Global terrestrial carbon fluxes of 1999-2019 estimated by upscaling eddy covariance data with a random forest.

The terrestrial biosphere is a key player in slowing the accumulation of carbon dioxide in the atmosphere. While quantification of carbon fluxes at global land scale is important for mitigation policy related to climate and carbon, measurements are only available at sites scarcely distributed in the world. This leads to using various methods to upscale site measurements to the whole terrestrial biosphere. This article reports a product obtained by using a Random Forest to upscale terrestrial net ecosystem exchange, gross primary production, and ecosystem respiration from FLUXNET 2015. Our product covers land from -60°S to 80°N with a spatial resolution of 0.1° × 0.1° every 10 days during the period 1999-2019. It was compared with four existing products. A distinguishable feature of our method is using three derived variables of leaf area index to represent plant functional type (PFT) so that measurements from different PFTs can be mixed better by the model. This product can be valuable for the carbon-cycle community to validate terrestrial biosphere models and cross check datasets.

Gold Nanoparticles Conjugated with Glycopeptides for Lectin Detection and Imaging on Cell Surface.

BACKGROUND: Lectins are carbohydrate binding proteins and related to various biological events and diseases including virus infection and cancer metastasis. In particular, galactose-binding lectins have attracted attention as targets for drug delivery and cancer markers. We, previously, demonstrated that sugar-modified peptides (glycopeptides) were useful ligands for the detection and characterization of lectins compared to the sugar unit alone. Gold nanoparticles (GNPs) conjugated with mannose-modified glycopeptides were useful in detection of concanavalin A, a mannose binding lectin. OBJECTIVES: The main objective of this study was to expand our glycopeptide-GNP conjugates for detection and imaging of galactose-binding lectins. METHODS: Four galactose-modified peptides (glycopeptides) were synthesized by Fmoc-based solid peptide synthesis method. Synthesized glycopeptides were conjugated with PEG-coated GNPs using thiol-maleimide chemistry. The interaction between glycopeptide-GNPs (GP/GNPs) (0.5 nM) and RCA120, a galactose binding lectin, (0.5-1000 nM) was evaluated by mesuring absorption spectra of GNPs. The inhibition experiment in the interaction between GP/GNPs (0.5 nM) and RCA120 (100 nM) was performed in the presence of 60 mM α- methyl mannose or 60 mM lactose. HepG2 and MCF7 cells were placed on 22×22 mm cover slip in 6 well cell culture plates (2×105 cells / well) and cultured overnight at 37°C under 5% CO2 condition. 1 mL of GP/GNPs (0.2 nM) were added in each well and incubated for 18 h at 37°C under 5% CO2 condition. After incubation, cells were washed twice with PBS and fixed with 4% paraformaldehyde solution. The cover slips were coated with 90% glycerol and sealed to slide glass. Dark-field images based on elastic light scattering were taken using a Nikon microscope (TieU) with an immersion dark field condenser. RESULTS: In the titration experiment of RCA120, GP/GNPs showed a decrease of absorbance according to the addition of RCA120, suggesting that the aggregation of GP/GNPs is induced through the binding to RCA120. The EC50 values of AA(Gal)/GNP, WF(Gal)/GNP, TS(Gal)/GNP and ED(Gal)/ GNP were estimated as 66.2 nM, 43.2 nM, 38.6 nM and 104.4 nM, respectively. TS(Gal)/GNP showed the lowest EC50 value among GP/GNPs. RCA120 has several binding sites for the galactose, and there are hydrophilic amino acids (Thr24, Glu26, Gln35, Asn42 and Asp44) around one of galactose binding sites. This result indicates that the hydrogen bonds between these amino acids and Thr/Ser residues of TS(Gal) contribute to the efficient aggregation of TS(Gal)/GNP. Next, inhibition experiments in the aggregation of WF(Gal)/GNP with RCA120 revealed that lactose inhibits the WF(Gal)/GNP binding with RCA120, but α-methyl mannose does not, and that WF(Gal)/GNP selectively interacts with RCA120 and forms the aggregate. Finally, a galactose binding protein on the surface of HepG2 cells was successfully visualized by using GP/GNPs as optical probes. CONCLUSION: Our results demonstrated that GP/GNPs could detect RCA120 by the selective binding and the aggregation formation. Furthermore, a galactose binding protein on the surface of HepG2 cells is successfully visualized using WF(Gal)/GNP as an optical probe. Thus, GNPs conjugated with glycopeptides will be useful probes for the selective detection and imaging of lectins.

Daily oral administration of crocetin attenuates physical fatigue in human subjects.

This study compared the effects of placebo with a carotenoid compound, crocetin, as well as an antioxidant, ascorbic acid, on physical fatigue in humans. In this double-blind, placebo-controlled, 3-way crossover study, 14 Japanese healthy volunteers (7 men and 7 women) were randomized to oral administration of crocetin (15 mg), ascorbic acid (3,000 mg), or placebo for 8 days. Subjects performed workload tests on a bicycle ergometer at fixed workloads for 120 minutes at 2 times (a total of 240 minutes) as a fatigue-inducing physical task. During the physical task, subjects performed nonworkload tests at maximum velocity (MV) of 10 seconds at 30 minutes (30-minute test) after the start of the physical task and at 30 minutes before the end of the task (210-minute test). The change in MV from the 30- to the 210-minute test was significantly higher in men who received crocetin compared with men who received placebo (P < .05). This effect of crocetin was specific to males. Administration of ascorbic acid did not change in MV from the 30-minute to the 210-minute test on males or females. These results suggest that daily administration of crocetin may attenuate physical fatigue in men.

Mental and physical fatigue-related biochemical alterations.

OBJECTIVE: To confirm fatigue-related biochemical alterations, we measured various parameters just before and after relaxation and fatigue-inducing mental or physical sessions. METHODS: Fifty-four healthy volunteers were randomized to perform relaxation and fatigue-inducing mental and physical sessions for 4 h in a double-blind, three-crossover design. Before and after each session, subjects were asked to rate their subjective sensations of fatigue, and blood, saliva, and urine samples were taken. RESULTS: After the fatigue-inducing mental and physical sessions, subjective scores of fatigue were increased. After the fatigue-inducing mental session, the vanillylmandelic acid level in urine was higher and plasma valine level was lower than after the relaxation session. In contrast, after the fatigue-inducing physical session, serum citric acid, triacylglycerol, free fatty acid, ketone bodies, total carnitine, acylcarnitine, uric acid, creatine kinase, aspartate aminotransferase, lactate dehydrogenase, cortisol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, plasma branched-chain amino acids, transforming growth factor-beta1 and -beta2, white blood cell and neutrophil counts, saliva cortisol and amylase, and urine vanillylmandelic acid levels were higher and serum free carnitine and plasma total amino acids and alanine levels were lower than those after the relaxation session. CONCLUSION: Some mental or physical fatigue-related biochemical changes were determined. Various biochemical alterations reflecting homeostatic perturbation and its responses might be shown. We believe that our results contribute to clarifying the mechanism of fatigue, developing evaluation methods, and establishing a basis for treatment.

L-ornithine supplementation attenuates physical fatigue in healthy volunteers by modulating lipid and amino acid metabolism.

We examined the effects of L-ornithine administration on physical fatigue. In a double-blind, placebo-controlled, 2-way crossover study, 17 healthy volunteers were randomized to L-ornithine (2000 mg/d for 7 days and 6000 mg/d for 1 day as L-ornithine hydrochloride) or placebo for 8 days. The fatigue-inducing physical task consisted of workload trials on a cycle ergometer at fixed workloads for 2 hours on 2 occasions. We found that oral L-ornithine administration promoted lipid metabolism and activated the urea cycle from serum triacylglycerol, ketone bodies, free fatty acids, and blood ammonia level changing. L-ornithine significantly attenuated the subjective feeling of fatigue (measured by visual analog scale at postrecovery) compared with postload (P < .01). Moreover, in female subjects, the subjective feeling of fatigue was significantly lower compared with the placebo group (P < .05). In the physical performance test in female subjects, the decrease in mean speed for 10 seconds maximum pedaling from 0.5- to 3.5-hour trials in the group receiving L-ornithine was smaller than that in the group receiving placebo (P < .05). These results suggest that L-ornithine has an antifatigue effect by increasing the efficiency of energy consumption and promoting the excretion of ammonia. L-ornithine is a free amino acid and is not rich in meats or fish, so it is difficult to obtain amounts of L-ornithine from ordinary meals that would be sufficient to promote the antifatigue effect. We recommend L-ornithine intake as a nutritional supplement in cases of physical fatigue.

Antifatigue effects of coenzyme Q10 during physical fatigue.

OBJECTIVE: This study examined the effects of coenzyme Q10 administration on physical fatigue. METHODS: In a double-blinded, placebo-controlled, three crossover design, 17 healthy volunteers were randomized to oral coenzyme Q10 (100 or 300 mg/d) or placebo administration for 8 d. As a fatigue-inducing physical task, subjects performed workload trials on a bicycle ergometer at fixed workloads twice for 2 h and then rested for 4 h. During the physical tasks, subjects performed non-workload trials with maximum velocity for 10 s at 30 min (30-min trial) after the start of physical tasks and 30 min before the end of the tasks (210-min trial). RESULTS: The change in maximum velocity from the 30- to the 210-min trial in the 300-mg coenzyme Q10-administered group was higher than that in the placebo group. In addition, subjective fatigue sensation measured on a visual analog scale in the 300-mg coenzyme Q10-administered group after the fatigue-inducing physical task and recovery period was alleviated when compared with that in the placebo group. CONCLUSION: Oral administration of coenzyme Q10 improved subjective fatigue sensation and physical performance during fatigue-inducing workload trials and might prevent unfavorable conditions as a result of physical fatigue.

Effects of oral administration of caffeine and D-ribose on mental fatigue.

OBJECTIVE: We examined the effects of administering two different candidate antifatigue substances, caffeine and D-ribose, on mental fatigue. METHODS: In a double-blinded, placebo-controlled, three-way crossover design, 17 healthy volunteers were randomized to oral caffeine (200 mg/d), D-ribose (2000 mg/d), or placebo for 8 d. As fatigue-inducing mental tasks, subjects performed a 30-min Uchida-Kraepelin psychodiagnostic test and a 30-min advanced trail-making test on four occasions. RESULTS: During the tasks, the task performance of the caffeine group was better than that of the placebo group. However, after the fatigue-inducing tasks, although subjective perception of fatigue, motivation, or sleepiness was not significantly different, plasma branched-chain amino acid levels in the caffeine group were lower than those of the placebo group. Administration of D-ribose had no effect. CONCLUSION: Because plasma branched-chain amino acid levels are decreased by mental fatigue, these results suggest that administration of caffeine improved task performance through the enhancement of central nervous system activity without increasing the sensation of fatigue. However, further decreases in branched-chain amino acid levels indicate that caffeine might promote deeper fatigue than placebo. Unfortunately, research subsequent to our study design has shown that D-ribose dosing higher than we used is needed to see a clinical effect and therefore no conclusions can be made from this study as to the efficacy of D-ribose.

Effects of Applephenon and ascorbic acid on physical fatigue.

OBJECTIVE: We examined the effects of Applephenon and ascorbic acid administration on physical fatigue. METHODS: In a double-blinded, placebo-controlled, three-way crossover design, 18 healthy volunteers were randomized to oral Applephenon (1200 mg/d), ascorbic acid (1000 mg/d), or placebo for 8 d. The fatigue-inducing physical task consisted of workload trials on a bicycle ergometer at fixed workloads for 2 h on two occasions. During the test, subjects performed non-workload trials with maximum velocity for 10 s at 30 min (30-min trial) after the start of the test and 30 min before the end of the test (210-min trial). RESULTS: The change in maximum velocity between the 30- and 210-min trials was higher in the group given Applephenon than in the group given placebo; ascorbic acid had no effect. CONCLUSION: These results suggest that Applephenon attenuates physical fatigue, whereas ascorbic acid does not.

Effects of Citric Acid and l-Carnitine on Physical Fatigue.

We examined the effects of citric acid and l-carnitine administration on physical fatigue. In a double-blind, placebo-controlled, 3-way crossover study, 18 healthy volunteers were randomized to oral citric acid (2,700 mg/day), l-carnitine (1,000 mg/day), or placebo for 8 days. The fatigue-inducing physical task consisted of workload trials on a cycle ergometer at fixed workloads for 2 h on 2 occasions. Before the physical load, salivary chromogranin A, measured as a physiological stress marker, was lower in the group given citric acid than in the group given placebo. Also, after the physical load, the subjective feeling of fatigue assessed with a visual analogue scale was lower in the citric acid group than in the placebo group. In contrast, l-carnitine had no effect on chromogranin A or subjective fatigue. These results suggest that citric acid reduces physiological stress and attenuates physical fatigue, whereas l-carnitine does not.