The phosphorylation of AMPKß1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids.

Fatty acids are vital for the survival of eukaryotes, but when present in excess can have deleterious consequences. The AMP-activated protein kinase (AMPK) is an important regulator of multiple branches of metabolism. Studies in purified enzyme preparations and cultured cells have shown that AMPK is allosterically activated by small molecules as well as fatty acyl-CoAs through a mechanism involving Ser108 within the regulatory AMPK ß1 isoform. However, the in vivo physiological significance of this residue has not been evaluated. In the current study, we generated mice with a targeted germline knock-in (KI) mutation of AMPKß1 Ser108 to Ala (S108A-KI), which renders the site phospho-deficient. S108A-KI mice had reduced AMPK activity (50 to 75%) in the liver but not in the skeletal muscle. On a chow diet, S108A-KI mice had impairments in exogenous lipid-induced fatty acid oxidation. Studies in mice fed a high-fat diet found that S108A-KI mice had a tendency for greater glucose intolerance and elevated liver triglycerides. Consistent with increased liver triglycerides, livers of S108A-KI mice had reductions in mitochondrial content and respiration that were accompanied by enlarged mitochondria, suggestive of impairments in mitophagy. Subsequent studies in primary hepatocytes found that S108A-KI mice had reductions in palmitate- stimulated Cpt1a and Ppargc1a mRNA, ULK1 phosphorylation and autophagic/mitophagic flux. These data demonstrate an important physiological role of AMPKß1 Ser108 phosphorylation in promoting fatty acid oxidation, mitochondrial biogenesis and autophagy under conditions of high lipid availability. As both ketogenic diets and intermittent fasting increase circulating free fatty acid levels, AMPK activity, mitochondrial biogenesis, and mitophagy, these data suggest a potential unifying mechanism which may be important in mediating these effects.

Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products.

BACKGROUND: High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins. METHOD: Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5 g kg-1 was extruded at three different temperatures (115, 140, and 165 °C) using a co-rotating twin-screw extruder. The feed rate (85 g min-1), the moisture content (600 g kg-1), and the screw speed (300 rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index. RESULTS: The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0 g kg-1. DISCUSSION: In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products. © 2024 Society of Chemical Industry.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review.

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and ß-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

Consensus-based recommendations for titrating cannabinoids and tapering opioids for chronic pain control.

AIMS: Opioid misuse and overuse have contributed to a widespread overdose crisis and many patients and physicians are considering medical cannabis to support opioid tapering and chronic pain control. Using a five-step modified Delphi process, we aimed to develop consensus-based recommendations on: 1) when and how to safely initiate and titrate cannabinoids in the presence of opioids, 2) when and how to safely taper opioids in the presence of cannabinoids and 3) how to monitor patients and evaluate outcomes when treating with opioids and cannabinoids. RESULTS: In patients with chronic pain taking opioids not reaching treatment goals, there was consensus that cannabinoids may be considered for patients experiencing or displaying opioid-related complications, despite psychological or physical interventions. There was consensus observed to initiate with a cannabidiol (CBD)-predominant oral extract in the daytime and consider adding tetrahydrocannabinol (THC). When adding THC, start with 0.5-3 mg, and increase by 1-2 mg once or twice weekly up to 30-40 mg/day. Initiate opioid tapering when the patient reports a minor/major improvement in function, seeks less as-needed medication to control pain and/or the cannabis dose has been optimised. The opioid tapering schedule may be 5%-10% of the morphine equivalent dose (MED) every 1 to 4 weeks. Clinical success could be defined by an improvement in function/quality of life, a ≥30% reduction in pain intensity, a ≥25% reduction in opioid dose, a reduction in opioid dose to <90 mg MED and/or reduction in opioid-related adverse events. CONCLUSIONS: This five-stage modified Delphi process led to the development of consensus-based recommendations surrounding the safe introduction and titration of cannabinoids in concert with tapering opioids.

Sevoflurane-induced hyperglycemia is attenuated by salsalate in obese insulin-resistant mice.

PURPOSE: Perioperative hyperglycemia is common and is associated with significant morbidity. Although patient characteristics and surgery influence perioperative glucose metabolism, anesthetics have a significant impact. We hypothesized that mice that were obese and insulin-resistant would experience greater hyperglycemia in response to sevoflurane anesthesia compared with lean controls. We further hypothesized that sevoflurane-induced hyperglycemia would be attenuated by salsalate pre-treatment. METHODS: Lean and obese male C57BL/6J mice were anesthetized with sevoflurane for 60 min with or without pre-treatment of 62.5 mg·kg-1 salsalate. Blood glucose, plasma insulin, and glucose uptake into different tissues were measured. RESULTS: Under sevoflurane anesthesia, obese mice had higher blood glucose compared to lean mice. Increases in blood glucose were attenuated with acute salsalate pre-treatment at 60 min under anesthesia in obese mice (mean ± standard error of the mean [SEM], delta blood glucose; vehicle 5.79 ± 1.09 vs salsalate 1.91 ± 1.32 mM; P = 0.04) but did not reach statistical significance in lean mice (delta blood glucose, vehicle 4.39 ± 0.55 vs salsalate 2.79 ± 0.71 mM; P = 0.10). This effect was independent of changes in insulin but associated with an approx. 1.7-fold increase in glucose uptake into brown adipose tissue (vehicle 45.28 ± 4.57 vs salsalate 76.89 ± 12.23 µmol·g-1 tissue·hr-1; P < 0.001). CONCLUSION: These data show that salsalate can reduce sevoflurane-induced hyperglycemia in mice. This indicates that salsalate may represent a new class of therapeutics that, in addition to its anti-inflammatory and analgesic properties, may be useful to reduce perioperative hyperglycemia.

RéSUMé: OBJECTIF: L'hyperglycémie périopératoire est fréquente et est associée à une morbidité significative. Bien que les caractéristiques propres au patient et à la chirurgie influencent le métabolisme périopératoire du glucose, les anesthésiques ont un impact significatif. Nous avons émis l'hypothèse que l'hyperglycémie en réponse à une anesthésie à base de sévoflurane serait plus prononcée chez des souris obèses et insulino-résistantes que chez des souris témoins maigres. Nous avons en outre émis l'hypothèse que l'hyperglycémie induite par le sévoflurane serait atténuée par un prétraitement au salsalate. MéTHODE: Des souris mâles C57BL/6J maigres et obèses ont été anesthésiées avec du sévoflurane pendant 60 min avec ou sans prétraitement de 62,5 mg·kg−1 de salsalate. La glycémie, l'insuline plasmatique et l'absorption glycémique ont été mesurées dans différents tissus. RéSULTATS: Sous une anesthésie au sévoflurane, les souris obèses ont affiché une glycémie plus élevée que les souris maigres. Des augmentations de glucose sanguin ont été atténuées lors d'un prétraitement aigu à base de salsalate à 60 min sous anesthésie chez les souris obèses (moyenne ± erreur-type sur la moyenne [ETM], delta glycémique; véhicule 5,79 ± 1,09 vs salsalate 1,91 ± 1,32 mM, P = 0,04), mais elles n'étaient pas statistiquement significative chez les souris maigres (delta glycémique, véhicule 4,39 ± 0,55 vs salsalate 2,79 ± 0,71 mM; P = 0,10). Cet effet était indépendant des changements de l'insuline mais associé à une augmentation d'environ 1,7 fois de l'absorption glycémique dans les tissus adipeux bruns (véhicule 45,28 ± 4,57 vs salsalate 76,89 ± 12,23 µmol·g−1 tissu·h−1; P < 0,001). CONCLUSION: Ces données montrent que le salsalate peut réduire l'hyperglycémie induite par le sévoflurane chez la souris. Ceci indique que le salsalate pourrait constituer une nouvelle classe d'agents thérapeutiques qui, en plus de leurs propriétés anti-inflammatoires et analgésiques, pourraient être utiles pour réduire l'hyperglycémie périopératoire.

Legume proteins are smart carriers to encapsulate hydrophilic and hydrophobic bioactive compounds and probiotic bacteria: A review.

Encapsulation is a promising technological process enabling the protection of bioactive compounds against harsh storage, processing, and gastrointestinal tract (GIT) conditions. Legume proteins (LPs) are unique carriers that can efficiently encapsulate these unstable and highly reactive ingredients. Stable LPs-based microcapsules loaded with active ingredients can thus develop to be embedded into processed functional foods. The recent advances in micro- and nanoencapsulation process of an extensive span of bioactive health-promoting probiotics and chemical compounds such as marine and plant fatty acid-rich oils, carotenoid pigments, vitamins, flavors, essential oils, phenolic and anthocyanin-rich extracts, iron, and phytase by LPs as single wall materials were highlighted. A technical summary of the use of single LP-based carriers in designing innovative delivery systems for natural bioactive molecules and probiotics was made. The encapsulation mechanisms, encapsulation efficiency, physicochemical and thermal stability, as well as the release and absorption behavior of bioactives were comprehensively discussed. Protein isolates and concentrates of soy and pea were the most common LPs to encapsulate nutraceuticals and probiotics. The microencapsulation of probiotics using LPs improved bacteria survivability, storage stability, and tolerance in the in vitro GIT conditions. Moreover, homogenization and high-pressure pretreatments as well as enzymatic cross-linking of LPs significantly modify their structure and functionality to better encapsulate the bioactive core materials. LPs can be attractive delivery devices for the controlled release and increased bioaccessibility of the main food-grade bioactives.

Ablating the protein TBC1D1 impairs contraction-induced sarcolemmal glucose transporter 4 redistribution but not insulin-mediated responses in rats.

TBC1 domain family member 1 (TBC1D1), a Rab GTPase-activating protein and paralogue of Akt substrate of 160 kDa (AS160), has been implicated in both insulin- and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase-mediated glucose transporter type 4 (GLUT4) translocation. However, the role of TBC1D1 in contracting muscle remains ambiguous. We therefore explored the metabolic consequence of ablating TBC1D1 in both resting and contracting skeletal muscles, utilizing a rat TBC1D1 KO model. Although insulin administration rapidly increased (p < 0.05) plasma membrane GLUT4 content in both red and white gastrocnemius muscles, the TBC1D1 ablation did not alter this response nor did it affect whole-body insulin tolerance, suggesting that TBC1D1 is not required for insulin-induced GLUT4 trafficking events. Consistent with findings in other models of altered TBC1D1 protein levels, whole-animal and ex vivo skeletal muscle fat oxidation was increased in the TBC1D1 KO rats. Although there was no change in mitochondrial content in the KO rats, maximal ADP-stimulated respiration was higher in permeabilized muscle fibers, which may contribute to the increased reliance on fatty acids in resting KO animals. Despite this increase in mitochondrial oxidative capacity, run time to exhaustion at various intensities was impaired in the KO rats. Moreover, contraction-induced increases in sarcolemmal GLUT4 content and glucose uptake were lower in the white gastrocnemius of the KO animals. Altogether, our results highlight a critical role for TBC1D1 in exercise tolerance and contraction-mediated translocation of GLUT4 to the plasma membrane in skeletal muscle.

Characterization of rheological and physicochemical properties of Alaska walleye pollock (Gadus chalcogrammus) roe.

Alaska walleye pollock (Gadus chalcogrammus) roe is a commercial product of the Alaska pollock fishery. Accordingly, the objective of this study was to determine functional properties of pollock roe through rheological and physicochemical analyses. Pollock roe rheological properties were determined by flow sweep and frequency sweep measurements. Zeta potential of the roe was measured at different pHs (2-12) and roe protein concentration of 0.05% (w/v). Protein solubility was determined by adjusting pH of the freeze-dried pollock roe powder between 2 and 12. Emulsion stability of the roe was determined by measuring creaming index at different oil:water ratios ranging from 5:95 to 65:35 (w/w). The obtained results showed that emulsifying activities of the pollock roe were high (2.93 ± 0.03 ml oil/g roe). Higher oil phase volume resulted in more stable emulsions. The highest charge densities were at pH 2 and 12, where the maximum protein solubility occurred. The DSC thermogram for the pollock roe exhibited a single endothermic peak at 82.89 °C in average, indicated thermal denaturation of the fish roe proteins. Rheological behaviors of the roe were determined as a function of temperature (5 and 25 °C). Viscosity profile showed shear thinning behavior in both samples. However, the pseudoplasticity degree (N) and viscosity values increased by decreasing temperature. The mechanical spectra derived from strain sweep and frequency sweep measurements indicated viscoelastic behavior in all of the samples. However, higher dynamic moduli values at lower temperatures suggested more molecular connectivity and network formation, which was likely caused by protein-protein interactions.

AMP-activated protein kinase, fatty acid metabolism, and insulin sensitivity.

PURPOSE OF REVIEW: Insulin resistance is an important risk factor for metabolic diseases such as type 2 diabetes, cardiovascular disease and certain cancers. A common characteristic of strategies that improve insulin sensitivity involves the activation of the energy sensing enzyme of the cell, AMP-activated protein kinase (AMPK). The purpose of this review is to explore the mechanisms associated with AMPK activation to improve insulin sensitivity with a focus on fatty acid metabolism. We will also discuss the literature surrounding direct AMPK activators to improve insulin resistance and important considerations for the design of direct AMPK activators. RECENT FINDINGS: AMPK activation can decrease de novo lipogenesis, increase fatty acid oxidation and promote mitochondrial integrity to improve insulin sensitivity. Drugs targeted to directly activate AMPK show therapeutic promise, yet in vivo data is lacking. SUMMARY: Designing a drug to directly activate AMPK may improve insulin resistance by reducing liver de novo lipogenesis and increasing brown and white adipose tissue mitochondrial function. However, in vivo experimental procedures to support this notion are not extensive and more research is required.

Treatment of nonalcoholic fatty liver disease: role of AMPK.

Nonalcoholic fatty liver disease (NAFLD) is a growing worldwide epidemic and an important risk factor for the development of insulin resistance, type 2 diabetes, nonalcoholic steatohepatitis (NASH), and hepatic cellular carcinoma (HCC). Despite the prevalence of NAFLD, lifestyle interventions involving exercise and weight loss are the only accepted treatments for this disease. Over the last decade, numerous experimental compounds have been shown to improve NAFLD in preclinical animal models, and many of these therapeutics have been shown to increase the activity of the cellular energy sensor AMP-activated protein kinase (AMPK). Because AMPK activity is reduced by inflammation, obesity, and diabetes, increasing AMPK activity has been viewed as a viable therapeutic strategy to improve NAFLD. In this review, we propose three primary mechanisms by which AMPK activation may improve NAFLD. In addition, we examine the mechanisms by which AMPK is activated. Finally, we identify 27 studies that have used AMPK activators to reduce NAFLD. Future considerations for studies examining the relationship between AMPK and NAFLD are highlighted.

Metformin and salicylate synergistically activate liver AMPK, inhibit lipogenesis and improve insulin sensitivity.

Metformin is the mainstay therapy for type 2 diabetes (T2D) and many patients also take salicylate-based drugs [i.e., aspirin (ASA)] for cardioprotection. Metformin and salicylate both increase AMP-activated protein kinase (AMPK) activity but by distinct mechanisms, with metformin altering cellular adenylate charge (increasing AMP) and salicylate interacting directly at the AMPK ß1 drug-binding site. AMPK activation by both drugs results in phosphorylation of ACC (acetyl-CoA carboxylase; P-ACC) and inhibition of acetyl-CoA carboxylase (ACC), the rate limiting enzyme controlling fatty acid synthesis (lipogenesis). We find doses of metformin and salicylate used clinically synergistically activate AMPK in vitro and in vivo, resulting in reduced liver lipogenesis, lower liver lipid levels and improved insulin sensitivity in mice. Synergism occurs in cell-free assays and is specific for the AMPK ß1 subunit. These effects are also observed in primary human hepatocytes and patients with dysglycaemia exhibit additional improvements in a marker of insulin resistance (proinsulin) when treated with ASA and metformin compared with either drug alone. These data indicate that metformin-salicylate combination therapy may be efficacious for the treatment of non-alcoholic fatty liver disease (NAFLD) and T2D.

AMPK phosphorylation of ACC2 is required for skeletal muscle fatty acid oxidation and insulin sensitivity in mice.

AIMS/HYPOTHESIS: Obesity is characterised by lipid accumulation in skeletal muscle, which increases the risk of developing insulin resistance and type 2 diabetes. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status and is activated in skeletal muscle by exercise, hormones (leptin, adiponectin, IL-6) and pharmacological agents (5-amino-4-imidazolecarboxamide ribonucleoside [AICAR] and metformin). Phosphorylation of acetyl-CoA carboxylase 2 (ACC2) at S221 (S212 in mice) by AMPK reduces ACC activity and malonyl-CoA content but the importance of the AMPK-ACC2-malonyl-CoA pathway in controlling fatty acid metabolism and insulin sensitivity is not understood; therefore, we characterised Acc2 S212A knock-in (ACC2 KI) mice. METHODS: Whole-body and skeletal muscle fatty acid oxidation and insulin sensitivity were assessed in ACC2 KI mice and wild-type littermates. RESULTS: ACC2 KI mice were resistant to increases in skeletal muscle fatty acid oxidation elicited by AICAR. These mice had normal adiposity and liver lipids but elevated contents of triacylglycerol and ceramide in skeletal muscle, which were associated with hyperinsulinaemia, glucose intolerance and skeletal muscle insulin resistance. CONCLUSIONS/INTERPRETATION: These findings indicate that the phosphorylation of ACC2 S212 is required for the maintenance of skeletal muscle lipid and glucose homeostasis.

Improved Quantification of Geosmin and 2-Methylisoborneol in Farmed Fish Using Stable Isotope Dilution Gas Chromatography-Mass Spectrometry.

A requisite to improving the taste and odor attributes of farmed fish is the availability of accurate and practical analytical methods to quantify 2-methylisoborneol (MIB) and geosmin (GSM). Solid-phase microextraction (SPME) enables reliable measurement of nanogram per liter quantities of MIB and GSM in water. In contrast, direct headspace (HS)-SPME of biological matrices with variable proximate compositions can increase bias and uncertainty in off-flavor determinations. Analytical recovery plays a crucial role in the accurate determination of MIB and GSM in fish, and this study investigates strategies to maximize and account for this recovery factor. MIB and GSM values in off-flavor catfish and trout were measured using direct HS-SPME and distillation as sample preparation techniques. Trout samples prepared by distillation yielded 10-fold higher GSM recoveries than those from direct HS-SPME (31% versus 3%). A stable isotope dilution method (SIDM) was implemented by routinely spiking samples with known quantities of deuterium-labeled MIB and GSM, allowing for the correction of sample-to-sample recovery deviations. SIDM-determined GSM values generated recoveries of 106 and 95% for direct HS-SPME and distilled trout, respectively. Aspects of the strategies and techniques presented can be incorporated into existing analytical methods to improve the accuracy and sample throughput. Particularly, routine inclusion of SIDM in the evaluation of MIB and GSM can facilitate identification of reliable practices to control off-flavors in aquaculture.

AMP-activated protein kinase is required for exercise-induced peroxisome proliferator-activated receptor co-activator 1 translocation to subsarcolemmal mitochondria in skeletal muscle.

In skeletal muscle, mitochondria exist as two subcellular populations known as subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria. SS mitochondria preferentially respond to exercise training, suggesting divergent transcriptional control of the mitochondrial genomes. The transcriptional co-activator peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) and mitochondrial transcription factor A (Tfam) have been implicated in the direct regulation of the mitochondrial genome in mice, although SS and IMF differences may exist, and the potential signalling events regulating the mitochondrial content of these proteins have not been elucidated. Therefore, we examined the potential for PGC-1α and Tfam to translocate to SS and IMF mitochondria in human subjects, and performed experiments in rodents to identify signalling mechanisms regulating these translocation events. Acute exercise in humans and rats increased PGC-1α content in SS but not IMF mitochondria. Acute exposure to 5-aminoimidazole-4-carboxamide-1-ß-ribofuranoside in rats recapitulated the exercise effect of increased PGC-1α protein within SS mitochondria only, suggesting that AMP-activated protein kinase (AMPK) signalling is involved. In addition, rendering AMPK inactive (AMPK kinase dead mice) prevented exercise-induced PGC-1α translocation to SS mitochondria, further suggesting that AMPK plays an integral role in these translocation events. In contrast to the conserved PGC-1α translocation to SS mitochondria across species (humans, rats and mice), acute exercise only increased mitochondrial Tfam in rats. Nevertheless, in rat resting muscle PGC-1α and Tfam co-immunoprecipate with α-tubulin, suggesting a common cytosolic localization. These data suggest that exercise causes translocation of PGC-1α preferentially to SS mitochondria in an AMPK-dependent manner.

Submaximal ADP-stimulated respiration is impaired in ZDF rats and recovered by resveratrol.

Mitochondrial dysfunction and reactive oxygen species (ROS) have been implicated in the aetiology of skeletal muscle insulin resistance, although there is considerable controversy regarding these concepts. Mitochondrial function has been traditionally assessed in the presence of saturating ADP, but ATP turnover and the resultant ADP is thought to limit respiration in vivo. Therefore, we investigated the potential link between submaximal ADP-stimulated respiration rates, ROS generation and skeletal muscle insulin sensitivity in a model of type 2 diabetes mellitus, the ZDF rat. Utilizing permeabilized muscle fibres we observed that submaximal ADP-stimulated respiration rates (250-2000 µm ADP) were lower in ZDF rats than in lean controls, which coincided with decreased adenine nucleotide translocase 2 (ANT2) protein content. This decrease in submaximal ADP-stimulated respiration occurred in the absence of a decrease in electron transport chain function. Treating ZDF rats with resveratrol improved skeletal muscle insulin resistance and this was associated with elevated submaximal ADP-stimulated respiration rates as well as an increase in ANT2 protein content. These results coincided with a greater ability of ADP to attenuate mitochondrial ROS emission and an improvement in cellular redox balance. Together, these data suggest that mitochondrial dysfunction is present in skeletal muscle insulin resistance when assessed at submaximal ADP concentrations and that ADP dynamics may influence skeletal muscle insulin sensitivity through alterations in the propensity for mitochondrial ROS emission.

In vivo, fatty acid translocase (CD36) critically regulates skeletal muscle fuel selection, exercise performance, and training-induced adaptation of fatty acid oxidation.

For ~40 years it has been widely accepted that (i) the exercise-induced increase in muscle fatty acid oxidation (FAO) is dependent on the increased delivery of circulating fatty acids, and (ii) exercise training-induced FAO up-regulation is largely attributable to muscle mitochondrial biogenesis. These long standing concepts were developed prior to the recent recognition that fatty acid entry into muscle occurs via a regulatable sarcolemmal CD36-mediated mechanism. We examined the role of CD36 in muscle fuel selection under basal conditions, during a metabolic challenge (exercise), and after exercise training. We also investigated whether CD36 overexpression, independent of mitochondrial changes, mimicked exercise training-induced FAO up-regulation. Under basal conditions CD36-KO versus WT mice displayed reduced fatty acid transport (-21%) and oxidation (-25%), intramuscular lipids (less than or equal to -31%), and hepatic glycogen (-20%); but muscle glycogen, VO(2max), and mitochondrial content and enzymes did not differ. In acutely exercised (78% VO(2max)) CD36-KO mice, fatty acid transport (-41%), oxidation (-37%), and exercise duration (-44%) were reduced, whereas muscle and hepatic glycogen depletions were accelerated by 27-55%, revealing 2-fold greater carbohydrate use. Exercise training increased mtDNA and ß-hydroxyacyl-CoA dehydrogenase similarly in WT and CD36-KO muscles, but FAO was increased only in WT muscle (+90%). Comparable CD36 increases, induced by exercise training (+44%) or by CD36 overexpression (+41%), increased FAO similarly (84-90%), either when mitochondrial biogenesis and FAO enzymes were up-regulated (exercise training) or when these were unaltered (CD36 overexpression). Thus, sarcolemmal CD36 has a key role in muscle fuel selection, exercise performance, and training-induced muscle FAO adaptation, challenging long held views of mechanisms involved in acute and adaptive regulation of muscle FAO.

Identification of a novel malonyl-CoA IC(50) for CPT-I: implications for predicting in vivo fatty acid oxidation rates.

Published values regarding the sensitivity (IC(50)) of CPT-I (carnitine palmitoyltransferase I) to M-CoA (malonyl-CoA) inhibition in isolated mitochondria are inconsistent with predicted in vivo rates of fatty acid oxidation. Therefore we have re-examined M-CoA inhibition kinetics under various P-CoA (palmitoyl-CoA) concentrations in both isolated mitochondria and PMFs (permeabilized muscle fibres). PMFs have an 18-fold higher IC(50) (0.61 compared with 0.034 µM) in the presence of 25 µM P-CoA and a 13-fold higher IC(50) (6.3 compared with 0.49 µM) in the presence of 150 µM P-CoA compared with isolated mitochondria. M-CoA inhibition kinetics determined in PMFs predicts that CPT-I activity is inhibited by 33% in resting muscle compared with >95% in isolated mitochondria. Additionally, the ability of M-CoA to inhibit CPT-I appears to be dependent on P-CoA concentration, as the relative inhibitory capacity of M-CoA is decreased with increasing P-CoA concentrations. Altogether, the use of PMFs appears to provide an M-CoA IC(50) that better reflects the predicted in vivo rates of fatty acid oxidation. These findings also demonstrate that the ratio of [P-CoA]/[M-CoA] is critical for regulating CPT-I activity and may partially rectify the in vivo disconnect between M-CoA content and CPT-I flux within the context of exercise and Type 2 diabetes.

Protein composition of pulses and their protein isolates from different sources and in different isolation pH values using a reverse phase high performance liquid chromatography method.

The objective of this study was to compare the composition of pulse proteins isolated from lentils and green and yellow peas at two isolation pH values (9 and 11) and determine the effect of this variability on protein functionality. Chromatogram peaks obtained from reverse-phase high performance liquid chromatography were identified by isolation of albumin-, vicilin- and legumin-rich fractions for the three pulses. Protein composition was obtained for each isolate and compared against that of the originating pulse flour. Lentil flour showed the highest level of vicilin with a vicilin/legumin ratio of âˆ¼ 2.5, while this ratio was 1.3 and 1.2 for green and yellow pea flour, respectively. Albumin content of yellow pea flour was high (∼36.1 %), which reduced to âˆ¼ 15-19 % in isolated proteins showing a loss in albumins during the isolation. Higher extraction pH increased pea protein yield but led to lower protein solubility with no changes in foaming properties and in-vitro digestibility.

Optimization of tannin-containing sorghum bran addition to gluten-free bread.

Ingredients used to enhance sensory quality of gluten-free (GF) bread often lack in nutrients. This presents nutritional challenges for celiac-positive individuals and fails to meet expectations of healthfulness for non-celiac GF consumers. Sorghum (Sorghum bicolor L. Moench) flour can provide acceptable GF bread properties, and tannin-containing varieties contain antioxidants concentrated in the bran along with dietary fiber. Using a central composite design, tannin-containing sumac sorghum bran, gum (xanthan + guar), and water levels were optimized in a GF sorghum-based bread formulation. Loaf specific volume and gas cells/cm2 were maximized while minimizing hardness and cell wall thickness. The optimum formulation containing 14.2% sorghum bran, 1% gum, and 145% water (flour basis) effectively increased dietary fiber in bread to 13.4% (considered "high fiber") and showed oxygen radical absorbance capacity of 61.6 µmol TE/g. This optimum formulation did not differ from a sorghum flour-based control bread in consumers' (N = 100) liking of color, texture, flavor, overall acceptability, nor willingness to buy (WTB). All mean hedonic scores (numbered 9-point scale) were above 5, whereas average WTB was 4.7 for the optimum formulation and 4.6 for the control (9-point Likert scale) among consumers varying in GF bread consumption habits. Perceived bread bitterness was low (averaging 2.85 on 9-point intensity scale), did not vary between samples despite marked differences in antioxidant capacity, and was not correlated with WTB. When utilizing effective optimization models with key functional ingredients, sumac sorghum bran addition can enhance dietary fiber and antioxidant potential in sorghum-based GF breads without compromising quality attributes.

Consumer perceptions and antioxidant profiling of acidified cold-brewed sorghum bran beverages.

Sumac sorghum (Sorghum bicolor L. Moench) bran contains polyphenolic compounds with health-promoting properties. Functional food product development can add economic value to sorghum bran, but acceptability may be limited by bitter taste. An acidified cold-brewed sorghum bran beverage was developed, and simplified sweetened (SB) and unsweetened (UB) versions were analyzed for antioxidant profiles (total phenolic content, phenolic profiling via HPLC, condensed tannins, oxygen radical absorbance capacity, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging) and sensory properties. Beverages contained condensed tannins (average of 0.33 mg catechin equivalents per milliliter) along with other flavonoids and demonstrated in vitro antioxidant capacity (3.32-3.96 mmol Trolox equivalents per milliliter). One hundred fourteen consumers, grouped by 6-n-propylthiouracil (bitterness) taster status, rated acceptability (9-point hedonic scales), bitterness intensity (5-point scale), and purchase intent (PI; yes/no) of model beverages. Although the concept was novel, SB was clearly more acceptable to consumers regardless of preference for sweet versus unsweet tea (as a reference product concept). Mean mouthfeel and flavor liking scores were significantly higher for SB (6.2 and 5.1, respectively) than UB (4.8 and 3.0, respectively). Bitterness was suppressed by the sweetness in SB (mean bitterness intensity of 1.8 vs. 2.6 for UB), although 21% of consumers still found it "too bitter." However, consumers' taster status did not affect beverage acceptability nor bitterness perceptions at present phenolic levels (0.53 gallic acid equivalents per milligram). After a sorghum/antioxidant information message, positive PI increased to 56% for SB, impacting more females than males. Enhanced familiarity and effective product messaging can improve acceptability of acidified cold-brewed sorghum bran beverages as a novel functional food product concept. PRACTICAL APPLICATION: New food applications of cereal bran can provide value in terms of byproduct utilization and delivery of health-promoting ingredients. Sorghum bran beverages demonstrated antioxidant activity, and the sweetened formulation showed decreased bitterness and increased acceptability. Consumers were positively influenced by antioxidant information, although most had not previously consumed sorghum.