Carbapenem-resistant Klebsiella pneumoniae capsular types, antibiotic resistance and virulence factors in China: a longitudinal, multi-centre study.

Epidemiological knowledge of circulating carbapenem-resistant Klebsiella pneumoniae (CRKP) is needed to develop effective strategies against this public health threat. Here we present a longitudinal analysis of 1,017 CRKP isolates recovered from patients from 40 hospitals across China between 2016 and 2020. Virulence gene and capsule typing revealed expansion of CRKP capsule type KL64 (59.5%) alongside decreases in KL47 prevalence. Hypervirulent CRKP increased in prevalence from 28.2% in 2016 to 45.7% in 2020. Phylogenetic and spatiotemporal analysis revealed Beijing and Shanghai as transmission hubs accounting for differential geographical prevalence of KL47 and KL64 strains across China. Moderate frequency capsule or O-antigen loss was also detected among isolates. Non-capsular CRKP were more susceptible to phagocytosis, attenuated during mouse infections, but showed increased serum resistance and biofilm formation. These findings give insight into CRKP serotype prevalence and dynamics, revealing the importance of monitoring serotype shifts for the future development of immunological strategies against CRKP infections.

Enhanced Electrorheological Performance of Core-Shell-Structured Polymerized Ionic Liquid@Doubly Polymerized Ionic Liquid Microspheres Prepared via Evaporation-Assisted Dispersion Polymerization.

A polymerized ionic liquid (PIL) provides a platform for the development of a high-performance water-free polyelectrolyte-based electrorheological fluid (ERF) because of the presence of large-size hydrophobic ion pairs. However, the large-size hydrophobic ion pairs also easily result in a low glass-transition temperature of an ordinary linear PIL, and consequently, the PIL-based ERF has to be subject to a high leaking current density and a narrow working temperature range. In this paper, we prepared a kind of core-shell-structured polymerized ionic liquid@doubly polymerized ionic liquid (PIL@D-PIL) microsphere with a linear PIL as the core and a physically cross-linked D-PIL as the shell via an evaporation-assisted dispersion polymerization method. The core-shell structure of the sample was observed by scanning electron microscopy and transmission electron microscopy. The thermal properties of the sample were tested by differential scanning calorimetery and thermogravimetric analysis. The ER effect and dielectric polarization of PIL@D-PIL microspheres when dispersed in an insulating nonpolar liquid were studied by a rheometer and dielectric spectroscopy. It shows that the glass-transition temperature and thermal stability of a PIL increased after coating with the D-PIL shell. Under electric fields, the ERF of the PIL@D-PIL microspheres exhibits a significantly reduced leaking current density and an enhanced operating temperature range compared to the ERF of single-PIL microspheres. The PIL@D-PIL microspheres can still maintain good ER effect even if the temperature is higher than the glass-transition point of the PIL core due to the protection of the D-PIL shell.

Albumin alleviated esketamine-induced neuronal apoptosis of rat retina through downregulation of Zn2+-dependent matrix metalloproteinase 9 during the early development.

AIMS: Esketamine upregulates Zn2+-dependent matrix metalloproteinase 9 (MMP9) and increases the neuronal apoptosis in retinal ganglion cell layer during the early development. We aimed to test whether albumin can alleviate esketamine-induced apoptosis through downregulating Zn2+-dependent MMP9. METHODS: We investigate the role of Zn2+ in esketamine-induced neuronal apoptosis by immunofluorescence. MMP9 protein expression and enzyme activity were investigated by zymography in situ., western blot and immunofluorescence. Whole-mount retinas from P7 Sprague-Dawley rats were used. RESULTS: We demonstrated that esketamine exposure increased Zn2+ in the retinal GCL during the early development. Zn2+-dependent MMP9 expression and enzyme activity up-regulated, which eventually aggravated apoptosis. Albumin effectively down-regulated MMP9 expression and activity via binding of free zinc, ultimately protected neurons from apoptosis. Meanwhile albumin treatment promoted activated microglia into multi-nucleated macrophagocytes and decreased the inflammation. CONCLUSION: Albumin alleviates esketamine-induced neuronal apoptosis through decreasing Zn2+ accumulation in GCL and downregulating Zn2+-dependent MMP9.

The Molecular Epidemiology of Prevalent Klebsiella pneumoniae Strains and Humoral Antibody Responses against Carbapenem-Resistant K. pneumoniae Infections among Pediatric Patients in Shanghai.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has caused wide dissemination among pediatric patients globally and thus has aroused public concern. Here, we investigated the clinical epidemiological characteristics of 140 nonreplicate clinical K. pneumoniae strains isolated from pediatric patients between January and December 2021. Of all isolates, 16.43% (23 of 140) were CRKP strains, which predominantly contained KPC carbapenemase. wzi sequencing demonstrated that KL47 (65.22%, 15 of 23) was the most frequent capsular type, followed by KL64 (17.39%, 4 of 23). A total of 23 CRKP strains were classified into three different O-genotypes, including OL101 (65.22%, 15 of 23), O1 (26.09%, 6 of 23), and O3 (8.7%, 2 of 23). Interestingly, KL47 strains were strongly associated with OL101, while KL64 strains were all linked with O1. Some capsule-deficient strains were identified by serological typing, phage-typing, depolymerase-typing, and uronic acid assay. In this study, compared with healthy children, higher titers of anti-capsular polysaccharides (CPS) IgG were first detected in the sera of K47 and K64 K. pneumoniae-infected children, which had the effective bactericidal activity against corresponding serotype K. pneumoniae strains. These findings will facilitate the development of novel therapeutic and vaccine strategies against K. pneumoniae infection in children. IMPORTANCE The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains resistant to numerous antibiotics and the limited therapeutic options available have become an urgent health threat to the immunocompromised pediatric population. Vaccines and antibodies, especially those targeting capsular polysaccharides, may be novel and effective prevention and treatment options. Thus, it is important to understand the spread of CRKP in pediatric populations. This research presents OL101:KL47 and O1:KL64 as the predominant combinations among CRKP strains in children in Shanghai, China. The primary carbapenemase gene is KPC in CRKP strains. Additionally, this study found elevated levels of anti-CPS IgG against K47 and K64 K. pneumoniae strains in pediatric patients for the first time. The significant bactericidal activity of these anti-CPS IgGs was confirmed.

Characterization and Functional Studies of a Novel Depolymerase Against K19-Type Klebsiella pneumoniae.

Carbapenem-resistant Klebsiella pneumoniae (CRKP), a pathogen that causes severe nosocomial infections and yields a high mortality rate, poses a serious threat to global public health due to its high antimicrobial resistance. Bacteriophages encode polysaccharide-degrading enzymes referred to as depolymerases that cleave the capsular polysaccharide (CPS), one of the main virulence factors of K. pneumoniae. In this study, we identified and characterized a new capsule depolymerase K19-Dpo41 from K. pneumoniae bacteriophage SH-KP156570. Our characterization of K19-Dpo41 demonstrated that this depolymerase showed specific activities against K19-type K. pneumoniae. K19-Dpo41-mediated treatments promoted the sensitivity of a multidrug-resistant K19-type K. pneumoniae strain to the bactericidal effect of human serum and significantly increased the survival rate of Galleria mellonella infected with K19-type K. pneumoniae. Our results provided strong primary evidence that K19-Dpo41 was not only effective in capsular typing of K19-type K. pneumoniae but promising in terms of developing new alternative therapeutic strategies against K19-type CRKP infections in the future.

Progress in Preparation of Sea Urchin-like Micro-/Nanoparticles.

Urchin-like microparticles/nanoparticles assembled from radial nanorods have a good appearance and high specific surface area, providing more exposed active sites and shortening the diffusion path of photoexcited carriers from the interior to the surface. The interfacial interaction and physical and chemical properties of the materials can be improved by the interfacial porous network induced by interlacing nano-branches. In addition, multiple reflections of the layered microstructure can absorb more incident light and improve the photocatalytic performance. Therefore, the synthesis and functionalization of three-dimensional urchin-like nanostructures with controllable size, shape, and hierarchy have attracted extensive attention. This review aims to provide an overview to summarize the structures, mechanism, and application of urchin-like microparticles/nanoparticles derived from diverse synthesis methods and decoration types. Firstly, the synthesis methods of solid urchin-like micro-/nanoparticles are listed, with emphasis on the hydrothermal/solvothermal method and the reaction mechanism of several typical examples. Subsequently, the preparation method of composite urchin-like micro-/nanoparticles is described from the perspective of coating and doping. Then, the research progress of urchin-like hollow microspheres is reviewed from the perspective of the step-by-step method and synchronous method, and the formation mechanism of forming urchin-like hollow microspheres is discussed. Finally, the application progress of sea urchin-like particles in the fields of photocatalysis, electrochemistry, electromagnetic wave absorption, electrorheological, and gas sensors is summarized.

Anti-inflammatory Constituents from Caulis Trachelospermi.

Caulis Trachelospermi, the stems with leaves of Trachelospermum jasminoides, is a well-known herbal drug of the Apocynaceae family recorded in the Chinese pharmacopeia and used for the treatment of inflammation-related diseases by ethnic minorities of China. The mechanism of anti-inflammatory activity and responsible constituents of T. jasminoides have not been well elucidated in previous studies. Preliminary investigation showed that both the water and the ethyl ester extracts of T. jasminoides exhibited potent inhibitory activity on nitric oxide (NO) production using lipopolysaccharide (LPS)-stimulated murine macrophages. Phytochemical investigation on these extracts afforded 23 compounds, including three new compounds (1:  -3: ) identified on the basis of spectroscopic and mass spectrometric data. Anti-inflammatory bioassay showed that compounds 17, 18, 22: , and 23: inhibited significantly the production of NO in a concentration-dependent manner. Further studies indicated that compound 23: inhibited significantly TNF-α and IL-6 produced by LPS-stimulated RAW 264.7 cells with good selectivity, as well as protein expression of iNOS in RAW 264.7 cells. These chemical constituents may contribute to the anti-inflammatory potential of T. jasminoides.

Identification of a Depolymerase Specific for K64-Serotype Klebsiella pneumoniae: Potential Applications in Capsular Typing and Treatment.

Carbapenem-resistant Klebsiella pneumoniae (CRKP), one of the major nosocomial pathogens, is increasingly becoming a serious threat to global public health. There is an urgent need to develop effective therapeutic and preventive approaches to combat the pathogen. Here, we identified and characterized a novel capsule depolymerase (K64-ORF41) derived from Klebsiella phage SH-KP152410, which showed specific activities for K. pneumoniae K64-serotype. We showed that this depolymerase could be used in the identification of K64 serotypes based on the capsular typing, and the results agreed well with those from the conventional serotyping method using antisera. From this study, we also identified K64 mutant strains, which showed typing discrepancy between wzi-sequencing based genotyping and depolymerase-based or antiserum-based typing methods. Further investigation indicated that the mutant strain has an insertion sequence (IS) in wcaJ, which led to the alteration of the capsular serotype structure. We further demonstrated that K64-ORF41 depolymerase could sensitize the bacteria to serum or neutrophil killing by degrading the capsular polysaccharide. In summary, the identified K64 depolymerase proves to be an accurate and reliable tool for capsular typing, which will facilitate the preventive intervention such as vaccine development. In addition, the polymerase may represent a potential and promising therapeutic biologics against CRKP-K64 infections.

Chemical constituents from the barks of Melia azedarach and their PTP1B inhibitory activity.

One new long-chain ester derivative of trans-ferulic acid 1 and one natural tirucallane-type triterpenoid 2, together with forty known compounds (3-42), were isolated from the barks of Melia azedarach. Their structures were established on the basis of spectroscopic data interpretation. Compounds 7, 9, 10, 12, 13 showed significant inhibitory activities against PTP1B with IC50 values of 13.82 ± 1.29 µM, 13.29 ± 2.26 µM, 20.27 ± 0.52 µM, 24.36 ± 1.25 µM, 15.23 ± 0.6 µM, respectively.

Potential anti-diabetic isoprenoids and a long-chain δ-lactone from frangipani (Plumeria rubra).

A decoction of Plumeria rubra flowers has been used traditionally for the treatment of diabetes in China and Mexico. Chemical investigations on the bioactive constituents of these flowers led to the isolation of 30 compounds, including the four new compounds, one iridoiod (1), two triterpenoids (4, 5), and a long-chain δ-lactone (16). In addition, 26 known compounds (2, 3, 6-15, 17-30) are also reported. All of these compounds were identified on the basis of spectroscopic data interpretation and the absolute configurations of compound 4, 5, 16 were determined by Mosher's method. Compounds 1-4, 7, 8 and 16 showed moderate to significant inhibitory activities against α-glucosidase and protein tyrosine phosphatase 1B, with 4 having IC50 values of 19.45 µM and 0.21 µM, respectively.

Phenolic Constituents with Antioxidative, Tyrosinase Inhibitory and Anti-aging Activities from Dendrobium loddigesii Rolfe.

Aqueous ethanol extracts of powdered stems of Dendrobium loddigesii afforded three new phenolics including threo-7-O-ethyl-9-O-(4-hydroxyphenyl)propionyl-guaiacylglycerol (1), (R)-4,5,4'-trihydroxy-3,3',α-trimethoxybibenzyl (2) and (S)-5,5',7-trihydroxy-3',4'-dimethoxyflavanone (3), together with eleven known analogues. Their structures were determined by extensive spectroscopic analysis. To identify natural antioxidants, whitening, and anti-aging agents, the abilities of these phenolics were assessed to scavenge the 1,2-diphenyl-2-picrylhydrazyl (DPPH) radical, their abilities to inhibit tyrosinase production, and their abilities to stimulate collagen production by human dermal fibroblasts-adult (HDFa) assay. It was found that compounds 1, 4-8, 13 and 14 exhibited significant DPPH radical scavenging activities, compound 10 exhibited tyrosinase inhibitory activity (IC50 37.904 µg/mL), and compound 9 showed significant collagen production with an EC50 value of 3.182 µg/mL. These results suggest that phenolic constituents from D. loddigesii may be candidate antioxidants, skin-whitening and/or anti-aging agents.

Erratum: Chen, F. et al. Advances of Metabolomics in Fungal Pathogen-Plant Interactions. Metabolites 2019, 9, 169.

The authors wish to make the following corrections to this paper [...].

Advances of Metabolomics in Fungal Pathogen-Plant Interactions.

Plant disease caused by fungus is one of the major threats to global food security, and understanding fungus-plant interactions is important for plant disease control. Research devoted to revealing the mechanisms of fungal pathogen-plant interactions has been conducted using genomics, transcriptomics, proteomics, and metabolomics. Metabolomics research based on mass spectrometric techniques is an important part of systems biology. In the past decade, the emerging field of metabolomics in plant pathogenic fungi has received wide attention. It not only provides a qualitative and quantitative approach for determining the pathogenesis of pathogenic fungi but also helps to elucidate the defense mechanisms of their host plants. This review focuses on the methods and progress of metabolomics research in fungal pathogen-plant interactions. In addition, the prospects and challenges of metabolomics research in plant pathogenic fungi and their hosts are addressed.

3α,19-Dihydroxyl-ent-pimara-8(14),15-diene, a new diterpenoid from the rhizomes of Ricinus communis.

A new natural product, 3α,19-dihydroxyl-ent-pimara-8(14),15-diene (1), which possesses an α-orientation hydroxymethyl at C-4 and ∆8,14 groups, as well as eight known compounds, was isolated from the rhizomes of Ricinus communis. The structure of 1 was elucidated by extensive spectroscopic methods and its absolute configurations were confirmed by X-ray crystallographic analysis. The inhibitory rate of 1 against protein tyrosine phosphatase 1B (PTP1B) was 49.49% at the concentration of 6.58 × 10-5 mol/L.

Chemical constituents from the leaves of Melia azedarach.

Six compounds, benzyl 3-O-ß-D-glucopyranosyl-7-hydroxybenzoate (1), spathulenol (2), 1,7,8-trihydroxy-2-naphtaldehyde (3), quercetin (4), astragalin (5) and 2-methoxy-4-(2-propenyl)phenyl ß-D-glucoside (6), were isolated from the leaves of Melia azedarach L. The structure elucidation of compound 1 was discussed in detail based on its 2D-NMR data. Compound 1 showed weak cytotoxicity against the cell lines of T-24, NCI-H460, HepG2, SMMC-7721, CNE, MDA-MB-231 and B16F10 with the inhibition rates from 10.01% to 34.05% at the concentration of 80 µM.

Selection of cuffed endotracheal tube for children with congenital heart disease based on an ultrasound-based linear regression formula.

It remains to be discovered whether a formula predicting the subglottic transverse diameter measured by ultrasound (SGDformula) for the selection of an appropriate endotracheal tube (ETT) for children without congenital heart disease (CHD) is useful for children with CHD. A formula for predicting SGD was established after assessing 60 children ≤ 8 years without CHD and validated on 60 children with CHD. We selected the cuffed ETT size based on the SGD by ultrasound (SGDultra). Subsequently, the fit of the ETT cuff in 60 children with CHD was examined via air-leak test. The maximum allowed difference between the SGDformula and the ETT size that fit was 0.2 mm. The agreement among and accuracy of SGDultra, SGDformula, and the ETT used in children was analyzed. For children without CHD, we adopted a linear formula, given by SGDformula (mm) = 0.4 × age + 5.3. For children with CHD, allometric formula was adopted, given by SGDformula (mm) = 5.4 × age0.18. A stronger agreement exists between SGDultra and ETT size compared to that between SGDformula and ETT size. And the mean bias (SGDformula-ETT size and SGDultra-ETT size) was 0.21 mm (95% confidence interval, - 0.59 to 1.01 mm) and 0.00 mm (- 0.79 to 0.84 mm). For the CHD group, the ultrasound-based method yielded a 78% success rate of ETT size choice, while the formula-based method permitted an appropriate ETT size in only 32% of subjects (P < 0.001). Our analysis showed that measuring the SGDultra was more accurate in predicting the correct OD of the ETT in children with CHD undergoing cardiovascular surgery, based on the correlation and agreement with ETT OD.

Synthesis and antitumor activity of biotinylated camptothecin derivatives as potent cytotoxic agents.

A series of biotinylated camptothecin derivatives were designed and synthesized. The key to the synthesis was achieved by employing an esterification reaction and click chemistry. All of the new derivatives were tested for cytotoxicity against five human tumor cell lines, including HL-60, SMMC-7721, A-549, MCF-7, and SW480 with IC50 values ranging from 0.13 to 21.53 µM. Most of the derivatives exhibited potent cytotoxicity, especially compound 17 (IC50 = 0.13-3.31 µM) and compound 18 (IC50 = 0.23-1.48 µM), which exhibited the highest potencies. The structure-activity relationships (SARs) of the biotinylated camptothecin derivatives were discussed for exploring novel anticancer agents.

Triterpenoids and iridoids from Patrinia scabiosaefolia.

Three new triterpenoids, patrinolides B-D (1-3), and two new iridoids, patriscabioins K-L (9-10), together with five known compounds (4-8) were isolated from the extract of the whole plants of Patrinia scabiosaefolia. Compounds 1, 9, and 10 contained the unique substituents in Valerianaceae family, such as isovalery and 3-methylcrotonyl. Compound 2 was a 24-nor-ursane triterpenoid. Their structures were established on the basis of extensive spectroscopic analysis (UV, IR, MS, 1D and 2D NMR). The inhibitory activities against nitric oxide synthase (NOS) of all triterpenoids were tested. The results showed that compound 4 had moderate inhibitory activity with IC50 of 10.1µM. Furthermore, it also showed strongest inhibitory activities on AChE with IC50 values of 10.0µM.

Caesalpinone A, a new type of gorgonane sesquiterpenoid containing an unprecedented 1,15-bridge, from the pods of Caesalpinia spinosa Kuntze.

Caesalpinone A (1), a new type of gorgonane sesquiterpenoid containing an unprecedented 1,15-bridge, along with ten known sesquiterpenoids (2-11) were isolated from the pods of Caesalpinia spinosa Kuntze (Tara). The structure of caesalpinone A was elucidated based on its 1D and 2D NMR spectra. The absolute configuration of 1 was assigned by the comparison of the experimental and calculated electronic circular dichroism spectra. Compound 1 was evaluated for the inhibitory activities against five human tumor cell lines. The sesquiterpenoids of isodaucane skeleton and caryolane skeleton were isolated from Caesalpinia genus for the first time. Compounds 5-9 were firstly reported from Tara.

Oleanane-type triterpene saponins from Hydrocotyle nepalensis.

Five new oleanane-type triterpene saponins including steganogenin 3-O-ß-D-glucopyranoside (1), steganogenin 3-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranoside (2), steganogenin 3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranoside (3), chichipegenin 3-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranoside (4) and chichipegenin 3-O-ß-D-glucopyranosyl-(1→2)-ß-D-glucopyranoside (5), along with four known oleanane-type triterpenes and triterpene saponins (6-9) were isolated from EtOH extract of the whole plant of Hydrocotyle nepalensis. To the best of our knowledge, oleanane-type triterpenes possessing skeleton with 17, 22-seco-backbone (1-3) are not common in natural products. Compound 8 was isolated as a new natural product. The structures of new compounds were elucidated by extensive spectroscopic methods and chemical evidence. Moreover, the cytotoxic activity of all the isolates against five selected human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) was evaluated and the results indicated that compounds 6 and 7 show stronger cytotoxic activity.