidation, and fibrosis. To study NOX2 activation, the interaction of p47phox (NOX2 regulatory subunit) and p52Shc was evaluated by proximity ligation and coimmunoprecipitations. Palmitate-induced p52Shc binding to p47phox , activating the NOX2 complex, more so at an older age. Kinetics of binding were assessed in Src homology 2 domain (SH2) or phosphotyrosine-binding (PTB) domain deletion mutants by biolayer interferometry, revealing the role of SH2 and the PTB domains. Lastly, an in silico model of p52Shc/p47phox interaction using RosettaDock was generated. CONCLUSIONS: Accelerated fibrosis in the aged is modulated by p52Shc/NOX2. We show a pathway for direct activation of the phagocytic NOX2 in hepatocytes by p52Shc binding and activating the p47phox subunit that results in redox stress and accelerated fibrosis in the aged.

Sex-specific alterations in whole body energetics and voluntary activity in heterozygous R163C malignant hyperthermia-susceptible mice.

Malignant hyperthermia (MH) is characterized by induction of skeletal muscle hyperthermia in response to a dysregulated increase in myoplasmic calcium. Although altered energetics play a central role in MH, MH-susceptible humans and mouse models are often described as having no phenotype until exposure to a triggering agent. The purpose of this study was to determine the influence of the R163C ryanodine receptor 1 mutation, a common MH mutation in humans, on energy expenditure, and voluntary wheel running in mice. Energy expenditure was measured by indirect respiration calorimetry in wild-type (WT) and heterozygous R163C (HET) mice over a range of ambient temperatures. Energy expenditure adjusted for body weight or lean mass was increased (P < .05) in male, but not female, HET mice housed at 22°C or when housed at 28°C with a running wheel. In female mice, voluntary wheel running was decreased (P < .05) in the HET vs WT animals when analyzed across ambient temperatures. The thermoneutral zone was also widened in both male and female HET mice. The results of the study show that the R163C mutations alters energetics even at temperatures that do not typically induce MH.

MeCP2 isoform e1 mutant mice recapitulate motor and metabolic phenotypes of Rett syndrome.

Mutations in the X-linked gene MECP2 cause the majority of Rett syndrome (RTT) cases. Two differentially spliced isoforms of exons 1 and 2 (MeCP2-e1 and MeCP2-e2) contribute to the diverse functions of MeCP2, but only mutations in exon 1, not exon 2, are observed in RTT. We previously described an isoform-specific MeCP2-e1-deficient male mouse model of a human RTT mutation that lacks MeCP2-e1 while preserving expression of MeCP2-e2. However, RTT patients are heterozygous females that exhibit delayed and progressive symptom onset beginning in late infancy, including neurologic as well as metabolic, immune, respiratory and gastrointestinal phenotypes. Consequently, we conducted a longitudinal assessment of symptom development in MeCP2-e1 mutant females and males. A delayed and progressive onset of motor impairments was observed in both female and male MeCP2-e1 mutant mice, including hind limb clasping and motor deficits in gait and balance. Because these motor impairments were significantly impacted by age-dependent increases in body weight, we also investigated metabolic phenotypes at an early stage of disease progression. Both male and female MeCP2-e1 mutants exhibited significantly increased body fat compared to sex-matched wild-type littermates prior to weight differences. Mecp2e1-/y males exhibited significant metabolic phenotypes of hypoactivity, decreased energy expenditure, increased respiratory exchange ratio, but decreased food intake compared to wild-type. Untargeted analysis of lipid metabolites demonstrated a distinguishable profile in MeCP2-e1 female mutant liver characterized by increased triglycerides. Together, these results demonstrate that MeCP2-e1 mutation in mice of both sexes recapitulates early and progressive metabolic and motor phenotypes of human RTT.

Inhibition of the chimeric DnaJ-PKAc enzyme by endogenous inhibitor proteins.

The chimeric DnaJ-PKAc enzymeresulting from an approximately 400-kb deletion of chromosome 19 is a primary contributor to the oncogenic transformation that occurs in fibrolamellar hepatocellular carcinoma, also called fibrolamellar carcinoma (FLC). This oncogenic deletion juxtaposes exon 1 of the DNAJB1 heat shock protein gene with exon 2 of the PRKACA gene encoding the protein kinase A catalytic subunit, resulting in DnaJ-PKAc fusion under the transcriptional control of the DNAJB1 promoter. The expression of DnaJ-PKAc is approximately 10 times that of wild-type (wt) PKAc catalytic subunits, causing elevated and dysregulated kinase activity that contributes to oncogenic transformation. In normal cells, PKAc activity is regulated by a group of endogenous proteins, termed protein kinase inhibitors (PKI) that competitively inhibit PKAc and assist with the nuclear export of the enzyme. Currently, it is scarcely known whether interactions with PKI are perturbed in DnaJ-PKAc. In this report, we survey existing data sets to assess the expression levels of the various PKI isoforms that exist in humans to identify those that are candidates to encounter DnaJ-PKAc in both normal liver and FLC tumors. We then compare inhibition profiles of wtPKAc and DnaJ-PKAc against PKI and demonstrate that extensive structural homology in the active site clefts of the two enzymes confers similar kinase activities and inhibition by full-length PKI and PKI-derived peptides.

Loss of RUNX1 is associated with aggressive lung adenocarcinomas.

The mammalian runt-related factor 1 (RUNX1) is a master transcription factor that regulates lineage specification of hematopoietic stem cells. RUNX1 translocations result in the development of myeloid leukemias. Recently, RUNX1 has been implicated as a tumor suppressor in other cancers. We postulated RUNX1 expression may be associated with lung adenocarcinoma etiology and/or progression. We evaluated the association of RUNX1 mRNA expression with overall survival data from The Cancer Genome Atlas (TCGA), a publically available database. Compared to high expression levels, Low RUNX1 levels from lung adenocarcinomas were associated with a worse overall survival (Hazard Ratio = 2.014 (1.042-3.730 95% confidence interval), log-rank p = 0.035) compared to those that expressed high RUNX1 levels. Further immunohistochemical examination of 85 surgical specimens resected at the University of Vermont Medical Center identified that low RUNX1 protein expression was associated with larger tumors (p = 0.038). Gene expression network analysis was performed on the same subset of TCGA cases that demonstrated differential survival by RUNX1 expression. This analysis, which reveals regulatory relationships, showed that reduced RUNX1 levels were closely linked to upregulation of the transcription factor E2F1. To interrogate this relationship, RUNX1 was depleted in a lung cancer cell line that expresses high levels of RUNX1. Loss of RUNX1 resulted in enhanced proliferation, migration, and invasion. RUNX1 depletion also resulted in increased mRNA expression of E2F1 and multiple E2F1 target genes. Our data implicate loss of RUNX1 as driver of lung adenocarcinoma aggression, potentially through deregulation of the E2F1 pathway.

Novel organometallic chloroquine derivative inhibits tumor growth.

Autophagy has emerged as a mechanism critical to both tumorigenesis and development of resistance to multiple lines of anti-cancer therapy. Therefore, targeting autophagy and alternative cell death pathways has arisen as a viable strategy for refractory tumors. The anti-malarial 4-aminoquinoline compounds chloroquine and hydroxychloroquine are currently being considered for re-purposing as anti-cancer therapies intended to sensitize different tumors by targeting the lysosomal cell death pathway. Here, we describe a novel organometallic chloroquine derivative, cymanquine, that exhibits enhanced bioactivity compared to chloroquine in both normal, and reduced pH tumor microenvironments, thus overcoming a defined limitation of traditional 4-aminoquinolines. In vitro, cymanquine exhibits greater potency than CQ in a diverse panel of human cancer cell lines, including melanoma, in both normal pH and in reduced pH conditions that mimic the tumor microenvironment. Cymanquine treatment results in greater lysosomal accumulation than chloroquine and induces lysosomal dysfunction leading to autophagy blockade. Using a mouse model of vemurafenib-resistant melanoma, cymanquine slowed tumor growth greater than hydroxychloroquine, and when used in combination with vemurafenib, cymanquine partially restored sensitivity to vemurafenib. Overall, we show that cymanquine exhibits superior lysosomal accumulation and autophagy blockade than either chloroquine or hydroxychloroquine in vitro; and in addition to its high level of tolerability in mice, exhibits superior in vivo efficacy in a model of human melanoma.

p46Shc Inhibits Thiolase and Lipid Oxidation in Mitochondria.

Although the p46Shc isoform has been known to be mitochondrially localized for 11 years, its function in mitochondria has been a mystery. We confirmed p46Shc to be mitochondrially localized and showed that the major mitochondrial partner of p46Shc is the lipid oxidation enzyme 3-ketoacylCoA thiolase ACAA2, to which p46Shc binds directly and with a strong affinity. Increasing p46Shc expression inhibits, and decreasing p46Shc stimulates enzymatic activity of thiolase in vitro Thus, we suggest p46Shc to be a negative mitochondrial thiolase activity regulator, and reduction of p46Shc expression activates thiolase. This is the first demonstration of a protein that directly binds and controls thiolase activity. Thiolase was thought previously only to be regulated by metabolite balance and steady-state flux control. Thiolase is the last enzyme of the mitochondrial fatty acid beta-oxidation spiral, and thus is important for energy metabolism. Mice with reduction of p46Shc are lean, resist obesity, have higher lipid oxidation capacity, and increased thiolase activity. The thiolase-p46Shc connection shown here in vitro and in organello may be an important underlying mechanism explaining the metabolic phenotype of Shc-depleted mice in vivo.

Effects of obesity, energy restriction and neutering on the faecal microbiota of cats.

Surveys report that 25-57 % of cats are overweight or obese. The most evinced cause is neutering. Weight loss often fails; thus, new strategies are needed. Obesity has been associated with altered gut bacterial populations and increases in microbial dietary energy extraction, body weight and adiposity. This study aimed to determine whether alterations in intestinal bacteria were associated with obesity, energy restriction and neutering by characterising faecal microbiota using 16S rRNA gene sequencing in eight lean intact, eight lean neutered and eight obese neutered cats before and after 6 weeks of energy restriction. Lean neutered cats had a bacterial profile similar to obese rodents and humans, with a greater abundance (P<0·05) of Firmicutes and lower abundance (P<0·05) of Bacteroidetes compared with the other groups. The greater abundance of Firmicutes in lean neutered cats was due to a bloom in Peptostreptococcaceae. Obese cats had an 18 % reduction in fat mass after energy restriction (P<0·05). Energy reduction was concurrent with significant shifts in two low-abundance bacterial genera and trends in four additional genera. The greatest change was a reduction in the Firmicutes genus, Sarcina, from 4·54 to 0·65 % abundance after energy restriction. The short duration of energy restriction may explain why few bacterial changes were observed in the obese cats. Additional work is needed to understand how neutering, obesity and weight loss are related to changes in feline microbiota and how these microbial shifts affect host physiology.

The influence of dietary fat source on liver and skeletal muscle mitochondrial modifications and lifespan changes in calorie-restricted mice.

The Membrane Theory of Aging proposes that lifespan is inversely related to the level of unsaturation in membrane phospholipids. Calorie restriction (CR) without malnutrition extends lifespan in many model organisms, which may be related to alterations in membrane phospholipids fatty acids. During the last few years our research focused on studying how altering the predominant fat source affects the outcome of CR in mice. We have established four dietary groups: one control group fed 95 % of a pre-determined ad libitum intake (in order to prevent obesity), and three CR groups fed 40 % less than ad libitum intake. Lipid source for the control and one of the CR groups was soybean oil (high in n-6 PUFA) whereas the two remaining CR groups were fed diets containing fish oil (high in n-3 PUFA), or lard (high in saturated and monounsaturated fatty acids). Dietary intervention periods ranged from 1 to 18 months. We performed a longitudinal lifespan study and a cross-sectional study set up to evaluate several mitochondrial parameters which included fatty acid composition, H(+) leak, activities of electron transport chain enzymes, ROS generation, lipid peroxidation, mitochondrial ultrastructure, and mitochondrial apoptotic signaling in liver and skeletal muscle. These approaches applied to different cohorts of mice have independently indicated that lard as a fat source often maximizes the effects of 40 % CR on mice. These effects could be due to significant increases of monounsaturated fatty acids levels, in accordance with the Membrane Theory of Aging.

Two-month ketogenic diet alters systemic and brain metabolism in middle-aged female mice.

The ketogenic diet (KD) is a very low-carbohydrate, high-fat diet that reduces glucose catabolism and enhances ß-oxidation and ketogenesis. While research in female rodents is limited, research in male rodents suggests that ketogenic interventions initiated at midlife may slow age-related cognitive decline, as well as preserve muscle mass and physical function later in life. This study aimed to investigate the effects of a KD on global metabolic changes in middle-aged females to inform potential mechanisms behind the anti-aging effects of this diet in an understudied sex. Targeted 1H-NMR metabolomics was conducted on serum, the liver, the kidney, and the gastrocnemius muscle, as well as the cortex and the hippocampal brain regions in 16-month-old female mice after a 2-month KD. Analysis of the serum and liver metabolome revealed that the 2-month KD resulted in increased concentrations of fatty acid catabolism metabolites, as well as system-wide elevations in ketones, consistent with the ketogenic phenotype. Metabolites involved in the glucose-alanine cycle were altered in the gastrocnemius muscle, serum and the liver. Other tissue-specific alterations were detected, including distinct effects on hepatic and renal one-carbon metabolism, as well as region specific differences in metabolism across hippocampal and cortical parts of the brain. Alterations to hippocampal metabolites involved in myelinogenesis could relate to the potential beneficial effects of a KD on memory.

The impact of continuous and intermittent ketogenic diets on cognitive behavior, motor function, and blood lipids in TgF344-AD rats.

Studies suggest that ketogenic diets (KD) may improve memory in mouse models of aging and Alzheimer's disease (AD). This study determined whether a continuous or intermittent KD (IKD) enhanced cognitive behavior in the TgF344-AD rat model of AD. At 6 months-old, TgF344-AD and wild-type (WT) littermates were placed on a control (CD), KD, or IKD (morning CD and afternoon KD) provided as two meals per day for 2 or 6 months. Cognitive and motor behavior and circulating ß-hydroxybutyrate (BHB), AD biomarkers and blood lipids were assessed. Animals on a KD diet had elevated circulating BHB, with IKD levels intermediate to CD and KD. TgF344-AD rats displayed impaired spatial learning memory in the Barnes maze at 8 and 12 months of age and impaired motor coordination at 12 months of age. Neither KD nor IKD improved performance compared to CD. At 12 months of age, TgF344-AD animals had elevated blood lipids. IKD reduced lipids to WT levels with KD further reducing cholesterol below WT levels. This study shows that at 8 or 12 months of age, KD or IKD intervention did not improve measures of cognitive or motor behavior in TgF344-AD rats; however, both IKD and KD positively impacted circulating lipids.

Ketogenic diet and BHB rescue the fall of long-term potentiation in an Alzheimer's mouse model and stimulates synaptic plasticity pathway enzymes.

The Ketogenic Diet (KD) improves memory and longevity in aged C57BL/6 mice. We tested 7 months KD vs. control diet (CD) in the mouse Alzheimer's Disease (AD) model APP/PS1. KD significantly rescued Long-Term-Potentiation (LTP) to wild-type levels, not by changing Amyloid-ß (Aß) levels. KD's 'main actor' is thought to be Beta-Hydroxy-butyrate (BHB) whose levels rose significantly in KD vs. CD mice, and BHB itself significantly rescued LTP in APP/PS1 hippocampi. KD's 6 most significant pathways induced in brains by RNAseq all related to Synaptic Plasticity. KD induced significant increases in synaptic plasticity enzymes p-ERK and p-CREB in both sexes, and of brain-derived neurotrophic factor (BDNF) in APP/PS1 females. We suggest KD rescues LTP through BHB's enhancement of synaptic plasticity. LTP falls in Mild-Cognitive Impairment (MCI) of human AD. KD and BHB, because they are an approved diet and supplement respectively, may be most therapeutically and translationally relevant to the MCI phase of Alzheimer's Disease.

Ketogenic diets initiated in late mid-life improved measures of spatial memory in male mice.

Studies have shown ketogenic diets (KD) started from early middle-age improved health span and longevity in mice. KDs started later in life or administered intermittently may be more feasible and promote compliance. Therefore, this study sought to test if continuous or intermittent KDs started in late-middle-aged mice would improve cognition and motor function at advanced age. Eighteen-month-old male C57BL/6JN mice were assigned to an isocaloric control (CD), KD, or intermittent ketogenic (IKD, 3-day KD/week) diet. A panel of behavior tests were performed to assess cognitive and motor functions with aging. Y-maze alternation rate was higher for both IKD and KD mice at 23 months of age and for KD mice at 26 months indicating an improved spatial working memory. Twenty-six-month-old KD mice also showed better spatial learning memory in Barnes maze when compared to the CD. Improved grid wire hang performance was observed in aged IKD and KD versus CD mice indicating better muscle endurance under isometric contraction. A reduced level of circulating proinflammatory cytokines in aged KD (IL-6 and TNF-α) and IKD (IL-6) mice may contribute to the phenotypic improvements observed with these interventions. This study demonstrates that when initiated at late-middle age, the KD improved measures of spatial memory and grid wire hang performance in aged male mice, with IKD showing results intermediate to the CD and KD groups.

When a calorie is not just a calorie: Diet quality and timing as mediators of metabolism and healthy aging.

An epidemic of obesity has affected large portions of the world, increasing the risk of developing many different age-associated diseases, including cancer, cardiovascular disease, and diabetes. In contrast with the prevailing notion that "a calorie is just a calorie," there are clear differences, within and between individuals, in the metabolic response to different macronutrient sources. Recent findings challenge this oversimplification; calories from different macronutrient sources or consumed at different times of day have metabolic effects beyond their value as fuel. Here, we summarize discussions conducted at a recent NIH workshop that brought together experts in calorie restriction, macronutrient composition, and time-restricted feeding to discuss how dietary composition and feeding schedule impact whole-body metabolism, longevity, and healthspan. These discussions may provide insights into the long-sought molecular mechanisms engaged by calorie restriction to extend lifespan, lead to novel therapies, and potentially inform the development of a personalized food-as-medicine approach to healthy aging.

2-month ketogenic diet preferentially alters skeletal muscle and augments cognitive function in middle aged female mice.

The effect of a ketogenic diet (KD) on middle aged female mice is poorly understood as most of this work have been conducted in young female mice or diseased models. We have previously shown that an isocaloric KD started at middle age in male mice results in enhanced mitochondrial mass and function after 2 months on diet and improved cognitive behavior after being on diet for 14 months when compared with their control diet (CD) fed counterparts. Here, we aimed to investigate the effect of an isocaloric 2-month KD or CD on healthy 14-month-old female mice. At 16 months of age cognitive behavior tests were performed and then serum, skeletal muscle, cortex, and hippocampal tissues were collected for biochemical analysis. Two months on a KD resulted in enhanced cognitive behavior associated with anxiety, memory, and willingness to explore. The improved neurocognitive function was associated with increased PGC1α protein in the gastrocnemius (GTN) muscle and nuclear fraction. The KD resulted in a tissue specific increase in mitochondrial mass and kynurenine aminotransferase (KAT) levels in the GTN and soleus muscles, with a corresponding decrease in kynurenine and increase in kynurenic acid levels in serum. With KAT proteins being responsible for converting kynurenine into kynurenic acid, which is unable to cross the blood brain barrier and be turned into quinolinic acid-a potent neurotoxin, this study provides a potential mechanism of crosstalk between muscle and brain in mice on a KD that may contribute to improved cognitive function in middle-aged female mice.