Identification and Quantification of S-Sulfenylation Proteome of Mycobacterium tuberculosis under Oxidative Stress.

The ability to maintain redox homeostasis is critical for Mycobacterium tuberculosis (Mtb) to survive the redox stress of the host. There are many antioxidant systems in Mtb to ensure its normal replication and survival in the host, and cysteine thiols are one of them. S-sulfenylation is one of the reversible modifications of cysteine thiols to resist oxidative stress. In the study, we investigated the total cysteine thiols modification and S-sulfenylation modification of Mtb proteome under the oxidative stress provided by hydrogen peroxide. To determine and quantify the S-sulfenylation modified proteins, high specific IodoTMT6plex reagents and high resolution mass spectrometry were used to label and quantify the peptides and proteins modified. There are significant differences for the total cysteine modification levels of 279 proteins and S-sulfenylation modification levels of 297 proteins under hydrogen peroxide stress. Functional enrichment analysis indicated that these cysteine-modified proteins were involved in the oxidation-reduction process, fatty acid biosynthetic process, stress response, protein repair, cell wall, etc. In conclusion, our study provides a view of cysteine modifications of the Mtb proteome under oxidative stress, revealing a series of proteins that may play a role in maintaining redox homeostasis. IMPORTANCE With the continuous spread of drug-resistant tuberculosis, there is an urgent need for new antituberculosis drugs with new mechanisms. The ability of Mtb to resist oxidative stress is extremely important for maintaining redox homeostasis and survival in the host. The reversible modifications of cysteine residues have a dual role of protection from irreversible damage to protein functions and regulation, which plays an important role in the redox homeostasis system. Thus, to discover cysteine modification changes in the proteome level under oxidative stress is quintessential to elucidate its antioxidant mechanism. Our results provided a list of proteins involved in the antioxidant process that potentially could be considered targets for drug discovery and vaccine development. Furthermore, it is the first study to determine and quantify the S-sulfenylation-modified proteins in Mtb, which provided better insight into the Mtb response to the host oxidative defense and enable a deeper understanding of Mtb survival strategies.

Serum glycoprotein non-metastatic melanoma protein B (GPNMB) level as a potential biomarker for diabetes mellitus-related cataract: A cross-sectional study.

Background: Diabetes mellitus (DM), a metabolic disease that has attracted significant research and clinical attention over the years, can affect the eye structure and induce cataract in patients diagnosed with DM. Recent studies have indicated the relationship between glycoprotein non-metastatic melanoma protein B (GPNMB) and DM and DM-related renal dysfunction. However, the role of circulating GPNMB in DM-associated cataract is still unknown. In this study, we explored the potential of serum GPNMB as a biomarker for DM and DM-associated cataract. Methods: A total of 406 subjects were enrolled, including 60 and 346 subjects with and without DM, respectively. The presence of cataract was evaluated and serum GPNMB levels were measured using a commercial enzyme-linked immunosorbent assay kit. Results: Serum GPNMB levels were higher in diabetic individuals and subjects with cataract than in those without DM or cataract. Subjects in the highest GPNMB tertile group were more likely to have metabolic disorder, cataract, and DM. Analysis performed in subjects with DM elucidated the correlation between serum GPNMB levels and cataract. Receiver operating characteristic (ROC) curve analysis also indicated that GPNMB could be used to diagnose DM and cataract. Multivariable logistic regression analysis illustrated that GPNMB levels were independently associated with DM and cataract. DM was also found to be an independent risk factor for cataract. Further surveys revealed the combination of serum GPNMB levels and presence of DM was associated with a more precise identification of cataract than either factor alone. Conclusions: Increased circulating GPNMB levels are associated with DM and cataract and can be used as a biomarker of DM-associated cataract.

Familial hypercholesterolaemia in pregnancy: Australian case series and review.

BACKGROUND: Familial hypercholesterolaemia (FH) is associated with a significant increase in the risk of premature coronary artery disease. Pregnancy is likely a vulnerable time for atherosclerosis progression, with a physiological rise in low-density lipoprotein cholesterol (LDL-C) further exaggerated by the discontinuation of cholesterol-lowering therapy. MATERIALS AND METHODS: A retrospective review was undertaken of 13 women with familial hypercholesterolemia who were managed during pregnancy between 2007 and 2021 by a multidisciplinary team following individualised risk assessment. RESULTS: Overall, pregnancy outcomes were good, with no maternal or fetal complications, including congenital abnormalities, maternal cardiac events or hypertensive complications. Loss of statin treatment time ranged between 12 months and 3.5 years resulting from the accumulation of the preconception, pregnancy and lactation periods and was magnified in women having more than one pregnancy. Of seven women treated with cholestyramine, one developed abnormal liver function with an elevated international normalisation ratio which was corrected with vitamin K. CONCLUSION: Pregnancy is associated with prolonged cessation of cholesterol-lowering therapy, a concern with respect to the risk of coronary artery disease in FH. Continuation of statin therapy up to conception and even during pregnancy in patients at higher risk of cardiovascular disease may be justified, especially with increasing evidence supporting the safety of statin therapy during pregnancy. However, more long-term maternal and fetal data are required for the routine use of statins during pregnancy. Guideline-informed models of care covering family planning and pregnancy should be implemented for all women with FH.

How Can Implementation Science Improve the Care of Familial Hypercholesterolaemia?

PURPOSE OF REVIEW: Describe the application of implementation science to improve the detection and management of familial hypercholesterolaemia. RECENT FINDINGS: Gaps between evidence and practice, such as underutilization of genetic testing, family cascade testing, failure to achieve LDL-cholesterol goals and low levels of knowledge and awareness, have been identified through clinical registry analyses and clinician surveys. Implementation science theories, models and frameworks have been applied to assess barriers and enablers in the literature specific to local contextual factors (e.g. stages of life). The effect of implementation strategies to overcome these factors has been evaluated; for example, automated identification of individuals with FH or training and education to improve statin adherence. Clinical registries were identified as a key infrastructure to monitor, evaluate and sustain improvements in care. The expansion in evidence supporting the care of familial hypercholesterolaemia requires a similar expansion of efforts to translate new knowledge into clinical practice.

Lipoprotein(a) is associated with thrombus burden in culprit arteries of younger patients with ST-segment elevation myocardial infarction.

Background Lipoprotein(a) [Lp(a)] is a risk factor for cardiovascular disease. The burden of thrombus in ST-segment elevation myocardial infarction (STEMI) has implications on treatment and outcomes. However, the association between Lp(a) and atherothrombosis in STEMI remains unclear. Objectives Determine the association between Lp(a) and culprit artery thrombus burden in younger patients with STEMI. Methods Single-centre study of 83 patients aged <65 years with STEMI between 2016-2018 who underwent percutaneous coronary intervention and measurement of Lp(a); those receiving thrombolytic therapy were excluded. Thrombus burden in the culprit artery was determined angiographically using the Thrombolysis in Myocardial Infarction score and classified as absent-to-small, moderate, or large. Elevated Lp(a) was defined as plasma mass concentration >30 mg/dL. Multivariate analysis was performed adjusting for cardiovascular risk factors. Results The mean age was 48.08.4 years and 78.3% were male. Thirteen (16%), 9 (11%) and 61 (73%) patients had small, moderate, or large thrombus burden, respectively, and 34 (41%) had elevated Lp(a). Elevated Lp(a) was associated with greater thrombus burden compared to normal Lp(a) (large burden 85% versus 65%; P=0.024). Elevated Lp(a) was associated with moderate or large thrombus in univariate [OR 10.70 (95% CI 1.32-86.82); P=0.026] and multivariate analysis [OR 10.33 (95% CI 1.19-89.52); P=0.034]. Lp(a) was not associated with culprit artery or stenosis location according to culprit artery. Conclusions Elevated Lp(a) is associated with greater thrombus burden in younger patients with STEMI. The finding of this observational study accords with the thrombotic and anti-fibrinolytic properties of Lp(a). A causal relationship requires verification.

Study of the Soft Magnetic Properties of FeSiAl Magnetic Powder Cores by Compounding with Different Content of Epoxy Resin.

FeSiAl is a commonly used soft magnetic material because of its high resistivity, low core loss, and low cost. In order to systematically study the effect of epoxy resin (EP) on the insulated coating and pressing effect of FeSiAl magnetic powders, six groups of composite powders and their corresponding soft magnetic powder cores (SMPCs) were prepared by changing the content of EP, and the soft magnetic properties of the powders and SMPCs were characterized. The results showed that FeSiAl powders exhibited good sphericity and morphology. The Ms of FeSiAl/EP composite powders was between 117.4-124.8 emu·g-1 after adding (0.3, 0.5, 0.7, 1, 1.5, and 2 wt. %) EP. The permeability µe of SMPCs increased first and then decreased with the increase in EP content. Among them, when the EP content was 1 wt. %, the corresponding SMPCs had the highest µe and excellent DC bias performance (63%, 100 Oe). In the whole test frequency range (50~1000 kHz), SMPCs with 1 wt. % EP content had the lowest core loss (1733.9 mW·cm-3 at 20 mT and 1000 kHz). After that, the loss separation study in the low-frequency range (50~250 kHz) was conducted, and the hysteresis loss and eddy current loss of SMPCs with 1 wt. % EP content were also the lowest. In addition, SMPCs also exhibited the best overall performance when the EP content was 1 wt. %. The results of this study can guide the design of composite insulation coating schemes and promote the development of soft magnetic materials for medium and high frequency applications.

Enzastaurin cardiotoxicity: QT interval prolongation, negative inotropic responses and negative chronotropic action.

Several clinical trials observed that enzastaurin prolonged QT interval in cancer patients. However, the mechanism of enzastaurin-induced QT interval prolongation is unclear. Therefore, this study aimed to assess the effect and mechanism of enzastaurin on QT interval and cardiac function. The Langendorff and Ion-Optix MyoCam systems were used to assess the effects of enzastaurin on QT interval, cardiac systolic function and intracellular Ca2+ transient in guinea pig hearts and ventricular myocytes. The effects of enzastaurin on the rapid delayed rectifier (IKr), the slow delayed rectifier K+ current (IKs), transient outward potassium current (Ito), action potentials, Ryanodine Receptor 2 (RyR2) and the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) expression and activity in HEK 293 cell system and primary cardiomyocytes were investigated using whole-cell recording technique and western blotting. We found that enzastaurin significantly prolonged QT interval in guinea pig hearts and increased the action potential duration (APD) in guinea pig cardiomyocytes in a dose-dependent manner. Enzastaurin potently inhibited IKr by binding to the human Ether-à-go-go-Related gene (hERG) channel in both open and closed states, and hERG mutant channels, including S636A, S631A, and F656V attenuated the inhibitory effect of enzastaurin. Enzastaurin also moderately decreased IKs. Additionally, enzastaurin also induced negative chronotropic action. Moreover, enzastaurin impaired cardiac systolic function and reduced intracellular Ca2+ transient via inhibition of RyR2 phosphorylation. Taken together, we found that enzastaurin prolongs QT, reduces heart rate and impairs cardiac systolic function. Therefore, we recommend that electrocardiogram (ECG) and cardiac function should be continuously monitored when enzastaurin is administered to cancer patients.

Progress in fed-batch culture for recombinant protein production in CHO cells.

Nearly 80% of the approved human therapeutic antibodies are produced by Chinese Hamster Ovary (CHO) cells. To achieve better cell growth and high-yield recombinant protein, fed-batch culture is typically used for recombinant protein production in CHO cells. According to the demand of nutrients consumption, feed medium containing multiple components in cell culture can affect the characteristics of cell growth and improve the yield and quality of recombinant protein. Fed-batch optimization should have a connection with comprehensive factors such as culture environmental parameters, feed composition, and feeding strategy. At present, process intensification (PI) is explored to maintain production flexible and meet forthcoming demands of biotherapeutics process. Here, CHO cell culture, feed composition in fed-batch culture, fed-batch culture environmental parameters, feeding strategies, metabolic byproducts in fed-batch culture, chemostat cultivation, and the intensified fed-batch are reviewed. KEY POINTS: • Fed-batch culture in CHO cells is reviewed. • Fed-batch has become a common technology for recombinant protein production. • Fed batch culture promotes recombinant protein production in CHO cells.

Antibacterial Activity of an FtsZ Inhibitor Celastrol and Its Synergistic Effect with Vancomycin against Enterococci In Vitro and In Vivo.

Enterococci can cause various infectious diseases, including urinary tract infection, wound infection, and life-threatening endocarditis and meningitis. The emergence and transmission of vancomycin-resistant enterococci (VRE) have presented a challenge to clinical treatment. There is an urgent need to develop new strategies to fight against this pathogen. This study investigated the antibacterial and anti-biofilm activity of celastrol (CEL), a natural product originating from Tripterygium wilfordii Hook F, against enterococci, and its adjuvant capacity of restoring the susceptibility of VRE to vancomycin in vitro and in vivo. CEL inhibited all enterococcus strains tested, with MICs ranging from 0.5 to 4 µg/mL. More than 50% of biofilm was eliminated by CEL at 16 µg/mL after 24 h of exposure. The combination of CEL and vancomycin showed a synergistic effect against all 23 strains tested in checkerboard assays. The combination of sub-MIC levels of CEL and vancomycin showed a synergistic effect in a time-kill assay and exhibited significant protective efficacy in Galleria mellonella larval infection model compared with either drug used alone. The underlying mechanisms of CEL were explored by conducting biomolecular binding interactions and an enzyme inhibition assay of CEL on bacterial cell-division protein FtsZ. CEL presented strong binding and suppression ability to FtsZ, with Kd and IC50 values of 2.454 µM and 1.04 ± 0.17 µg/mL, respectively. CEL exhibits a significant antibacterial and synergic activity against VRE in vitro and in vivo and has the potential to be a new antibacterial agent or adjuvant to vancomycin as a therapeutic option in combating VRE. IMPORTANCE The emergence and transmission of VRE pose a significant medical and public health challenge. CEL, well-known for a wide range of biological activities, has not previously been investigated for its synergistic effect with vancomycin against VRE. In the present study, CEL exhibited antibacterial activity against enterococci, including VRE strains, and restored the activity of vancomycin against VRE in vitro and in vivo. Hence, CEL has the potential to be a new antibacterial adjuvant to vancomycin and could provide a promising therapeutic option in combating VRE.

A bio-orthogonal linear ubiquitin probe identifies STAT3 as a direct substrate of OTULIN in glioblastoma.

While linear ubiquitin plays critical roles in multiple cell signaling pathways, few substrates have been identified. Global profiling of linear ubiquitin substrates represents a significant challenge because of the low endogenous level of linear ubiquitination and the background interference arising from highly abundant ubiquitin linkages (e.g. K48- and K63-) and from the non-specific attachment of interfering proteins to the linear polyubiquitin chain. We developed a bio-orthogonal linear ubiquitin probe by site-specific encoding of a norbornene amino acid on ubiquitin (NAEK-Ub). This probe facilitates covalent labeling of linear ubiquitin substrates in live cells and enables selective enrichment and identification of linear ubiquitin-modified proteins. Given the fact that the frequent overexpression of the linear linkage-specific deubiquitinase OTULIN correlates with poor prognosis in glioblastoma, we demonstrated the feasibility of the NAEK-Ub strategy by identifying and validating substrates of linear ubiquitination in patient-derived glioblastoma stem-like cells (GSCs). We identified STAT3 as a bona fide substrate of linear ubiquitin, and showed that linear ubiquitination negatively regulates STAT3 activity by recruitment of the phosphatase TC-PTP to STAT3. Furthermore, we demonstrated that preferential expression of OTULIN in GSCs restricts linear ubiquitination on STAT3 and drives persistent STAT3 signaling, and thereby maintains the stemness and self-renewal of GSCs.

Modelling and analysis of penetration resistance of probes in cultivated soils.

At present, the measurement of tillage depth is mainly based on manual measurement, but the manual raking method results in low measurement accuracy and high labor intensity. Due to the complexity of soil, theoretical research on tillage depth is relatively scarce. In order to provide a new research direction and research idea for soil stratification, topsoil was taken as the research object of this paper. The correlation between penetration resistance and penetration depth of a probe in a cultivated soil was studied, and a mathematical model was established. There is a certain similarity between the process of spherical cavity expansion and the process of probe penetration, so we introduced the theory of spherical cavity expansion into the modeling of penetration resistance of the cultivated soil. In this paper, the spherical cavity expansion theory of unsaturated soil was used as the basis for solving the penetration resistance. And the unified strength criterion was employed as a yield condition of the soil to set a stress solution and a displacement solutionin into of the probe penetrating into the elasto-plastic zone of the cultivated soil to determine the model of expansion force. We have carried out indoor tests to revise the expansion force model. Firstly, according to the range of soil density and water content in the field, the soil densities were classified into 1.1×103kg/m3, 1.2×103kg/m3 and 1.3×103kg/m3, and the water contents were divided into 10%, 15% and 20%. In addition, the orthogonal tests were performed at different levels. The soil was put into the barrel, and the probe was inserted into the soil in the barrel at the speed of 8mm/s to determine the test values of the change of the probe penetration resistance with depth. Finally, the expansion force model was fitted with the results of the indoor test, and coefficient B was introduced to express the influence degree of density and water content on the resistance. Coefficient B was substituted into the expansion force model to obtain the penetration resistance model of the cultivated soil. Through the goodness of fit analysis of the penetration resistance model, the results show that the overall average goodness of fit of the penetration resistance modelat was up to 0.871 at different water contents and densities, which was a good fit and could present novel insights into the study relating to soil stratification theory.

DELE1 is protective for mitochondrial cardiomyopathy.

Mitochondrial dysfunction in heart triggers an integrated stress response (ISR) through phosphorylation of eIF2α and subsequent ATF4 activation. DAP3 Binding Cell Death Enhancer 1 (DELE1) is a mitochondrial protein recently found to be critical for mediating mitochondrial stress-triggered ISR (MSR)-induced eIF2α-ATF4 pathway activation. However, the specific role of DELE1 in heart at baseline or in response to mitochondrial stress remains largely unknown. In this study, we report that DELE1 is dispensable for cardiac development and function under baseline conditions. Conversely, DELE1 is essential for mediating an adaptive response to mitochondrial dysfunction-triggered stress in the heart, playing a protective role in mitochondrial cardiomyopathy.

Real-Time In Situ Volatile Organic Compound Sensing by a Dual-Emissive Polynuclear Ln-MOF with Pronounced LnIII Luminescence Response.

Lanthanide metal-organic frameworks (Ln-MOFs) are promising for luminescence detection of volatile organic compound (VOC) vapors, but usually suffer from the silent or quenched Ln3+ emission. Herein, we report a new dual-emissive Eu-MOF composed of the coordinatively unsaturated Eu9 clusters that afford abundant open metal sites to form a confined "binding pocket" to facilitate the preconcentration and recognition of VOCs. Single-crystal structural analyses reveal that specific analytes can replace the OH oscillators in the first coordination sphere of Eu3+ and form a unique hydrogen-bonding second-sphere adduct tying adjacent Eu9 clusters together to minimize their nonradiative vibrational decay. With the promoted Eu3+ luminescence, the MOF realizes real-time in situ visual sensing of THF vapor (<1 s) and shows a quantitative ratiometric response to the vapor pressure with a limit of detection down to 17.33 Pa. Also, it represents a top-performing ratiometric luminescent thermometer.

A CT-Based Deep Learning Radiomics Nomogram to Predict Histological Grades of Head and Neck Squamous Cell Carcinoma.

RATIONALE AND OBJECTIVES: Accurate pretreatment assessment of histological differentiation grade of head and neck squamous cell carcinoma (HNSCC) is crucial for prognosis evaluation. This study aimed to construct and validate a contrast-enhanced computed tomography (CECT)-based deep learning radiomics nomogram (DLRN) to predict histological differentiation grades of HNSCC. MATERIALS AND METHODS: A total of 204 patients with HNSCC who underwent CECT scans were enrolled in this study. The participants recruited from two hospitals were split into a training set (n=124, 74 well/moderately differentiated and 50 poorly differentiated) of patients from one hospital and an external test set of patients from the other hospital (n=80, 49 well/moderately differentiated and 31 poorly differentiated). CECT-based manually-extracted radiomics (MER) features and deep learning (DL) features were extracted and selected. The selected MER features and DL features were then combined to construct a DLRN via multivariate logistic regression. The predictive performance of the DLRN was assessed using ROCs and decision curve analysis (DCA). RESULTS: Three MER features and seven DL features were finally selected. The DLRN incorporating the selected MER and DL features showed good predictive value for the histological differentiation grades of HNSCC (well/moderately differentiated vs. poorly differentiated) in both the training (AUC, 0.878) and test (AUC, 0.822) sets. DCA demonstrated that the DLRN was clinically useful for predicting histological differentiation grades of HNSCC. CONCLUSION: A CECT-based DLRN was constructed to predict histological differentiation grades of HNSCC. The DLRN showed good predictive efficacy and might be useful for prognostic evaluation of patients with HNSCC.

Hepatic fat as a novel marker for high-risk coronary atherosclerotic plaque features in familial hypercholesterolaemia.

BACKGROUND & AIMS: Hepatic steatosis has been associated with increased risk of coronary artery disease. Individuals with familial hypercholesterolaemia have accelerated but variable progression of coronary artery disease. We investigated whether hepatic steatosis is associated with novel coronary atherosclerosis biomarkers in adults with heterozygous familial hypercholesterolaemia, using comprehensive coronary computed tomographic angiography. METHODS: We conducted a cross-sectional study of 213 asymptomatic patients with familial hypercholesterolaemia (median age 54.0 years, 59 % female) who underwent coronary computed tomographic angiography for cardiovascular risk assessment in an outpatient clinic. High-risk plaque features, plaque volume and pericoronary adipose tissue attenuation were assessed. From concurrently captured upper abdominal images, severity of hepatic steatosis was computed, as liver minus spleen computed tomography attenuation and stratified into quartiles. RESULTS: Of 213 familial hypercholesterolaemia patients, 59 % had coronary artery calcium, 36 % obstructive coronary artery disease (≥50 % stenosis) and 77 % high-risk plaque features. Increasing hepatic steatosis was associated with higher calcium scores, more high-risk plaque features and presence of obstructive coronary artery disease. Hepatic steatosis was associated with the presence of high-risk plaque features (OR: 1.48; 95 % CI: 1.09-2.00; p = 0.01), particularly in the proximal coronary segments (OR: 1.52; 95 % CI: 1.18-1.96; p = 0.001). Associations persisted on multivariable logistic regression analysis adjusting for cardiometabolic factors, obstructive coronary artery disease and calcium score. Hepatic steatosis was associated with higher plaque volumes (Q4: 499 mm3 vs Q1: 414 mm3, p = 0.02), involving mainly low attenuation and noncalcified plaques (both p = 0.03). No differences in pericoronary adipose tissue attenuation were observed. CONCLUSIONS: Hepatic steatosis is associated with multiple indices of advanced coronary atherosclerosis in familial hypercholesterolaemia patients, particularly high-risk plaque features, independent of conventional cardiovascular risk factors and markers. This may involve specific mechanisms related to hepatic steatosis. CLINICAL TRIAL NUMBER: N/A.

The catalytic mechanism, metal dependence, substrate specificity, and biodiversity of ribonuclease H.

Ribonucleoside monophosphates are inevitably misincorporated into the DNA genome inside cells, and they need to be excised to avoid chromosome instability. Ribonucleases H (RNases H) are enzymes that specifically hydrolyze the RNA strand of RNA/DNA hybrids or the RNA moiety from DNA containing a stretch of RNA, they therefore are required for DNA integrity. Extensive studies have drawn a mostly clear picture of the mechanisms of RNase H catalysis, but some questions are still lacking definitive answers. This review summarizes three alternative models of RNase H catalysis. The two-metal model is prevalent, but a three-metal model suggests the involvement of a third cation in catalysis. Apparently, the mechanisms underlying metal-dependent hydrolyzation are more complicated than initially thought. We also discuss the metal choices of RNases H and analyze how chemically similar cations function differently. Substrate and cleavage-site specificities vary among RNases H, and this is explicated in detail. An intriguing phenomenon is that organisms have diverse RNase H combinations, which may provide important hints to how rnh genes were transferred during evolution. Whether RNase H is essential for cellular growth, a key question in the study of in vivo functions, is also discussed. This article may aid in understanding the mechanisms underlying RNase H and in developing potentially promising applications of it.

Two three-dimensional Fe(II) frameworks based on {P4Mo6} tetrameric clusters exhibiting efficient visible-light photocatalytic properties for the degradation of Cr(VI) and methylene blue.

Two three-dimensional frameworks based on the {P4Mo6} unit, H(4,4'-bipy)2[Fe4(PO4)(H2O)4Na6][Fe6(H2O)4][(Mo6O12)(HPO4)3(PO4)(OH)3]4·5H2O (4,4'-bipy = 4,4'-bipyridine) (1) and H3(C12H14N2)4[Fe4(PO4)(H2O)4Na4][Fe2(Mo6O12(HPO4)3(PO4)(OH)3)4]·6H2O (2) were successfully synthesized by varying the solvent. The extended structures of the two compounds were formed by transition metal Fe(II) ions bridging the {P4Mo6}-based tetrameric clusters around [NaXFe4(PO4)] (X = 6 (1), or X = 4 (2)) core. The 4,4'-bipy molecules and in situ generated methyl viologen cations as templates induce the formation of two three-dimensional structures, an 8-connected bcu topology framework for 1 and a 4-connected 2-fold interpenetrating diamond-like topological network for 2, respectively. Additionally, multiform hydrogen bonds are found in the framework and also play an important role in stabilizing the structure. The proton conduction mechanism of the two compounds can be mainly classified as the Grotthuss mechanism; the proton conductivity values are 1.06 × 10-3 S cm-1 for 1 and 3.13 × 10-3 S cm-1 for 2 at 75 °C under 98% relative humidity. The visible-light photocatalytic activity was evaluated by photocatalytic decomposition of Cr(VI) and MB dye, and the removal ratios can reach 95.6% (1) and 82% (2) for Cr(VI), and 98% (1) and 99% (2) for MB.

Evaluation of Agar Dilution Method in Susceptibility Testing of Polymyxins for Enterobacteriaceae and Non-Fermentative Rods: Advantages Compared to Broth Microdilution and Broth Macrodilution.

An accurate and reliable susceptibility testing method for polymyxins is urgently needed not only for the clinical laboratory but also for new polymyxin-like lipopeptide development. Reference broth microdilution (rBMD), which was the recommended method by CLSI-EUCAST in clinics, has been proven not to be ideal, while the agar dilution (AD) method that was widely used in new antibiotics discovery has been neglected. In the present study, the AD method was compared with rBMD and broth macrodilution (BMAD) in susceptibility testing of polymyxin B and colistin against >200 Gram-negative isolates. AD showed strong agreement with BMAD for colistin (except for Klebsiella aerogenes and Pseudomonas aeruginosa); however, its performance was poor for polymyxin B or compared to rBMD. MICs of AD method were not affected when different types of Petri dishes were used, while glass-bottom microtiter plates could lower the MIC of polymyxins 2-8 times compared to tissue-culture-treated polystyrene plates when using rBMD, which demonstrated that tissue-culture-treated plates were not suitable. It was then validated with non-tissue-culture-treated plates. The culture volume was another influencing factor of accuracy for rBMD, and 200 µL seemed to be the most suitable volume for MIC detection of polymyxins. Additionally, no lack of growth phenomenon (skipped well) was observed for AD when it frequently occurred for both BMAD and rBMD. As for strains carrying mcr-1 gene, 100% of AD results were in essential agreement (EA) and categorical agreement (CA) with both rBMD and BMAD. Overall, rBMD is convenient and widely accepted for susceptibility testing of polymyxins. Although it may be too early to say that AD is superior compared to rBMD and BMAD, it did show some advantages in repeatability and anti-interference ability.

Discovery of N-quinazolinone-4-hydroxy-2-quinolone-3-carboxamides as DNA gyrase B-targeted antibacterial agents.

Emerging drug resistance is generating an urgent need for novel and effective antibiotics. A promising target that has not yet been addressed by approved antibiotics is the bacterial DNA gyrase subunit B (GyrB), and GyrB inhibitors could be effective against drug-resistant bacteria, such as methicillin-resistant S. aureus (MRSA). Here, we used the 4-hydroxy-2-quinolone fragment to search the Specs database of purchasable compounds for potential inhibitors of GyrB and identified AG-690/11765367, or f1, as a novel and potent inhibitor of the target protein (IC50: 1.21 µM). Structural modification was used to further identify two more potent GyrB inhibitors: f4 (IC50: 0.31 µM) and f14 (IC50: 0.28 µM). Additional experiments indicated that compound f1 is more potent than the others in terms of antibacterial activity against MRSA (MICs: 4-8 µg/mL), non-toxic to HUVEC and HepG2 (CC50: approximately 50 µM), and metabolically stable (t1/2: > 372.8 min for plasma; 24.5 min for liver microsomes). In summary, this study showed that the discovered N-quinazolinone-4-hydroxy-2-quinolone-3-carboxamides are novel GyrB-targeted antibacterial agents; compound f1 is promising for further development.