Interaction of biofilm and efflux pump in clinical isolates of carbapenem resistant P. aeruginosa

OBJECTIVE

Carbapenem-resistant P. aeruginosa (CRPA) is particularly worrisome because of its resistance against multiple antimicrobial agents which reduces treatment options. The efflux pump decreases antibiotic abundance, and biofilm impairs the penetration of antibiotics. The aim of the present study was to evaluate the role and relationship of efflux pump and biofilm formation in CRPA isolates obtained from different clinical samples.

PATIENTS AND METHODS

A total of 110 different clinical samples were collected from three tertiary medical hospitals. The samples were subjected to isolation and identification by standard operating procedures. Species level were identified using Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system. Antibiotic susceptibility testing was done by broth microdilution method. Crystal violet (CV) staining for observing the biofilm forming ability and amplification of efflux pump mexA gene were also performed on clinical CRPA isolates. Three efflux pump MexAB-OprM regulatory genes were analyzed using sequencing methods. The expression of mexA gene both in biofilm and planktonic bacteria was observed by Quantitative real-time PCR (qRT-PCR).

RESULTS

The results showed that 110 samples were CRPA and among them 83 (75.5%) were MDR isolates. The CV staining showed 105 (95.5%) isolates as biofilm producers while 78 (74.3%) MDR isolates showed biofilm formation. mexA hyperexpression was detected in 27 (24.5%) CRPA isolates while 26 (96.3%) in biofilm forming isolates and 96.3% (26/27) in MDR P. aeruginosa. Multiple mutations in nalC, nalD, and mexR genes were detected. The distinct difference confirmed that the expression of mexA gene in P. aeruginosa biofilm producer was significantly higher than that of planktonic bacteria in vitro, and the efflux pump inhibitor PAβN significantly inhibited biofilms in CRPA isolated from clinical samples.

CONCLUSIONS

The biofilm and efflux pumps might be two intertwined processes involved in CRPA isolates. Their synergistic effect magnified the drug resistance characteristics of P. aeruginosa.

Complete Genomic Data of Pantoea ananatis Strain TZ39 Associated with New Bacterial Blight of Rice in China

Pantoea ananatis is a phytopathogen infecting many economically important crops, including rice worldwide. Here, we report the complete genome of P. ananatis strain TZ39 identified as causative agent of a new bacterial blight of rice that emerged in China in 2020. The assembled genome consists of one circular chromosome of 4,483,976 bp and two plasmids of 135,135 and 276,579 bp. This complete genome of the first Chinese pathogenic P. ananatis strain will provide new insights into the traits of pathogenicity on genomic level from China and worldwide.

Preoperative MRI of breast squamous cell carcinoma: diagnostic value of distinguishing between two subtypes

AIM

To retrospectively analyse the clinical and MRI data of primary squamous cell carcinoma (SCC), particularly pure squamous cell carcinoma (PSCC) and mixed squamous cell carcinoma (MSCC).

MATERIALS AND METHODS

The MRI data and clinicopathological characteristics of 20 patients with histopathologically confirmed SCC of the breast, including eight PSCC patients and 12 MSCC patients, from multiple centres between January 2013 and December 2020 were analysed retrospectively.

RESULTS

Nine of 12 patients in the MSCC group showed hyperintensity on T1-weighted imaging (WI), while this feature was not observed in the PSCC group (p=0.001). Most of the PSCC group showed rim enhancement, whereas most of the MSCC group showed heterogeneous enhancement (p=0.007). In addition, there was no significant difference in the thickness of the rim enhancement and the percentage of necrotic components in the tumours between the two types of SCCs of the breast (p=0.545 and p=0.662, respectively). Four patients (4/12) in the MSCC group had sentinel lymph node metastasis, while only one patient (1/8) in the PSCC group showed lymph node metastasis (p=0.603). Metastatic disease occurred in 25% of patients with PSCC and in approximately 41.7% of patients with MSCC.

CONCLUSION

The signal on T1WI and internal enhancement characteristics were the key features for differentiating PSCC and MSCC. Therefore, MRI phenotypes may provide additional information for the pathological classification of breast SCC.

Measurement of the Sixth-Order Cumulant of Net-Proton Multiplicity Distributions in Au+Au Collisions at sqrt[s_{NN}]=27, 54.4, and 200 GeV at RHIC

According to first-principle lattice QCD calculations, the transition from quark-gluon plasma to hadronic matter is a smooth crossover in the region μ_{B}≤T_{c}. In this range the ratio, C_{6}/C_{2}, of net-baryon distributions are predicted to be negative. In this Letter, we report the first measurement of the midrapidity net-proton C_{6}/C_{2} from 27, 54.4, and 200 GeV Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). The dependence on collision centrality and kinematic acceptance in (p_{T}, y) are analyzed. While for 27 and 54.4 GeV collisions the C_{6}/C_{2} values are close to zero within uncertainties, it is observed that for 200 GeV collisions, the C_{6}/C_{2} ratio becomes progressively negative from peripheral to central collisions. Transport model calculations without critical dynamics predict mostly positive values except for the most central collisions within uncertainties. These observations seem to favor a smooth crossover in the high-energy nuclear collisions at top RHIC energy.

[Prognostic evaluation value of (18)F-FDG PET-CT in Hodgkin's lymphoma after treatment]

Objective: To investigate the prognostic value of (18)F-fluorodeoxygen-D-glucose-positron emission tomography /computerized tomography ((18)F-FDG-PET-CT) in Hodgkin's lymphoma (HL) at the end of first-line treatment (PET-end), by comparing the ratio of maximum standardized uptake value (SUV(max)) of lesion and liver SUV (rLL), SUV(max) reduction between baseline PET (PET-0) and PET-end (ΔSUV(max)), and Deauville 5-point scale (5-PS). Methods: Patients with HL newly treated in our hospital from August 2006 to December 2015 were retrospectively analyzed. All the patients enrolled in the study underwent post-treatment FDG PET-CT. The rLL and ΔSUV(max) were calculated, and all the cases were scored using Deauville 5-PS. The receiver operating characteristic (ROC) approach was applied to identify the optimal cut-point value, and survival curves according to different PET-CT assessment methods were estimated using the Kaplan-Meier analysis. The prognostic efficacy of different PET-CT assessment methods was compared, and DeLong test was used to verify it. Kaplan-Meier method and multivariate analysis using the Cox proportional hazards model were performed to analyze the potential independent risk factors. Results: There were 5 patients progressed within a 3-year follow-up. In the three PET-CT assessment methods, the predictive value of rLL and Deauville 5-PS were significant effective. ROC analysis for rLL as a progression predictor showed an optimal cut-point of 1.29. Deauville 5-PS=4 and rLL=1.29 showed the best prognostic accuracy. The sensitivity of rLL and Deauville 5-PS were both 80.0%, and the specificity of each was 98.0% and 93.7%, respectively. The positive predictive value (PPV) and negative predictive value (NPV) of rLL were 66.7% and 98.7%, while the PPV and NPV of 5-PS were 44.4% and 98.7%. The 3-years progression-free survival (PFS) rates of rLL≥1.29 group and rLL<1.29 group were 33.3% and 98.7%, with significant difference (P<0.001). The 3-years PFS rates of post-treatment Deauville 5-PS<4 group and Deauville 5-PS≥4 group were 98.7% and 55.6%, with significant difference (P<0.001). The prognostic evaluation efficacy of rLL was positively correlated with that of Deauville 5-PS (r=0.75, P<0.05). Area under curves (AUC) of rLL and Deauville 5-PS were 0.93 (95%CI: 0.825-1.000) and 0.91 (95%CI: 0.757-1.000), respectively. DeLong test showed the significant difference between the two methods (P<0.05). The univariate analysis results showed that clinical baseline stage, post-treatment rLL and Deauville 5-PS were associated with the prognoses of HL patients (P<0.05). The multivariate analysis results showed that post-treatment rLL and Deauville 5-PS were independent prognostic factors of HL (P<0.05). Conclusions: The rLL and Deauville 5-PS are potential prognostic factors for HL response assessment. The new semi-quantitative method rLL has methodological advantages over visual analysis, and it is a good supplement for Deauville 5-PS. rLL can improve prognostic evaluation accuracy of PET-CT and is useful to early identify patients with HL at a high risk of relapsing after first-line treatment.

Diversity and functions of microbes in surface sediments under heavy metal pollution of western Chaohu Lake

Heavy metal pollution is a global concern. Targeting at the surface sediments in western Chaohu Lake and using metagenome sequencing, we probed into the mechanism of how microbes adapted to heavy metal-polluted sediments under natural conditions. It was found the heavy metal pollution intensity of the three typical sampling places ranked as estuary of Nanfeihe River (NFH) > Zhongmiao Town (HZ) > Hongshizui (HSZ). Totally 129 phyla, 2631 genera and 12 989 species were detected in the sediment samples, and HSZ, HZ and NFH had 35, 51 and 67 exclusive genera, respectively. The bacterial biomass and virus quantity from NFH accounted for 22·84 and 70·69% of total quantities, respectively, and the microbial community compositions in NFH were also different from those in HSZ and HZ. Metagenomics sequencing and functional gene annotation showed NFH contained many functional genes related to nucleic acid transport and metabolism, ribosome structures and biological origin, replication recombining and repair and inorganic ion transport and metabolism. Kyoto Encyclopedia of Genes and Genomes analysis suggested the sediments from NFH were rich in enzymes correlated with heavy metal transport and reduction. Our findings offer some scientific basis for Chaohu Lake control and microbe resource utilization.

Alternating therapeutic plasma exchange (TPE) with double plasma molecular adsorption system (DPMAS) for the treatment of fulminant hepatic failure (FHF)

Alternating therapeutic plasma exchange with double plasma molecular adsorption system can rapidly remove bilirubin and ammonia and supplement the essential substance from the blood, which could be used as an effective treatment for fulminant hepatic failure.

The potential mechanism of PPP2R3A in myocardial cells and its interacting proteins

OBJECTIVE

PPP2R3A plays a key role in the cardiac pathological and physiological processes, yet little is known about how the protein involved in normal myocardium formation and the protein-protein interaction pathways involved. To address this issue, we investigated the role of PPP2R3A in cardiac myocytes and identify PPP2R3A specific protein interaction partners to accelerate the developmental process of the mechanistic studies.

MATERIALS AND METHODS

PPP2R3A-silenced primary myocardial cell of neonatal rats and H9c2 cells were established by infecting shRNA lentiviral particles. RT-PCR and Western blot were used to determine the expression of PPP2R3A and silencing efficiency. The cell viability was analyzed by CCK-8 kit, then the cell cycles and apoptosis assays were detected by flow cytometry. Novel protein-protein interactions of PPP2R3A were detected by Yeast Two-Hybrid assays using a high-quality human primary cardiomyocyte cDNA library.

RESULTS

PPP2R3A-silencing rat primary cardiomyocytes and H9c2 cells were established successfully, and the expression of PPP2R3A was downregulated significantly as confirmed by RT-PCR and Western blot. PPP2R3A silencing can inhibit the myocardial cell proliferation, arrest the cell cycle in the S phase and promote the cardiomyocytes apoptosis. 19 potential candidates like COL1A2, GIPC1and BCL6 specifically interact with PPP2R3A, and COL1A2 was the highest screening frequency, covering 12.5% of the 24 clones. These partners are highly enriched in signaling pathways associated with a variety of cellular processes.

CONCLUSIONS

A series of studies have discovered that PPP2R3A was closely associated with heart failure and arrhythmia. Our data further confirmed PPP2R3A plays an important role in the cardiomyocytes and PPP2R3A in the regulation of cardiac events via its interaction partners. Therefore, it is a potential therapeutic target for the disease.

Speciation and Potential Ecological Risk of Heavy Metals in Soils from Overlapped Areas of Farmland and Coal Resources in Northern Xuzhou, China

Contamination caused by heavy metals (HMs) in soil of overlapped area of farmland and coal resources (OAFCR) has impact on crops. The concentrations and speciation of As, Cd, Cr, Cu, Pb and Zn were investigated in topsoil of an OAFCR in Xuzhou, China. The results showed that mean concentrations of all six metals were higher than the background values of Xuzhou city and Cd was moderate accumulated with the maximum I_geo equalled to 2.13. Cd showed moderate contamination level (IP_i = 1.75) and potential ecological risk (Er = 44.06). Most of the total Cr, Cu, Ni, Pb, and Zn were presented in the residual forms (above 60%), and the percentages of reducible, oxidisable and residual forms of Pb were 23%, 21% and 43% respectively. Pb and Cd reflected a moderate degree of potential ecological risk and a considerable migration risk and ecotoxicity.

Stoichioproteomics study of differentially expressed proteins and pathways in head and neck cancer

Hypoxia is a prominent feature of head and neck cancer. However, the oxygen element characteristics of proteins and how they adapt to hypoxia microenvironments of head and neck cancer are still unknown. Human genome sequences and proteins expressed data of head and neck cancer were retrieved from pathology atlas of Human Protein Atlas project. Then compared the oxygen and carbon element contents between proteomes of head and neck cancer and normal oral mucosa-squamous epithelial cells, genome locations, pathways, and functional dissection associated with head and neck cancer were also studied. A total of 902 differentially expressed proteins were observed where the average oxygen content is higher than that of the lowly expressed proteins in head and neck cancer proteins. Further, the average oxygen content of the up regulated proteins was 2.54% higher than other. None of their coding genes were distributed on the Y chromosome. The up regulated proteins were enriched in endocytosis, apoptosis and regulation of actin cytoskeleton. The increased oxygen contents of the highly expressed and the up regulated proteins might be caused by frequent activity of cytoskeleton and adapted to the rapid growth and fast division of the head and neck cancer cells. The oxygen usage bias and key proteins may help us to understand the mechanisms behind head and neck cancer in targeted therapy, which lays a foundation for the application of stoichioproteomics in targeted therapy and provides promise for potential treatments for head and neck cancer.

Highly Sensitive Fluorescence Detection of Global 5-Hydroxymethylcytosine from Nanogram Input with Strongly Emitting Copper Nanotags

Quantitative analysis of 5-hydroxymethylcytosine (5hmC) has remarkable clinical significance to early cancer diagnosis; however, it is limited by the requirement in current assays for large amounts of starting material and expensive instruments requring expertise. Herein, we present a highly sensitive fluorescence method, termed hmC-TACN, for global 5hmC quantification from several nanogram inputs based on terminal deoxynucleotide transferase (TdT)-assisted formation of fluorescent copper (Cu) nanotags. In this method, 5hmC is labeled with click tags by T4 phage β-glucosyltransferase (β-GT) and cross-linked with a random DNA primer via click chemistry. TdT initiates the template-free extension along the primer at the modified 5hmC site and then generates a long polythymine (T) tail, which can template the production of strongly emitting Cu nanoparticles (CuNPs). Consequently, an intensely fluorescent tag containing numerous CuNPs can be labeled onto the 5hmC site, providing the sensitive quantification of 5hmC with a limit of detection (LOD) as low as 0.021% of total nucleotides (S/N = 3). With only a 5 ng input (∼1000 cells) of genomic DNA, global 5hmC levels were accurately determined in mouse tissues, human cell lines (including normal and cancer cells of breast, lung, and liver), and urines of a bladder cancer patient and healthy control. Moreover, as few as 100 cells can also be distinguished between normal and cancer cells. The hmC-TACN method has great promise of being cost effective and easily mastered, with low-input clinical utility, and even for the microzone analysis of tumor models.

Development of a human heart-on-a-chip model using induced pluripotent stem cells, fibroblasts and endothelial cells

Background

The use of animal models in cardiovascular research is associated with two serious, intrinsic problems: inaccuracy in the extrapolation of data obtained from animals such as rodents due to different cardiac physiology and animal ethics.

Purpose

To develop an artificial human heart model for cardiovascular research using organ-on-a-chip technology and human cells

Methods

Organ chips made of silicone (polydimethylsiloxane) that have two microfluidic channels, a top channel and a bottom channel, separated by a 50-μm thick membrane with 7-μm pores hexagonally packed at 40-μm intervals (Figure 1), were used in this study.

We seeded 10,000 human umbilical vein endothelial cells on the membrane surface in the bottom channel to mimic the vasculature. Next, we seeded a mixture of 100,000 human-induced pluripotent stem cells (hiPSCs) and 50,000 human gingival fibroblasts on the membrane surface in the top channel (Figure 1). Human gingival fibroblasts facilitate cardiac differentiation of hiPSCs [1]. We performed the cardiac differentiation of hiPSCs using a previously described protocol [1]. Culture medium was perfused at a constant rate of 60 μl/h to maintain the culture.

Results

We observed spontaneous contraction of hiPSC-derived cardiomyocytes 20–26 days after the start of the differentiation protocol. Simultaneously, we conducted live intracellular calcium imaging using a fluorogenic calcium-sensitive dye, Cal-520 AM (5 μM in the culture medium). hiPSC-derived cardiomyocytes exhibited a periodic, coordinated pattern of calcium influx synchronised with their contraction under fluorescence microscopy (Figure 2A). Moreover, we found that the β-adrenergic agonist noradrenaline elevated the heart rate of hiPSC-derived cardiomyocytes on the organ chips in a dose-dependent manner (Figures 2A, B).

After observing the contraction and intracellular calcium influx of hiPSC-derived cardiomyocytes, we performed immunocytochemistry. Confocal microscopy indicated that the fluorescent signal obtained from anti-cardiac troponin T antibody staining in the top channel exhibited a typical striated pattern with 1.56±0.12-μm interval that reflected sarcomere structure (Figure 2C, yellow). Moreover, the fluorescent signal obtained from anti-CD31 antibody staining in the bottom channel exhibited a typical pattern at the boundary between cells, which is expected at the cell–cell junction of endothelial cells.

Conclusion

We developed a human heart-on-a-chip model that was confirmed by the functional response to noradrenaline and the histological evidence of sarcomere structure and vasculature, with a capability of live imaging. We expect that this model would be useful for examining the physiological function and for the pharmacological analysis of not only the normal heart but also the heart that reflects specific patient's pathophysiology using patient-derived hiPSCs.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Japan Society for the Promotion of Science Figure 1Figure 2

5-hydroxymethylcytosine profiles in circulating cell-free DNA as candidate diagnostic and predictive biomarkers for coronary artery disease

Background

DNA 5-hydroxymethylcytosine (5hmC) modification is an epigenetic marker involved in a range of biological processes. However, little information is available about its role in coronary artery disease (CAD), particularly in the acute phase of acute coronary syndrome (ACS).

Aims

To investigate whether 5hmC modification correlates with the pathogenesis and progression of CAD and whether 5hmC in cfDNA can be used as biomarkers.

Methods

We utilized 5hmC-Seal to generate genome-wide 5hmC profiles in plasma cell-free DNA (cfDNA) of normal coronary artery (NCA, n=200) controls and CAD patients, including stable coronary artery disease (sCAD, n=200) patients and ACS patients (n=371). To investigate the correlation between 5hmC modifications and CAD subtypes, we separated samples into training and validation cohorts and developed a 5hmC-based logistic regression model from the training cohort to predict the progression of CAD in the validation cohort.

Results

We detected a significant difference of 5hmC enrichment in gene bodies from CAD patients compared with NCA individuals. Particularly, our results showed that patients of CAD subgroups can be well separated from NCA individuals by 5hmC markers. The prediction performance of the model established by differentially regulated 5hmC modified genes achieved an AUC of 0.81 (sCAD vs. NCA) and 0.74 (ACS vs. NCA) in validation cohorts.

Conclusions

Our results demonstrated that patients of CAD subtypes and NCA individuals had distinct differences in 5hmC enrichment. 5hmC markers derived from plasma cfDNA may potentially serve as a clinical-applicable, minimally invasive, and liquid biopsy-based approach to diagnose CAD, particularly used to predict the occurrence of fetal ACS.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Chinese Academy of Medical Science (CAMS) Innovation Fund for Medical Sciences Figure 1Figure 2

Methionine supplementation during a hydrogen peroxide challenge alters components of insulin signaling and antioxidant proteins in subcutaneous adipose explants from dairy cows

Enhanced postruminal supply of methionine (Met) during the peripartal period alters protein abundance of insulin, AA, and antioxidant signaling pathways in subcutaneous adipose tissue (SAT). Whether SAT is directly responsive to supply of Met and can induce molecular alterations is unknown. Our objective was to examine whether enhanced Met supply during an oxidative stress challenge in vitro alters insulin, AA, inflammation, and antioxidant signaling-related protein networks. Four late-lactation Holstein cows (average 27.0 kg of milk per day) were used for SAT collection. Tissue was incubated in duplicate for 4 h in a humidified incubator with 5% CO₂ at 37°C according to the following experimental design: control medium with an "ideal" profile of essential AA (CTR; Lys:Met 2.9:1), CTR plus 100 μM H₂O₂ (HP), or CTR with greater Met supply plus 100 μM H₂O₂ (HPMET; Lys:Met 2.5:1). Molecular targets associated with insulin signaling, lipolysis, antioxidant nuclear factor, erythroid 2 like 2 (NFE2L2), inflammation, and AA metabolism were determined through reverse-transcription quantitative PCR and western blotting. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Institute Inc.). Among proteins associated with insulin signaling, compared with CTR, HP led to lower abundance of phosphorylated AKT serine/threonine kinase (p-AKT) and solute carrier family 2 member 4 (SLC2A4; insulin-induced glucose transporter). Although incubation with HPMET restored abundance of SLC2A4 to levels in the CTR and upregulated abundance of fatty acid synthase (FASN) and phosphorylated 5'-prime-AMP-activated protein kinase (p-AMPK), it did not alter p-AKT, which remained similar to HP. Among proteins associated with AA signaling, compared with CTR, challenge with HP led to lower abundance of phosphorylated mechanistic target of rapamycin (p-MTOR), and HPMET did not restore abundance to CTR levels. Among inflammation-related targets studied, incubation with HPMET led to greater protein abundance of nuclear factor kappa B subunit p65 (NFKB-RELA). The response in NFKB observed with HPMET was associated with a marked upregulation of the antioxidant transcription regulator NFE2L2 and the antioxidant enzyme glutathione peroxidase 1 (GPX1). No effects of treatment were detected for mRNA abundance of proinflammatory cytokines or antioxidant enzymes, underscoring the importance of post-transcriptional regulation. Overall, data indicated that short-term challenge with H₂O₂ was particularly effective in reducing insulin and AA signaling. Although a greater supply of Met had little effect on those pathways, it seemed to restore the protein abundance of the insulin-induced glucose transporter. Overall, the concomitant upregulation of key inflammation and antioxidant signaling proteins when a greater level of Met was supplemented to oxidant-challenged SAT highlighted the potential role of this AA in regulating the inflammatory response and oxidant status. Further studies should be conducted to assess the role of postruminal supply of Met and other AA in the regulation of immune, antioxidant, and metabolic systems in peripartal cow adipose tissue.

A MOF-Shell-Confined I-Motif-Based pH Probe (MOFC-i) Strategy for Sensitive and Dynamic Imaging of Cell Surface pH

Dynamic imaging of cell surface pH is extremely challenging due to the slight changes in pH and the fast diffusion of secreted acid to the extracellular environment. In this work, we construct a novel metal-organic framework (MOF)-shell-confined i-motif-based pH probe (MOFC-i) strategy that enables sensitive and dynamic imaging of cell surface pH. The CY3- and CY5-labeled i-motif, which is hybridized via its short complementary chain with two-base mismatches, is optimized for sensing at physiological pH. After efficiently anchoring the optimized pH probes onto the cell membrane with the aid of cholesterol groups, a biocompatible microporous MOF shell is then formed around the cell by cross-linking ZIF-8 nanoparticles via tannic acid. The microporous MOF shell can confine secreted acid without inhibiting the normal physiological activities of cells; thus, the MOFC-i strategy can be used to monitor dynamic changes in the cell surface pH of living cells. Furthermore, this method can not only clearly distinguish the different metabolic behaviors of cancer cells and normal cells but also reveal drug effects on the cell surface pH or metabolism, providing promising prospects in pH-related diagnostics and drug screening.