Intermittent fasting (IF) is a term used to describe a variety of eating patterns in which no or few calories are consumed for time periods that can range from 12 hours to several days, on a recurring basis. Here we focus on the physiological responses of major organ systems, including the musculoskeletal system, to the onset of the metabolic switch – the point of negative energy balance at which liver glycogen stores are depleted and fatty acids are mobilized (typically beyond 12 hours after cessation of food intake). Emerging findings suggest the metabolic switch from glucose to fatty acid-derived ketones represents an evolutionarily conserved trigger point that shifts metabolism from lipid/cholesterol synthesis and fat storage to mobilization of fat through fatty acid oxidation and fatty-acid derived ketones, which serve to preserve muscle mass and function. Thus, IF regimens that induce the metabolic switch have the potential to improve body composition in overweight individuals. Moreover, IF regimens also induce the coordinated activation of signaling pathways that optimize physiological function, enhance performance, and slow aging and disease processes. Future randomized controlled IF trials should use biomarkers of the metabolic switch (e.g., plasma ketone levels) as a measure of compliance and the magnitude of negative energy balance during the fasting period.

A growing body of evidence indicates that time restricted feeding (TRF), a popular form of intermittent fasting, can activate similar biological pathways as caloric restriction, the only intervention consistently found to extend healthy lifespan in a variety of species. Thus, TRF may have the potential to also improve function in older adults. Given the challenges many individuals have in following calorie restriction regimens over long-time periods, evaluation of alternative approaches that may produce weight loss and improve function in overweight, older adults is important. Ten overweight, sedentary older adults (≥65 years) at risk for, or with mobility impairments, defined by slow gait speed (<1.0 m/s) participated in this trial. All participants received the intervention and were instructed to fast for approximately 16 h per day over the entire four-week intervention. Outcomes included changes in body weight, waist circumference, cognitive and physical function, health-related quality of life, and adverse events. Adherence levels were high (mean = 84%) based on days goal was met, and mean weight loss was 2.6 kg (p < 0.01). Since body composition was not measured in this study, it is unclear if the observed weight loss was due to loss of fat mass, muscle mass, or the combination of fat and muscle mass. There were no significant changes in other outcomes; however, there were clinically meaningful changes in walking speed and improvements in quality of life, with few reported adverse events. The findings of this pilot study suggest that time restricted feeding is an acceptable and feasible eating pattern for overweight, sedentary older adults to follow.

Specific recognition of phosphatidylinositol 3-phosphate [PtdIns(3)P] by the FYVE domain targets cytosolic proteins to endosomal membranes during key signaling and trafficking events within eukaryotic cells. Here, we show that this membrane targeting is regulated by the acidic cellular environment. Lowering the cytosolic pH enhances PtdIns(3)P affinity of the FYVE domain, reinforcing the anchoring of early endosome antigen 1 (EEA1) to endosomal membranes. Reversibly, increasing the pH disrupts phosphoinositide binding and leads to cytoplasmic redistribution of EEA1. pH dependency is due to a pair of conserved His residues, the successive protonation of which is required for PtdIns(3)P head group recognition as revealed by NMR. Substitution of the His residues abolishes PtdIns(3)P binding by the FYVE domain in vitro and in vivo. Another PtdIns(3)P-binding module, the PX domain of Vam7 and p40 phox is shown to be pH-independent. This provides the fundamental functional distinction between the two phosphoinositide-recognizing domains. The presented mode of FYVE regulation establishes the unique function of FYVE proteins as low pH sensors of PtdIns(3)P and reveals the critical role of the histidine switch in targeting of these proteins to endosomal membranes.phosphoinositide ͉ early endosome antigen 1 T he specific recruitment of FYVE proteins to endosomes, multivesicular bodies, and phagosomes is primarily mediated by FYVE domain binding to membrane-embedded phosphatidylinositol 3-phosphate [PtdIns(3)P] (1-3). Additional membrane anchoring is provided by hydrophobic insertion into the bilayer, electrostatic interactions with acidic lipids (4, 5), and dimerization (6, 7). These synergistic factors are thought to be largely responsible for directing FYVE proteins to PtdIns(3)P-enriched membranes. Yet, the current model of FYVE domain function has several limitations and is not predictive. Some FYVE proteins localize inexplicably to sites that contain little PtdIns(3)P, such as the Golgi and endoplasmic reticulum (8, 9). On the other hand, places with significant PtdIns(3)P concentrations, such as the nucleus and mitochondria (10), do not appear to attract FYVE proteins. All canonical FYVE domains have been found to target PtdIns(3)P (refs. 6, 10-16); however, their binding properties were investigated at pH values of 6.5-8.0, leading to a discrepancy in estimated affinities despite the highly conserved sequences and structures of the FYVE proteins.The FYVE domain is defined by the three conserved elements: the N-terminal WxxD, the central RR͞KHHCR, and the Cterminal RVC motifs that form the PtdIns(3)P binding site seen in the solution and crystal structures of early endosome antigen 1 (EEA1), Hrs, and Vps27p FYVE (6,13,17,18). The PtdIns(3)P headgroup is coordinated by a cluster of four Arg͞Lys and two His residues and the N-terminal Asp. Among them, the two adjacent His residues are the most conserved in the FYVE domain sequences. In this work, we demonstrate that anchoring of the FYVE domain to PtdIns(3)P-enriched ...

Growing evidence suggests chronic low-grade inflammation (LGI) as a possible mechanism underlying the aging process. Some biological and pharmaceutical compounds may reduce systemic inflammation and potentially avert functional decline occurring with aging. The aim of the present meta-analysis was to examine the association of pre-selected interventions on two established biomarkers of inflammation, interleukin-6 (IL-6), and C-reactive protein (CRP) in middle-age and older adults with chronic LGI. We reviewed the literature on potential anti-inflammatory compounds, selecting them based on safety, tolerability, acceptability, innovation, affordability, and evidence from randomized controlled trials. Six compounds met all five inclusion criteria for our systematic review and meta-analysis: angiotensin II receptor blockers (ARBs), metformin, omega-3, probiotics, resveratrol and vitamin D. We searched in MEDLINE, PubMed and EMBASE database until January 2017. A total of 49 articles fulfilled the selection criteria. Effect size of each study and pooled effect size for each compound were measured by the standardized mean difference. I2 was computed to measure heterogeneity of effects across studies. The following compounds showed a significant small to large effect in reducing IL-6 levels: probiotics (−0.68 pg/ml), ARBs (−0.37 pg/ml) and omega-3 (−0.19 pg/ml). For CRP, a significant small to medium effect was observed with probiotics (−0.43 mg/L), ARBs (−0.2 mg/L), omega-3 (−0.17 mg/L) and metformin (−0.16 mg/L). Resveratrol and vitamin D were not associated with any significant reductions in either biomarker. These results suggest that nutritional and pharmaceutical compounds can significantly reduce established biomarkers of systemic inflammation in middle-age and older adults. The findings should be interpreted with caution, however, due to the evidence of heterogeneity across the studies.

Time-restricted feeding (TRF) is a type of intermittent fasting in which no calories are commonly consumed for approximately 12–18 hours on a daily basis. The health benefits of this eating pattern have been shown in overweight adults, with improvements in cardiometabolic risk factors as well as the preservation of lean mass during weight loss. Although TRF has been well studied in younger and middle-aged adults, few studies have evaluated the effects of TRF in older adults. Thus, the goal of this study was to evaluate older-adult perspectives regarding the real-world advantages, disadvantages, and challenges to adopting a TRF eating pattern among participants aged 65 and over. A four-week single-arm pre- and post-test design was used for this clinical pilot trial TRF intervention study. Participants were instructed to fast for approximately 16 h per day with the daily target range between 14 and 18 h. Participants were provided with the TRF protocol at a baseline visit, along with a pictorial guide that depicted food items and beverages that were allowed and not allowed during fasting windows to reinforce that calorie-containing items were to be avoided. The trial interventionist called each participant weekly to promote adherence, review the protocol, monitor for adverse events, and provide support and guidance for any challenges faced during the intervention. Participants were instructed to complete daily eating time logs by recording the times at which they first consumed calories and when they stopped consuming calories. At the end of the intervention, participants completed an exit interview and a study-specific Diet Satisfaction Survey (Table 1) to assess their satisfaction, feasibility, and overall experience with the study intervention. Of the 10 participants who commenced the study (mean age = 77.1 y; 6 women, 4 men), nine completed the entire protocol. Seven of the ten participants reported easy adjustment to a 16-hour fast and rated the difference from normal eating patterns as minimal. Eight participants reported no decrease in energy during fasting periods, with greater self-reported activity levels in yardwork and light exercise. Adverse events were rare, and included transient headaches, which dissipated with increased water intake, and dizziness in one participant, which subsided with a small snack. The findings of the current trial suggest that TRF is an eating approach that is well tolerated by most older adults. Six participants, however, did not fully understand the requirements of the fasting regimen, despite being provided with specific instructions and a pictorial guide at a baseline visit. This suggests that more instruction and/or participant contact is needed in the early stages of a TRF intervention to promote adherence.

The Vam7p t-SNARE is an essential component of the vacuole fusion machinery that mediates membrane trafficking and protein sorting in yeast. Vam7p is recruited to vacuoles by its N-terminal PX domain that specifically recognizes PtdIns(3)P in the bilayers, however the precise mechanism of membrane anchoring remains unclear. Here we describe a molecular basis for membrane targeting and penetration by the Vam7p PX domain based on structural and quantitative analysis of its interactions with lipids and micelles. Our results derived from in vitro binding measurements using NMR, monolayer surface tension experiments and mutagenesis reveal a multivalent membrane docking mechanism involving specific PtdIns ( The inositol headgroup of PIs is reversibly phosphorylated at three positions yielding seven isoforms, which cluster in distinct intracellular membranes. The apparent segregation of PIs is important for the fine-tuned regulation of protein and membrane traffic and also provides reliable and handy markers of organelles, such as the plasma membrane, trans-Golgi network, early endosomes, and multivesicular bodies. PIs were first recognized to function as precursors of secondary messengers in various signal transduction cascades and later as docking sites for modular effectors. A number of cytosolic protein effectors that are recruited to membranes and activated through interactions with PIs have recently been identified and structurally or biochemically characterized. The major PI binding modules include the ANTH (AP180 N-terminal homology), ENTH (epsin N-terminal homology), FERM (four-point one, ezrin, radixin, moesin), FYVE (Fab1, YOTB, Vac1, EEA1), PH (pleckstrin homology), and PX (Phox homology) domains (reviewed in Refs. 2-5, 50).The PX domain was first identified within a set of eukaryotic proteins in 1996 and named after the two phagocyte NADPH oxidase subunits, p40 phox and p47 phox (7). Since then, it has been found in at least 69 human and 15 yeast signaling proteins, protein kinases, PtdIns kinases and phospholipases (SMART). These proteins are implicated in a variety of physiological events playing fundamental roles in endocytosis, protein sorting, membrane trafficking, transcription, signaling, cell growth, differentiation, and proliferation (5, 7-9). The PX domain consists of ϳ130 residues that are folded in a highly conserved three-dimensional structure despite little sequence similarity between the family members. A proline-rich region (PXXP), involved in the interaction with SH3 domains, and a set of basic residues, shown to coordinate PIs, comprise the most con-

The remodeling of phosphatidylinositol polyphosphates in cellular membranes by phosphatases and kinases orchestrates the signaling by these lipids in space and time. In order to provide chemical tools to study of the changes in cell physiology mediated by these lipids, three new metabolically-stabilized (ms) analogues of phosphatidylinositol-3-phosphate (PtdIns(3)P were synthesized. We describe herein the total asymmetric synthesis of 3-methylphosphonate, 3-monofluoromethylphosphonate and 3-phosphorothioate analogues of PtdIns(3)P. From differentially protected D-myo-inositol key intermediates, a versatile phosphoramidite reagent was employed in the synthesis of PtdIns(3)P analogues with diacylglyceryl moieties containing dioleoyl, dipalmitoyl and dibutyryl chains. In addition, we introduce a new phosphorlyation reagent, monofluoromethylphosphonyl chloride, which has general applications for the preparation of "pKa-matched" monofluorophosphonates. These ms-PtdIns(3)P analogues exhibited reduced binding activities with 15 N-labelled FYVE and PX domains, as significant 1 H and 15 N chemical shift changes in the FYVE domain were induced by titrating ms-PtdIns(3)Ps into membrane-mimetic dodecylphosphocholine (DPC) micelles. In addition, the PtdIns(3)P analogues with dioleyl and dipalmitoyl chains were substrates for the 5-kinase enzyme PIKfyve; the corresponding phosphorylated ms-PI(3,5)P 2 products were detected by radio-TLC analysis.

ASPECTS may serve as a surrogate marker of infarct extent on DWI.