Prediction Modelling for Gastroesophageal Variceal Bleeding in Patients With Chronic Hepatitis B Using Four-dimensional Flow MRI.

Background/Aims: In this study, we aim to develop a model for predicting gastroesophageal varices (GEV) bleeding in patients with chronic hepatitis B (CHB) by utilizing hemodynamic parameters obtained through four-dimensional flow MRI (4D flow MRI). Methods: This study conducted a prospective enrollment of CHB patients suspected of GEV from October 2021 to May 2022. The severity of varices and bleeding risk were evaluated using clinical findings and upper gastrointestinal endoscopy, and patients were classified into high-risk and non-high-risk groups. The study utilized serological examination, ultrasonographic examination, and 4D flow MRI. Relevant parameters were selected through univariate and multivariate analyses, and a prediction model was established using binary logistic regression analysis. The model was combined with the Baveno Ⅵ/Ⅶ and Expanded Baveno Ⅵ/Ⅶ criteria to evaluate diagnostic efficacy and the risk of avoiding endoscopic examination. Results: A total of 40 CHB patients were enrolled and categorized into the high-risk group (n = 15) and the non-high-risk group (n = 25). The spleen diameter and regurgitant fraction (R%) were independent predictors of variceal bleeding and a predictive model was established. The combination of this prediction model and the Baveno Ⅵ/Ⅶ criteria achieved high diagnostic efficiency, enabling 45.00% (18/40) of patients to be exempted from the unnecessary endoscopic procedure and the high-risk misclassification rate (0%) was less than 5%. Conclusion: The prediction model generated by 4D flow MRI has the potential to assess the likelihood of varices and can be supplemented by the Baveno VI/VII criteria to improve diagnostic accuracy in CHB patients.

Tumor suppressor heterozygosity and homologous recombination deficiency mediate resistance to front-line therapy in breast cancer.

The co-occurrence of germline and somatic oncogenic alterations is frequently observed in breast cancer, but their combined biologic and clinical significance has not been evaluated. To assess the role of germline-somatic interactions on outcomes in routine practice, we developed an integrated clinicogenomic pipeline to analyze the genomes of over 4,500 patients with breast cancer. We find that germline (g) BRCA2 -associated tumors are enriched for RB1 loss-of-function mutations and manifest poor outcomes on standard-of-care, front-line CDK4/6 inhibitor (CDK4/6i) combinations. Amongst these tumors, g BRCA2 -related homologous recombination deficiency (HRD) as well as baseline RB1 LOH status promote acquisition of RB1 loss-of- function mutations under the selective pressure of CDK4/6i, causing therapy resistance. These findings suggest an alternative therapeutic strategy using sequential targeting of HRD in g BRCA- associated breast cancers through PARP inhibitors prior to CDK4/6i therapy to intercept deleterious RB1 -loss trajectories and thus suppress the emergence of CDK4/6 inhibitor resistance. More broadly, our findings demonstrate how germline-somatic driven genomic configurations shape response to systemic therapy and can be exploited therapeutically as part of biomarker-directed clinical strategies.

Utilizing machine learning algorithms for predicting risk factors for bone metastasis from right-sided colon carcinoma after complete mesocolic excision: a 10-year retrospective multicenter study.

BACKGROUND: Bone metastasis (BM) occurs when colon cancer cells disseminate from the primary tumor site to the skeletal system via the bloodstream or lymphatic system. The emergence of such bone metastases typically heralds a significantly poor prognosis for the patient. This study's primary aim is to develop a machine learning model to identify patients at elevated risk of bone metastasis among those with right-sided colon cancer undergoing complete mesocolonectomy (CME). PATIENTS AND METHODS: The study cohort comprised 1,151 individuals diagnosed with right-sided colon cancer, with a subset of 73 patients presenting with bone metastases originating from the colon. We used univariate and multivariate regression analyses as well as four machine learning algorithms to screen variables for 38 characteristic variables such as patient demographic characteristics and surgical information. The study employed four distinct machine learning algorithms, namely, extreme gradient boosting (XGBoost), random forest (RF), support vector machine (SVM), and k-nearest neighbor algorithm (KNN), to develop the predictive model. Additionally, the model was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA), while Shapley additive explanation (SHAP) was utilized to visualize and analyze the model. RESULTS: The XGBoost algorithm performed the best performance among the four prediction models. In the training set, the XGBoost algorithm had an area under curve (AUC) value of 0.973 (0.953-0.994), an accuracy of 0.925 (0.913-0.936), a sensitivity of 0.921 (0.902-0.940), and a specificity of 0.908 (0.894-0.922). In the validation set, the XGBoost algorithm had an AUC value of 0.922 (0.833-0.995), an accuracy of 0.908 (0.889-0.926), a sensitivity of 0.924 (0.873-0.975), and a specificity of 0.883 (0.810-0.956). Furthermore, the AUC value of 0.83 for the external validation set suggests that the XGBoost prediction model possesses strong extrapolation capabilities. The results of SHAP analysis identified alkaline phosphatase (ALP) levels, tumor size, invasion depth, lymph node metastasis, lung metastasis, and postoperative neutrophil-to-lymphocyte ratio (NLR) levels as significant risk factors for BM from right-sided colon cancer subsequent to CME. CONCLUSION: The prediction model for BM from right-sided colon cancer developed using the XGBoost machine learning algorithm in this study is both highly precise and clinically valuable.

EEG Characteristic Comparison of Motor Imagery between Supernumerary and Inherent limb: Sixth-finger MI Enhances the ERD Pattern and Classification Performance.

Adding supernumerary robotic limbs (SRLs) to humans and controlling them directly through the brain are main goals for movement augmentation. However, it remains uncertain whether neural patterns different from the traditional inherent limbs motor imagery (MI) can be extracted, which is essential for high-dimensional control of external devices. In this work, we established a MI neo-framework consisting of novel supernumerary robotic sixth-finger MI (SRF-MI) and traditional right-hand MI (RH-MI) paradigms and validated the distinctness of EEG response patterns between two MI tasks for the first time. Twenty-four subjects were recruited for this experiment involving three mental tasks. Event-related spectral perturbation was adopted to supply details about event-related desynchronization (ERD). Activation region, intensity and response time (RT) of ERD were compared between SRF-MI and RH-MI tasks. Three classical classification algorithms were utilized to verify the separability between different mental tasks. And genetic algorithm aims to select optimal combination of channels for neo-framework. A bilateral sensorimotor and prefrontal modulation was found during the SRF-MI task, whereas in RH-MI only contralateral sensorimotor modulation was exhibited. The novel SRF-MI paradigm enhanced ERD intensity by a maximum of 117% in prefrontal area and 188% in the ipsilateral somatosensory-association cortex. And, a global decrease of RT was exhibited during SRF-MI tasks compared to RH-MI. Classification results indicate well separable performance among different mental tasks (88.1% maximum for 2-class and 88.2% maximum for 3-class). This work demonstrated the difference between the SRF-MI and RH-MI paradigms, widening the control bandwidth of the BCI system.

Cinnamic Acid Derivatives: Recent Discoveries and Development Strategies for Alzheimer's Disease.

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder that leads to cognitive decline and memory impairment. It is characterized by the accumulation of Amyloid-beta (Aß) plaques, the abnormal phosphorylation of tau protein forming neurofibrillary tangles, and is often accompanied by neuroinflammation and oxidative stress, which contribute to neuronal loss and brain atrophy. At present, clinical anti-AD drugs are mostly single-target, improving the cognitive ability of AD patients, but failing to effectively slow down the progression of AD. Therefore, research on effective multi-target drugs for AD has become an urgent problem to address. The main derivatives of hydroxycinnamic acid, caffeic acid, and ferulic acid, are widely present in nature and have many pharmacological activities, such as antimicrobial, antioxidant, anti-inflammatory, neuroprotective, anti-Aß deposition, and so on. The occurrence and development of AD are often accompanied by pathologies, such as oxidative stress, neuroinflammation, and Aß deposition, suggesting that caffeic acid and ferulic acid can be used in the research on anti-AD drugs. Therefore, in this article, we have summarized the multi-target anti-AD derivatives based on caffeic acid and ferulic acid in recent years, and discussed the new design direction of cinnamic acid derivatives as backbone compounds. It is hoped that this review will provide some useful strategies for anti-AD drugs based on cinnamic acid derivatives.

Breaking graphite through a ball-milling process: the thermal conductivity and mechanical properties of polyethylene composites.

Exfoliated graphite platelets (EGPs) have attracted extensive attention owing to their exceptional combinations of thermal conductivity and mechanical properties. Mechanical exfoliation is a facile and high-throughput approach to produce single-layer or few-layer graphite platelets. Herein, octadecylamine (ODA)-grafted EGP (ODA@EGP) and subsequent polyethylene/ODA@EGP (PE/ODA@EGP) composites with different contents of ODA@EGPs were successfully prepared via ball-milling and melt-mixing methods, respectively. The thermal conductivity, crystallinity, and mechanical properties of the composites were investigated using tensile tests, the hot-wire method, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and thermogravimetric analysis (TGA). The results demonstrated that the thermal conductivity, mechanical properties, and thermal stability of the composites can be improved by regulating the additive contents of ODA@EGPs. When the content of ODA@EGPs was 10 wt%, the thermal conductivity of the composite reached up to 1.276 W (m-1 K-1), which is 216% higher than that of bare PE, while the tensile strength of the composite was 38.4% higher than that of PE. Additionally, thermal decomposition temperature increased by 16.2 °C. Therefore, the PE/ODA@EGP nanocomposites have great application potential in thermal management.

Copper ions-photo dual-crosslinked alginate hydrogel for angiogenesis and osteogenesis.

Early healing of bone defects is still a clinical challenge. Many bone-filling materials have been studied, among which photocrosslinked alginate has received significant attention due to its good biocompatibility and morphological plasticity. Although it has been confirmed that photocrosslinked alginate can be used as an extracellular matrix for 3D cell culture, it lacks osteogenesis-related biological functions. This study constructed a copper ions-photo dual-crosslinked alginate hydrogel scaffold by controlling the copper ion concentration. The scaffolds were shaped by photocrosslinking and then endowed with biological functions by copper ions crosslinking. According to in vitro research, the dual-crosslinked hydrogel increased the compressive strength and favored copper dose-dependent osteoblast differentiation and cell surface adherence of rat bone marrow mesenchymal stem cells and the expression of type I collagen (Col1), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), vascular endothelial growth factor (VEGF). In addition, hydrogel scaffolds were implanted into rat skull defects, and more angiogenesis and osteogenesis could be observed in in vivo studies. The above results show that the copper-photo-crosslinked hydrogel scaffold has excellent osseointegration properties and can potentially promote angiogenesis and early healing of bone defects, providing a reference solution for bone tissue engineering materials.

Exogenous salicylic acid treatment enhances the disease resistance of Panax vietnamensis by regulating secondary metabolite production.

Introduction: Salicylic acid (SA) is a phenolic compound widely found in plants. It plays a key role in exerting plant disease resistance. Panax vietnamensis Ha & Grushv., a valuable medicinal plant, contains high levels of phenolic compounds, which contribute significantly to the resilience of the plant against stress. However, the precise role of SA in regulating the synthesis of secondary metabolites in P.vietnamensis remains elusive. Methods: Two-year-old P. vietnamensis seedlings were treated with exogenous SA. We systematically assessed the changes in the physiological parameters of SA-treated P. vietnamensis leaves, employing transcriptome and metabolome analyses to elucidate the underlying mechanisms. Results: Our results revealed a significant improvement of the plant's antioxidant capacity at 6 h post-treatment. Furthermore, exogenous SA treatment promoted the biosynthesis of lignin and flavonoids such as rutin, coumarin, and cyanidin. In addition, it increased the levels of endogenous SA and jasmonic acid (JA), promoting the disease resistance of the plants. Thus, SA pretreatment enhanced the defense of P. vietnamensis against pathogens. Conclusions: Our study provided novel insights into the potential molecular mechanisms underlying SA-mediated biosynthesis of secondary metabolites. Furthermore, our results provided a theoretical foundation for optimizing the cultivation practices of P.vietnamensis and the application of SA as a plant immunomodulator.

Experiences and prospects for national survey of terrestrial wildlife resources in China.

Wildlife resources are strategic resources of a country, and the investigation of which is a key task for effective management in protection and utilization. Since the 1990s, two national surveys of terrestrial wildlife resources have been carried out in China, and the situation of wildlife resources has been known to a certain extent. Due to the complexity and difficulty of national wildlife survey, we are still not able to grasp the background and dynamics of wildlife resources as a whole promptly and effectively. The results and effectiveness of wildlife resources investigation will directly affect the decision-making related in wildlife protection. According to Law of the People's Republic of China on the Protection of Wildlife and Regulations of the People's Republic of China for the Implementation of the Protection of Terrestrial Wildlife, it is imperative to carry out the third national survey of terrestrial wildlife resources, and to be integrated with the national strategy of ecological civilization construction. The aims of this review were to summarize the earlier experiences in time, to further improve the investigation scheme and technical methods, to serve the third national survey of terrestrial wildlife resources, in addition to obtain more comprehensive and reliable data of wildlife resources, grasp the development trend of domestic wildlife resources, and provide more effective supports for the wildlife conservation in China.

Peritoneal fibrosis: from pathophysiological mechanism to medicine.

Peritoneal dialysis (PD) is currently one of the effective methods for treating end-stage renal disease (ESRD). However, long-term exposure to high concentration glucose in peritoneal dialysis environment could lead to peritoneal fibrosis (PF), impaired peritoneal filtration function, decreased peritoneal dialysis efficiency, and even withdrawal from peritoneal dialysis in patients. Considerable evidence suggests that peritoneal fibrosis after peritoneal dialysis is related to crucial factors such as mesothelial-to-mesenchymal transition (MMT), inflammatory response, and angiogenesis, etc. In our review, we summarize the pathophysiological mechanisms and further illustrate the future strategies against PF.

Objective performance indicators differ in obese and nonobese patients during robotic proctectomy.

BACKGROUND: Robotic surgery is perceived to be more complex in obese patients. Objective performance indicators, machine learning-enabled metrics, can provide objective data regarding surgeon movements and robotic arm kinematics. In this feasibility study, we identified differences in objective performance indicators during robotic proctectomy in obese and nonobese patients. METHODS: Endoscopic videos were annotated to delineate individual surgical steps across 39 robotic proctectomies (1880 total steps). Thirteen patients were obese and 26 were nonobese. Objective performance indicators during the following steps were analyzed: splenic flexure mobilization, left colon mobilization, pelvic dissection, and rectal transection. RESULTS: The following differences were noted during robotic proctectomy in obese patients: during splenic flexure mobilization, more arm swaps, longer camera path length and velocity; during left colon mobilization, longer step time, more arm swaps, higher camera-related metrics (movement, path length, velocity, acceleration, and jerk), greater dominant arm path length, moving time, and wrist articulation; during anterior pelvic dissection, longer energy activation time, camera path length, and moving time; during posterior pelvic dissection, lower nondominant arm velocity, jerk, and acceleration; during left pelvic dissection, longer energy activation time; during right pelvic dissection, greater camera-related metrics (movement, path length, moving time, and velocity); and during rectal transection, longer step time, more arm swaps, master clutch use and camera movements, greater dominant wrist articulation, and longer dominant arm path length. CONCLUSION: We report step-specific objective performance indicators that differ during robotic proctectomy for obese and nonobese patients. This is the first study to use objective performance indicators to correlate a patient attribute with surgeon movements and robotic arm kinematics during robotic colorectal surgery.

Secondary Cancer in Prostate Cancer Patients Treated With Advanced External Beam Radiation Therapy.

Purpose: Previous studies have shown that external beam radiation therapy is associated with an increased risk of second primary cancer (SPC) among prostate cancer (PCa) patients, but the relative risks associated with newer and advanced radiation modalities such as proton beam therapy (PBT) and stereotactic body radiation therapy (SBRT) are unclear. This study aimed to assess the relative probability of SPC among patients treated with these newer modalities compared to intensity-modulated radiation therapy (IMRT). Patients and Methods: Using the National Cancer Database (NCDB), N0M0 PCa cases diagnosed between 2004 and 2018 were identified. Second primary cancer probabilities were compared among those treated with curative-intent PBT, SBRT, and IMRT. Multivariable logistic regression and inverse probability of treatment weighting were used to generate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Results: In total, 133 898 patients were included, with a median age of 69 years and median follow-up of 6.4 years. As their first course of treatment, 3420 (2.6%) received PBT, 121 211 (90.5%) received IMRT, and 9267 (6.9%) received SBRT. Compared with IMRT, PBT and SBRT were associated with lower SPC risk (aORs and 95% CIs, PBT: 0.49 [0.40-0.60], SBRT: 0.57 (0.51-0.63), P < .001). Inverse probability of treatment weighting analyses corroborated these results. Conclusion: In this large national cohort, PBT and SBRT performed similarly and were associated with reduced SPC risk compared to IMRT when used as the first course of treatment.

Association between persistent musculoskeletal pain and incident sarcopenia in China: the mediating effect of depressive symptoms.

Objective: To evaluate the association between musculoskeletal pain and incident sarcopenia and further explore the mediating effect of depressive symptoms among middle-aged and older Chinese adults. Methods: Using the data from the China Health and Retirement Longitudinal Study 2011 and 2015, we included 12,788 participants in the cross-sectional analysis and 8,322 for the longitudinal analysis. Musculoskeletal pains located in the neck, back, waist, shoulder, arm, wrist, leg, knee, and ankle were self-reported at baseline and follow-up. The diagnosis criteria of sarcopenia was based on the Asian Working Group for Sarcopenia 2019. Multivariable logistic regression models were used to evaluate the association between musculoskeletal pain, and the Karlson-Holm-Breen (KHB) method was used to explore the mediating effect of depressive symptoms. Results: Over the 4-year follow-up, 445 participants were identified with incident sarcopenia. In the longitudinal analysis, participants with baseline musculoskeletal pain (adjusted odds ratio (OR): 1.37, 95% confidence interval (CI): 1.07-1.76), persistent musculoskeletal pain (OR:1.68, 95%CI: 1.28-2.24), and persistent waist pain (OR:1.46, 95%CI: 1.04-2.03) were significantly associated with increased the risk of incident sarcopenia. Furthermore, depressive symptoms were found to partially mediate the association between musculoskeletal pain and incident sarcopenia. Conclusion: Persistent musculoskeletal pain, especially in waist area, was positively associated with a higher risk of sarcopenia among the middle-aged and older Chinese. Depressive symptoms played a partial mediating role in this association.

Added value of histogram analysis of intravoxel incoherent motion and diffusion kurtosis imaging for the evaluation of complete response to neoadjuvant therapy in locally advanced rectal cancer.

OBJECTIVE: To evaluate how intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) histogram analysis contribute to assessing complete response (CR) to neoadjuvant therapy (NAT) in locally advanced rectal cancer (LARC). MATERIAL AND METHODS: In this prospective study, participants with LARC, who underwent NAT and subsequent surgery, with adequate MR image quality, were enrolled from November 2021 to March 2023. Conventional MRI (T2WI and DWI), IVIM, and DKI were performed before NAT (pre-NAT) and within two weeks before surgery (post-NAT). Image evaluation was independently performed by two experienced radiologists. Pathological complete response (pCR) was used as the reference standard. An IVIM-DKI-added model (a combination of IVIM and DKI histogram parameters with T2WI and DWI) was constructed. Receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic performance of conventional MRI and the IVIM-DKI-added model. RESULTS: A total of 59 participants (median age: 58.00 years [IQR: 52.00, 62.00]; 38 [64%] men) were evaluated, including 21 pCR and 38 non-pCR cases. The histogram parameters of DKI, including skewness of kurtosis post-NAT (post-KSkewness) and root mean squared of change ratio of diffusivity (Δ%DDKI-root mean squared), were entered into the IVIM-DKI-added model. The area under the ROC curve (AUC) of the IVIM-DKI-added model for assessing CR to NAT was significantly higher than that of conventional MRI (0.855 [95% CI: 0.749-0.960] vs 0.685 [95% CI: 0.565-0.806], p < 0.001). CONCLUSION: IVIM and DKI provide added value in the evaluation of CR to NAT in LARC. KEY POINTS: Question The current conventional imaging evaluation system lacks adequacy for assessing CR to NAT in LARC. Findings Significantly improved diagnostic performance was observed with the histogram analysis of IVIM and DKI in conjunction with conventional MRI. Clinical relevance IVIM and DKI provide significant value in evaluating CR to NAT in LARC, which bears significant implications for reducing surgical complications and facilitating organ preservation.

Bioaccessibility and bioavailability of exogenous and endogenous toxic substances in traditional Chinese medicine and their significance in risk assessment.

Scientific risk assessment of exogenous and endogenous toxic substances in traditional Chinese medicine (TCM) is of great significance. The present review comprises a comprehensive summary of progress in the health risk assessment of harmful exogenous substances in TCMs. Such substances include heavy metals, pesticide residues, biotoxins, and endogenous toxic components involving pyrrolizidine alkaloids. The review also discusses the strengths and weaknesses of various bioaccessibility and bioavailability models, and their applications in risk assessment. Future avenues of risk assessment research are highlighted, including further exploration of risk assessment parameters, innovation of bioaccessibility and bioavailability techniques, enhancement of probabilistic risk assessment combined with bioavailability, improvement of cumulative risk assessment strategies, and formulation of strategies for reducing relative bioavailability (RBA) values in TCMs. Such efforts represent an attempt to develop a risk assessment system that is capable of evaluating the exogenous and endogenous toxic substances in TCMs to ensure its safe use in clinics, and to promote the sustainable development of the TCM industry.

Unexpected and divergent mechanosynthesis of furanoid-bridged fullerene dimers C120O and C120O2.

An unexpected, divergent and efficient approach toward furanoid-bridged fullerene dimers C120O and C120O2 was established under different solvent-free ball-milling conditions by simply using pristine C60 as the starting material, water as the oxygen source and FeCl3 as the mediator. The structures of C120O and C120O2 were unambiguously established by single-crystal X-ray crystallography. A plausible reaction mechanism is proposed on the basis of control experiments. Furthermore, C120O2 has been applied in organic solar cells as the third component and exhibits good performance.

A tellurium-based small compound ameliorates tumor metastasis by downregulating heparanase expression.

Tellurium is a rare element, and ammonium trichloro (dioxoethylene-o,o') tellurate (AS101) is the most bioactive molecule among several synthetic tellurium compounds. AS101 was found to be immunomodulatory and can modulate types of cytokines. However, the effect of AS101 on tumor metastasis remains unclear. Heparanase, an endo-glucuronidase, cleaves heparin sulfate side chains of proteoglycans on the cell surface, further leading to the degradation of the extracellular matrix. Heparanase also releases angiogenic factors in the extracellular matrix, is overexpressed in tumor cells, and promotes tumor metastasis and angiogenesis. In this study, we investigated the effect of AS101 in 4T1 and CT26 cells, especially heparanase. Heparanase expression was downregulated in 4T1 and CT26 cells after treatment with AS101 in vitro. The protein level involved in the protein kinase-B/mammalian target of rapamycin (AKT/mTOR) signaling pathway also declined. Cell migration assays revealed the inhibitory effect of AS101 on migration. The results of this study indicate that AS101 inhibits tumor migration by downregulating heparanase through the AKT/mTOR signaling pathway and has positive effects in vivo.

High-quality genome of a modern soybean cultivar and resequencing of 547 accessions provide insights into the role of structural variation.

Soybean provides protein, oil and multiple health-related compounds. Understanding the effects of structural variations (SVs) on economic traits in modern breeding is important for soybean improvement. Here we assembled the high-quality genome of modern cultivar Nongdadou2 (NDD2) and identified 25,814 SV-gene pairs compared to 29 reported genomes, with 13 NDD2-private SVs validated in 547 deep-resequencing (average = 18.05-fold) accessions, which advances our understanding of genomic variation biology. We found some insertions/deletions involved in seed protein and weight formation, an inversion related to adaptation to drought and a large intertranslocation implicated in a key divergence event in soybean. Of 749,714 SVs from 547 accessions, 6,013 were significantly associated with 22 yield-related and seed-quality-related traits determined in ten location × year environments. We uncovered 1,761 associated SVs that hit genes or regulatory regions, with 12 in GmMQT influencing oil and isoflavone contents. Our work provides resources and insights into SV roles in soybean improvement.

Inosine reverses multidrug resistance in Gram-negative bacteria carrying mobilized RND-type efflux pump gene cluster tmexCD-toprJ.

Antimicrobial resistance is rapidly increasing worldwide, highlighting the urgent need for pharmaceutical and nonpharmaceutical interventions to tackle different-to-treat bacterial infections. Tigecycline, a semi-synthesis glycylcycline for parenteral administration, is widely recognized as one of the few effective therapies available against pan-drug resistant Gram-negative pathogens. Regrettably, the efficacy of multiple drugs, including tigecycline, is currently being undermined due to the emergence of a recently discovered mobilized resistance-nodulation-division-type efflux pump gene cluster tmexCD1-toprJ1. Herein, by employing untargeted metabolomic approaches, we reveal that the expression of tmexCD1-toprJ1 disrupts bacterial purine metabolism, with inosine being identified as a crucial biomarker. Notably, the supplementation of inosine effectively reverses tigecycline resistance in tmexCD1-toprJ1-positive bacteria. Mechanistically, exogenous inosine enhanced bacterial proton motive force, which promotes the uptake of tigecycline. Furthermore, inosine enhances succinate biosynthesis by stimulating the tricarboxylic acid cycle. Succinate interacts with the two-component system EnvZ/OmpR and upregulates OmpK 36, thereby promoting the influx of tigecycline. These actions collectively lead to the increased intracellular accumulation of tigecycline. Overall, our study offers a distinct combinational strategy to manage infections caused by tmexCD-toprJ-positive bacteria. IMPORTANCE: TMexCD1-TOprJ1, a mobilized resistance-nodulation-division-type efflux pump, confers phenotypic resistance to multiple classes of antibiotics. Nowadays, tmexCD-toprJ has disseminated among diverse species of clinical pathogens, exacerbating the need for novel anti-infective strategies. In this study, we report that tmexCD1-toprJ1-negative and -positive bacteria exhibit significantly different metabolic flux and characteristics, especially in purine metabolism. Intriguingly, the addition of inosine, a purine metabolite, effectively restores the antibacterial activity of tigecycline by promoting antibiotic uptake. Our findings highlight the correlation between bacterial mechanism and antibiotic resistance, and offer a distinct approach to overcome tmexCD-toprJ-mediated multidrug resistance.

Seasonal dynamics of dissolved inorganic nitrogen in groundwater: Tracing environmental controls and land use impact.

High levels of dissolved inorganic nitrogen (DIN) in groundwater pose challenges for regions like northern Anhui Province, China, where groundwater is a crucial domestic resource. This study utilized modern geostatistics to explore the spatial and temporal dynamics of DIN in groundwater. Significant seasonal influences on DIN concentrations were identified: ammonium peaks during wet season driven by agricultural activities, while nitrate peaks during the dry season primarily influenced by municipal inputs. This study established a Bayesian Maximum Entropy - Random Forest (BME-RF) model based on Land Use/Land Cover data to infer the spatio-temporal performance of DIN, achieving an interpretation rate above 90 %. It also highlighted the role of hydrogeological conditions and aquifer types in the evolution of DIN. By employing a DIN environmental interaction model, it further analyzed the eco-hydrological drivers and seasonal trends affecting DIN variability, enhancing the understanding of groundwater nitrogen dynamics and their link to environmental factors with low consumption. SYNOPSIS: This study reveals seasonal shifts in groundwater DIN, links them to human activity, and uses the BME model to guide targeted nitrogen fluctuation.