Mechanisms Of Resistance Research Articles

Photodynamic Inactivation in agriculture: combating fungal phytopathogens resistant to conventional treatment.

Botrytiscinerea is a severe threat in agriculture, as it can infect over 200 different crop species with gray mold affecting food yields and quality. The conventional treatment using fungicides lead to emerging resistance over the past decades. Here, we introduce Photodynamic Inactivation (PDI) as a strategy to combat B.cinerea infections, independent of fungicide resistance. PDI uses photoactive compounds, which upon illumination create reactive oxygen species toxic forkilling target organisms. This study focuses on different formulations of sodium-magnesium-chlorophyllin (Chl, food additive E140) as photoactive compound in combination with EDTA disodium salt dihydrate (Na2EDTA) as cell-wall permeabilizer and a surfactant. In an in vitro experiment, three different photosensitizers (PS)with varying Chl and Na2EDTA concentrations were tested against five B.cinerea strains with different resistance mechanisms. We showed that all B.cinerea mycelial spheres of all tested strains were eradicated with concentrations as low as 224µM Chl and 3.076mM Na2EDTA (LED illumination with main wavelength of 395nm, radiant exposure 106Jcm-2). To further test PDI as a Botrytis treatment strategy in agriculture a greenhouse trial was performed on B.cinerea infected bell pepper plants (CapsicumannumL). Two different rates (560 or 1120gHa-1) of PS formulation (0.204M Chl and 1.279M Na2EDTA) and a combination of PS formulation with 0.05% of the surfactant BRIJL4 (560gHa-1) were applied weekly for 4 weeks by spray application. Foliar lesions, percentage of leaves affected, percentage of leaf area diseased and AUDPC were significantly reduced, while percentage of marketable plants were increased by all treatments compared to a watertreated control, however, did not statistically differ from each other. No phytotoxicity was observed in any treatment. These results add to the proposition of employing PDI with the naturally sourced PS Chl in agricultural settings aimed at controlling B.cinerea disease. This approach seems to be effective regardless of the evolving resistance mechanisms observed in response to conventional antifungal treatments.

Testing the disintegration and texture-related palatability predictions for orodispersible tablets using an instrumental tool coupled with multivariate analysis: Focus on process variables and analysis settings

Orodispersible tablets (ODTs) represent a growing category of dosage forms intended to increase the treatment acceptability for special groups of patients. ODTs are designed to rapidly disintegrate in the oral cavity and to be administered without water. In addition, ODTs are easy to manufacture using standard excipients and pharmaceutical equipment.This study adds to previously published research that developed an instrumental tool to predict oral disintegration and texture-related palatability of ODTs with different formulations. The current study aimed to challenge the predictive capacity of the models under variable process conditions. The studied process parameters with potential impact on the pharmaceutical properties, texture profiles, and palatability were the compression pressure, punch shape and diameter. Subsequently, for all the placebo and drug-loaded ODTs, the in vivo disintegration time and texture-related palatability were determined with healthy volunteers.Previously developed regression models were applied to predict the formulation's disintegration time and texture-related palatability characteristics of ODTs obtained under different experimental conditions. The influence of process variables on the predictive performance of the models was estimated by calculating the residuals as the difference between the predicted and observed values for the investigated response. Increasing the speed of the analyser`s probe from 0.01 mm/s to 0.02 mm/s led to an improved differentiation of the texture profiles. The in vivo disintegration time and texture-related palatability scores were only influenced by the mechanical resistance and the tablet shape. Lower score was observed for the larger diameter tablets (10 mm). Overall, the prediction of the disintegration time at 0.02 mm/s was more accurate, except for stronger tablets. The best prediction of texture-related palatability was achieved for the 10 mm tablets, tested at 0.01 mm/s speed.The same model achieved good predictions of the oral disintegration time for all API-loaded formulations, which confirmed the ability of the texture analysis to capture process-related variability. Drug loading decreased the predictive capacity of the texture-related palatability because of the taste effect.

Magnaporthe oryzae infection triggers rice resistance to brown planthopper through the influence of jasmonic acid on the flavonoid biosynthesis pathway.

In agroecosystems, plants are constantly exposed to attack from diverse herbivorous insects and microbes, and infestation with one species may change the plant defense response to other species. In our investigation of the relationships among rice plants, the brown planthopper Nilaparvata lugens (Stål) and the rice blast fungus Magnaporthe oryzae, we observed a significant increase in the resistance of rice treated with rice blast to N.lugens, as evidenced by improved plant survival rates in a small population resistance study. Subsequent transcriptome data analysis revealed that the rice blast fungus can induce the expression of genes in the jasmonic acid (JA) and flavonoid pathways. Similar to the flavonoid pathway, the JA pathway also contains 2 types of genes that exhibit similar and opposite trends in response to N.lugens and rice blast. Among these genes, the osjaz1 mutant and the osmyc2 mutant were phenotypically confirmed to positively and negatively regulate rice resistance to N.lugens and rice blast, respectively. Subsequent mass spectrometry and quantification experiments showed that the exogenous application of methyl jasmonate (MeJA) can induce the accumulation of eriodictyol, naringenin and quercetin, as well as the expression of OsF3H, Os4CL5 and OsCHI in the flavonoid pathway. This suggests a close connection between the JA pathway and the flavonoid pathway. However, OsF3'H, which negatively regulates rice resistance to N.lugens and rice blast, did not show increased expression. Phenotypic and molecular experiments confirmed that OsMYC2 can bind to and inhibit the expression of OsF3'H, thus revealing the mechanism of rice resistance to N.lugens after treatment with rice blast. These findings will deepen our understanding of the interactions among rice, N.lugens and rice blast.

Physiological and transcriptomic analyses reveal the cadmium tolerance mechanism of Miscanthus lutarioriparia.

Miscanthus lutarioriparia is a promising energy crop that is used for abandoned mine soil phytoremediation because of its high biomass yield and strong tolerance to heavy metals. However, the biological mechanism of heavy metal resistance is limited, especially for applications in the soil restoration of mining areas. Here, through the investigation of soil cadmium(Cd) in different mining areas and soil potted under Cd stress, the adsorption capacity of Miscanthus lutarioriparia was analyzed. The physiological and transcriptional effects of Cd stress on M. lutarioriparia leaves and roots under hydroponic conditions were analyzed. The results showed that M. lutarioriparia could reduce the Cd content in mining soil by 29.82%. Moreover, different Cd varieties have different Cd adsorption capacities in soils with higher Cd concentration. The highest cadmium concentrations in the aboveground and belowground parts of the plants were 185.65 mg/kg and 186.8 mg/kg, respectively. The total chlorophyll content, superoxide dismutase and catalase activities all showed a trend of increasing first and then decreasing. In total, 24,372 differentially expressed genes were obtained, including 7735 unique to leaves, 7725 unique to roots, and 8912 unique to leaves and roots, which showed differences in gene expression between leaves and roots. These genes were predominantly involved in plant hormone signal transduction, glutathione metabolism, flavonoid biosynthesis, ABC transporters, photosynthesis and the metal ion transport pathway. In addition, the number of upregulated genes was greater than the number of downregulated genes at different stress intervals, which indicated that M. lutarioriparia adapted to Cd stress mainly through positive regulation. These results lay a solid foundation for breeding excellent Cd resistant M. lutarioriparia and other plants. The results also have an important theoretical significance for further understanding the detoxification mechanism of Cd stress and the remediation of heavy metal pollution in mining soil.

Combating antimicrobial resistance in malaria, HIV and tuberculosis.

Antimicrobial resistance poses a significant threat to the sustainability of effective treatments against the three most prevalent infectious diseases: malaria, human immunodeficiency virus (HIV) infection and tuberculosis. Therefore, there is an urgent need to develop novel drugs and treatment protocols capable of reducing the emergence of resistance and combating it when it does occur. In this Review, we present an overview of the status and underlying molecular mechanisms of drug resistance in these three diseases. We also discuss current strategies to address resistance during the research and development of next-generation therapies. These strategies vary depending on the infectious agent and the array of resistance mechanisms involved. Furthermore, we explore the potential for cross-fertilization of knowledge and technology among these diseases to create innovative approaches for minimizing drug resistance and advancing the discovery and development of new anti-infective treatments. In conclusion, we advocate for the implementation of well-defined strategies to effectively mitigate and manage resistance in all interventions against infectious diseases.

Genome-wide identification analysis in wild-type Solanum pinnatisectum reveals some genes defending against Phytophthora infestans

Solanum pinnatisectum exhibits strong resistance to late blight caused by Phytophthora infestans but only an incomplete genome assembly based on short Illumina reads has been published. In this study, we generated the first chromosome-level draft genome for the wild-type potato species S. pinnatisectum in China using Oxford Nanopore technology sequencing and Hi-C technology. The high-quality assembled genome size is 664 Mb with a scaffold N50 value of 49.17 Mb, of which 65.87% was occupied by repetitive sequences, and predominant long terminal repeats (42.51% of the entire genome). The genome of S. pinnatisectum was predicted to contain 34,245 genes, of which 99.34% were functionally annotated. Moreover, 303 NBS-coding disease resistance (R) genes were predicted in the S. pinnatisectum genome to investigate the potential mechanisms of resistance to late blight disease. The high-quality chromosome-level reference genome of S. pinnatisectum is expected to provide potential valuable resources for intensively and effectively investigating molecular breeding and genetic research in the future.

Transcriptomic analysis of fludioxonil resistance mechanisms in Botrytis cinerea

Botrytis cinerea is a destructive plant pathogen that infects a wide range of economically important crops. Limiting pathogen infection during production and post-harvest is largely dependent on fungicide applications; fungicide resistant isolates of B. cinerea have been recovered from various hosts. Resistance of B. cinerea to fludioxonil has been associated with overexpression of transporter genes (BcatrB and mfsM2) and mutations on histidine kinase proteins (Bos1, Bchhk2, Bchhk17). To identify possible mechanisms associated with fludioxonil resistance, genomic expression of three sensitive and three low-resistant isolates were studied. Overexpression of BcatrB was observed when comparing low-resistant and sensitive isolates, but was not specific to the fludioxonil treatment. Seven amino acid substitutions and one deletion were identified in the transcription factor Bcmrr1 in low-resistant isolates, associated with overexpression of BcatrB. The L497 deletion, previously associated with highly resistance isolates (MDR1h), was observed in two low-resistant isolates. Other differentially expressed genes associated with transmembrane transport, oxidoreductase activity and lipid metabolic processes could be key in understanding the fungicidal mechanism(s) of fludioxonil. Expression profiles were isolate-specific. Following fludioxonil exposure, two sensitive isolates of B. cinerea sensu stricto showed a change in gene expression levels associated with cell membrane and peroxidase activity. In one low-resistant isolate of B. cinerea group S, fludioxonil exposure resulted in the overexpression of stress response genes and MFS transporter Bcstl1; one sensitive and two low-resistant isolates showed no significant changes in gene expression profiles. This work provides insight into the effect of fludioxonil on B. cinerea and potential fungicide resistance mechanisms.

Trends in serotype distribution and antimicrobial susceptibility pattern of invasive Haemophilus influenzae isolates from Brazil, 2009-2021.

Invasive Haemophilus influenzae (Hi) disease poses a significant global health challenge. With the relaxation of COVID-19 pandemic measures and declining H. influenzae serotype b (Hib) vaccination coverage, there is concern about a potential increase in Hi cases worldwide. This study analyzed 1437 invasive Hi isolates in Brazil over 13years, determining capsular serotypes, antimicrobial susceptibility, and genetic relatedness through multilocus sequence typing. The primary source of isolation for these invasive H. influenzae isolates was blood (54.4%), followed by cerebrospinal fluid (37.1%) and lung specimens (8.5%), respectively. Consequently, bacteremia (47%) was the most common clinical presentation, followed by meningitis (39.6%) and pneumonia (13.4%). Non-encapsulated Hi (NTHi) predominated among the isolates (51.4%), along with serotype a (22%) and serotype b (21.5%) among the encapsulated isolates. The majority of the encapsulated isolates were isolated from children under 14years of age (76.7%), while NTHi isolates were identified in patients older than 15years, particularly those ≥ 60years old (40%). Ampicillin resistance was observed in 17.1% of cases, displaying β-lactamase production as the principal resistance mechanism. MLST revealed a diverse NTHi population, whereas the encapsulated isolates presented a clonal structure. This study describes the prevalence of NTHi isolates circulating in Brazil after two decades of the Hib vaccine immunization program. Continuous universal surveillance is crucial for implementing prompt public health measures to prevent and control invasive Hi disease and monitor changes in antibiotic resistance profiles.

Quantitative systems pharmacology modeling of tumor heterogeneity in response to BH3-mimetics using virtual tumors calibrated with cell viability assays.

Both primary and acquired resistance mechanisms that involve intra-tumoral cell heterogeneity limit the use of BH3-mimetics to trigger tumor cell apoptosis. This article proposes a new quantitative systems pharmacology (QSP)-based methodology in which cell viability assays are used to calibrate virtual tumors (VTs) made of virtual cells whose fate is determined by simulations from an apoptosis QSP model. VTs representing SU-DHL-4 and KARPAS-422 cell lines were calibrated using invitro data involving venetoclax (anti-BCL2), A-1155463 (anti-BCLXL), and/or A-1210477 (anti-MCL1). The calibrated VTs provide insights into the combination of several BH3-mimetics, such as the distinction between cells eliminated by at least one of the drugs (monotherapies) from the cells eliminated by a pharmacological combination only. Calibrated VTs can also be used as initial conditions in an agent-based model (ABM) framework, and a minimal ABM was developed to bridge invitro SU-DHL-4 cell viability results to tumor growth inhibition experiments in mice.

Multi-omics strategy reveals potential role of antimicrobial resistance and virulence factor genes responsible for Simmental diarrheic calves caused by Escherichia coli.

Escherichia coli (E. coli) is reported to be an important pathogen associated with calf diarrhea. Antibiotic resistance genes (ARGs) and virulence factor genes (VFGs) pose a considerable threat to both animal and human health. However, little is known about the characterization of ARGs and VFGs presented in the gut microbiota of diarrheic calves caused by E. coli. In this study, we used multi-omics strategy to analyze the ARG and VFG profiles of Simmental calves with diarrhea caused by E. coli K99. We found that gut bacterial composition and their microbiome metabolic functions varied greatly in diarrheic calves compared to healthy calves. In total, 175 ARGs were identified, and diarrheal calves showed a significantly higher diversity and abundance of ARGs than healthy calves. Simmental calves with diarrhea showed higher association of VFGs with pili function, curli assembly, and ferrienterobactin transport of E. coli. Co-occurrence patterns based on Pearson correlation analysis revealed that E. coli had a highly significant (P < 0.0001) correlation coefficient (>0.8) with 16 ARGs and 7 VFGs. Metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Phylotype analysis of E. coli genomes showed that the predominant phylogroup B1 in diarrheic Simmental calves was associated with 10 ARGs and 3 VFGs. These findings provide an overview of the diversity and abundance of the gut microbiota in diarrheic calves caused by E. coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the calves affected with diarrhea.IMPORTANCESimmental is a well-recognized beef cattle breed worldwide. They also suffer significant economic losses due to diarrhea. In this study, fecal metagenomic analysis was applied to characterize the antibiotic resistance gene (ARG) and virulence factor gene (VFG) profiles of diarrheic Simmental calves. We identified key ARGs and VFGs correlated with Escherichia coli isolated from Simmental calves. Additionally, metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Our findings provide an insight into the diversity and abundance of the gut microbiota in diarrheic calves caused by Escherichia coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the diarrheal calves from cattle hosts.

Identification of novel single nucleotide variants in the drug resistance mechanism of Mycobacterium tuberculosis isolates by whole-genome analysis

BackgroundTuberculosis (TB) represents a major global health challenge. Drug resistance in Mycobacterium tuberculosis (MTB) poses a substantial obstacle to effective TB treatment. Identifying genomic mutations in MTB isolates holds promise for unraveling the underlying mechanisms of drug resistance in this bacterium.MethodsIn this study, we investigated the roles of single nucleotide variants (SNVs) in MTB isolates resistant to four antibiotics (moxifloxacin, ofloxacin, amikacin, and capreomycin) through whole-genome analysis. We identified the drug-resistance-associated SNVs by comparing the genomes of MTB isolates with reference genomes using the MuMmer4 tool.ResultsWe observed a strikingly high proportion (94.2%) of MTB isolates resistant to ofloxacin, underscoring the current prevalence of drug resistance in MTB. An average of 3529 SNVs were detected in a single ofloxacin-resistant isolate, indicating a mutation rate of approximately 0.08% under the selective pressure of ofloxacin exposure. We identified a set of 60 SNVs associated with extensively drug-resistant tuberculosis (XDR-TB), among which 42 SNVs were non-synonymous mutations located in the coding regions of nine key genes (ctpI, desA3, mce1R, moeB1, ndhA, PE_PGRS4, PPE18, rpsA, secF). Protein structure modeling revealed that SNVs of three genes (PE_PGRS4, desA3, secF) are close to the critical catalytic active sites in the three-dimensional structure of the coding proteins.ConclusionThis comprehensive study elucidates novel resistance mechanisms in MTB against antibiotics, paving the way for future design and development of anti-tuberculosis drugs.

Metabolic pathways and antimicrobial peptide resistance in bacteria.

Antimicrobial resistance is a pressing concern that poses a significant threat to global public health, necessitating the exploration of alternative strategies to combat drug-resistant microbial infections. Recently, antimicrobial peptides (AMPs) have gained substantial attention as possible replacements for conventional antibiotics. Because of their pharmacodynamics and killing mechanisms, AMPs display a lower risk of bacterial resistance evolution compared with most conventional antibiotics. However, bacteria display different mechanisms to resist AMPs, and the role of metabolic pathways in the resistance mechanism is not fully understood. This review examines the intricate relationship between metabolic genes and AMP resistance, focusing on the impact of metabolic pathways on various aspects of resistance. Metabolic pathways related to guanosine pentaphosphate (pppGpp) and guanosine tetraphosphate (ppGpp) [collectively (p)ppGpp], the tricarboxylic acid (TCA) cycle, haem biosynthesis, purine and pyrimidine biosynthesis, and amino acid and lipid metabolism influence in different ways metabolic adjustments, biofilm formation and energy production that could be involved in AMP resistance. By targeting metabolic pathways and their associated genes, it could be possible to enhance the efficacy of existing antimicrobial therapies and overcome the challenges exhibited by phenotypic (recalcitrance) and genetic resistance toward AMPs. Further research in this area is needed to provide valuable insights into specific mechanisms, uncover novel therapeutic targets, and aid in the fight against antimicrobial resistance.

Effect of Artificial Aging in the Microstructure and Corrosion Performance of Superduplex UNS S32750 Stainless Steel

Superduplex stainless steels have great mechanical and corrosion properties. However, its chemical composition makes it prone to intermetallic phase precipitation during thermal processing. Sigma (σ), chi (χ), and chromium nitrides (Cr2N) remove Cr and Mo from the matrix, reducing the corrosion and mechanical resistance. Understanding the effects of thermal processing on the secondary phase’s precipitation and depletion of the material’s performance is crucial to its applications. Thus, this work aims to analyze the behavior of the corrosion performance of the UNS S32750 after thermal treatment at 800°C, for 60, 180, 300, and 420 minutes, in comparison to the as-received material. Optical emission spectrometry, X-ray diffraction, and SEM with backscattered electrons (BSE) were used to evaluate the material. The corrosion performance was evaluated with the cyclic potentiodynamic polarization technique. The main results and conclusions obtained in the study were a decomposition of the ferrite phase into the χ and σ phases, with the formation of the χ phase being predominant in shorter times, while for longer aging times σ formed in greater quantities. It was also possible to verify a more aggressive corrosion trend for aged samples in the regions adjacent to the formation of the χ and σ phases. It was also possible to observe that the losses generated in corrosion resistance were greater for aging times longer than 60 minutes. The aging treatment significantly reduced the material’s corrosion resistance in conjunction with the formation of precipitates.

Hypoxia inhibits ferritinophagy-mediated ferroptosis in esophageal squamous cell carcinoma via the USP2-NCOA4 axis.

Esophageal squamous cell carcinoma (ESCC) is a prevalent malignancy of the digestive system. Hypoxia is a crucial player in tumor ferroptosis resistance. However, the molecular mechanism of hypoxia-mediated ferroptosis resistance in ESCC remains unclear. Here, USP2 expression was decreased in ESCC cell lines subjected to hypoxia treatment and was lowly expressed in clinical ESCC specimens. Ubiquitin-specific protease 2 (USP2) depletion facilitated cell growth, which was blocked in USP2-overexpressing cells. Moreover, USP2 silencing enhanced the iron ion concentration and lipid peroxidation accumulation as well as suppressed ferroptosis, while upregulating USP2 promoted ferroptotic cell death in ESCC cells. Furthermore, knockout of USP2 in ESCC models discloses the essential role of USP2 in promoting ESCC tumorigenesis and inhibiting ferroptosis. In contrast, overexpression of USP2 contributes to antitumor effect and ferroptosis events in vivo. Specifically, USP2 stably bound to and suppressed the degradation of nuclear receptor coactivator 4 (NCOA4) by eliminating the Lys48-linked chain, which in turn triggered ferritinophagy and ferroptosis in ESCC cells. Our findings suggest that USP2 plays a crucial role in iron metabolism and ferroptosis and that the USP2/NCOA4 axis is a promising therapeutic target for the management of ESCC.

Properties of radiation-induced point defects in austenitic steels: a molecular dynamics study

Abstract Austenitic steels are recognized as excellent structural materials for pressurized water reactors (PWRs) due to their outstanding mechanical properties and radiation resistance. However, compared to the widely studied FeCrNi series of steels, little is known about the radiation resistance of FeCrNiMn steel. In this study, the generation and evolution of radiation-induced defects in FeCrNiMn steel were investigated by molecular dynamics (MD) simulations. The results showed that more defect atoms were produced in the thermal spike stage, but fewer defects survived at the end of the cascades in FeCrNiMn compared to pure Fe. Point defect properties were analyzed by molecular static (MS), and the formation energies of defects in FeCrNiMn were lower than those of pure Fe, while the migration energies were higher. Compared to FeCrNi, FeCrNiMn had smaller migration energies and a larger overlap of vacancy and interstitial migration energies. The low vacancy formation energies and widely overlapping migration energies suggested that the number of point defects in the thermal spike stage was higher, but the possibility of recombination was greater. Additionally, Mn exhibited the smallest interstitial formation energy and migration energy. The difference in defect migration energies revealed that vacancy and interstitial defects migrate through different alloy constituent elements. This study revealed the underlying mechanism for the excellent irradiation resistance of FeCrNiMn.

Bacteria inhabiting spider webs enhance host silk extensibility

Spider silk is a promising material with great potential in biomedical applications due to its incredible mechanical properties and resistance to degradation of commercially available bacterial strains. However, little is known about the bacterial communities that may inhabit spider webs and how these microorganisms interact with spider silk. In this study, we exposed two exopolysaccharide-secreting bacteria, isolated from webs of an orb spider, to major ampullate (MA) silk from host spiders. The naturally occurring lipid and glycoprotein surface layers of MA silk were experimentally removed to further probe the interaction between bacteria and silk. Extensibility of major ampullate silk produced by Triconephila clavata that was exposed to either Microbacterium sp. or Novosphigobium sp. was significantly higher than that of silk that was not exposed to bacteria (differed by 58.7%). This strain-enhancing effect was not observed when the lipid and glycoprotein surface layers of MA silks were removed. The presence of exopolysaccharides was detected through NMR from MA silks exposed to these two bacteria but not from those without exposure. Here we report for the first time that exopolysaccharide-secreting bacteria inhabiting spider webs can enhance extensibility of host MA silks and silk surface layers play a vital role in mediating such effects.

Trastuzumab deruxtecan in HER2-positive advanced gastric cancer: exploratory biomarker analysis of the randomized, phase 2 DESTINY-Gastric01 trial.

Trastuzumab deruxtecan (T-DXd) showed statistically significant clinical improvement in patients with human epidermal growth factor receptor 2-positive (HER2+) gastric cancer in the DESTINY-Gastric01 trial. Exploratory results from DESTINY-Gastric01 suggested a potential benefit in patients with HER2-low gastric cancer. Spatial and temporal heterogeneity in HER2 expression or gene alteration, an inherent characteristic of gastric cancer tumors, presents a challenge in identifying patients who may respond to T-DXd. Specific biomarkers related to therapeutic response have not been explored extensively. Exploratory analyses were conducted to assess baseline HER2-associated biomarkers in circulating tumor DNA and tissue samples, and to investigate mechanisms of resistance to T-DXd. Baseline HER2-associated biomarkers were correlated with objective response rate (ORR) in the primary cohort of patients with HER2+ gastric cancer. The primary cohort had 64% concordance between HER2 positivity and HER2 (ERBB2) plasma gene amplification. Other key driver gene amplifications, specifically MET, EGFR and FGFR2, in circulating tumor DNA were associated with numerically lower ORR. Among 12 patients with HER2 gain-of-function mutations, ORR was 58.3% (7 of 12). ORR was consistent regardless of timing of immunohistochemistry sample collection. Further investigations are required in larger studies.

Study On Bioremediation Of Heavymetals Present In Cement

Cement, crucial for construction, poses significant environmental risks due to heavy metal contamination, including lead, cadmium, chromium, nickel, etc. These metals, released during cement production, endanger both human health and ecosystems. An innovative approach involves utilizing microorganisms for bioremediation, converting pollutants into less harmful forms. Microbes develop resistance mechanisms against heavy metals, reducing their concentration and mobility within cement. In this project, various brands and types of cement were collected, and different bacteria were cultured. A comparison was made regarding the mechanical properties, concentration of heavy metals, elemental composition, surface morphology, and particle size of the cement before and after bioremediation using Atomic Absorption Spectroscopy (AAS), Energy Dispersive X-ray Analysis (EDAX), and Scanning Electron Microscopy (SEM), respectively. The results obtained from the tests conducted were compared between the conventional and bacteria-induced cement samples. Implementation of such biotechnological approaches not only addresses environmental concerns but also promotes the development of innovative and sustainable solutions in construction

Discordant results between Xpert MTB/RIF assay and Bactec MGIT 960 culture system regarding the detection of rifampin-resistant Mycobacterium tuberculosis isolates in Wenzhou, China.

This study aimed to assess the possible causes of discordant results between Xpert MTB/RIF (Xpert) and Bactec MGIT 960 Culture System (MGIT960) regarding rifampicin (RIF) susceptibility in Mycobacterium tuberculosis. Patients with previous RIF-resistant tuberculosis who were admitted to Wenzhou Central Hospital from January 2020 to December 2022 were enrolled. The isolates obtained from these patients were subjected to RIF susceptibility tests using Xpert and MGIT960, and the minimum inhibitory concentration (MIC) of RIF was determined by the MYCOTB MIC plate test. Additionally, molecular docking and molecular dynamics (MD) simulations were performed to evaluate the binding efficacy of rpoB and RIF based on rpoB mutations detected in the isolates with discordant RIF susceptibility results. A total of 28 isolates with discordant RIF susceptibility test results were detected, 15 of them were RIF susceptible with MICs ≤ 0.5 µg/mL. Twelve out of 15 isolates contained borderline RIF resistance-associated mutations [L430P (n = 6), H445N (n = 6)], 1 isolate had D435Y and Q429H double mutation, and the remaining 2 isolates had a silent (Q432Q) mutation. Compared with the affinity of RIF toward the wild type (WT) (-45.83 kcal/mol) by MD, its affinity toward L452P (-55.52 kcal/mol), D435Y (-47.39 kcal/mol), L430P (approximately -69.72 kcal/mol), H445N (-49.53 kcal/mol), and Q429H (-55.67 kcal/mol) increased. Borderline RIF resistance-associated mutations were the main cause for the discordant RIF susceptibility results between Xpert and MGIT960, and the mechanisms of the resistance need further investigated.IMPORTANCEThis study is aimed at assessing discordant results between Xpert MTB/RIF (Xpert) assay and Bactec MGIT 960 Culture System (MGIT960) regarding the detection of rifampicin (RIF)-resistant Mycobacterium tuberculosis isolates in Wenzhou, China. The discordant results of RIF between these two assays were mainly caused by borderline RIF resistance-associated mutations, subsequently by silent mutations of rpoB. Borderline RIF resistance- associated mutations detected in our study were demonstrated to not be affected by the affinity of rpoB and RIF by molecular dynamics, and the mechanism of resistance was needed to be clarified. For the discordant results of RIF by Xpert and MGIT960 that occurred, rpoB DNA sequencing was recommended to investigate its association with resistance to RIF.

Chemical Profile with Antibacterial and Modulatory Activity of Extracts from the Stem Bark of Cnidoscolus quercifolius Pohl.

Objective: The present study aimed to investigate the chemical profile and evaluate the antibacterial and antibiotic-modulating activity of the methanolic extract and ethyl acetate of the stem bark of C. quercifolius against standard and multiresistant strains. Methods: The Minimum Inhibitory Concentration was determined by the microdilution method, and the modulating potential of the extracts on aminoglycoside and β-lactam antibiotics was evaluated. Results: The classes of secondary metabolites identified from qualitative chemical prospecting were flavones, flavonols, xanthones, flavonones, flavonols, catechins and leucoanthocyanidins. The assays showed inhibition only for Klebsiella pneumoniae-producing extended-spectrum β- lactamase, Klebsiella pneumoniae carbapenemase and Escherichia coli ATCC 25922 with MICs of 256, 512 and 512 μg/mL, respectively. The extracts, when associated with gentamicin and amoxicillin, showed synergism against all standard and multiresistant strains, with the exception of Klebsiella pneumoniae carbapenemase and Klebsiella pneumoniae producing extendedspectrum β-lactamase, respectively. When combined with amikacin, they also demonstrated synergism against multidrug-resistant strains; however, only the ethyl acetate extract had a synergistic effect against E. coli ATCC 25922. The association of penicillin with methanolic extract showed synergism only for Klebsiella pneumoniae producing extended-spectrum β-lactamase and S. aureus ATCC 29213, while the ethyl acetate extracts demonstrated synergism against S. aureus and Klebsiella pneumoniae producing extended-spectrum β-lactamase. Conclusion: It was found that C. quercifolius extracts have antibacterial potential against gramnegative bacteria. However, the need for additional research using specific methods against bacteria carrying different resistance mechanisms, especially gram-positive ones, is highlighted, with the aim of elucidating their mechanism of action. conclusion: The species was found to have substances with potential against Gram-negative bacteria. However, the need for additional research using specific methods against bacteria carrying different resistance mechanisms, especially Gram-positive ones, is highlighted, with the aim of elucidating their mechanism of action.