The resistance of Staphylococcus aureus (S. aureus) to various antibiotics has increased dramatically due to the misuse of antibiotics, and thus the development of new anti-infective drugs with new ...targets is urgently needed to combat resistance. Caseinolytic peptidase P is a case in hydrolase that regulates the virulence level of S. aureus. Here, we found that nepetin, a small-molecule compound from traditional Chinese herbal flavonoids, effectively inhibits ClpP activity. Nepetin suppressed the virulence of S. aureus and effectively combated the lethal pneumonia caused by MRSA. The results of cellular thermal shift assay showed that nepetin could bind to ClpP and reduce the thermal stability of ClpP, and the K
D
value of 602 nM between them was determined using localized surface plasmon resonance. The binding mode of nepetin and ClpP was further investigated by molecular docking, and it was found that Ser-22 and Gln-47 of ClpP residues were found to be involved in the binding of nepetin to ClpP. In conclusion, we determined that nepetin is a ClpP inhibitor and an effective lead compound for the development of a virulence factor-based treatment for MRSA infection.
Pertuzumab is a monoclonal antibody for the treatment of breast cancer. The aim of this study was to compare the pharmacokinetics, immunogenicity and safety of the test preparation SHR-1309 injecta ...and the reference preparation Perjeta® in healthy Chinese male subjects.
In this randomized, double-blind, single dose, two-way, parallel bioequivalence trial, a total of 80 qualified Chinese male subjects were selected and randomly divided into two groups. Each subject was intravenously injected with SHR-1309 or Perjeta®. Blood samples were collected at 21 different time points for pharmacokinetic analysis. In addition, immunogenicity was assessed at five different time points. The safety of the medication was monitored throughout the whole trial.
C
and AUC
were the primary pharmacokinetic parameters. Under a 90% confidence interval, their geometric mean ratios were 98.30 and 88.41% for SHR-1309 injection and Perjeta®, respectively. The geometric mean ratio of secondary pharmacokinetic parameters AUC
was 88.58%. These evaluation indexes are in the standard range of 80-125%, so SHR-1309 can be considered bioequivalent to Perjeta®. After 1,680 h (day 70) of administration, the two groups had 12 and 13 subjects who produced antidrug antibody (ADA), respectively. The occurrence time and proportion of ADA in SHR-1309 and Perjeta® were similar between subjects, and they had similar immunogenicity. During the entire trial period, there were 71 drug-related adverse reactions in 29 subjects who received SHR-1309 and 61 drug-related adverse reactions in 32 subjects who received Perjeta®. The incidence of adverse reactions between the two drugs was similar.
The pharmacokinetic parameters, immunogenicity and safety of the biosimilar SHR-1309 injection produced by Shanghai Hengrui Pharmaceutical Co. Ltd. were similar to the original drug Perjeta® produced by Roche Pharma AG. The two drugs met the bioequivalence evaluation criteria. Therefore, SHR-1309 is bioequivalent to Perjeta®. Clinical trial registration: CTR20200,738.
Staphylococcus aureus (S. aureus) infection causes dramatic harm to human health as well as to livestock development. As an important virulence factor, alpha-hemolysin (hla) is critical in the ...process of S. aureus infection. In this report, we found that bavachin, a natural flavonoid, not only efficiently inhibited the hemolytic activity of hla, but was also capable of inhibiting it on transcriptional and translational levels. Moreover, further data revealed that bavachin had no neutralizing activity on hla, which did not affect the formation of hla heptamers and exhibited no effects on the hla thermal stability. In vitro assays showed that bavachin was able to reduce the S. aureus-induced damage of A549 cells. Thus, bavachin repressed the lethality of pneumonia infection, lung bacterial load and lung tissue inflammation in mice, providing potent protection to mice models in vivo. Our results indicated that bavachin has the potential for development as a candidate hla inhibitor against S. aureus.
Monopile-supported offshore wind turbines (OWTs) are dynamically sensitive structures whose fundamental frequencies may be close to those of environmental and turbine-related excitations. The changes ...in fundamental frequencies caused by pile-soil interaction (PSI) may result in unwanted resonance and serious O&M (Operation and Maintenance) issues, which have been identified as major challenges in the research field. Therefore, a novel model updating framework with an implicit objective function is proposed to monitor both the stiffness and damping variation of the OWT system based on the measured vibration characteristics, which is further verified by laboratory tests. In particular, layered soil was considered in the tests to simulate the practical soil conditions of Chinese seas. Different pile lengths were introduced to consider the long-term PSI effects for rigid piles and slender piles. The results showed that the variation in the fundamental frequency is significantly reduced in layered soil compared with the pure sand scenario. For the OWT systems in layered soil, the variation in foundation stiffness is negatively related to the burial depth under cyclic loading. The proposed model updating framework is proven reliable for support condition monitoring of OWT systems in complicated soil conditions.
•A novel model updating framework is proposed to monitor both the stiffness and damping variation of the OWT system.•Layered soil was considered in the laboratory tests to simulate the complicated soil conditions of the China Sea.•The long-term pile-soil interaction effects for rigid piles and slender piles were observed in the laboratory tests.
Lightweight, flexible, ultrahigh-performance electromagnetic-interference (EMI) shielding materials are urgently required in the areas of aircraft/aerospace, portable and wearable electronics. ...Herein, 1D carbon nanotubes (CNT) and carbon nanofibers (CNF) with 2D edge-rich graphene (ERG) are used to form a lightweight, flexible CNT-ERG-CNF hybrid foam. This foam was fabricated through a self-sacrificial templating chemical vapor deposition process, where nanocarbons bond through covalent bonding, forming a hierarchical 3D hybridized carbon nanostructure. Multistage conductive networks and heterogeneous interfaces were constructed using edge-rich nanocarbons to increase the induced currents and interfacial polarization which makes great contributions to achieve high absorption electromagnetic shielding effectiveness (SEA). The CNT-ERG-CNF hybrid foam exhibits EMI shielding effectiveness (SE) exceeding 55.4 dB in the X-band while the specific SE (SSE, SE divided by mass density) achieves 9200 dB cm3 g-1, which surpasses that of nearly all other carbon-based composite materials. Furthermore, the structural stability and durability of the flexible CNT-ERG-CNF hybrid foams is examined by measuring EMI SE after 10000 times cyclic bending. Remarkably, this work not only provides a new idea for preparing hierarchical carbon materials for a wide range of applications, but presents some fundamental insights for achieving higher absorption losses in EMI shielding materials.
The increasing prevalence of infections related to methicillin-resistant
Staphylococcus aureus
(MRSA) necessitates the exploration of innovative therapeutic strategies that diverge from conventional ...antibiotic treatments. This is imperative to effectively combat resistance and manage these infections. The adoption of antivirulence strategies has emerged as a particularly promising avenue. This approach applies a heightened selective pressure on pathogens, thereby diminishing the likelihood of bacteria evolving resistance to antibiotics. In our pursuit of novel therapeutics for treating MRSA infections, we have focused on agents that inhibit the virulence of
S. aureus
without impeding its growth, aiming to minimize the development of drug resistance. α-Hemolysin, a critical virulence factor encoded by the
hla
gene, is a cytotoxin that forms pores in host cell membranes and plays a pivotal role in the progression of disease during bacterial infections. Herein, we identified that norwogonin could effectively inhibit
Hla
production via targeting
agrA
C
, a crucial protein in quorum sensing, resulting in dose-dependent inhibition of hemolytic activity without suppressing
S. aureus
growth. In vitro assays illustrated that norwogonin decreased the thermal stability of
agrA
C
, providing evidence of interaction between norwogonin and
agrA
C
. Meanwhile, norwogonin alleviated
Hla
-mediated A549 cell damage and reduced lactate dehydrogenase release. In vivo studies suggested that norwogonin treatment blocked the establishment of a mouse model of pneumonia caused by
S. aureus
USA300. Notably, norwogonin enhanced the antibacterial potency of oxacillin. In conclusion, norwogonin is a promising candidate for treating
S. aureus
infections, offering a novel alternative to traditional antibiotics by targeting virulence factors and enhancing the efficacy of existing treatments.
The emergence of drug-resistant Staphylococcus aureus (S. aureus) has limited drug options for the clinical treatment of S. aureus infections. Considering recent reports, therapeutic strategies ...targeting bacterial virulence hold great promise, and alpha-hemolysin (encoded by hla), a critical virulence factor of S. aureus, plays a vital role during bacterial infection. Herein, we demonstrated that hispidulin effectively inhibited the hemolytic activity of S. aureus USA300 without suppressing bacterial growth, along with inhibiting hla transcription and expression in a dose-dependent manner. As heptamer formation is essential for hla-mediated invasion of cells, nevertheless, hispidulin did not affect the deoxycholate-induced oligomerization of hla, suggesting that hispidulin did not affect the protein activity of hla. In vitro assays illustrated that hispidulin bound to agrAC, a crucial protein in quorum sensing. Meanwhile, hispidulin alleviated A549 cell damage caused by S. aureus USA300 and reduced lactate dehydrogenase release. In vivo studies showed that hispidulin had a protective effect against pneumonia caused by S. aureus USA300 in mice. S. aureus did not develop resistance to hispidulin in the short term. Interestingly, our research indicated that hispidulin synergized with the antibacterial activity of cefoxitin. These results showed that hispidulin effectively inhibited α-hemolysin expression by inhibiting the agr quorum sensing of S. aureus. It has promise as an agent to treat S. aureus infection.
A frequently asked question regarding L3 acquisition is which preexisting language system(s), L1, L2 or both L1 and L2, can be transferred to L3. Different models on L3 transfer have been p roposed, ...but mainly based on morphosyntactic studies. To study L3 transfer in the domain of phonetics and phonology, the current thesis does not aim at only finding out which pre language(s) will transfer to L3, in order to test the syntax-based L3 models, but it will also investigate the role of general phonetic factors, i.e., acoustic and perceived similarity and stableness of L1 and L2 categories, in influencing the learning of L3 sounds. In this manner, we can understand under what circumstance s L1, L2 and L1+L2 transfer occur respectively. Specifically, L3 production and perception of Korean vowels /u, o, ʌ / in adult learners with L1 Cantonese (native), L2 English (acquired in childhood) and L3 Korean (acquired through classroom learning at university) are examined in this thesis.For the transfer patterns in L3 production (Study 1 in Chapter 3), the acoustic analyses of L1 Cantonese, L2 English and L3 Korean recordings of 23 L3 learners showed that considering different acoustic dimensions, i.e ., F1, F2 and vowel duration, the target L3 vowels were influenced by both L1 and L2 categories. The Mahalanobis Distance (DS), which is a more comprehensive measurement, indicates that L1 had a stronger influence on L3 compared with L2, since L3 was assimilated to L1 categories in terms of DS for all the Korean target vowels /u/, /o/, and /ʌ/.To account for the cross-linguistic influences (CLI) from specific L1 and L2 vowels to L3 vowel production (Study 2 in Chapter 3), the effects of acoustic distance (i.e., acoustic similarity), perceived similarity and vowel variation (i.e., stableness of L1 and L2 categories) were evaluated through acoustic comparisons between target Korean vowel productions by 17 native Seoul Korean speakers and the L1 and L2 vowel productions by the 23 L3 learners, L3 perceptual mapping tasks with all possible vowels in Cantonese and English as choices, and acoustic analyses of L1 and L2 vowel productions by the L3 learners, respectively. The results showed that the L3 CLI patterns can be predicted by a combination of the three factors, in that L3 vowel productions tend to be assimilated to perceptually similar and less variable L1/L2 vowels. However, for the effect of acoustic distance, while L3 /u/ was assimilated to acoustically similar L1/L2 categories, L3 /o/ and /ʌ/ were dissimilated from acoustically similar L1/L2 categories, which diverges from relevant L2 speech models’ predictions. In L3 vowel perception (Chapter 4), it was found that L3 identification results of target Korean vowels in different consonantal contexts (labial, alveolar, velar and bare vowel) can be predicted by the perceptual and acoustic categorization of the L3 vowel stimuli to L1/L2 categories, as were proposed by the Perceptual Assimilation Model (PAM) (Best, 1994, 1995) and the Second Language Linguistic Perception (L2LP) model (Escudero, 2005, 2009) respectively. Moreover, besides acoustic and perceived similarity, the effect of vowel variation has also been confirmed to influence L3 perception in a way that if both sounds in an L3 contrast are categorized into the same L1/L2 vowels, the less variable the L1/L2 vowels are, the more accurate the L3 perception will be. Collectively, these results suggest that L3 vowel production and perception can be influenced by both L1 and L2, dependent on the acoustic and perceived similarity between the target L3 and the corresponding L1/L2 vowels as well as the vowel variation of L1 and L2 categories. A new L3 hypothesis was proposed, which is the Phonetic Factor Hypothesis (PFH), to account for CLIs in L3 speech acquisition based on relevant findings in the thesis.
In the search for novel succinate dehydrogenase inhibitor (SDHI) fungicides to control Rhizoctonia solani, thirty-five novel pyrazole-4-carboxamides bearing either an oxime ether or an oxime ester ...group were designed and prepared based on the strategy of molecular hybridization, and their antifungal activities against five plant pathogenic fungi were also investigated. The results indicated that the majority of the compounds containing oxime ether demonstrated outstanding in vitro antifungal activity against R. solani, and some compounds also displayed pronounced antifungal activities against Sclerotinia sclerotiorum and Botrytis cinerea. Particularly, compound 5e exhibited the most promising antifungal activity against R. solani with an EC50 value of 0.039 μg/mL, which was about 20-fold better than that of boscalid (EC50 = 0.799 μg/mL) and 4-fold more potent than fluxapyroxad (EC50 = 0.131 μg/mL). Moreover, the results of the detached leaf assay showed that compound 5e could suppress the growth of R. solani in rice leaves with significant protective efficacies (86.8%) at 100 μg/mL, superior to boscalid (68.1%) and fluxapyroxad (80.6%), indicating promising application prospects. In addition, the succinate dehydrogenase (SDH) enzymatic inhibition assay revealed that compound 5e generated remarkable SDH inhibition (IC50 = 2.04 μM), which was obviously more potent than those of boscalid (IC50 = 7.92 μM) and fluxapyroxad (IC50 = 6.15 μM). Furthermore, SEM analysis showed that compound 5e caused a remarkable disruption to the characteristic structure and morphology of R. solani hyphae, resulting in significant damage. The molecular docking analysis demonstrated that compound 5e could fit into the identical binding pocket of SDH through hydrogen bond interactions as well as fluxapyroxad, indicating that they had a similar antifungal mechanism. The density functional theory and electrostatic potential calculations provided useful information regarding electron distribution and electron transfer, which contributed to understanding the structural features and antifungal mechanism of the lead compound. These findings suggested that compound 5e could be a promising candidate for SDHI fungicides to control R. solani, warranting further investigation.
PDF
