Formation of Volatile Pyrazinones in the Asparagine Maillard Reaction Systems and Novel Pyrazinone Formation Pathways in the Amidated-Alanine Maillard Reaction Systems.

Maillard reaction (MR) plays a pivotal role in the food flavor industry, including a cascade of reactions starting with the reaction between amino compounds and reducing sugars, and thus provides various colors and flavors. A new group of volatile compounds called pyrazinones found in MR are now getting more attention. In this study, eight volatile pyrazinones were found in the asparagine MR systems, in which 3,5-dimethyl- and 3,6-dimethyl-2(1H)-pyrazinones were reported for the first time. The major formation pathways were the reactions between asparagine and α-dicarbonyls, with decarboxylation as a critical step. Besides, novel alternative pathways involving alanine amidation and successive reactions with α-dicarbonyls were explored and successfully formed eight pyrazinones. The major differences between alanine-amidated pathways and decarboxylation pathways are the amidation step and absence of the decarboxylation step. For the alanine-amidated pathways, the higher the temperature, the better the amidation effect. The optimal amidation temperature was 200 °C in this study. The reaction between the alanine amide and α-dicarbonyls after amidation can happen at low temperatures, such as 35 and 50 °C, proposing the possibility of pyrazinone formation in real food systems. Further investigations should be conducted to investigate volatile pyrazinones in various food systems as well as the biological effects and kinetic formation differences of the volatile pyrazinones.

Formation of Volatile Pyrazinones in Amadori Rearrangement Products and Maillard Reaction Systems and the Major Formation Pathways.

Amadori rearrangement products (ARPs) are gaining more attention for their potential usage in the food flavor industry. Peptide-ARPs have been studied, but pyrazinones that were theoretically found in the Maillard reaction (MR) have not been reported to be formed from small peptide-ARPs. This study found four pyrazinones: 1-methyl-, 1,5-dimethyl-, 1,6-dimethyl-, and 1,5,6-trimethyl-2(1H)-pyrazinones in both MR and ARP systems. It was the first time 1-methyl-2(1H)-pyrazinone was reported, along with 1,5-dimethyl- and 1,5,6-trimethyl-2(1H)-pyrazinones being purified and analyzed by nuclear magnetic resonance for the first time. The primary formation routes of the pyrazinones were also proven as the reaction between diglycine and α-dicarbonyls, including glyoxal, methylglyoxal, and diacetyl. The pyrazinones, especially 1,5-dimethyl-2(1H)-pyrazinone, have strong fluorescence intensity, which may be the reason for the increase of fluorescence intensity in MR besides α-dicarbonyls. Cytotoxicity analysis showed that both Gly-/Digly-/Trigly-ARP and the three pyrazinones [1-methyl-, 1,5-dimethyl-, and 1,5,6-trimethyl-2(1H)-pyrazinones] showed no prominent cytotoxicity in the HepG2 cell line below 100 µg/mL, further suggesting that ARPs or pyrazinones could be used as flavor additives in the future. Further research should be conducted to investigate pyrazinones in various systems, especially the peptide-ARPs, which are ubiquitous in real food systems.

Significance of a minor pilin PilV in biofilm cohesion of Geobacter sulfurreducens.

Bacterial adhesion plays a vital role in forming and shaping the structure of electroactive biofilms that are essential for the performance of bioelectrochemical systems (BESs). Type IV pili are known to mediate cell adhesion in many Gram-negative bacteria, but the mechanism of pili-mediated cell adhesion of Geobacter species on anode surface remains unclear. Herein, a minor pilin PilV2 was found to be essential for cell adhesion ability of Geobacter sulfurreducens since the lack of pilV2 gene depressed the cell adhesion capability by 81.2% in microplate and the anodic biofilm density by 23.1 % at -0.1 V and 37.7 % at -0.3 V in BESs. The less cohesiveness of mutant biofilms increased the charge transfer resistance and biofilm resistance, which correspondingly lowered current generation of the pilV2-deficient strain by up to 63.2 % compared with that of the wild-type strain in BESs. The deletion of pilV2 posed an insignificant effect on the production of extracellular polysaccharides, pili, extracellular cytochromes and electron shuttles that are involved in biofilm formation or extracellular electron transfer (EET) process. This study demonstrated the significance of pilV2 gene in cell adhesion and biofilm formation of G. sulfurreducens, as well as the importance of pili-mediated adhesion for EET of electroactive biofilm.

Feasibility Study of Amadori Rearrangement Products of Glycine, Diglycine, Triglycine, and Glucose as Potential Food Additives for Production, Stability, and Flavor Formation.

Amadori rearrangement products (ARPs), as intermediates of the Maillard reaction (MR), are potential natural flavor additives but there is a lack of investigation especially in oligopeptide-ARPs. This study for the first time conducted a systematic analysis in comparing ARPs of glycine, diglycine, triglycine, and glucose to corresponding classic MR systems, including production, stability, and flavor analysis. The ARPs were effectively produced by prelyophilization with heating at 70 °C for 60 min and purified to 96% by a two-step purification method. Correlated with the stability order of amino compounds (glycine > diglycine > triglycine), the stability order of ARPs was Gly-ARP > Digly-ARP ≈ Trigly-ARP. In a negative correlation with heating temperature and time, ARPs were less stable than original amino compounds at high temperatures (100, 130, and 160 °C). ARPs exhibited better flavor formation ability in pyrazines and furans than MR systems, with similar flavor compositions but different preferences. Diglycine- and triglycine-ARPs exhibited better flavor formation efficiency than glycine-ARP. Heating temperature and time, initial pH, and carbon chain length were found to be the parameters that affect the stability and flavor formation of ARPs. This study suggested that ARPs, especially peptide-ARPs, have great potential for usage as food flavor additives in the future.

Gallic acid ameliorates colitis by trapping deleterious metabolite ammonia and improving gut microbiota dysbiosis.

Gut microbiota dysbiosis is causally related to inflammatory bowel disease (IBD), and increased levels of the gut metabolite ammonia have been proposed to contribute to IBD development. In this study, we aimed to clarify the anti-colitis mechanism of gallic acid (GA) based on its ability to trap the deleterious metabolite ammonia and improve gut microbiota. Aminated product was detected in the fecal samples of mice after oral gavage of gallic acid (GA) and identified as 4-amino-substituted gallic acid (4-NH2-GA), thus confirming the ability of GA to trap ammonia in vivo. Then, we compared the beneficial effects of GA and 4-NH2-GA on dextran sulfate sodium (DSS)-induced colitis mouse and found that both compounds managed to alleviate colitis phenotypes, indicating ammonia trapping had no adverse effect on the original anti-colitis activity of GA. In addition, both GA and 4-NH2-GA improved the gut microbiota dysbiosis induced by DSS, and fecal microbiota transplantation was subsequently performed, which further revealed that the gut microbiota mediated the anti-colitis activity of both GA and 4-NH2-GA. In summary, this study clarified that GA alleviated colitis by targeting both the symptoms and root causes: it directly reduced the deleterious metabolite ammonia by forming aminated metabolites without compromising the original anti-colitis activity, and it also improved gut microbiota dysbiosis, which in turn contributed to the alleviation of colitis. Since the GA structure is presented in various polyphenols as a common building block, the novel anti-colitis mechanism obtained from GA may also apply to other complex polyphenols.IMPORTANCEThe dysbiosis of the gut microbiota and its metabolism directly cause the emergence of IBD. In this study, we aimed to clarify the anti-colitis mechanism of GA in sight of gut microbiota and its metabolite ammonia. We discovered that GA directly captured and reduced the harmful metabolite ammonia in vivo to produce the aminated metabolite 4-NH2-GA, while the amination of GA had no adverse effect on its initial anti-colitis activity. In addition, both GA and its aminated metabolite improved the gut microbiota in colitis mice, and the modified gut microbiota, in turn, helped to relieve colitis. Since the GA structure is presented in diverse polyphenols as a common building block, the novel anti-colitis mechanism targeting the symptoms and root causes might also apply to other complex polyphenols.

Thermal Aging Degradation of High-Viscosity Asphalt Based on Rheological Methods.

With the acceleration of the construction of sponge cities in China, porous asphalt pavement (PA) is has been widely used. High-viscosity asphalt (HVA) is the core material in building PA because it has good rheology properties, which can provide good raveling and rutting resistance. However, due to the open-graded structure of PA, HVA was more susceptible to rapid aging, which significantly affects the durability of PA. To investigate the thermal aging effect on the rheological properties of self-modified HVA (SHVA), five types of asphalts were aged using a rolling thin film oven (RTFO) and pressure aging vessel (PAV). Then, rheological tests were adopted, such as temperature sweep test (TS), repeated creep and recovery test (RCR), and bending beam rheometer test (BBR). The results indicate that during the aging process, the oxidation-induced hardening effect of neat asphalt and the degradation-induced softening effect of the modifier changes the rheology properties of HVA significantly. As the aging progresses, the contribution of the modifiers of HVA to anti-aging performance is greatly reduced. At high temperatures, HVA demonstrates better anti-aging performance than conventional styrene-butadiene-styrene (SBS)-modified asphalt (Guo Chuang, GC). The change of the high-temperature rheological indices of the two HVA types (SHVA and TAFPACK-super HVA (TPS)) showed a smaller activation energy index (EAI), a more considerable viscous component of binder creep stiffness (Gv), and more minor accumulated stain (racc), indicating a more significant anti-short-term and long-term aging performance, which is beneficial to the high-temperature performance of asphalts. However, the changes in low-temperature rheological properties do not align with those in high-temperature rheological properties after long-term aging. The BBR test results reveal that TPS exhibits worse low-temperature performance than GC and SHVA. During the thermal aging process, the contribution rate of the modifiers in SHVA against RTFO and PAV aging is higher than that of the modifiers in TPS, which contributes to the superior anti-aging property. Overall, SHVA demonstrates the best anti-aging performance among the five asphalts tested.

Heptamethoxyflavone Alleviates Metabolic Syndrome in High-Fat Diet-Fed Mice by Regulating the Composition, Function, and Metabolism of Gut Microbiota.

3,5,6,7,8,3',4'-Heptamethoxyflavone (HMF) could prevent obesity and hyperlipidemia, but its effects on gut microbiota and fecal metabolites remain unclear. Here, the effect of HMF on metabolic syndrome (MS) was evaluated in high-fat diet (HFD)-fed mice, and its underlying mechanisms were revealed by integrative metagenomic and metabolomic analyses. We demonstrated that HMF could effectively ameliorate HFD-induced MS by alleviating body-weight gain, fat accumulation, hepatic steatosis, and lipid and glucose abnormalities. HMF significantly altered the gut microbiota composition in HFD-fed mice with enrichment of short-chain fatty acid (SCFA)- and bile acid-producing beneficial bacteria and inhibition of harmful bacteria. Also, HMF improved microbial functions by up-regulating bile acid metabolism and down-regulating fatty acid metabolism and inflammatory response-related pathways. Consistent with the gut microbial changes, HMF altered the fecal metabolite profile of HFD-fed mice, mainly characterized by increasing SCFA and several bile acid levels as well as lowering several lysophospholipids and fatty acid levels. Correlation analysis indicated that three key species Faecalibaculum rodentium, Collinsella aerofaciens, and Lactobacillus fermentum and the increase in microbial metabolites, i.e., SCFAs and secondary bile acids, might play a positive role in alleviating MS. Our results suggested that HMF alleviated HFD-induced MS possibly by modulating the composition, function, and metabolism of gut microbiota.

An Effective Docking-Guided Strategy for Rational Tailoring of Fluorescent Aptamer Switches of Dimethylindole Red Analogue.

The light-up aptamer-dimethylindole red (DIR) complexes have been applied in biochemistry analysis as promising signal transduction tools. However, the unfavorable repulsions between DIR and the long-sequence aptamer switch hinder the complex's further development, and it is urgent to engineer a feasible and efficient strategy for synchronously and rationally adjusting the DIR chemical structure and the DIR aptamer performance. Herein, we communicate a versatile docking-guided rational tailoring strategy to effectively upgrade a DNA aptamer which specifically turns on the fluorescence of a synthesized amino-functionalized DIR analogue (NH2-DIR). After optimizing with three-level tailoring strategies including molecule docking-guided tailoring, coarse tailoring, and fine tailoring, the NH2-DIR aptamer switch with higher binding affinity and specificity, considerable fluorescence-activation ability, and 40% shortened length was obtained. Integrating the experimental and docking results, the binding mechanism between NH2-DIR and the tailored aptamer was deciphered via three types of interactions.

Biosynthesis of 6- and 7-Mono-Demethylated Nobiletins by a Newly Isolated Strain of Yeast.

Demethylated nobiletins (DMNs), which are generally recognized as the metabolites of orally administered nobiletin, are widely investigated. However, studies related to 8-demethylated-nobiletin, 7-demethylated-nobiletin (7DMN), and 6-demethylated-nobiletin (6DMN) are limited due to the lack of a synthesis method. In this study, a strain of microbe able to metabolize nobiletin was isolated from aged orange peel. Internal transcribed spacers (ITS) rRNA sequencing analysis showed it belonged to the yeast family, Filobasidium magnum specie. High-performance liquid chromatography (HPLC), HPLC-MS, and 13C NMR results proved that the metabolites were 7DMN and 6DMN. Growth curves of the isolated yeast were studied at different temperatures, media pH, NaCl, and glucose concentrations. Meanwhile, factors that influence the demethylation efficiencies were also investigated. This study lays the groundwork for the investigation of the biological functions of these two compounds and opens a new window for further research of the metabolic fate of nobiletin in the human body.

Effect of Fiber Reinforcement on Creep and Recovery Behavior of Cement-Emulsified Asphalt Binder.

In order to evaluate and improve the deformation behavior of cement-emulsified asphalt binder (CA) in cement-emulsified asphalt mixture, this study investigated the reinforcement of small additions of fibers (2%, 4%, and 6% addition by mass of cement) on the deformation resistance of CA. A repeated creep recovery test was implemented that measures the recovery rate of creep deformation and accumulated strain. Further, an improved piecewise curve-fitting method was used to determine the parameters of Burgers model, then the creep compliances were fitted and calculated. The results show the repeated creep recovery test to be a suitable method for obtaining useful information about creep and recovery deformation of fiber-reinforced CA. The influence of fiber types and dosages on the deformation recovery ability is determined based on the creep recovery ratio and accumulated strain. The improved piecewise curve-fitting method has high accuracy. Thereafter, the reinforcement effect was analyzed through the evolution of creep compliance under loading. Therefore, this paper can provide a reference for enhancing the properties of cement-emulsified asphalt mixture by maximizing the fiber reinforcement.

Deep Learning-Based Emergency Care Process Reengineering of Interventional Data for Patients with Emergency Time-Series Events of Myocardial Infarction.

This paper proposes a representation learning framework HE-LSTM model for heterogeneous temporal events, which can automatically adapt to the multiscale sampling frequency of multisource heterogeneous data. The proposed model also demonstrates its superiority over other typical approaches on real data sets. A controlled study is performed according to computerized randomization, with 38 patients in each of the two groups. The study group has a higher resuscitation success rate and patient satisfaction than the conventional group (P < 0.05), and the time from the first consultation to the completion of the first ECG, the time from the completion of the ECG to the activation of the path lab, and the time from the emergency admission to the balloon dilation were significantly shorter in the study group than in the conventional group (P < 0.05). The emergency care process reengineering intervention helps patients with acute myocardial infarction to be treated quickly and effectively, thus improving their resuscitation success rate and satisfaction rate, and is worthy to be caused in the clinic and widely applied.

Fiber-Reinforcing Effect in the Mechanical and Road Performance of Cement-Emulsified Asphalt Mixtures.

Cement-emulsified asphalt mixture (CEAM), a kind of cold mix asphalt mixture, has the advantages of energy conservation and emission reduction as well as easy construction. However, the performance of CEAM is not as good as hot mixed asphalt mixtures. Hence, in this study, two different fibers were adopted as the reinforcing phase to improve the comprehensive properties of CEAM. The results indicated that the addition proportion and curing time were crucial to fiber-reinforced cement-emulsified asphalt mixture (FRCEAM). The compressive strengths, water stability, and raveling resistances of FRCEAM preparations with polyester or brucite fibers (FRCEAM-PF and -BF, respectively) were enhanced significantly. FRCEAM-PF had the maximum flexural tensile strength and strain, which meant that its low-temperature performance was the best compared to FRCEAM-PF and CEAM. However, the contribution of PF to CEAM high-temperature stability was greater than that of BF. Fiber addition to CEAM not only enhanced the cycles of fatigue loading but also reduced sensitivity to changes in stress level. Furthermore, FRCEAM-BF durability was slightly better than that of FRCEAM-PF. SEM analysis indicated that fibers provided bridging and meshing effects. Although PF and BF showed different enhancement effects, both mixtures met the requirements for hot mixed asphalt mixtures.

The biological fate and bioefficacy of citrus flavonoids: bioavailability, biotransformation, and delivery systems.

Citrus fruits are among the most popularly consumed fruits worldwide, including oranges, grapefruits, pomelos and lemons. Citrus flavonoids such as hesperidin, naringin and nobiletin have shown an array of health benefits in cell, animal and clinical studies, including antioxidative, anti-inflammatory, neuroprotective, anticancer, and anti-obesity activities. Citrus flavonoids have limited bioavailability after oral administration, leaving the major part unabsorbed and persisted in the colon. Recent studies have highlighted the important role of the gut microbiota and in vivo biotransformation on the bioactivity of citrus flavonoids. This article discusses the biological fate of citrus flavonoids from the viewpoint of their absorption, distribution, metabolism and excretion in vivo. Many delivery systems have been designed to enhance the oral bioavailability of citrus flavonoids, such as emulsions, self-emulsifying systems, nanoparticles and solid dispersions. The ultimate goal of these delivery systems is to enhance the bioefficacy of citrus flavonoids. Several studies have found that the increased bioavailability leads to enhanced bioefficacy of citrus flavonoids in specific animal models. Regarding the complex dynamics of citrus flavonoids and gut microbiota, the bioavailability-bioactivity relationship is an interesting but under-discussed area. Comprehensively understanding the biological fate and bioefficacy of citrus flavonoids would be helpful to develop functional foods with better health benefits.

Knowledge, Attitudes and Practices related to standard precautions among nurses: A comparative study.

AIM AND OBJECTIVE: To describe and compare the Knowledge, Attitudes and Practices (KAP) pertaining to standard precautions (SPs) among nurses in China and Ethiopia. BACKGROUND: SPs are guidelines for reducing the risk of transmission of blood-borne and other pathogens in hospital settings. SPs have been widely promoted to protect healthcare workers (HCW); however, these are not fully practised worldwide, especially in resource-constrained countries like China and Ethiopia. DESIGN: A descriptive, cross-sectional, comparative study was performed between February-April 2018. The study followed the "Strengthening the Reporting of Observational Studies in Epidemiology" (STROBE) guideline. METHODS: Self-administered questionnaire survey of a convenience sample of 357 nurses (237 Chinese and 120 Ethiopian nurses) from one teaching hospital each in China and Ethiopia. KAP pertaining to SPs were measured. RESULTS: Nurses of both countries were found to have a good understanding of the concept of SPs; however, the acceptance to organisation of policies for prevention of hospital-acquired infections (HAI) was lower in Ethiopia. Fewer medical resources in Ethiopia resulted in poorer adherence to use of personal protective equipment (PPE). The usage rate of PPE (except apron and goggles) among Ethiopian nurses was significantly lower than that among Chinese nurses. CONCLUSIONS: Both Ethiopian and Chinese nurses showed favourable attitudes towards SPs; however, Chinese nurses reported better knowledge and practices. The organisation should strengthen formal and on-the-job training, implement targeted infection prevention strategies and provide adequate medical supplies to improve infection control in Ethiopia. RELEVANCE TO CLINICAL PRACTICE: Our findings highlight some of the reasons for low compliance to SPs in both countries and potentially other similar settings. The information provided here can help develop infection prevention and control strategies for resource-constrained countries.