Water-Insoluble Polysaccharide Extracted from Poria cocos Alleviates Antibiotic-Associated Diarrhea Based on Regulating the Gut Microbiota in Mice.

Antibiotics are very effective in treating a variety of bacterial infections, while clinical overuse of antibiotics can lead to diseases such as antibiotic-associated diarrhea. Numerous studies have shown that natural polysaccharides can be used as prebiotics to alleviate antibiotic-associated diarrhea (AAD). Poria cocos is a medicinal and edible mushroom widely used for thousands of years in China, and our former study demonstrated that water-insoluble polysaccharide (PCY) has the potential prebiotic function. Therefore, we simulated the digestion and fermentation of PCY using feces from volunteers, and then administered it to C57BL/6 mice with AAD to study its effects on the gut microbiota and metabolites. The results indicated that PCY effectively alleviated the symptoms of AAD in mice, restored the intestinal barrier function, improved the content of short-chain fatty acids (SCFAs), decreased the level of inflammatory cytokines, and changed the structure of gut microbiota by increasing the relative abundance of norank_f__Muribaculaceae and unclassified_f__Lachnospiraceae, and decreasing that of Escherichia-Shigella, Staphylococcus and Acinetobacter. This study further demonstrated that PCY is an effective functional prebiotic for improving AAD disease, and provided a new avenue and insight for developing PCY as a functional food or prebiotic for alleviating gastrointestinal diseases.

Achieved systolic blood pressure and cardiovascular outcomes in 60-80-year-old patients: the Strategy of Blood Pressure Intervention in the Elderly Hypertensive Patients (STEP) trial.

AIMS: Intensive systolic blood pressure (SBP) lowering has been increasingly used; however, data is missing on patients who had target-achieved (TA). This study aims to show the cardiovascular effect of maintaining SBP at intensive levels. METHODS: The Strategy of Blood Pressure Intervention in Elderly Hypertensive Patients (STEP) trial was a multicentre, randomized, controlled trial which enrolled 8511 young-older (60-80 years) hypertensive patients without prior stroke to compare the cardiovascular prognosis of the intensive treatment (SBP target, 110 to <130 mmHg) vs. the standard treatment (130 to <150 mmHg). This secondary analysis assessed data in patients who achieved a mean SBP within target values. The association of mean achieved SBP and cardiovascular events was examined using a cubic spline function. RESULTS: In total, 3053 patients (72.0%) in the intensive-treatment group and 3427 (80.3%) in the standard-treatment group had an SBP target achieved, with mean follow-up SBP values of 124.2 mmHg and 137.4 mmHg, respectively. Throughout the median 3.38-year follow-up, the cardiovascular risk was significantly lower in the TA intensive-treatment group than in the TA standard-treatment group [adjusted hazard ratio (HR) 0.61, 95% confidence interval (CI) 0.46-0.80; P < 0.001]. In the intensive-treatment group, patients failing to achieve SBP targets presented higher cardiovascular risk than those TA patients (HR 2.04, 95% CI 1.44-2.88; P < 0.001). A J-shaped relationship was observed between the mean achieved SBP and risk of cardiovascular events, with the lowest risk at an SBP of 126.9 mmHg. CONCLUSIONS: Maintaining SBP at <130 mmHg offers additional cardiovascular benefits among young-older patients with hypertension. REGISTRATION: ClinicalTrials.gov: NCT03015311.

This present study is a secondary analysis that investigated the association between mean achieved BP in the two treatment groups (SBP target, 110 to <130 vs. 130 to <150 mmHg) and their cardiovascular outcomes in the STEP study (60­80-year-old patients with hypertension).Patients achieving a target in the intensive-treatment group have better cardiovascular outcome than patients achieving a target in the standard treatment arm, supporting the cardiovascular benefits of maintaining SBP <130 mmHg.J-shaped relationships were observed between mean achieved SBP and cardiovascular outcomes (with the nadir around 130 mmHg), but not for stroke.

Gut microbiota regulation and prebiotic properties of polysaccharides from Oudemansiella raphanipes mushroom.

Oudemansiella raphanipes is a type of fungus used as both medicine and food. Fungal polysaccharides have demonstrated various bioactivities, involving the adjust and control of gut microbiota, but no such studies on O. raphanipes polysaccharides (OrPs) have been reported. It is by extracting and purifying that OrPs was obtained from O. raphanipes crude polysaccharide and study their effects in mice. The sample contents of total sugar was 97.26%, and the monosaccharide content comprised mannose, rhamnose, glucose, and xylose in a molar ratio of 35.2:2.8:21.2:40.8. The effects of OrPs on body weight (BW), gut microbiota, fecal short-chain fatty acids (SCFAs), and the correlation between fecal SCFAs and gut microbes, in mice were investigated. The results of the experiment found that OrPs significantly (P < 0.01) inhibited the increase in BW, altered the constitution of the gut microbiota, and significantly (P < 0.05) enhanced the content of fecal SCFAs in mice. Moreover, among the top ten bacteria in terms of relative abundance, the Lachnospiraceae and Lachnospiraceae NK4A136 groups were positively associated with the increased production of SCFAs. Other bacteria, such as Atopobiaceae and Bifidobacterium of Actinobacteriota, and Faecalibaculum, Dubosiella, and Clostridium sensu stricto 5 of Firmicutes, were also positively associated with higher content of fecal SCFAs. The results of the experiment suggest that OrPs have a potential prebiotic effect on gut microbiota and may prevent BW gain. Furthermore, the major producers of SCFAs were Firmicutes and Actinobacteriota.

Dynamics of a delayed stochastic epidemic model with double epidemic hypothesis and saturated incidence.

This article explores a delayed stochastic epidemic model with double epidemic hypothesis and saturated incidence. First, we give some preliminaries of the epidemic system. Second, by building Lyapunov functions and utilizing inequalities, we study the asymptotic properties of the delayed stochastic system around each equilibrium point. Furthermore, we prove the persistence in mean of the epidemic system. In the end, several numerical simulations are presented to show that stochastic disturbance and time delay can impact the dynamics of the epidemic system.

Three main metabolites from Wolfiporia cocos (F. A. Wolf) Ryvarden & Gilb regulate the gut microbiota in mice: A comparative study using microbiome-metabolomics.

Wolfiporia cocos (F. A. Wolf) Ryvarden & Gilb, also known as Poria cocos is an ancient edible and medicinal mushroom that has been valued for thousands of years for its tranquilizing, diuretic, and spleen-enhancing properties. Because of the mushroom's complex composition, its pharmacological effects have not been fully clarified. Therefore, to expand our knowledge of these effects from a pharmacological perspective and exploit potential medicinal value of fungal mushroom, we extracted three main metabolites from P. cocos, including water-soluble polysaccharides (PCX), water-insoluble polysaccharides (PCY), and triterpenoid saponins (PCZ) for intragastric injection into mice. These injections were made to explore the component's effects on the mice's gut microbiota and their metabolomics. The microbiota analysis showed that PCY had the strongest effect on regulating gut microbiota through altering its composition and increasing the number of Lactobacillus (p < 0.01). A total of 1,828 metabolites were detected using metabolomics methods, and the results showed that the three main active metabolites of P. cocos significantly changed the content of short-chain peptides in intestinal metabolites. In conclusion, our study further investigated the pharmacological functions of P. cocos, and revealed the differing effects of its three main metabolites on gut microbiota. The results suggested that PCY is a prominent prebiotic, and provided us with new insights into the potential development of fungal polysaccharides in Chinese traditional medicine.

Study of Ce, Ca, Fe, and Mn-Doped LaCoO3 Perovskite Oxide for the Four-Way Purification of PM, NOx, CO, and HC from Diesel Engine Exhaust.

Perovskite-type catalysts were widely used in the field of automobile exhaust purification due to their inherent physicochemical properties and excellent doping characteristics. A series of La1-xMxCo1-yNyO3 (M = Ce, Ca; N = Fe, Mn) perovskite-type catalyst samples were prepared by sol-gel method for the four-way purification of PM, NOx, CO, and HC emitted by diesel exhaust. The activity of catalyst samples was tested by simulation experiments and hydrogen temperature-programmed reduction (H2-TPR). Catalyst samples were characterized by means of XRD, FT-IR, SEM, BET, and XPS analysis. The results demonstrated that the perovskite-type catalyst samples with a particle pore size of 3-5 µm can be prepared by sol-gel method. When A-site of LaCoO3 perovskite-type oxide was doped by cerium ions, the catalyst samples produced small distortion. The doping of cerium ions to A-site was more conducive to the four-way purification of diesel exhaust than calcium ions. La0.8Ce0.2CoO3 perovskite-type samples showed the best purification efficiency, and the purification efficiencies of PM, NOx, CO, and HC were 90%, 85%, 94%, and 100%, respectively. When the B-site of La0.8Ce0.2CoO3 perovskite was doped with iron ions, the purification efficiency of catalyst samples for PM and NOx can be further enhanced. When the B-site of La0.8Ce0.2CoO3 perovskite was doped with manganese ions, the purification efficiency of the catalyst samples for PM can be further enhanced. It can be seen from the simulation experiments that La0.8Ce0.2Co0.7Fe0.3O3 perovskite was the best doping amount, and the purification efficiencies of PM, NOx, CO, and HC were 95%, 92%, 94%, and 100%, respectively.

Enhancement of Activity and Thermostability of Keratinase From Pseudomonas aeruginosa CCTCC AB2013184 by Directed Evolution With Noncanonical Amino Acids.

A keratinase from Pseudomonas aeruginosa (KerPA), which belongs to the M4 family of metallopeptidases, was characterised in this study. This enzyme was engineered with non-canonical amino acids (ncAAs) using genetic code expansion. Several variants with enhanced activity and thermostability were identified and the most prominent, Y21pBpF/Y70pBpF/Y114pBpF, showed an increase in enzyme activity and half-life of approximately 1.3-fold and 8.2-fold, respectively. Considering that keratinases usually require reducing agents to efficiently degrade keratin, the Y21pBpF/Y70pBpF/Y114pBpF variant with enhanced activity and stability under reducing conditions may have great significance for practical applications. Molecular Dynamics (MD) was performed to identify the potential mechanisms underlying these improvements. The results showed that mutation with pBpF at specific sites of the enzyme could fill voids, form new interactions, and reshape the local structure of the active site of the enzyme.

Comparative Analyses of the Transcriptome and Proteome of Escherichia coli C321.△A and Further Improving Its Noncanonical Amino Acids Containing Protein Expression Ability by Integration of T7 RNA Polymerase.

Incorporation of noncanonical amino acids (ncAAs) into proteins has been proven to be a powerful tool to manipulate protein structure and function, and to investigate many biological processes. Improving the yields of ncAA-containing proteins is of great significance in industrial-scale applications. Escherichia coli C321.ΔA was generated by the replacement of all known amber codons and the deletion of RF1 in the genome and has been proven to be an ideal host for ncAA-containing protein expression using genetic code expansion. In this study, we investigated the transcriptome and proteome profiles of this first codon reassignment strain and found that some functions and metabolic pathways were differentially expressed when compared with those of its parent strain. Genes involved in carbohydrate and energy metabolism were remarkably downregulated. Our results may provide important clues about the growth defects in E. coli C321.ΔA. Furthermore, we improved the yields of ncAA-containing proteins in E. coli C321.ΔA by integrating the T7 RNA polymerase system.

Metagenomic Analysis of Antibiotic Resistance Genes in Untreated Wastewater From Three Different Hospitals.

Controlling antibiotic resistance genes (ARGs) is a worldwide intervention to ensure global health. Hospital wastewater is the main pollution source of antibiotic-resistant bacteria and ARGs in the environment. Expanding our knowledge on the bacterial composition of hospital wastewater could help us to control infections in hospitals and decrease pathogen release into the environment. In this study, a high-throughput sequencing-based metagenomic approach was applied to investigate the community composition of bacteria and ARGs in untreated wastewater from three different types of hospitals [the general hospital, traditional Chinese medicine (TCM) hospital, and stomatology hospital]. In total, 130 phyla and 2,554 genera were identified from the microbiota of the wastewaters, with significantly different bacterial community compositions among the three hospitals. Total ARG analysis using the Antibiotic Resistance Genes Database (ARDB) and Comprehensive Antibiotic Resistance Database (CARD) revealed that the microbiota in the wastewaters from the three hospitals harbored different types and percentage of ARGs, and their composition was specific to the hospital type based on the correlation analysis between species and ARG abundance, some ARGs contributed to different bacterial genera with various relationships in different hospitals. In summary, our findings demonstrated a widespread occurrence of ARGs and ARG-harboring microbiota in untreated wastewaters of different hospitals, suggesting that protection measures should be applied to prevent human infections. Concurrently, hospital wastewater should be treated more specifically for the removal of pathogens before its discharge into the urban sewage system.

Effects of Filling Rate and Resin Concentration on Pore Characteristics and Properties of Carbon Based Wood Ceramics.

As a kind of novel porous ceramics, wood ceramics can be used for filtration, friction, energy storage and electrode materials, etc. In current work, the carbon based wood ceramics (C WCMs) was prepared using pine wood powder and phenolic resin as starting materials. The effects of filling rate of wood powder and resin concentration on pore characteristics and properties of C WCMs were characterized and analyzed with different techniques. Furthermore, the association among porosity of C WCMs, filling rate of wood powder and resin concentration was explored with multiple regression model. The results showed that: increasing the resin concentration and the filling rate of wood powder can improve the mechanical properties of C WCMs, but reduce the porosity and air permeability; when resin concentration is more than 50%, a large amount of caking will appear in the C WCMs, causing internal defects; changing the filling rate under a certain resin concentration can obtain the C WCMs with better pore structure; the porosity of C WCMs has a good linear relationship with resin concentration and filling rate, under the condition that sintering process and the size of wood powder are determined.

Effect of different sweeteners on the oral microbiota and immune system of Sprague Dawley rats.

Sucrose, xylose, and saccharin are commonly used beverage additives and long-term consumption of these compounds inevitably affects the oral immune system and the composition of oral microbiomes. In this study, we used 24 Sprague Dawley rats divided into four groups, i.e., sucrose, saccharin, xylose, or pure water treated over an eight week period to evaluate any changes in the composition, community structure, and function of the oral microbiomes. At the end of the treatment period, we collected oral microbiome samples from each animal and subjected them to high-throughput sequencing. We also used ELISA to determine the concentration of salivary immunoglobulin in these rats to reveal the effect of sweetener on the oral immune system. Sequencing results demonstrated that Firmicutes and Proteobacteria, remained the predominant phyla, but we found that the oral microbial diversity of rats drinking sucrose water was significantly higher than that of the other groups. Our results indicate that drinking water supplemented with sweeteners may influence oral immunity as well as the composition, metabolic function, and diversity of the oral microbiota, thereby disrupting the oral microbiome.

Temporal-Spatial Evolution of Kinetic and Thermal Energy Dissipation Rates in a Three-Dimensional Turbulent Rayleigh-Taylor Mixing Zone.

In this work, the temporal-spatial evolution of kinetic and thermal energy dissipation rates in three-dimensional (3D) turbulent Rayleigh-Taylor (RT) mixing are investigated numerically by the lattice Boltzmann method. The temperature fields, kinetic and thermal energy dissipation rates with temporal-spatial evolution, the probability density functions, the fractal dimension of mixing interface, spatial scaling law of structure function for the kinetic and the thermal energy dissipation rates in 3D space are analysed in detail to provide an improved physical understanding of the temporal-spatial dissipation-rate characteristic in the 3D turbulent Rayleigh-Taylor mixing zone. Our numerical results indicate that the kinetic and thermal energy dissipation rates are concentrated in areas with large gradients of velocity and temperature with temporal evolution, respectively, which is consistent with the theoretical assumption. However, small scale thermal plumes initially at the section of half vertical height increasingly develop large scale plumes with time evolution. The probability density function tail of thermal energy dissipation gradually rises and approaches the stretched exponent function with temporal evolution. The slope of fractal dimension increases at an early time, however, the fractal dimension for the fluid interfaces is 2.4 at times t/τ ≥ 2, which demonstrates the self-similarity of the turbulent RT mixing zone in 3D space. It is further demonstrated that the second, fourth and sixth-order structure functions for velocity and temperature structure functions have a linear scaling within the inertial range.

Heterochiral DNA with Complementary Strands with α-d and ß-d Configurations: Hydrogen-Bonded and Silver-Mediated Base Pairs with Impact of 7-Deazapurines Replacing Purines.

Heterochiral DNA with hydrogen-bonded and silver-mediated base pairs have been constructed using complementary strands with nucleosides with α-d or ß-d configuration. Anomeric phosphoramidites were employed to assemble the oligonucleotides. According to the Tm values and thermodynamic data, the duplex stability of the heterochiral duplexes was similar to that of homochiral DNA, but mismatch discrimination was better in heterochiral DNA. Replacement of purines by 7-deazapurines resulted in stable parallel duplexes, thereby confirming Watson-Crick-type base pairing. When cytosine was facing cytosine, thymine or adenine residues, duplex DNA formed silver-mediated base pairs in the presence of silver ions. Although the CD spectra of single strands with α-d configuration display mirror-like shapes to those with the ß-d configuration, the CD spectra of the hydrogen-bonded duplexes and those with a limited number of silver pairs show a B-type double helix almost indistinguishable from natural DNA. Nonmelting silver ion-DNA complexes with entirely different CD spectra were generated when the number of silver ions was equal to the number of base pairs.

Silver-Mediated Homochiral and Heterochiral α-dC/ß-dC Base Pairs: Synthesis of α-dC through Glycosylation and Impact of Consecutive, Isolated, and Multiple Metal Ion Pairs on DNA Stability.

Isolated and consecutive heterochiral α-dC- base pairs have been incorporated into 12-mer oligonucleotide duplexes at various positions, thereby replacing Watson-Crick pairs. To this end, a new synthesis of the α-d anomer of dC has been developed, and oligonucleotides containing α-dC residues have been synthesized. Silver-mediated base pairs were formed upon the addition of silver ions. Furthermore, we have established that heterochiral α-dC-dC base pairs can approach the stability of a Watson-Crick pair, whereas homochiral dC-dC pairs are significantly less stable. A positional change of the silver-mediated base pairs affects the duplex stability and reveals the nearest-neighbor influence. When the number of silver ions was equivalent to the number of duplex base pairs (12), non-melting silver-rich complexes were formed. Structural changes have been supported by circular dichroism (CD) spectra, which showed that the B-DNA structure was maintained whilst the silver ion concentration was low. At high silver ion concentration, silver-rich complexes displaying different CD spectra were formed.

5-Aza-7-deaza-2'-deoxyguanosine and 2'-Deoxycytidine Form Programmable Silver-Mediated Base Pairs with Metal Ions in the Core of the DNA Double Helix.

5-Aza-7-deaza-2'-deoxyguanosine (dZ) forms a silver-mediated base pair with dC. The metal ion pair represents a mimic of the H-bonded Watson-Crick dG-dC pair. The modified nucleoside displays a similar shape as the parent 2'-deoxyguanosine from which it can be constructed by transposition of nitrogen-7 to the bridgehead position-5. It lacks the major groove binding site as the positional change moves the dG- acceptor position from nitrogen-7 to nitrogen-1. As a shape mimic of dG, it fits nicely in the DNA double helix. The purine-pyrimidine dZ-dC hetero pair shows a relationship to the pyrimidine-pyrimidine dC-dC homo base pair. The dZ-dC pair forms a mismatch in the absence of silver ions and matches after addition of metal ions. Base-pair formation was verified on self-complementary 6-mer duplexes and 12-mer DNA with random composition by UV-dependent Tm measurements. Modified silver-mediated and hydrogen-bonded canonical base pairs can coexist. The dZ-Ag+ -dC base pair is slightly less stable than the dG-dC pair, shows sequence dependence, and consumes one or two silver ions. These properties make the dZ-Ag+ -dC pair suitable for programmable incorporation of silver ions in DNA which cannot be achieved by canonical base pairs. If the silver ion content is higher than the total number of base pairs the duplexes turn into very stable structures in which all base pairs are considered to be in the silver-mediated pairing mode.

Gemcitabine, Pyrrologemcitabine, and 2'-Fluoro-2'-Deoxycytidines: Synthesis, Physical Properties, and Impact of Sugar Fluorination on Silver Ion Mediated Base Pairing.

The stability of silver-mediated "dC-dC" base pairs relies not only on the structure of the nucleobase, but is also sensitive to structural modification of the sugar moiety. 2'-Fluorinated 2'-deoxycytidines with fluorine atoms in the arabino (up) and ribo (down) configuration as well as with geminal fluorine substitution (anticancer drug gemcitabine) and the novel fluorescent phenylpyrrolo-gemcitabine (ph PyrGem) have been synthesized. All the nucleosides display the recognition face of naturally occurring 2'-deoxycytidine. The nucleosides were converted into phosphoramidites and incorporated into 12-mer oligonucleotides by solid-phase synthesis. The addition of silver ions to DNA duplexes with a fluorine-modified "dC-dC" pair near the central position led to significant duplex stabilization. The increase in stability was higher for duplexes with fluorinated sugar residues than for those with an unchanged 2'-deoxyribose moiety. Similar observations were made for "dC-dT" pairs and to a minor extent for "dC-dA" pairs. The increase in silver ion mediated base-pair stability was reversed by annulation of a pyrrole ring to the cytosine moiety, as shown for 2'-fluorinated ph PyrGem in comparison with phenylpyrrolo-dC (ph PyrdC). This phenomenon results from stereoelectronic effects induced by fluoro substitution, which are transmitted from the sugar moiety to the silver ion mediated base pairs. The extent of the effect depends on the number of fluorine substituents, their configuration, and the structure of the nucleobase.

Anomeric 2'-Deoxycytidines and Silver Ions: Hybrid Base Pairs with Greatly Enhanced Stability and Efficient DNA Mismatch Detection with α-dC.

α-d-Nucleosides are rare in nature but can develop fascinating properties when incorporated into DNA. This work reports on the first silver-mediated base pair constructed from two anomeric nucleosides: α-dC and ß-dC. The hybrid base pair was integrated into the DNA and DNA/RNA double helix. A 12-mer duplex with α-dC and ß-dC pair exhibits a higher thermal stability (Tm =43 °C) than that incorporating the ß-dC-Ag+ -ß-dC homo pair (Tm =34 °C). Furthermore, α-dC shows excellent mismatch discrimination for DNA single nucleotide polymorphism (SNP). All four SNPs were identified on the basis of large Tm value differences measured in the presence of silver ions. High resolution melting was not required.

Silver-Mediated Base Pairs in DNA Incorporating Purines, 7-Deazapurines, and 8-Aza-7-deazapurines: Impact of Reduced Nucleobase Binding Sites and an Altered Glycosylation Position.

Formation of silver-mediated DNA was studied with oligonucleotides incorporating 8-aza-7-deazapurine, 7-deazapurine, and purine nucleosides. The investigation was performed on non-self-complementary duplexes with one or two modifications and self-complementary duplexes with an alternating dA-dT motif. Homo base pairs as well as base pair mismatches of dA analogues with dC and Watson-Crick pairs with dT were studied by stoichiometric silver ion titration and Tm measurements. N8 -Glycosylated 8-aza-7-deazaadenine forms silver-ion-mediated base pairs capturing two silver ions (low silver content) whereas regularly glycosylated 8-aza-7-deazapurine, 7-deazapurine (c7 Ad ), and dA do not form comparable structures. Stable silver-mediated "dA-dC" base pair mismatches were detected for all nucleosides. Two silver ions per base pair are bound by 8-aza-7-deazapurine whereas c7 Ad binds only one silver ion. The situation is different when the equivalents of silver ions were increased to the number of total base pairs. Surprisingly, in 12-mer duplexes as well as in related 25-mer duplexes every base pair consumed one silver ion.

MercuryII-mediated base pairs in DNA: unexpected behavior in metal ion binding and duplex stability induced by 2'-deoxyuridine 5-substituents.

The stability of the mercury ion mediated dU-HgII-dU pair depends on substituents introduced at the 5-position of the pyrimidine moiety. To this end, a series of oligonucleotides were synthesized with dU modification in central position. Common and new phosphoramidites were utilized. Hybridization experiments provided 12-mer duplexes with non-canonical "dU-dU" pairs. In most cases Hg2+ stabilizes duplexes by metal ion mediated base pair formation identified by higher duplex melting. Among the three types of dU derivatives incorporated in duplex DNA those with small aliphatic side chains have only a minor impact on the stability of the mercury-mediated base pair, while those with a triple bond in the side chain show hysteresis during duplex heating and cooling cycle implying triple bond interaction with mercury ions. Formation of metal ion mediated base pairs is blocked by space occupying aromatic side chains by side chain-helix stacking interactions. These interactions are too strong to permit mercury ion mediated base pair formation and drive the uridine N(3) acceptor atoms in an unfavorable pairing position.