Influence of venous emptying on the reactive hyperemic blood flow response

Background

Previous research indicates that venous emptying serves as a stimulus for vasodilation in the human forearm. This suggests the importance of recognizing the potential influence of venous volume on reactive hyperemic blood flow (RHBF) following occlusion. The purpose of this study was to examine the influence of venous emptying on forearm vascular function.

Methods

Forearm RHBF, venous capacitance and venous outflow were examined in 35 individuals (age = 22 ± 2 years), using mercury in-Silastic strain gauge plethysmography, at rest and following five minutes of upper arm occlusion using standard procedures (Control). In addition, the same measures were obtained following five minutes of upper arm occlusion preceded by two minutes of passive arm elevation (Pre-elevation).

Results

Average resting arterial inflow was 2.42 ± 1.11 ml·100 ml^-1·min^-1. RHBF and venous capacitance were significantly greater during Pre-elevation compared to Control (RHBF; Pre-elevation: 23.76 ± 5.95 ml·100 ml^-1 ·min^-1 vs. Control: 19.33 ± 4.50; p = 0.001), (venous capacitance; Pre-elevation: 2.74 ± 0.89 % vs. Control: 2.19 ± 0.97, p = 0.001). Venous outflow did not differ between the two conditions.

Conclusion

Venous emptying prior to upper arm occlusion results in a significant greater RHBF response and venous capacitance. Recognition of the influence of venous volume on RHBF is particularly important in studies focusing on arterial inflow, and also provides further evidence for the interplay between the venous and arterial system.

     

Effects of increased meal frequency on fat oxidation and perceived hunger

Objective:

Consuming smaller, more frequent meals is often advocated as a means of controlling body weight, but studies demonstrating a mechanistic effect of this practice on factors associated with body weight regulation are lacking. The purpose of this study was to compare the effect of consuming three (3M) vs. six meals (6M) per day on 24‐h fat oxidation and subjective ratings of hunger.

Design and Methods:

Lean (body mass index <25 kg/m²) subjects (7M, 8F) were studied in a whole‐room calorimeter on two occasions in a randomized cross‐over design. Subjects were provided isoenergetic, energy balanced diets with a 1‐ to 2‐week washout between conditions. Hunger, fullness, and “desire to eat” ratings were assessed throughout the day using visual analog scales and quantified as area under the curve (AUC).

Results:

There were no differences (P < 0.05) in 24‐h energy expenditure (8.7 ± 0.3 vs. 8.6 ± 0.3 mj d^?1), 24‐h respiratory quotient (0.85 ± 0.01 vs. 0.85 ± 0.01), or 24‐h fat oxidation (82 ± 6 vs. 80 ± 7 g day^‐1) between 3M and 6M, respectively. There was no difference in fullness 24‐h AUC, but hunger AUC (41850 ± 2255 vs. 36612 ± 2556 mm.24 h, P = 0.03) and “desire to eat” AUC (47061 ± 1791 vs. 41170 ± 2574 mm.24 h, P = 0.03) were greater during 6M than 3M.

Conclusion:

We conclude that increasing meal frequency from three to six per day has no significant effect on 24‐h fat oxidation, but may increase hunger and the desire to eat.

     

Interstitial lactate,lactate/pyruvate and glucose in rat muscle before,during and in the recovery from global hypoxia

Background

Hypoxia results in an imbalance between oxygen supply and oxygen consumption. This study utilized microdialysis to monitor changes in the energy-related metabolites lactate, pyruvate and glucose in rat muscle before, during and after 30 minutes of transient global hypoxia. Hypoxia was induced in anaesthetised rats by reducing inspired oxygen to 6% O₂ in nitrogen.

Results

Basal values for lactate, the lactate/pyruvate ratio and glucose were 0.72 ± 0.04 mmol/l, 10.03 ± 1.16 and 3.55 ± 0.19 mmol/l (n = 10), respectively. Significant increases in lactate and the lactate/pyruvate ratio were found in the muscle after the induction of hypoxia. Maximum values of 2.26 ± 0.37 mmol/l for lactate were reached during early reperfusion, while the lactate/pyruvate ratio reached maximum values of 35.84 ± 7.81 at the end of hypoxia. Following recovery to ventilation with air, extracellular lactate levels and the lactate/pyruvate ratio returned to control levels within 30-40 minutes. Extracellular glucose levels showed no significant difference between hypoxia and control experiments.

Conclusions

In our study, the complete post-hypoxic recovery of metabolite levels suggests that metabolic enzymes of the skeletal muscle and their related cellular components may be able to tolerate severe hypoxic periods without prolonged damage. The consumption of glucose in the muscle in relation to its delivery seems to be unaffected.

     

Effects of melatonin administration on embryo implantation and offspring growth in mice under different schedules of photoperiodic exposure

Background

Embryo implantation is crucial for animal reproduction. Unsuccessful embryo implantation leads to pregnancy failure, especially in human-assisted conception. Environmental factors have a profound impact on embryo implantation. Because people are being exposed to more light at night, the influence of long-term light exposure on embryo implantation should be explored.

Methods

The effects of long photoperiodic exposure and melatonin on embryo implantation and offspring growth were examined. Long photoperiodic exposure (18:6 h light:dark) was selected to resemble light pollution. Melatonin (10^?2, 10^?3, 10^?4, 10^?5 M) was added to the drinking water of mice starting at Day 1 (vaginal plugs) until delivery.

Results

Melatonin treatment (10^?4,10^?5 M) significantly increased litter sizes compared to untreated controls (12.9 ± 0.40 and 12.2 ± 1.01 vs. 11.5 ± 0.43; P < 0.05). The most effective concentration of melatonin (10^?4 M) was selected for further investigation. No remarkable differences were found between melatonin-treated mice and controls in terms of the pups’ birth weights, weaning survival rates, and weaning weights. Long photoperiodic exposure significantly reduced the number of implantation sites in treated mice compared to controls (light/dark, 12/12 h), and melatonin rescued this negative effect. Mechanistic studies revealed that melatonin enhanced the serum 17β-estradiol (E₂) levels in the pregnant mice and upregulated the expression of the receptors MT1 and MT2 and p53 in uterine tissue. All of these factors may contribute to the beneficial effects of melatonin on embryo implantation in mice.

Conclusion

Melatonin treatment was associated with beneficial effects in pregnant mice, especially those subjected to long photoperiodic exposure. This was achieved by enhanced embryo implantation. At the molecular level, melatonin administration probably increases the E₂ level during pregnancy and upregulates p53 expression by activating MT1/2 in the uterus. All of the changes may improve the microenvironment of the uterus and, thus, the outcomes of pregnancy.

     

Effects of negative air ions on oxygen uptake kinetics,recovery and performance in exercise: a randomized,double-blinded study

Limited research has suggested that acute exposure to negatively charged ions may enhance cardio-respiratory function, aerobic metabolism and recovery following exercise. To test the physiological effects of negatively charged air ions, 14 trained males (age: 32?±?7 years; \( \overset{\cdotp }{V}{\mathrm{O}}_{2 \max } \) : 57?±?7 mL min^?1 kg^?1) were exposed for 20 min to either a high-concentration of air ions (ION: 220?±?30?×?10³ ions cm^?3) or normal room conditions (PLA: 0.1?±?0.06?×?10³ ions cm^?3) in an ionization chamber in a double-blinded, randomized order, prior to performing: (1) a bout of severe-intensity cycling exercise for determining the time constant of the phase II \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) response (τ) and the magnitude of the \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) slow component (SC); and (2) a 30-s Wingate test that was preceded by three 30-s Wingate tests to measure plasma [adrenaline] (ADR), [nor-adrenaline] (N-ADR) and blood [lactate] (B_Lac) over 20 min during recovery in the ionization chamber. There was no difference between ION and PLA for the phase II \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) τ (32?±?14 s vs. 32?±?14 s; P?=?0.7) or \( \overset{\cdotp }{V}{\mathrm{O}}_2 \) SC (404?±?214 mL vs 482?±?217 mL; P?=?0.17). No differences between ION and PLA were observed at any time-point for ADR, N-ADR and B_Lac as well as on peak and mean power output during the Wingate tests (all P?>?0.05). A high-concentration of negatively charged air ions had no effect on aerobic metabolism during severe-intensity exercise or on performance or the recovery of the adrenergic and metabolic responses after repeated-sprint exercise in trained athletes.     

A novel malic enzyme gene, <Emphasis Type="Italic">Mime2</Emphasis>, from <Emphasis Type="Italic">Mortierella isabellina</Emphasis> M6-22 contributes to lipid accumulation

Objective

This study was aimed at cloning and characterizing a novel malic enzyme (ME) gene of Mortierella isabellina M6-22 and identifying its relation with lipid accumulation.

Methods

Mime2 was cloned from strain M6-22. Plasmid pET32aMIME2 was constructed to express ME of MIME2 in Escherichia coli BL21. After purification, the optimal pH and temperature of MIME2, as well as K_m and V_max for NADP⁺ were determined. The effects of EDTA or metal ions (Mn²⁺, Mg²⁺, Co²⁺, Cu²⁺, Ca²⁺, or Zn²⁺) on the enzymatic activity of MIME2 were evaluated. Besides, plasmid pRHMIME2 was created to express MIME2 in Rhodosporidium kratochvilovae YM25235, and its cell lipid content was measured by the acid-heating method. The optimal pH and temperature of MIME2 are 5.8 and 30 °C, respectively.

Results

The act ivity of MIME2 was significantly increased by Mg²⁺, Ca²⁺, or Mn²⁺ at 0.5 mM but inhibited by Cu²⁺ or Zn²⁺ (p?<?0.05). The optimal enzymatic activity of MIME2 is 177.46 U/mg, and the K_m and V_max for NADP⁺ are 0.703 mM and 156.25 μg/min, respectively. Besides, Mime2 transformation significantly increased the cell lipid content in strain YM25235 (3.15?±?0.24 vs. 2.17?±?0.31 g/L, p?<?0.01).

Conclusions

The novel ME gene Mime2 isolated from strain M6-22 contributes to lipid accumulation in strain YM25235.

     

Improving EGSB reactor performance for simultaneous bioenergy and organic acid production from cheese whey via continuous biological H<Subscript>2</Subscript> production

Objectives

To evaluate the influence of hydraulic retention time (HRT) and cheese whey (CW) substrate concentration (15 and 25 g lactose l^?1) on the performance of EGSB reactors (R15 and R25, respectively) for H₂ production.

Results

A decrease in the HRT from 8 to 4 h favored the H₂ yield and H₂ production rate (HPR) in R15, with maximum values of 0.86 ± 0.11 mmol H₂ g COD^?1 and 0.23 ± 0.024 l H₂ h^?1 l^?1, respectively. H₂ production in R25 was also favored at a HRT of 4 h, with maximum yield and HPR values of 0.64 ± 0.023 mmol H₂ g COD^?1 and 0.31 ± 0.032 l H₂ h^?1 l^?1, respectively. The main metabolites produced were butyric, acetic and lactic acids.

Conclusions

The EGSB reactor was evaluated as a viable acidogenic step in the two-stage anaerobic treatment of CW for the increase of COD removal efficiency and biomethane production.

     

Comparison of mitral annulus geometry between patients with ischemic and non-ischemic functional mitral regurgitation: implications for transcatheter mitral valve implantation

Background

Transcatheter mitral valve replacement (TMVR) is a new therapeutic option for high surgical risk patients with mitral regurgitation (MR). Mitral valve (MV) geometry quantification is of paramount importance for success of the procedure and transthoracic 3D echocardiography represents a useful screening tool. Accordingly, we sought to asses MV geometry in patients with functional MR (FMR) that would potentially benefit of TMVR, focusing on the comparison of mitral annulus (MA) geometry between patients with ischemic (IMR) and non ischemic mitral regurgitation (nIMR).

Methods

We retrospectively selected 94 patients with severe FMR: 41 (43,6%) with IMR and 53 (56,4%) with nIMR. 3D MA analysis was performed on dedicated transthoracic 3D data sets using a new, commercially-available software package in two moments of the cardiac cycle (early-diastole and mid-systole). We measured MA dimension and geometry parameters, left atrial and left ventricular volumes.

Results

Maximum (MA area 10.7?±?2.5 cm² vs 11.6?±?2.7 cm², p?>?0.05) and the best fit plane MA area (9.9?±?2.3 cm² vs 10.7?±?2.5 cm², p?>?0.05, respectively) were similar between IMR and nIMR. nIMR patients showed larger mid-systolic 3D area (9.8?±?2.3 cm² vs 10.8?±?2.7 cm², p?<?0.05) and perimeter (11.2?±?1.3 cm vs 11.8?±?1.5 cm, p?<?0.05) with longer and larger leaflets, and wider aorto-mitral angle (135?±?10° vs 141?±?11°, p?<?0.05). Conversely, the area of MA at the best fit plane did not differ between IMR and nIMR patients (9?±?1.1 cm² vs 9.9?±?1.5 cm², p?>?0.05).

Conclusions

Patients with ischemic and non-ischemic etiology of FMR have similar maximum dimension, yet systolic differences between the two groups should be taken into account to tailor prosthesis’s selection.

Trial registration

N.A.

     

The relationships among endurance performance measures as estimated from VO<Subscript>2PEAK</Subscript>, ventilatory threshold,and electromyographic fatigue threshold: a relationship design

Background

The use of surface electromyography has been accepted as a valid, non-invasive measure of neuromuscular fatigue. In particular, the electromyographic fatigue threshold test (EMG_FT) is a reliable submaximal tool to identify the onset of fatigue. This study examined the metabolic relationship between VO_2PEAK, ventilatory threshold (VT), and the EMG_FT, as well as compared the power output at VO_2PEAK, VT, and EMG_FT.

Methods

Thirty-eight college-aged males (mean ± SD = 22.5 ± 3.5 yrs) performed an incremental test to exhaustion on an electronically-braked cycle ergometer for the determination of VO_2PEAK and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMG_FT value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2-minute work bouts (ranging from 75–325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10-second intervals and plotted over the 2-minute work bout. The resulting slopes from each successive work bout were used to calculate EMG_FT.

Results

Power outputs and VO₂ values from each subject's incremental test to exhaustion were regressed. The linear equations were used to compute the VO₂ value that corresponded to each fatigue threshold. Two separate one-way repeated measure ANOVAs indicated significant differences (p < 0.05) among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 ± 0.50 l·min^-1) and EMG_FTVO₂(1.84 ± 0.53 l·min^-1) were not significantly different (p > 0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 ± 37.8 W compared with 134.1 ± 43.5 W at EMG_FT (p > 0.05) with a strong correlation between the two variables (r = 0.766).

Conclusion

Metabolic measurements, as well as the power outputs at VT and EMG_FT, were strongly correlated. The significant relationship between VT and EMG_FT suggests that both procedures may reflect similar physiological factors associated with the onset of fatigue. As a result of these findings, the EMG_FT test may provide an attractive alternative to estimating VT.

     

2-h postchallenge plasma glucose predicts cardiovascular events in patients with myocardial infarction without known diabetes mellitus

Background

Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin.

Objectives

We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO₂) in type 2 diabetic patients during mechanical ventilation or oxygen therapy.

Methods

Arterial oxygen saturation (SaO₂) and partial pressure of oxygen (PO₂) were determined with simultaneous monitoring of SpO₂ in 261 type 2 diabetic patients during ventilation or oxygen inhalation.

Results

Blood concentration of HbA1c was >7% in 114 patients and????7% in 147 patients. Both SaO₂ (96.2?±?2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1?±?2.8%, 95% CI 94.7-95.6%) and SpO₂ (98.0?±?2.6%, 95% CI 97.6-98.5% vs. 95.3?±?2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c????7% (Data are mean?±?SD, all p?<?0.01), but PO₂ did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO₂ and SaO₂ (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO₂ and SaO₂ correlated closely with blood HbA1c levels (Pearson??s r?=?0.307, p?<?0.01).

Conclusions

Elevated blood HbA1c levels lead to an overestimation of SaO₂ by SpO₂, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia.     

Sleep apnea modifies the long‐term impact of surgically induced weight loss on cardiac function and inflammation

Objective:

Obesity is frequently associated with obstructive sleep apnea (OSA). Both conditions are proinflammatory and proposed to deteriorate cardiac function. We used a nested cohort study design to evaluate the long‐term impact of bariatric surgery on OSA and how weight loss and OSA relate to inflammation and cardiac performance.

Design and Methods:

At 10‐year follow‐up in the Swedish Obese Subjects (SOS) study, we identified 19 obese subjects (BMI 31.2 ± 5.3 kg m^?2), who following bariatric surgery at SOS‐baseline had displayed sustained weight losses (surgery group), and 20 obese controls (BMI 42.0 ± 6.2 kg m^?2), who during the same time‐period had maintained stable weight (control group). All study participants underwent overnight polysomnography examination, echocardiography and analysis of inflammatory markers.

Results:

The surgery group displayed a lower apnea hypopnea index (AHI) (19.9 ± 21.5 vs. 37.8 ± 27.7 n/h, P = 0.013), lower inflammatory activity (hsCRP 2.3 ± 3.0 vs. 7.2 ± 5.0 mg L^?1, P < 0.001), reduced left ventricular mass (165 ± 22 vs. 207 ± 22 g, P < 0.001) and superior left ventricular diastolic function (E/A ratio 1.24 ± 1.10 vs. 1.05 ± 0.20, P = 0.006) as compared with weight stable obese controls. In multiple regression analyses including all subjects (n = 39) and controlling for BMI, the AHI remained independently associated with hsCRP (β = 0.09, P < 0.001), TNF‐α (β = 0.03, P = 0.031), IL‐6 (β = 0.01, P = 0.007), IL 10 (β = ?0.06; P = 0.018), left ventricular mass (β = 0.64, P < 0.001), left atrial area (β = 0.08, P = 0.002), pulmonary artery pressure (β = 0.08, P = 0.011) and E/E_a ratio (β = 0.04, P = 0.021).

Conclusions:

Patients with sustained weight loss after bariatric surgery display less severe sleep apnea, reduced inflammatory activity, and enhanced cardiac function. Persisting sleep apnea appears to limit the beneficial effect of weight loss on inflammation and cardiac performance.

     

Inhibitory effect of flavonoids against NS2B-NS3 protease of ZIKA virus and their structure activity relationship

Objectives

To determine the inhibitory activities of flavonoids against NS2B-NS3 protease of ZIKA virus (ZIKV NS2B-NS3^pro) expressed in Escherichia coli BL21 (DE3) and their structure activity relationship.

Results

ZIKV NS2B-NS3^pro was expressed in E. coli BL21(DE3) as a 35 kDa protein. It had a K _m of 26 µM with the fluorogenic peptide Dabcyl-KTSAVLQSGFRKME-Edan. The purified ZIKV NS2B-NS3^pro was used for inhibition and kinetic assays to determine the activities of 22 polyphenol compounds. These polyphenol compounds at 100 µM inhibited the activity of ZIKV NS2B-NS3^pro by 6.2–88%. Seven polyphenol compounds had IC₅₀ ranging from 22 ± 0.2 to 112 ± 5.5 µM. Myricetin showed a mixed type inhibitory pattern against ZIKV NS2B-NS3^pro protease. Its IC₅₀ value was 22 ± 0.2 µM with a K _i value of 8.9 ± 1.9 µM.

Conclusion

The chemical structure of a polyphenol compound and its inhibitory activity against ZIKV NS2B-NS3^pro can be explored to develop highly selective inhibitors against ZIKV NS2B-NS3^pro.

     

Swimming exercise to control precocious maturation in male seabass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>)

Background

Male European seabass, already predominant (~?70%) in cultured stocks, show a high incidence (20–30%) of precocious sexual maturation under current aquaculture practices, leading to important economic losses for the industry. In view of the known modulation of reproductive development by swimming exercise in other teleost species, we aimed at investigating the effects of sustained swimming on reproductive development in seabass males during the first year of life in order to determine if swimming could potentially reduce precocious sexual maturation.

Methods

Pre-pubertal seabass (3.91?±?0.22 g of body weight (BW)) were subjected to a 10 week swimming regime at their optimal swimming speed (U_opt) in an oval-shaped Brett-type flume or kept at rest during this period. Using Blazka-type swim tunnels, U_opt was determined three times during the course of the experiment: 0.66 m s^??1 at 19?±?1 g BW, 10.2?±?0.2 cm of standard length (SL) (week 1); 0.69 m s^??1 at 38?±?3 g BW, 12.7?±?0.3 cm SL (week 5), and also 0.69 m s^??1 at 77?±?7 g BW, 15.7?±?0.5 cm SL (week 9). Every 2 weeks, size and gonadal weight were monitored in the exercised (N?=?15) and non-exercised fish (N?=?15). After 10 weeks, exercised and non-exercised males were sampled to determine plasma 11-ketotestosterone levels, testicular mRNA expression levels of genes involved in steroidogenesis and gametogenesis by qPCR, as well as the relative abundance of germ cells representing the different spermatogenic stages by histological examination.

Results

Our results indicate that sustained swimming exercise at U_opt delays testicular development in male European seabass as evidenced by decreased gonado-somatic index, slower progression of testicular development and by reduced mRNA expression levels of follicle stimulating hormone receptor (fshR), 3-beta-hydroxysteroid dehydrogenase (3βhsd), 11-beta hydroxysteroid dehydrogenase (11βhsd), estrogen receptor-beta (erβ2), anti-mullerian hormone (amh), structural maintenance of chromosomes protein 1B (smc1β), inhibin beta A (inhba) and gonado-somal derived factor 1 (gsdf1) in exercised males as compared with the non-exercised males.

Conclusions

Swimming exercise may represent a natural and non-invasive tool to reduce the incidence of sexually precocious males in seabass aquaculture.

     

High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate

Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake (V.O₂) and carbon dioxide production (V.CO₂) decrease. Aim of the present study was to test whether a higher RPM reduces the fraction (%) of the V.O₂ used for carbohydrate oxidation (relCHO) at a given BLC. Eight males (23.9 ± 1.6 yrs; 177 ± 3 cm; 70.3 ± 3.4 kg) performed incremental load tests at 50 and 100 RPM. BLC, V.O₂ and V.CO₂ were measured. At respiratory exchange ratios (RER) < 1, relCHO were calculated and the constant determining 50 % relCHO (k_CHO) was approximated as a function of the BLC. At submaximal workload V.O₂, V.CO₂, and relCHO were lower (all p < 0.002; η² > 0.209) at 50 than at 100 RPM. No differences were observed in V.O₂peak (3.96 ± 0.22 vs. 4.00 ± 0.25 l · min⁻¹) and RER_peak (1.18 ± 0.02 vs. 1.15 ± 0.02). BLC was lower (p < 0.001; η² = 0.680) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, kCHO (4.2 ± 1.4 (mmol · l⁻¹)³) was lower (p = 0.043; η² = 0.466) than at 100 RPM (5.9 ± 1.9 (mmol · l⁻¹)³). This difference in k_CHO reflects a reduced CHO oxidation at a given BLC at 100 than at 50 RPM. At a low exercise intensity, a higher cycling cadence can substantially reduce the reliance on CHO at a given metabolic rate and/or BLC.     

Elevated CO<Subscript>2</Subscript> and virus infection impacts wheat and aphid metabolism

Introduction

The aphid Rhopalosiphum padi L. is a vector of Barley yellow dwarf virus (BYDV) in wheat and other economically important cereal crops. Increased atmospheric CO₂ has been shown to alter plant growth and metabolism, enhancing BYDV disease in wheat. However, the biochemical influences on aphid metabolism are not known.

Objectives

This work aims to determine whether altered host-plant quality, influenced by virus infection and elevated CO₂, impacts aphid weight and metabolism.

Methods

Untargeted ¹H NMR metabolomics coupled with multivariate statistics were employed to profile the metabolism of R. padi reared on virus-infected and non-infected (sham-inoculated) wheat grown under ambient CO₂ (aCO₂, 400 µmol mol^?1) and future, predicted elevated CO₂ (eCO₂, 650 µmol mol^?1) concentrations. Un-colonised wheat was also profiled to observe changes to host-plant quality (i.e., amino acids and sugars).

Results

The direct impacts of virus or eCO₂ were compared. Virus presence increased aphid weight under aCO₂ but decreased weight under eCO₂; whilst eCO₂ increased non-viruliferous (sham) aphid weight but decreased viruliferous aphid weight. Discriminatory metabolites due to eCO₂ were succinate and sucrose (in sham wheat), glucose, choline and betaine (in infected wheat), and threonine, lactate, alanine, GABA, glutamine, glutamate and asparagine (in aphids), irrespective of virus presence. Discriminatory metabolites due to virus presence were alanine, GABA, succinate and betaine (in wheat) and threonine and lactate (in aphids), irrespective of CO₂ treatment.

Conclusion

This study confirms that virus and eCO₂ alter host-plant quality, and these differences are reflected by aphid weight and metabolism.

     

Single point mutations enhance activity of <Emphasis Type="Italic">cis</Emphasis>-epoxysuccinate hydrolase

Objectives

To enhance activity of cis-epoxysuccinate hydrolase from Klebsiella sp. BK-58 for converting cis-epoxysuccinate to tartrate.

Results

By semi-saturation mutagenesis, all the mutants of the six important conserved residues almost completely lost activity. Then random mutation by error-prone PCR and high throughput screening were further performed to screen higher activity enzyme. We obtained a positive mutant F10D after screening 6000 mutations. Saturation mutagenesis on residues Phe10 showed that most of mutants exhibited higher activity than the wild-type, and the highest mutant was F10Q with activity of 812 U mg^?1 (k _cat /K _m , 9.8 ± 0.1 mM^?1 s^?1), which was 230 % higher than that of wild-type enzyme 355 U mg^?1 (k _cat /K _m , 5.3 ± 0.1 mM^?1 s^?1). However, the thermostability of the mutant F10Q slightly decreased.

Conclusions

The catalytic activity of a cis-epoxysuccinate hydrolase was efficient improved by a single mutation F10Q and Phe10 might play an important role in the catalysis.

     

Overexpression of Sirtuin2 prevents high glucose-induced vascular endothelial cell injury by regulating the p53 and NF-κB signaling pathways

Objectives

To investigate the potential role and underlying mechanism of Sirtuin2 (SIRT2) in regulating high glucose (HG)-induced vascular endothelial cell injury by using human umbilical vein endothelial cells (HUVECs).

Results

SIRT2 mRNA and protein expression levels were decreased in HG-treated HUVECs. SIRT2 overexpression increased viability, decreased apoptosis and reduced levels of reactive oxygen species in HG-treated HUVECs. SIRT2 overexpression decreased TNF-α expression (146.5 ± 22.8 pg TNF-α ml^?1) relative to that in the empty vector group (263.5 ± 18.5 pg TNF-α ml^?1) and decreased MCP-1 expression (63.8 ± 9.85 pg MCP-1 ml^?1) relative to that in the empty vector group (105.8 ± 8.5 pg MCP-1 ml^?1). SIRT2 overexpression decreased the acetylation of p53 by 33% and decreased the acetylation of NF-κB p65 by 58% in HG-treated HUVECs.

Conclusion

SIRT2 prevents HG-induced vascular endothelial cell injury through suppressing the p53 and NF-κB signaling pathways.

     

The influence of obesity on falls and quality of life

Objective

To determine (1) whether obese older adults had higher prevalence of falls and ambulatory stumbling, impaired balance and lower health-related quality of life (HRQL) than their normal weight counterparts, and (2) whether the falls and balance measures were associated with HRQL in obese adults.

Methods

Subjects who had a body mass index (BMI) greater than 30 kg/m² were classified into an obese group (n = 128) while those with BMI between 18.5 and 24.9 kg/m² were included into a normal weight group (n = 88). Functional tests were performed to assess balance, and questionnaires were administered to assess history of falls, ambulatory stumbling, and HRQL.

Results

The obese group reported a higher prevalence of falls (27% vs. 15%), and ambulatory stumbling (32% vs. 14%) than the normal weight group. Furthermore, the obese group had lower HRQL, (p ≤ 0.05) for physical function (63 ± 27 vs. 75 ± 26; mean ± SD), role-physical (59 ± 40 vs. 74 ± 37), vitality (58 ± 23 vs. 66 ± 20), bodily pain (62 ± 25 vs. 74 ± 21) and general health (64 ± 19 vs. 70 ± 18). In the obese group, a history of falls was related (p ≤ 0.05) to lower scores in 4 domains of HRQL, and ambulatory stumbling was related (p ≤ 0.01) to 7 domains.

Conclusion

In middle-aged and older adults, obesity was associated with a higher prevalence of falls and stumbling during ambulation, as well as lower values in multiple domains of HRQL. Furthermore, a history of falls and ambulatory stumbling were related to lower measures of HRQL in obese adults.