Ketone Monoester Plus Carbohydrate Supplementation Does Not Alter Exogenous and Plasma Glucose Oxidation or Metabolic Clearance Rate During Exercise in Men Compared with Carbohydrate Alone.

BACKGROUND: Increasing ß-hydroxybutyrate (ßHB) availability through ketone monoester (KE) plus carbohydrate supplementation is suggested to enhance physical performance by sparing glucose use during exercise. However, no studies have examined the effect of ketone supplementation on glucose kinetics during exercise. OBJECTIVES: This exploratory study primarily aimed to determine the effect of KE plus carbohydrate supplementation on glucose oxidation during steady-state exercise and physical performance compared with carbohydrate alone. METHODS: Using a randomly assigned, crossover design, 12 men consumed 573 mg KE/kg body mass plus 110 g glucose (KE+CHO) or 110 g glucose (CHO) before and during 90 min of steady-state treadmill exercise [54 ± 3% peak oxygen uptake (V˙O2peak)] wearing a weighted vest (30% body mass; 25 ± 3 kg). Glucose oxidation and turnover were determined using indirect calorimetry and stable isotopes. Participants performed an unweighted time to exhaustion (TTE; 85% V˙O2peak) after steady-state exercise and a weighted (25 ± 3 kg) 6.4 km time trial (TT) the next day after consuming a bolus of KE+CHO or CHO. Data were analyzed by paired t-tests and mixed model ANOVA. RESULTS: ßHB concentrations were higher (P < 0.05) after exercise [2.1 mM (95% CI: 1.6, .6)] and the TT [2.6 mM (2.1, 3.1)] in KE+CHO compared with CHO. TTE was lower [-104 s (-201, -8)], and TT performance was slower [141 s (19,262)] in KE+CHO than in CHO (P < 0.05). Exogenous [-0.01 g/min (-0.07, 0.04)] and plasma [-0.02 g/min (-0.08, 0.04)] glucose oxidation and metabolic clearance rate {MCR [0.38 mg·kg-1·min-1 (-0.79, 1.54)]} were not different, and glucose rate of appearance [-0.51 mg·kg-1·min-1 (-0.97, -0.04)], and disappearance [-0.50 mg·kg-1·min-1 (-0.96, -0.04)] were lower (P < 0.05) in KE+CHO compared with CHO during steady-state exercise. CONCLUSIONS: In the current study, rates of exogenous and plasma glucose oxidation and MCR were not different between treatments during steady-state exercise, suggesting blood glucose utilization is similar between KE+CHO and CHO. KE+CHO supplementation also results in lower physical performance compared with CHO alone. This trial was registered at www. CLINICALTRIALS: gov as NCT04737694.

Characterizing Relationships Among the Cognitive, Physical, Social-emotional, and Health-related Traits of Military Personnel.

INTRODUCTION: Personnel engaged in high-stakes occupations, such as military personnel, law enforcement, and emergency first responders, must sustain performance through a range of environmental stressors. To maximize the effectiveness of military personnel, an a priori understanding of traits can help predict their physical and cognitive performance under stress and adversity. This work developed and assessed a suite of measures that have the potential to predict performance during operational scenarios. These measures were designed to characterize four specific trait-based domains: cognitive, health, physical, and social-emotional. MATERIALS AND METHODS: One hundred and ninety-one active duty U.S. Army soldiers completed interleaved questionnaire-based, seated task-based, and physical task-based measures over a period of 3-5 days. Redundancy analysis, dimensionality reduction, and network analyses revealed several patterns of interest. RESULTS: First, unique variable analysis revealed a minimally redundant battery of instruments. Second, principal component analysis showed that metrics tended to cluster together in three to five components within each domain. Finally, analyses of cross-domain associations using network analysis illustrated that cognitive, health, physical, and social-emotional domains showed strong construct solidarity. CONCLUSIONS: The present battery of metrics presents a fieldable toolkit that may be used to predict operational performance that can be clustered into separate components or used independently. It will aid predictive algorithm development aimed to identify critical predictors of individual military personnel and small-unit performance outcomes.

Quantitatively Assessing the Respiratory Burst in Innate Immune Cells.

The respiratory burst is a rapid cellular consumption of oxygen resulting in abundant production of reactive oxygen species (ROS), most often associated with primary mediators of innate immunity, neutrophils and macrophages. These myeloid cells convert ROS into potent antimicrobial oxidants that efficiently kill pathogens. The respiratory burst also can have destructive consequences, as ROS are well known to support chronic inflammation and aberrant autoimmune responses. Interestingly, ROS perform conflicting roles in the tumor microenvironment; ROS and derived cytotoxic products can destroy cancer cells but also suppress important tumor-fighting functions of T cells or natural killer cells, or yield mutagenized proteins that can promote tumorigenesis or support tumor cell growth. Moreover, high numbers of neutrophils or macrophages in tumors are associated with poor prognosis. Therefore, accurate and quantitative assays to assess the respiratory burst are an important tool for measuring ROS production by neutrophils or cells of the monocyte/macrophage system, each recently identified in the tumor microenvironment. Described are methods to derive mouse or human models of neutrophils or macrophages, which are then used in a detailed assay to quantitatively measure ROS produced by either cell type using luminescence-enhanced reagents and a multi-well platform along with different stimulants that cause rapid ROS production.

Utility of Ketone Supplementation to Enhance Physical Performance: A Systematic Review.

Ingesting exogenous ketone bodies has been touted as producing ergogenic effects by altering substrate metabolism; however, research findings from recent studies appear inconsistent. This systematic review aimed to aggregate data from the current literature to examine the impact of consuming ketone supplements on enhancing physical performance. A systematic search was performed for randomized controlled trials that measured physical performance outcomes in response to ingesting exogenous ketone supplements compared with a control (nutritive or non-nutritive) in humans. A total of 161 articles were screened. Data were extracted from 10 eligible studies (112 participants; 109 men, 3 women ) containing 16 performance outcomes [lower-body power (n = 8) and endurance performance (n = 8)]. Ketone supplements were grouped as ketone esters (n = 8) or ketone salts/precursors (n = 8). Of the 16 performance outcomes identified by the systematic review, 3 reported positive, 10 reported null, and 3 reported negative effects of ketone supplementation on physical performance compared with controls. Heterogeneity was detected for lower-body power ( Q = 40, I2 = 83%, P < 0.01) and endurance performance (Q = 95, I2 = 93%, P < 0.01) between studies. Similarly high levels of heterogeneity were detected in studies providing ketone esters (Q = 111, I2 = 93%, P < 0.01), and to a lesser extent studies with ketone salts/precursors (Q = 25, I2 = 72%, P < 0.01). Heterogeneity across studies makes it difficult to conclude any benefit or detriment to consuming ketone supplements on physical performance. This systematic review discusses factors within individual studies that may contribute to discordant outcomes across investigations to elucidate if there is sufficient evidence to warrant recommendation of consuming exogenous ketone supplements to enhance physical performance.

Ingested engineered nanomaterials: state of science in nanotoxicity testing and future research needs.

BACKGROUND: Engineered nanomaterials (ENM) are used extensively in food products to fulfill a number of roles, including enhancement of color and texture, for nutritional fortification, enhanced bioavailability, improved barrier properties of packaging, and enhanced food preservation. Safety assessment of ingested engineered nanomaterials (iENM) has gained interest in the nanotoxicology community in recent years. A variety of test systems and approaches have been used for such evaluations, with in vitro monoculture cell models being the most common test systems, owing to their low cost and ease-of-use. The goal of this review is to systematically assess the current state of science in toxicological testing of iENM, with particular emphasis on model test systems, their physiological relevance, methodological strengths and challenges, realistic doses (ranges and rates), and then to identify future research needs and priorities based on these assessments. METHODS: Extensive searches were conducted in Google Scholar, PubMed and Web of Science to identify peer-reviewed literature on safety assessment of iENM over the last decade, using keywords such as "nanoparticle", "food", "toxicity", and combinations thereof. Relevant literature was assessed based on a set of criteria that included the relevance of nanomaterials tested; ENM physicochemical and morphological characterization; dispersion and dosimetry in an in vitro system; dose ranges employed, the rationale and dose realism; dissolution behavior of iENM; endpoints tested, and the main findings of each study. Observations were entered into an excel spreadsheet, transferred to Origin, from where summary statistics were calculated to assess patterns, trends, and research gaps. RESULTS: A total of 650 peer-reviewed publications were identified from 2007 to 2017, of which 39 were deemed relevant. Only 21% of the studies used food grade nanomaterials for testing; adequate physicochemical and morphological characterization was performed in 53% of the studies. All in vitro studies lacked dosimetry and 60% of them did not provide a rationale for the doses tested and their relevance. Only 12% of the studies attempted to consider the dissolution kinetics of nanomaterials. Moreover, only 1 study attempted to prepare and characterize standardized nanoparticle dispersions. CONCLUSION: We identified 5 clusters of factors deemed relevant to nanotoxicology of food-grade iENM: (i) using food-grade nanomaterials for toxicity testing; (ii) performing comprehensive physicochemical and morphological characterization of iENM in the dry state, (iii) establishing standard NP dispersions and their characterization in cell culture medium, (iv) employing realistic dose ranges and standardized in vitro dosimetry models, and (v) investigating dissolution kinetics and biotransformation behavior of iENM in synthetic media representative of the gastrointestinal (GI) tract fluids, including analyses in a fasted state and in the presence of a food matrix. We discussed how these factors, when not considered thoughtfully, could influence the results and generalizability of in vitro and in vivo testing. We conclude with a set of recommendations to guide future iENM toxicity studies and to develop/adopt more relevant in vitro model systems representative of in vivo animal and human iENM exposure scenarios.

Dissolution Behavior and Biodurability of Ingested Engineered Nanomaterials in the Gastrointestinal Environment.

Engineered nanomaterials (ENM) are extensively used as food additives in numerous food products, and at present, little is known about the fate of ingested ENM (iENM) in the gastrointestinal (GI) environment. Here, we investigated the dissolution behavior, biodurability, and persistence of four major iENM (TiO2, SiO2, ZnO, and two Fe2O3) in individual simulated GI fluids (saliva, gastric, and intestinal) and a physiologically relevant digestion cascade (saliva → gastric → intestinal) in the fasted state over physiologically relevant time frames. TiO2 was found to be the most biodurable and persistent iENM in simulated GI fluids with a maximum of only 0.42% (4 µM Ti4+ ion release) dissolution in cascade digestion, followed by iron oxides, of which the rod-like morphology was more biodurable and persistent (0.7% maximum dissolution, 8.7 µM Fe3+) than the acicular one (2.27% maximum dissolution, 16.7 µM Fe3+) in the cascade digestion, respectively. SiO2 and ZnO were less biodurable than Fe2O3, with 65.5% (416 µM Si4+) and 100% (1718.1 µM Zn2+) dissolution in the gastric phase, respectively. In the intestinal phase, however, Si4+ ions reprecipitated, possibly due to sudden pH changes, while ZnO remained completely dissolved. These observations were also confirmed using high-resolution particle size and concentration, and electron microscopy, time-dependent analysis. In terms of decreasing biodurability and persistence in the simulated GI environment, the tested nanomaterials can be ranked as follows: TiO2 ≫ rod-like Fe2O3 > acicular Fe2O3 ≫ SiO2 > ZnO, which is in agreement with limited animal biokinetics data. Chronic uptake of these iENM as particles or ions by the GI tract, especially in the presence of a food matrix and authentic digestive media, and associated implications for human health warrants further investigation.

Characterization of neutrophils and macrophages from ex vivo-cultured murine bone marrow for morphologic maturation and functional responses by imaging flow cytometry.

Neutrophils and macrophages differentiate from common myeloid progenitors in the bone marrow, where they undergo nuclear morphologic changes during maturation. During this process, both cell types acquire critical innate immune functions that include phagocytosis of pathogens, and for neutrophils the release of nuclear material called nuclear extracellular traps (NETs). Primary cells used to study these functions are typically purified from mature mouse tissues, but bone marrow-derived ex vivo cultures provide more abundant numbers of progenitors and functionally mature cells. Routine analyses of these cells use conventional microscopy and flow cytometry, which present limitations; microscopy is laborious and subjective, whereas flow cytometry lacks spatial resolution. Here we describe methods to generate enriched populations of neutrophils or macrophages from cryopreserved mouse bone marrow cultured ex vivo, and to use imaging flow cytometry that combines the resolution of microscopy with flow cytometry to analyze cells for morphologic features, phagocytosis, and NETosis.

Pericyte NF-κB activation enhances endothelial cell proliferation and proangiogenic cytokine secretion in vitro.

Pericytes are skeletal muscle resident, multipotent stem cells that are localized to the microvasculature. In vivo, studies have shown that they respond to damage through activation of nuclear-factor kappa-B (NF-κB), but the downstream effects of NF-κB activation on endothelial cell proliferation and cell-cell signaling during repair remain unknown. The purpose of this study was to examine pericyte NF-κB activation in a model of skeletal muscle damage; and use genetic manipulation to study the effects of changes in pericyte NF-κB activation on endothelial cell proliferation and cytokine secretion. We utilized scratch injury to C2C12 cells in coculture with human primary pericytes to assess NF-κB activation and monocyte chemoattractant protein-1 (MCP-1) secretion from pericytes and C2C12 cells. We also cocultured endothelial cells with pericytes that expressed genetically altered NF-κB activation levels, and then quantified endothelial cell proliferation and screened the conditioned media for secreted cytokines. Pericytes trended toward greater NF-κB activation in injured compared to control cocultures (P = 0.085) and in comparison to C2C12 cells (P = 0.079). Second, increased NF-κB activation in pericytes enhanced the proliferation of cocultured endothelial cells (1.3-fold, P = 0.002). Finally, we identified inflammatory signaling molecules, including MCP-1 and interleukin 8 (IL-8) that may mediate the crosstalk between pericytes and endothelial cells. The results of this study show that pericyte NF-κB activation may be an important mechanism in skeletal muscle repair with implications for the development of therapies for musculoskeletal and vascular diseases, including peripheral artery disease.

Effects of quercetin supplementation on markers of muscle damage and inflammation after eccentric exercise.

The flavonoid quercetin is purported to have potent antioxidant and anti-inflammatory properties. This study examined if quercetin supplementation attenuates indicators of exercise-induced muscle damage in a double-blind laboratory study. Thirty healthy subjects were randomized to quercetin (QU) or placebo (PL) supplementation and performed 2 separate sessions of 24 eccentric contractions of the elbow flexors. Muscle strength, soreness, resting arm angle, upper arm swelling, serum creatine kinase (CK) activity, plasma quercetin (PQ), interleukin-6 (IL-6), and C-reactive protein (CRP) were assessed before and for 5 d after exercise. Subjects then ingested nutrition bars containing 1,000 mg/d QU or PL for 7 d before and 5 d after the second exercise session, using the opposite arm. PQ reached 202 ± 52 ng/ml after 7 d of supplementation and remained elevated during the 5-d postexercise recovery period (p < .05). Subjects experienced strength loss (peak = 47%), muscle soreness (peak = 39 ± 6 mm), reduced arm angle (-7° ± 1°), CK elevations (peak = 3,307 ± 1,481 U/L), and arm swelling (peak = 11 ± 2 mm; p < .0001), indicating muscle damage and inflammation; however, differences between treatments were not detected. Eccentric exercise did not alter plasma IL-6 (peak = 1.9 pg/ml) or CRP (peak = 1.6 mg/L) relative to baseline or by treatment. QU supplementation had no effect on markers of muscle damage or inflammation after eccentric exercise of the elbow flexors.

Knockdown of metallothionein 1 and 2 does not affect atrophy or oxidant activity in a novel in vitro model.

Skeletal muscle atrophy is a significant health problem that results in decreased muscle size and function and has been associated with increases in oxidative stress. The molecular mechanisms that regulate muscle atrophy, however, are largely unknown. The metallothioneins (MT), a family of genes with antioxidant properties, have been found to be consistently upregulated during muscle atrophy, although their function during muscle atrophy is unknown. Therefore, we hypothesized that MT knockdown would result in greater oxidative stress and an enhanced atrophy response in C(2)C(12) myotubes subjected to serum reduction (SR), a novel atrophy-inducing stimulus. Forty-eight hours before SR, myotubes were transfected with small interfering RNA (siRNA) sequences designed to decrease MT expression. Muscle atrophy and oxidative stress were then measured at baseline and for 72 h following SR. Muscle atrophy was quantified by immunocytochemistry and myotube diameter measurements. Oxidative stress was measured using the fluorescent probe 5-(and-6)-carboxy-2',7'-dichlorodihydrofluorescein. SR resulted in a significant increase in oxidative stress and a decrease in myotube size and protein content. However, there were no differences observed in the extent of muscle atrophy or oxidant activity following MT knockdown. We therefore conclude that the novel SR model results in a strong atrophy response and an increase in oxidant activity in cultured myotubes and that knockdown of MT does not affect that response.

The creatine kinase response to eccentric exercise with atorvastatin 10 mg or 80 mg.

INTRODUCTION: Hydroxy-methyl-glutaryl co-enzyme A (HMG-CoA) reductase inhibitors or statins are well tolerated by most patients, but can produce a variety of skeletal muscle problems including myalgia, creatine kinase (CK) elevations and clinically important rhabdomyolysis. We have previously demonstrated that the CK response to downhill walking is greater in statin compared to placebo treated subjects. This study examined the CK response to downhill walking in subjects treated with low and high dose of atorvastatin. METHODS: 79 subjects with LDL cholesterol>100mg/dL were randomly assigned to atorvastatin 10mg (N=42) or 80 mg (N=37) for 5 weeks. Subjects performed a downhill walking exercise during the fifth week of treatment. Leg muscle soreness, plasma CK and CK-MB levels were measured daily for 4 days following the exercise. RESULTS: CK, CK-MB and muscle soreness increased above pre-exercise levels in all subjects after the exercise. There were no differences in the CK, CK-MB or soreness response between the high and low dose treatment groups at any time point. CONCLUSION: The downhill walking model of muscle injury does not distinguish between high and low dose atorvastatin therapy either because this test is insensitive to differences among statin doses or because there is no difference in muscle injury between these two drug doses with this statin. Clinicians should be aware, however, that exercise can increase CK levels with even low dose statin therapy.