Antimicrobial peptides fight against Pseudomonas aeruginosa at a sub-inhibitory concentration via anti-QS pathway.

The broad-spectrum antimicrobial ability of de novo designed amphiphilic antimicrobial peptides (AMPs) G(IIKK)3I-NH2 (G3) and C8-G(IIKK)2I-NH2 (C8G2) have been demonstrated. Nonetheless, their potential as anti-quorum-sensing (anti-QS) agents, particularly against the opportunistic pathogen Pseudomonas aeruginosa at subinhibitory concentrations, has received limited attention. In this study, we proved that treating P. aeruginosa PAO1 with both AMPs at subinhibitory concentrations led to significant inhibition of QS-regulated virulence factors, including pyocyanin, elastase, proteases, and bacterial motility. Additionally, the AMPs exhibited remarkable capabilities in suppressing biofilm formation and their elimination rate of mature biofilm exceeded 95%. Moreover, both AMPs substantially downregulated the expression of QS-related genes. CD analysis revealed that both AMPs induced structural alterations in the important QS-related protein LasR in vitro. Molecular docking results indicated that both peptides bind to the hydrophobic groove of the LasR dimer. Notably, upon mutating key binding sites (D5, E11, and F87) to Ala, the binding efficiency of LasR to both peptides significantly decreased. We revealed the potential of antibacterial peptides G3 and C8G2 at their sub-MIC concentrations as QS inhibitors against P. aeruginosa and elucidated their action mechanism. These findings contribute to our understanding of the therapeutic potential of these peptides in combating P. aeruginosa infections by targeting the QS system.

An additive-free multifunctional ß-glucan-peptide hydrogel participates in the whole process of bacterial-infected wound healing.

Bacterial infections and excessive inflammation can impede the healing of wounds. Hydrogels have emerged as a promising approach for dressing bacterial-infected injuries. However, some antibacterial hydrogels are complex, costly, and even require assistance with other instruments such as light, making them unsuitable for routine outdoor injuries. Here, we developed an in-situ generating hydrogel via hybridizing oxidized ß-D-glucan with antimicrobial peptide C8G2 through the Schiff base reaction. This hydrogel is easily accessible and actively contributes to the whole healing process of bacterial-infected wounds, demonstrating remarkable antibacterial activity and biological compatibility. The pH-sensitive reversible imine bond enables the hydrogel to self-heal and sustainably release the antibacterial peptide, thereby improving its bioavailability and reducing toxicity. Meanwhile, the immunoregulating ß-D-glucan inhibits the release of inflammatory factors while promoting the release of anti-inflammatory factors. In methicillin-resistant Staphylococcus aureus (MRSA)-infected full-thickness skin wound models, the hybrid hydrogel showed superior antibacterial and anti-inflammatory activity, enhanced the M2 macrophage polarization, expedited wound closure, and regenerated epidermis tissue. These features make this hydrogel an appealing wound dressing for treating multi-drug-resistant bacteria-infected wounds.

Effects of hydroxyl group in cyclo(Pro-Tyr)-like cyclic dipeptides on their anti-QS activity and self-assembly.

We investigated the influence of hydroxyl groups on the anti-quorum-sensing (anti-QS) and anti-biofilm activity of structurally similar cyclic dipeptides, namely cyclo(L-Pro-L-Tyr), cyclo(L-Hyp-L-Tyr), and cyclo(L-Pro-L-Phe), against Pseudomonas aeruginosa PAO1. Cyclo(L-Pro-L-Phe), lacking hydroxyl groups, displayed higher virulence factor inhibition and cytotoxicity, but showed less inhibitory ability in biofilm formation. Cyclo(L-Pro-L-Tyr) and cyclo(L-Hyp-L-Tyr) suppressed genes in both the las and rhl systems, whereas cyclo(L-Pro-L-Phe) mainly downregulated rhlI and pqsR expression. These cyclic dipeptides interacted with the QS-related protein LasR, with similar binding efficiency to the autoinducer 3OC12-HSL, except for cyclo(L-Pro-L-Phe) which had lower affinity. In addition, the introduction of hydroxyl groups significantly improved the self-assembly ability of these peptides. Both cyclo(L-Pro-L-Tyr) and cyclo(L-Hyp-L-Tyr) formed assembly particles at the highest tested concentration. The findings revealed the structure-function relationship of this kind of cyclic dipeptides and provided basis for our follow-up research in the design and modification of anti-QS compounds.

The lipidation and glycosylation enabling bioactivity enhancement and structural change of antibacterial peptide G3.

Bacterial resistance has led to increased interest in the use of antibacterial peptides (AMPs), but their clinical application is limited by poor stability and solubility, as well as complex cytotoxicity. Chemical modification is a common strategy to modulate AMPs. In this study, a de novo designed AMP (G3) was modified by adding an alkyl acid at the N-terminal and a monosaccharide at the C-terminal. Bio-activity assays demonstrated that conjugation with n-caprylic acid increased the peptide's antibacterial activity and permeabilized the membrane. Attachment of glucose or galactose at the C-terminal improved its biofilm inhibitory capacity and marginally reduced cytotoxicity. The hybrid peptide, containing both n-caprylic acid and galactose, exhibited excellent antibacterial and antibiofilm activity, as well as permeabilized the outer membrane.

Engineering Oxygen Vacancies on Mixed-Valent Mesoporous α-MnO2 for High-Performance Asymmetric Supercapacitors.

Intrinsically poor conductivity and sluggish ion-transfer kinetics limit the further development of electrochemical storage of mesoporous manganese dioxide. In order to overcome the challenge, defect engineering is an effective way to improve electrochemical capability by regulating electronic configuration at the atomic level of manganese dioxide. Herein, we demonstrate effective construction of defects on mesoporous α-MnO2 through simply controlling the degree of redox reaction process, which could obtain a balance between Mn3+/Mn4+ ratio and oxygen vacancy concentration for efficient supercapacitors. The different structures of α-MnO2 including the morphology, specific surface area, and composition are successfully constructed by tuning the mole ratio of KMnO4 to Na2SO3. The electrode materials of α-MnO2-0.25 with an appropriate Mn3+/Mn4+ ratio and abundant oxygen vacancy showed an outstanding specific capacitance of 324 F g-1 at 0.5 A g-1, beyond most reported MnO2-based materials. The asymmetric supercapacitors formed from α-MnO2-0.25 and activated carbon can present an energy density as high as of 36.33 W h kg-1 at 200 W kg-1 and also exhibited good cycle stability over a wide voltage range from 0 to 2.0 voltage (kept at approximately 98% after 10 000 cycles in galvanostatic cycling tests) and nearly 100% Coulombic efficiency. Our strategy lays a foundation for fine regulation of defects to improve charge-transfer kinetics.

Association of Elevated Thyroid Stimulating Hormone with Atherosclerotic Cardiovascular Disease and Its Mortality in Elderly Community-Dwelling Chinese.

Purpose: With increase of population aging, the prevalence of atherosclerotic cardiovascular disease (ASCVD) and elevated serum thyroid stimulating hormone (TSH) in elderly is increasing. High TSH level was reported to be associated with ASCVD and CVD mortality; however, few are studied in Chinese population, especially in the elderly. This study aimed to investigate the prevalence of elevated serum TSH and ASCVD in an elderly population of Chinese community and to explore the association between high serum TSH and ASCVD or CVD mortality. Patients and Methods: We conducted a study involving 3814 adults who were at least 60 years of age. Questionnaires, physical examinations, and laboratory blood samples were collected in 2014, and a 78-months follow-up for cardiovascular and all-cause mortality was performed till December of 2020. Logistics regression was used to analyze the association between TSH and ASCVD. We used Cox models to assess the hazard ratios (HRs) for all-cause and CVD mortality across changes in serum TSH. Results: In this study, the prevalence of the elevated serum TSH was 19.8%, and significantly higher in women than in men (24.5% vs 13.9%, p < 0.001). The prevalence of ASCVD was 21.7%. In logistics regression models, elevated TSH was associated with ASCVD after adjusting for the risk factors of ASCVD in people over the age of 70 years (adjusted OR 1.054, P = 0.014). After a follow-up of 6.5 years, total 441 (11.6%) all-cause death and 174 (4.6%) death of CVD were observed. In Cox regression model, no significant correlation was found between TSH and all-cause mortality or CVD mortality in the elderly population. Conclusion: In the elderly population, there is high prevalence of elevated serum TSH and ASCVD. Elevated TSH seemed to be not associated with risk of all-cause or CVD mortality.

Glycosylation increases the anti-QS as well as anti-biofilm and anti-adhesion ability of the cyclo (L-Trp-L-Ser) against Pseudomonas aeruginosa.

Pseudomonas aeruginosa infections pose a huge threat to cystic fibrosis patients, as well as those suffering from immunodeficiency. Antimicrobial resistance, especially multi-drug resistance, due to its ability to aggregate the compact biofilm, makes it more inefficient to treat this pathogen with traditional antibiotics. Biofilm and quorum sensing (QS) have become the alternative targets for treating P. aeruginosa infections. Previously, a cyclic dipeptide cyclo(L-Trp-L-Ser) has been identified as a QS inhibitor of P. aeruginosa. On the other hand, some monosaccharides have been proved lectin-targeting behavior and to mediate biofilm formation and adhesion of P. aeruginosa. We constructed novel cyclic dipeptide-carbohydrate conjugates as a low molecular weight dual-functional QS inhibitor, which can not only enhance its anti-QS activity but also enable good anti-biofilm and anti-adhesion ability. The IC50 of galactosylated c(WS) on biofilm formation and glass adhesion was 1/6 and 1/4 of that of the unmodified cyclic dipeptide, respectively. And the ability to eliminate the preformed biofilm was increased 10-fold. Furthermore, the carbohydrate conjugates can increase the germicidal efficiency of clinical antibiotic azithromycin when used synergistically. Our results provide a novel scaffold for developing anti-virulence adjuvants when taken with clinical antibiotics.

Anti-Quorum-Sensing Activity of Tryptophan-Containing Cyclic Dipeptides.

Quorum sensing (QS) can regulate the pathogenicity of bacteria and the production of some virulence factors. It is a promising target for screening to find anti-virulence agents in the coming post-antibiotics era. Cyclo (L-Trp-L-Ser), one variety of cyclic dipeptides (CDPs), isolated from a marine bacterium Rheinheimera aquimaris, exhibited anti-QS activity against Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1. Unlike the CDPs composed of phenylalanine or tyrosine, the anti-QS activity has been widely studied; however, cyclo (L-Trp-L-Ser) and derivatives, containing one tryptophan unit and one non-aromatic amino acid, have not been systematically explored. Herein, the cyclo (L-Trp-L-Ser) and seven derivatives were synthesized and evaluated. All tryptophane-contained CDPs were able to decrease the production of violacein in C.violaceum CV026 and predicted as binding within the same pocket of receptor protein CviR, but in lower binding energy compared with the natural ligand C6HSL. As for P. aeruginosa PAO1, owning more complicated QS systems, these CDPs also exhibited inhibitory effects on pyocyanin production, swimming motility, biofilm formation, and adhesion. These investigations suggested a promising way to keep the tryptophan untouched and make modifications on the non-aromatic unit to increase the anti-QS activity and decrease the cytotoxicity, thus developing a novel CDP-based anti-virulence agent.

A Stronger Association of Epicardial Fat Volume with Non-Valvular Atrial Fibrillation Than Measures of General Obesity in Chinese Patients Undergoing Computed Tomography Coronary Angiography.

OBJECTIVE: An association of atrial fibrillation (AF) with epicardial fat volume (EFV) varied in different ethnic groups. We evaluated the AF-related risk factors and its association with pericardial fat in Chinese patients. METHODS: Patients referred for coronary computed tomography angiography (CCTA) in Shanghai East Hospital during 2012 to 2014 (n=2042, 43.8% women, mean age 65.0 years) had AF and cardiovascular risk assessment. Pericardial fat depots were measured from CT and the association of EFV with non-valvular AF risk factors was evaluated by multivariate logistic regression models. RESULTS: AF was present in 8.5% of patients with 11.6% of AF patients having rheumatic heart disease (RHD) and 8.7% having other valvular diseases. With increasing age, the proportion of RHD-related AF decreased and the risk factors for non-valvular AF increased. There was a significantly higher proportion of risk factors for non-valvular AF in men than in women (p=0.008), but RHD-related AF was more prevalent in women than men (p=0.013). The patients with non-valvular AF had significantly higher BMI and EFV with more pronounced elevation of EFV (p<0.001). Multivariate logistic regression showed a significant association of EFV with AF after adjustment for BMI and clinical risk factors, and the highest EFV quartile was associated with AF independent of left atrial size and obstructive coronary artery disease. CONCLUSION: The association of EFV with non-valvular AF in Chinese patients was independent of generalized adiposity and clinical risk factors especially in highest EFV quartile. These findings support the growing appreciation of the association of EFV with AF.

A Cyclic Dipeptide from Marine Fungus Penicillium chrysogenum DXY-1 Exhibits Anti-quorum Sensing Activity.

Bacterial quorum sensing (QS) is anticipated as a new potential target for the development of antimicrobial drugs. An anti-QS substance against Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PA01 has been isolated and purified from the crude extracts of the marine fungus Penicillium chrysogenum DXY-1, and the accurate structure was identified as cyclo(l-Tyr-l-Pro). This cyclic dipeptide at sub-minimum inhibitory concentration can decrease the QS-regulated violacein production of C. violaceum CV026 by 79% and QS-mediated pyocyanin production, proteases, and elastase activity of P. aeruginosa PA01 by 41%, 20%, and 32%, respectively. In addition, it can also destroy the biofilm formation and decrease QS gene expression of P. aeruginosa PA01. Molecular docking was further performed, and the obtained data indicated that this dipeptide blocks the effect of QS autoinducers through competitive binding to the same pocket of the receptor proteins. We expect this anti-QS cyclic dipeptide to be a potential pro-drug treating drug-resistant P. aeruginosa infections, and these findings could relieve the alarming problem of microbial resistance to antimicrobial drugs.

Characterization and Function of a Novel Welan Gum Lyase From Marine Sphingomonas sp. WG.

Welan gum, a kind of microbial exopolysaccharides, produced by the genus Sphingomonas, have great potential for application in many fields, such as the food industry, cement production, and enhanced oil recovery. But there are still challenges to reduce the cost, enhance the production and the quality. Herein, the bioinformatics analysis of WelR gene was preformed, and the characterization and function of WelR, welan gum lyase, from Sphingomonas sp. WG were investigated for the first time. The results indicated that 382nd (Asn), 383rd (Met), 494th (Asn), and 568th (Glu) were the key amino acid residues, and C-terminal amino acids were essential to keeping the stability of WelR. The optimal temperature and pH of the enzymatic activity were found to be 25°C and 7.4, respectively. And WelR was good low temperature resistance and alkali resistant. K+, Mg2+, Ca2+, Mn2+, and EDTA increased WelR activities, in contrast to Zn2+. Coupled with the change in glucose concentration and growth profile, the qRT-PCR results indicated that WelR may degrade welan gum existing in the culture to maintain bacterial metabolism when glucose was depleted. This work will lay a theoretical foundation to establish new strategies for the regulation of welan gum biosynthesis.

Site-Specific Photochemical Desaturation Enables Divergent Syntheses of Illicium Sesquiterpenes.

Desaturation of unactivated alkanes remains a challenging yet desirable strategy to make olefins. The Illicium sesquiterpenes usually possess highly oxygenated cage-like architectures, and some of them exhibit prominent neurotrophic effects. Here, we disclose a unique photochemical desaturation strategy for the efficient, highly stereocontrolled total syntheses of five Illicium sesquiterpenes from inexpensive (R)-pulegone, featuring a 13-step gram-scale synthesis of (-)-merrilactone A. The efficiency of the syntheses derives from an expedient construction of a tetracyclic framework via two annulations, a site-specific photoinduced single-step desaturation in a complex hydrocarbon system, and diverse oxygenation manipulations around the resultant olefin intermediate. This work highlights how late-stage desaturation can dramatically streamline the synthesis of complex terpenes and diverse non-natural analogues for establishing the structure-activity relationship and elucidating their molecular mechanisms of bioactivity.

Hyperhomocysteinemia Increases Risk of Metabolic Syndrome and Cardiovascular Death in an Elderly Chinese Community Population of a 7-Year Follow-Up Study.

BACKGROUND: Hyperhomocysteinemia (HHcy) and abdominal obesity are risk factors for metabolic syndrome (MetS) and death from cardiovascular disease (CVD). Recent studies have shown a correlation between HHcy and abdominal obesity, suggesting that they may have a combined effect on the risk of MetS and CVD mortality. However, this suspicion remains to be confirmed, particularly in the elderly population. We explored their combined effects on the risk of MetS and CVD mortality among the community population aged 65 and above in China. METHODS AND RESULTS: This prospective study enrolled 3,675 Chinese community residents aged 65 and above in May 2013 with 7-year follow-up of all-cause and CVD mortality. HHcy was defined as the blood homocysteine (Hcy) level >15 µmol/L and abdominal obesity as waist circumference (WC) ≥90 cm for men and ≥80 cm for women (HWC). All participants were grouped into four categories by WC and the blood level of Hcy: NWC (normal WC) /HHcy(-), NWC/HHcy(+), HWC/HHcy(-), and HWC/HHcy(+). The relationship of combined HHcy and abdominal obesity with MetS and metabolic profile was evaluated by logistic regression analysis and the association of combined HHcy and abdominal obesity with CVD and all-cause mortality evaluated by Cox regression analysis. The prevalence of HHcy, abdominal obesity and MetS in elderly Chinese community residents was 40.1, 59.3, and 41.4%, respectively. Using group without HHcy and abdominal obesity [NWC/HHcy(-)] as reference, the participants of other three groups had significantly higher risk of MetS and its component abnormalities, with HWC/HHcy(+) group having the highest risk (OR = 13.52; 95% CI = 8.61-14.55). After a median of 6.94 (±1.48) years follow-up, 454 deaths occurred with 135 CVD deaths. Compared with NWC/HHcy(-) group, the risk of 7-year follow-up CVD mortality (HR = 1.75; 95% CI = 1.02-3.03) and all-cause mortality (HR = 1.23; 95% CI = 1.04-2.18) of HWC/HHcy(+) group increased considerably after adjustment for major MetS and CVD risk factors. CONCLUSIONS: There is high prevalence of HHcy, abdominal obesity, and MetS in the elderly Chinese community population. HHcy increases risk of MetS, CVD, and all-cause mortality, especially in the populations with abdominal obesity.

Fault Diagnosis of Ball Screw in Industrial Robots Using Non-Stationary Motor Current Signals.

With the advancement of intelligent manufacturing, different kinds of industrial robots have been applied in modern factories. The liquid crystal display transfer robot (LCDTR) has been widely used in LCD production lines to transport panels. Effective fault diagnosis and prognosis of the industrial robots are of great importance, since unplanned downtime caused by faulty robots significantly reduces the production capacity. Specifically, the ball screw is the critical component in the LCDTR. The failure of the ball screw can cause long downtime. Conventionally, the fault diagnosis of the ball screw is usually based on the vibration signals. However, it is extremely difficult to install the vibration sensors in the industrial robots. Therefore, in order to address this issue in condition monitoring, this paper proposes a data-driven fault diagnosis methodology using the motor current signals of the ball screw. Two time-frequency domain analysis methods are investigated, including short-time Fourier transform (STFT) and wavelet packet decomposition (WPD). The statistical features are extracted, and Fisher score is used to select features. Furthermore, the logistic regression and k-nearest neighbors are applied for the final fault diagnosis. Experiments on a real-world industrial robot dataset are carried out for validation. 100% diagnosis accuracy can be basically achieved by the proposed method, which indicates the non-stationary current signal can be effectively used to identify the health states of the ball screw in the LCDTR.

ß-Glucan as an immune activator and a carrier in the construction of a synthetic MUC1 vaccine.

We describe the preparation of a cancer vaccine candidate by conjugating a MUC1 peptide antigen to the ß-glucan polysaccharide, which serves both as a carrier and an immune activator. In contrast to amorphous polysaccharides, peptide-ß-glucan conjugates form uniform nanoparticles that facilitate the delivery of antigens and binding to myeloid cells, thus leading to the activation of both innate and adaptive immunity.

Traceless ß-mercaptan-assisted activation of valinyl benzimidazolinones in peptide ligations.

Peptidyl thioesters or their surrogates with C-terminal ß-branched hydrophobic amino acid residues usually exhibit poor reactivities in ligation reactions. Thus, activation using exogenous additives is required to ensure an acceptable reaction efficiency. Herein, we report a traceless ligation at Val-Xaa sites under mild thiol additive-free reaction conditions, whereby the introduction of ß-mercaptan on the C-terminal valine residue effectively activates the otherwise unreactive N-acyl-benzimidazolinone (Nbz), and enables the use of a one-pot ligation-desulfurization strategy to generate the desired peptide products. The orthogonality between ß-thiovaline-Nbz and a conventional alkyl thioester, as well as the convenient access to the former from readily available penicillamine, also allowed expedited assembly of the peptidic hormone ß-LPH and hPTH analogues, based on a kinetically controlled one-pot three-segment ligation and desulfurization strategy.

Total Synthesis of (+)-Fusarisetin A Driven by a One-Pot Four-Reaction Process.

A concise, asymmetric total synthesis of (+)-fusarisetin A, a hybrid natural product, has been achieved. A one-pot four-reaction process efficiently delivered the tetracycle 2 which served as a key intermediate for the synthesis of the title natural product and its analogues through amino acid incorporation.

Protecting-Group-Free Total Synthesis of (-)-Jiadifenolide: Development of a [4 + 1] Annulation toward Multisubstituted Tetrahydrofurans.

A concise, protecting-group-free total synthesis of (-)-jiadifenolide, a synthetically challenging seco-prezizaane sesquiterpene with potent neurotrophic activity, is reported. The convergent route features a SmI2/H2O-mediated stereoselective reductive cyclization, an unprecedented formal [4 + 1] annulative tetrahydrofuran-forming reaction and programmed redox manipulations. The newly developed annulation of ß-hydroxy aldehydes or ketones with lithium trimethylsilyldiazomethane provides access to a diverse array of multisubstituted tetrahydrofurans. The synthetic jiadifenolide exhibited weak cytotoxicity against five human cancer cell lines.

Identification and characterization of two homologues of interferon-stimulated gene ISG15 in crucian carp.

ISG15 is one of the most strongly induced genes upon viral infection, interferon (IFN) stimulation, and lipopolysaccharide (LPS) stimulation, and only one copy has been found in mammals so far. Here two fish ISG15 genes, termed CaISG15-1 and CaISG15-2, have been cloned and sequenced from UV-inactivated GCHV (grass carp haemorrhagic virus)-infected and IFN-produced CAB cells (crucian carp Carassius auratus blastulae embryonic cells) by suppression subtractive hybridization. The full-length cDNA sequences of two crucian carp ISG15 encode a 155-amino-acid protein and a 161-amino-acid protein, both of which show 78.9% identity overall and possess the characteristic structures of mammalian ISG15 proteins including two tandem ubiquitin-like domains and the C-terminal canonical LRLRGG motif. In CAB cells treated with different stimuli including active virus, UV-inactivated GCHV and IFN containing supernatant (ICS), the expression of both CaISG15-1 and CaISG15-2 was upregulated but displayed different kinetics. Poly I:C and LPS were also able to induce an increase in mRNA for both genes. In CAB cells responsive to active GCHV, UV-inactivated GCHV, CAB ICS, Poly I:C and LPS, CaISG15-1 was upregulated more significantly than CaISG15-2. These results suggest that there are two ISG15 homologues in crucian carp, both of which might play distinct roles in innate immunity against viral and bacterial infection.