Heterogeneous nanoscopic lipid diffusion in the live cell membrane and its dependency on cholesterol.

Cholesterol plays a unique role in the regulation of membrane organization and dynamics by modulating the membrane phase transition at the nanoscale. Unfortunately, due to their small sizes and dynamic nature, the effects of cholesterol-mediated membrane nanodomains on membrane dynamics remain elusive. Here, using ultrahigh-speed single-molecule tracking with advanced optical microscope techniques, we investigate the diffusive motion of single phospholipids in the live cell plasma membrane at the nanoscale and its dependency on the cholesterol concentration. We find that both saturated and unsaturated phospholipids undergo anomalous subdiffusion on the length scale of 10-100 nm. The diffusion characteristics exhibit considerable variations in space and in time, indicating that the nanoscopic lipid diffusion is highly heterogeneous. Importantly, through the statistical analysis, apparent dual-mobility subdiffusion is observed from the mixed diffusion behaviors. The measured subdiffusion agrees well with the hop diffusion model that represents a diffuser moving in a compartmentalized membrane created by the cytoskeleton meshwork. Cholesterol depletion diminishes the lipid mobility with an apparently smaller compartment size and a stronger confinement strength. Similar results are measured with temperature reduction, suggesting that the more heterogeneous and restricted diffusion is connected to the nanoscopic membrane phase transition. Our conclusion supports the model that cholesterol depletion induces the formation of gel-phase, solid-like membrane nanodomains. These nanodomains undergo restricted diffusion and act as diffusion obstacles to the membrane molecules that are excluded from the nanodomains. This work provides the experimental evidence that the nanoscopic lipid diffusion in the cell plasma membrane is heterogeneous and sensitive to the cholesterol concentration and temperature, shedding new light on the regulation mechanisms of nanoscopic membrane dynamics.

Amyloid-ß40 E22K fibril in familial Alzheimer's disease is more thermostable and susceptible to seeding.

Alzheimer's disease (AD) is the most prevalent and devastating neurodegenerative disease occurred in the elderly. One of the pathogenic hallmarks is senile plaques composed of amyloid-ß (Aß) fibrils. Single mutations resided in Aß were found in familial AD (FAD) patients that have early onset of the disease. The molecular details and properties of each FAD Aß variants are still elusive. Here, we employed collective spectroscopic techniques to examine the properties of various Aß40 fibrils. We generated fibrils of wild type (WT) and three FAD mutants on residue E22 including E22G, E22K, and E22Q. We monitored fibril formation by thioflavin T (ThT) assay, examined secondary structure by Fourier transform infrared and far-UV circular dichroism spectroscopy, imaged fibril morphology by transmission electron microscopy, and evaluated ThT-binding kinetics. In the thermal experiments, we found E22K fibrils resisted to high temperature and retained significant ß-sheet content than the others. E22K fibril seeds after high-temperature treatment still possess the seeding property, whereas WT fibril seeds are disturbed after the treatment. Therefore, in this study we demonstrated the mutation at E22K increases the thermal stability and seeding function of amyloid fibrils.

Do E2 and P4 contribute to the explained variance in core temperature response for trained women during exertional heat stress when metabolic rates are very high?

PURPOSE: Women remain underrepresented in the exercise thermoregulation literature despite their participation in leisure-time and occupational physical activity in heat-stressful environments continuing to increase. Here, we determined the relative contribution of the primary ovarian hormones (estrogen [E2] and progesterone [P4]) alongside other morphological (e.g., body mass), physiological (e.g., sweat rates), functional (e.g., aerobic fitness) and environmental (e.g., vapor pressure) factors in explaining the individual variation in core temperature responses for trained women working at very high metabolic rates, specifically peak core temperature (Tpeak) and work output (mean power output). METHODS: Thirty-six trained women (32 ± 9 year, 53 ± 9 ml·kg-1·min-1), distinguished by intra-participant (early follicular and mid-luteal phases) or inter-participant (ovulatory vs. anovulatory vs. oral contraceptive pill user) differences in their endogenous E2 and P4 concentrations, completed a self-paced 30-min cycling work trial in warm-dry (2.2 ± 0.2 kPa, 34.1 ± 0.2 °C, 41.4 ± 3.4% RH) and/or warm-humid (3.4 ± 0.1 kPa, 30.2 ± 1.2 °C, 79.8 ± 3.7% RH) conditions that yielded 115 separate trials. Stepwise linear regression was used to explain the variance of the dependent variables. RESULTS: Models were able to account for 60% of the variance in Tpeak ([Formula: see text]2: 41% core temperature at the start of work trial, [Formula: see text]2: 15% power output, [Formula: see text]2: 4% [E2]) and 44% of the variance in mean power output ([Formula: see text]2: 35% peak aerobic power, [Formula: see text]2: 9% perceived exertion). CONCLUSION: E2 contributes a small amount toward the core temperature response in trained women, whereby starting core temperature and peak aerobic power explain the greatest variance in Tpeak and work output, respectively.

Menstrual phase and ambient temperature do not influence iron regulation in the acute exercise period.

The current study investigated whether ambient heat augments the inflammatory and postexercise hepcidin response in women and if menstrual phase and/or self-pacing modulate these physiological effects. Eight trained females (age: 37 ± 7 yr; V̇o2max: 46 ± 7 mL·kg-1·min-1; peak power output: 4.5 ± 0.8 W·kg-1) underwent 20 min of fixed-intensity cycling (100 W and 125 W) followed by a 30-min work trial (∼75% V̇o2max) in a moderate (MOD: 20 ± 1°C, 53 ± 8% relative humidity) and warm-humid (WARM: 32 ± 0°C, 75 ± 3% relative humidity) environment in both their early follicular (days 5 ± 2) and midluteal (days 21 ± 3) phases. Mean power output was 5 ± 4 W higher in MOD than in WARM (P = 0.02) such that the difference in core temperature rise was limited between environments (-0.29 ± 0.18°C in MOD, P < 0.01). IL-6 and hepcidin both increased postexercise (198% and 38%, respectively); however, neither was affected by ambient temperature or menstrual phase (all P > 0.15). Multiple regression analysis demonstrated that the IL-6 response to exercise was explained by leukocyte and platelet count (r2 = 0.72, P < 0.01), and the hepcidin response to exercise was explained by serum iron and ferritin (r2 = 0.62, P < 0.01). During exercise, participants almost matched their fluid loss (0.48 ± 0.18 kg·h-1) with water intake (0.35 ± 0.15 L·h-1) such that changes in body mass (-0.3 ± 0.3%) and serum osmolality (0.5 ± 2.0 osmol·kgH2O-1) were minimal or negligible, indicating a behavioral fluid-regulatory response. These results indicate that trained, iron-sufficient women suffer no detriment to their iron regulation in response to exercise with acute ambient heat stress or between menstrual phases on account of a performance-physiological trade-off.

Twelve-Weeks of Bench-Step Exercise Training Ameliorates Cardiopulmonary Fitness and Mood State in Patients with Schizophrenia: A Pilot Study.

Background and objectives: Unhealthy, physically inactive lifestyles increase the risk of future cardiovascular events and impaired physical fitness in individuals with schizophrenia. Insufficient literature exists to provide fundamental information about appropriate exercise training modality for this population. This pilot study preliminarily investigated the effects of a 12-week moderate-intensity bench-step exercise training (BSET) program on cardiopulmonary fitness, mood state, and cognition in patients with schizophrenia. Methods: Twenty-eight patients with schizophrenia completed this study. The participants were allocated into either bench-step exercise-training (BSET; N = 14) or control (CTRL; N = 14) groups according to their preferences. The BSET group received a 12-week bench-step intervention, whereas the CTRL group did not participate in any training. The Beck Depression Inventory-II (BDI-II), 6-min walk test (6MWD), and Symbol Digit Modalities Test (SDMT) were assessed at baseline (PRE) and at the end of the intervention (POST) to determine mood state, endurance fitness, and attention, respectively. Results: After a 12-week BSET intervention, the 6MWD was significantly increased in the BSET (p = 0.007) but not in the CTRL (p > 0.05). The participants with BSET intervention showed a significant decrease in BDI-II at the end of the intervention (p = 0.03). However, SDMT scores were not different in both BSET and CTRL (p > 0.05). Conclusions: This study demonstrated that the 12-week intervention of moderate-intensity bench-step exercise training (frequency: 1 session/week; each session of 30 min; step cadence: 96 beats/min) might effectively enhance cardiopulmonary fitness and mood state in patients with schizophrenia. However, attention did not change after the bench-step exercise intervention.

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes.

The purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO2max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO2 = 20.9%), 2) hypoxic placebo (HPLA; FiO2 = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO2 = 16.3%). During the TT, physiological responses (SpO2, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5-4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.

Short-Term High-Dose Vitamin C and E Supplementation Attenuates Muscle Damage and Inflammatory Responses to Repeated Taekwondo Competitions: A Randomized Placebo-Controlled Trial.

Background: Exercise-induced muscle damage during intensive sport events is a very common issue in sport medicine. Therefore, the purpose is to investigate the effects of short-term high-dose vitamin C and E supplementation on muscle damage, hemolysis, and inflammatory responses to simulated competitive Olympic Taekwondo (TKD) matches in elite athletes. Methods: Using a randomized placebo-controlled and double-blind study design, eighteen elite male TKD athletes were weight-matched and randomly assigned into either a vitamin C and E group (Vit C+E; N = 9) or placebo group (PLA; N = 9). Vit C+E or PLA supplements were taken daily (Vit C+E: 2000 mg/d vitamin C; 1400 U/d vitamin E) for 4 days (3 days before and on competition day) before taking part in 4 consecutive TKD matches on a single day. Plasma samples were obtained before each match and 24-hours after the first match for determination of markers of muscle damage, hemolysis, and systemic inflammatory state. Results: Myoglobin was lower in the Vit C+E group, compared to PLA, during the match day (area under curve, AUC -47.0% vs. PLA, p = 0.021). Plasma creatine kinase was lower in the Vit C+E group (AUC -57.5% vs. PLA, p = 0.017) and hemolysis was lower in the Vit C+E group (AUC -40.5% vs. PLA, p = 0.034). Conclusions: We demonstrated that short-term (4-days) vitamin C and E supplementation effectively attenuated exercise-induced tissue damage and inflammatory response during and after successive TKD matches.

An Amino Acids Mixture Attenuates Glycemic Impairment but not Affects Adiposity Development in Rats Fed with AGEs-containing Diet.

Background: Unhealthy western dietary patterns lead to over-consumption of fat and advanced glycation end-products (AGEs), and these account for the developments of obesity, diabetes, and related metabolic disorders. Certain amino acids (AAs) have been recently demonstrated to improve glycemia and reduce adiposity. Therefore, our primary aims were to examine whether feeding an isoleucine-enriched AA mixture (4.5% AAs; Ile: 3.0%, Leu: 1.0%, Val: 0.2%, Arg: 0.3% in the drinking water) would affect adiposity development and prevent the impairments of glycemic control in rats fed with the fat/AGE-containing diet (FAD). Methods: Twenty-four male Sprague-Dawley rats were assigned into 1) control diet (CD, N = 8), 2) FAD diet (FAD, N = 8), and 3) FAD diet plus AA (FAD/AA, N = 8). After 9-weeks intervention, the glycemic control capacity (glucose level, ITT, and HbA1c levels), body composition, and spontaneous locomotor activity (SLA) were evaluated, and the fasting blood samples were collected for analyzing metabolic related hormones (insulin, leptin, adiponectin, and corticosterone). The adipose tissues were also surgically collected and weighed. Results: FAD rats showed significant increases in weight gain, body fat %, blood glucose, HbA1c, leptin, and area under the curve of glucose during insulin tolerance test (ITT-glucose-AUC) in compared with the CD rats. However, the fasting levels of blood glucose, HbA1c, leptin, and ITT-glucose-AUC did not differ between CD and FAD/AA rats. FAD/AA rats also showed a greater increase in serum testosterone. Conclusion: The amino acid mixture consisting of Ile, Leu, Val, and Arg showed clear protective benefits on preventing the FAD-induced obesity and impaired glycemic control.

Hot Water Bathing Impairs Training Adaptation in Elite Teen Archers.

Despite heat imposes considerable physiological stress to human body, hot water immersion remains as a popular relaxation modality for athletes. Here we examined the lingering effect of hot tub relaxation after training on performance-associated measures and dehydroepiandrosterone sulfate (DHEA-S) in junior archers. Ten national level archers, aged 16.6 ± 0.3 years (M = 8, F = 2), participated in a randomized counter-balanced crossover study after baseline measurements. In particular, half participants were assigned to the hot water immersion (HOT) group, whereas another halves were assigned to the untreated control (CON) group. Crossover trial was conducted following a 2-week washout period. During the HOT trial, participants immersed in hot water for 30 min at 40°C, 1 h after training, twice a week (every 3 days) for 2 weeks. Participants during CON trial sat at the same environment without hot water after training. Performance-associated measures and salivary DHEA-S were determined 3 days after the last HOT session. We found that the HOT intervention significantly decreased shooting performance (CON: -4%; HOT: -22%, P < 0.05), postural stability (CON: +15%; HOT: -16%, P < 0.05), and DHEA-S levels (CON: -3%; HOT: -60%, P < 0.05) of archers, compared with untreated CON trial. No group differences were found in motor unit recruitment (root mean square electromyography, RMS EMG) of arm muscles during aiming, autonomic nervous activity (sympathetic and vagal powers of heart rate variability, HRV), and plasma cortisol levels after treatments. Our data suggest that physiological adaptation against heat exposure takes away the sources needed for normal training adaptation specific to shooting performance in archers.

Investigation of Sensitivities and Drift Effects of the Arrayed Flexible Chloride Sensor Based on RuO2/GO at Different Temperatures.

We investigate the temperature effect on sensing characteristics and drift effect of an arrayed flexible ruthenium dioxide (RuO2)/graphene oxide (GO) chloride sensor at different solution temperatures between 10 °C and 50 °C. The average sensor sensitivities according to our experimental results were 28.2 ± 1.4 mV/pCl (10 °C), 42.5 ± 2.0 mV/pCl (20 °C), 47.1 ± 1.8 mV/pCl (30 °C), 54.1 ± 2.01 mV/pCl (40 °C) and 46.6 ± 2.1 mV/pCl (50 °C). We found the drift effects of an arrayed flexible RuO2/GO chloride sensor in a 1 M NaCl solution to be between 8.2 mV/h and 2.5 mV/h with solution temperatures from 10 °C to 50 °C.

Diet-induced obesity accelerates blood lactate accumulation of rats in response to incremental exercise to maximum.

Blood lactate increases during incremental exercise at high-intensity workloads, and limited exercise capacity is a characteristic of obese animals. This study examined whether blood lactate changes in response to incremental exercise is disrupted in obese animals. Muscular and hepatic proteins that are critical in lactate metabolism were also investigated. Rats were randomized to either standard chow (control) or high-fat diet (HFD) groups. All animals underwent an incremental treadmill test after 14 wk of diet intervention. Blood lactate levels were measured before and after the treadmill test. Activities of mitochondrial oxidative phosphorylation and glycolysis were examined in muscle tissues. Proteins in the liver and skeletal muscles that participate in the turnover of blood lactate were determined by Western blot. Running time in the incremental treadmill test decreased in the HFD group, and blood lactate accumulated faster in these animals than in the control group. Animals with HFD had a decreased level of hepatic monocarboxylate transporter 2, the protein responsible for blood lactate uptake in the liver. Skeletal muscles of animals with HFD showed greater glycolytic activity and decreased content of lactate dehydrogenase B, which converts lactate to pyruvate. We conclude that blood lactate accumulated faster during incremental exercise in obese animals and was associated with their decreased exercise performance. Changes in the metabolic pattern of muscles and changes of liver and muscle proteins associated with lactate utilization likely contribute to the abnormal response of blood lactate to incremental exercise in obese animals.

Effect of green tea extract supplementation on glycogen replenishment in exercised human skeletal muscle.

The purpose of this study was to investigate the effects of 8-week green tea extract (GTE) supplementation on promoting postexercise muscle glycogen resynthesis and systemic energy substrate utilisation in young college students. A total of eight healthy male participants (age: 22·0 (se 1·0) years, BMI: 24·2 (se 0·7) kg/m2, VO2max: 43·2 (se 2·4) ml/kg per min) participated in this study. GTE (500 mg/d for 8 weeks) was compared with placebo in participants in a double-blind/placebo-controlled and crossover study design with an 8-week washout period. Thereafter, all participants performed a 60-min cycling exercise (75 % VO2max) and consumed a carbohydrate-enriched meal immediately after exercise. Vastus lateralis muscle samples were collected immediately (0 h) and 3 h after exercise, and blood and gaseous samples were collected during the 3-h postexercise recovery period. An 8-week oral GTE supplementation had no effects on further promoting muscle glycogen resynthesis in exercised human skeletal muscle, but the exercise-induced muscle GLUT type 4 (GLUT4) protein content was greater in the GTE supplementation trial (P<0·05). We observed that, during the postexercise recovery period, GTE supplementation elicited an increase in energy reliance on fat oxidation compared with the placebo trial (P<0·05), although there were no differences in blood glucose and insulin responses between the two trials. In summary, 8-week oral GTE supplementation increases postexercise systemic fat oxidation and exercise-induced muscle GLUT4 protein content in response to an acute bout of endurance exercise. However, GTE supplementation has no further benefit on promoting muscle glycogen resynthesis during the postexercise period.

Acute changes in blood lipid profiles and metabolic risk factors in collegiate elite taekwondo athletes after short-term de-training: a prospective insight for athletic health management.

BACKGROUND: This study used a short-term de-training model to mimic the physiological weight changes during the early retirement stage in Taekwondo (TKD) athletes. This study investigates whether the negative changes in body composition, blood lipid profiles, and metabolic biomarkers occur in elite collegiate TKD athletes when experiencing a two-months de-training period. METHODS: Fourteen collegiate Division Ι elite TKD athletes (age: 21.1 ± 0.2 years, BMI: 22.3 ± 1.1 kg/m2; 10 males and 4 females) participated in this study. The body composition, blood lipid profiles, atherogenic dyslipidemia indexes, metabolic biomarkers and baseline systemic inflammation states were measured before and after two-months de-training. RESULTS: The body weight and BMI did not change after de-training in these elite TKD athletes. The total muscle mass displayed a significant decline after de-training (-2.0%, p = 0.019), with an increase in fat mass (+24.3%, p < 0.01). The blood triglyceride did not change, but the total cholesterol was higher after de-training (+8.3%, p = 0.047). The CHOL-to-HDL and LDL-to-HDL ratios increased by 12.4% (p < 0.001) and 13.2% (p = 0.002) after de-training, respectively. The blood platelet number, plateletcrit, and platelet-to-lymphocyte ratio increased significantly by 5.0% (p = 0.013), 7.3% (p = 0.009), and 20.6% (p = 0.018) after de-training, respectively. The McAuley's Index decreased (-6.9%, p = 0.025) after de-training. CONCLUSION: We demonstrated that a two-months de-training period resulted in adverse effects on early atherogenic dyslipidemia development, progressing insulin resistance, low-grade inflammation, and visceral adiposity in young elite TKD athletes. Our findings provide clear insights into the possible deleterious impacts at early stage retirement in former combative sports athletes.

Fabrication of Flexible Arrayed Lactate Biosensor Based on Immobilizing LDH-NAD⁺ on NiO Film Modified by GO and MBs.

We proposed the flexible arrayed lactate biosensor based on immobilizing l-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide ( NAD + ) on nickel oxide (NiO) film, and which the average sensitivity could be enhanced by using graphene oxide (GO) and magnetic beads (MBs). By using GO and MBs, it exhibits excellent sensitivity (45.397 mV/mM) with a linearity of 0.992 in a range of 0.2 mM to 3 mM. According to the results of electrochemical impedance spectroscopy (EIS), the electron transfer resistance of LDH- NAD + -MBs/GPTS/GO/NiO film was smaller than those of LDH-NAD⁺/GPTS/GO/NiO film and LDH- NAD + /GPTS/NiO film, and it presented the outstanding electron transfer ability. After that, the limit of detection, anti-interference effect and bending test were also investigated.

Neuromuscular Activity and Muscular Oxygenation Through Different Movement Cadences During In-water and On-land Knee Extension Exercise.

Chien, K-Y, Kan, N-W, Liao, Y-H, Lin, Y-L, Lin, C-L, and Chen, W-C. Neuromuscular activity and muscular oxygenation through different movement cadences during in-water and on-land knee extension exercise. J Strength Cond Res 31(3): 750-757, 2017-The purpose of this study was to determine the influence of various knee extension exercise cadences on neuromuscular activation and hemodynamic properties of the quadriceps muscle in water and on land. Seventeen young women participated in this study, and the subjects were randomly allocated to perform loaded knee extension exercises in water and on land at 4 different cadences of 30, 50, 70, and 90 b·min. Heart rate (HR), blood flow (BF), total saturation index (TSI) of oxygen, electromyography (EMG) for the extent of muscular activity, and rate of perceived exertion (RPE) were measured. Response values of HR, BF, TSI, and RPE at each cadence were obtained by subtracting the resting values from the indicator values measured at the respective cadences. We observed that BF, EMG, and RPE in water at 90 b·min were comparable with those on land. The HR and TSI changes were higher in water compared with on land (p = 0.004 and p = 0.013, respectively). In conclusion, we demonstrate that the neuromuscular activity when performing knee extension exercises at 90 b·min in water was comparable with that on land. However, exercising in water at the same cadence evoked higher TSI responses and greater cardiovascular challenges. A knee extension exercise at 90 b·min is the recommended operating speed of rehabilitation in water.

Late-onset caloric restriction alters skeletal muscle metabolism by modulating pyruvate metabolism.

Caloric restriction (CR) attenuates age-related muscle loss. However, the underlying mechanism responsible for this attenuation is not fully understood. This study evaluated the role of energy metabolism in the CR-induced attenuation of muscle loss. The aims of this study were twofold: 1) to evaluate the effect of CR on energy metabolism and determine its relationship with muscle mass, and 2) to determine whether the effects of CR are age dependent. Young and middle-aged rats were randomized into either 40% CR or ad libitum (AL) diet groups for 14 wk. Major energy-producing pathways in muscles, i.e., glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), were examined. We found that the effects of CR were age dependent. CR improved muscle metabolism and normalized muscle mass in middle-aged animals but not young animals. CR decreased glycolysis and increased the cellular dependency for OXPHOS vs. glycolysis in muscles of middle-aged rats, which was associated with the improvement of normalized muscle mass. The metabolic reprogramming induced by CR was related to modulation of pyruvate metabolism and increased mitochondrial biogenesis. Compared with animals fed AL, middle-aged animals with CR had lower lactate dehydrogenase A content and greater mitochondrial pyruvate carrier content. Markers of mitochondrial biogenesis, including AMPK activation levels and SIRT1 and COX-IV content, also showed increased levels. In conclusion, 14 wk of CR improved muscle metabolism and preserved muscle mass in middle-aged animals but not in young developing animals. CR-attenuated age-related muscle loss is associated with reprogramming of the metabolic pathway from glycolysis to OXPHOS.

A novel method for expression and purification of authentic amyloid-ß with and without (15)N labels.

Amyloid-ß (Aß) is a major constituent in the senile plaques of patients with Alzheimer's disease (AD). Aß has been intensively studied in amyloid research; however, challenges posed by data reproducibility arise from purity of synthetic Aß and high expense for its isotope-labeling. The difficulties motivate development and optimization of recombinant Aß (rAß) production. Here, we report a new procedure to express and purify high quality rAß40 from Escherichia coli. The new Aß construct expressed insoluble Aß fused with an N-terminal histidine-tag connected by a linker harboring TEV protease cut site. After purification and partial refolding, the fusion tag was removed by TEV protease cleavage, immobilized metal affinity chromatography (IMAC), and reversed phase-HPLC purification with a yield of 3.5 mg/L culture with and without (15)N label. The rAß adopts classic amyloid fibrillization and is capable of binding to its clinical relevant metal ions.

The effect of an amino acid beverage on glucose response and glycogen replenishment after strenuous exercise.

PURPOSE: We previously reported that an amino acid mixture (AA) was able to lower the glucose response to an oral glucose challenge in both rats and humans. Increased glucose uptake and glycogen storage in muscle might be associated with the faster blood glucose clearance. We therefore tested the effect of two different doses of AA provided with a carbohydrate supplement on blood glucose homeostasis and muscle glycogen replenishment in human subjects after strenuous aerobic exercise. METHODS: Ten subjects received a carbohydrate (1.2 g/kg body weight, CHO), CHO/HAA (CHO + 13 g AA), or CHO/LAA (CHO + 6.5 g AA) supplement immediately and 2 h after an intense cycling bout. Muscle biopsies were performed immediately and 4 h after exercise. RESULTS: The glucose responses for CHO/HAA and CHO/LAA during recovery were significantly lower than CHO, as was the glucose area under the curve (CHO/HAA 1259.9 ± 27.7, CHO/LAA 1251.5 ± 47.7, CHO 1376.8 ± 52.9 mmol/L 4 h, p < 0.05). Glycogen storage rate was significantly lower in CHO/HAA compared with CHO, while it did not differ significantly between CHO/LAA or CHO (CHO/HAA 15.4 ± 2.0, CHO/LAA 18.1 ± 2.0, CHO 21.5 ± 1.4 µmol/g wet muscle 4 h). CHO/HAA caused a significantly higher insulin response and a greater effect on mTOR and Akt/PKB phosphorylation compared with CHO. Phosphorylation of AS160 and glycogen synthase did not differ across treatments. Likewise, there were no differences in blood lactate across treatments. CONCLUSIONS: The AA lowered the glucose response to a carbohydrate supplement after strenuous exercise. However, it was not effective in facilitating subsequent muscle glycogen storage.

Effect of acute concurrent exercise training and the mediating role of lactate on executive function: An ERP study.

Both acute aerobic (AE) and resistance exercise (RE) have been acknowledged to be effective methods in enhancing executive function and brain-related P3 amplitudes. Nevertheless, the effect of acute concurrent exercise training (CET), combining both AE and RE, on executive function remains subject to speculation. Moreover, investigation of the mechanisms that underlie improvements in executive function would facilitate scientific understanding. Notably, lactate has emerged as a candidate among several potential mechanisms. Therefore, the main aim of the present study was to investigate the effect of acute CET on the cognitive flexibility dimension of executive function using behavioural and neuro-electric measures. A secondary aim was to determine the mediating effect of blood lactate in the acute exercise-executive function relationship. Seventy-eight young adults (38 women, 40 men; 22.8 ± 1.8 years) were randomly assigned to one of the following groups: CET, AE, or reading control (RC). Cognitive flexibility was evaluated using the Task-Switching Test and its derived electroencephalography (EEG) was assessed immediately prior to and following each treatment. Fingertip lactate assays were taken prior to, at the midpoint, and after each treatment. Both acute CET and AE shortened response time regardless of test conditions when compared to the RC group. Greater P3 amplitude was observed following CET in the heterogeneous condition and under AE in the switch condition. A significant mediation of blood lactate for response time emerged in both the CET and AE groups for the heterogeneous and switch conditions. The blood lactate mediation was not reflected in P3 amplitude. The present findings suggest that acute CET leads to positive behavioural and neuro-electric alterations of cognitive flexibility, and its effect is similar to AE. Additionally, blood lactate serves as a mediator of the effects of acute exercise on executive function from a behavioural, but not neuro-electric standpoint.

An amino acid mixture improves glucose tolerance and lowers insulin resistance in the obese Zucker rat.

The purpose of this investigation was to test an amino acid mixture on glucose tolerance in obese Zucker rats [experiment (Exp)-1] and determine whether differences in blood glucose were associated with alterations in muscle glucose uptake [experiment (Exp)-2]. Exp-1 rats were gavaged with either carbohydrate (OB-CHO), carbohydrate plus amino acid mixture (OB-AA-1), carbohydrate plus amino acid mixture with increased leucine concentration (OB-AA-2) or water (OB-PLA). The glucose response in OB-AA-1 and OB-AA-2 were similar, and both were lower compared to OB-CHO. This effect of the amino acid mixtures did not appear to be solely attributable to an increase in plasma insulin. Rats in Exp-2 were gavaged with carbohydrate (OB-CHO), carbohydrate plus amino acid mixture (OB-AA-1) or water (OB-PLA). Lean Zuckers were gavaged with carbohydrate (LN-CHO). Fifteen minutes after gavage, a radiolabeled glucose analog was infused through a catheter previously implanted in the right jugular vein. Blood glucose was significantly lower in OB-AA-1 compared to OB-CHO while the insulin responses were similar. Glucose uptake was greater in OB-AA-1 compared with OB-CHO, and similar to that in LN-CHO in red gastrocnemius muscle (5.15 ± 0.29, 3.8 ± 0.27, 5.18 ± 0.34 µmol/100 g/min, respectively). Western blot analysis showed that Akt substrate of 160 kDa (AS160) phosphorylation was enhanced for OB-AA-1 and LN-CHO compared to OB-CHO. These findings suggest that an amino acid mixture improves glucose tolerance in an insulin resistant model and that these improvements are associated with an increase in skeletal muscle glucose uptake possibly due to improved intracellular signaling.