Biology subjects

Wang, B.

Publications and source records attributed to Wang, B..

At least 217 records · Page 12Linked to original sources

bioRxiv2025

Shear stress inhibits adipocyte differentiation via downregulating lncRNA MALAT1

Adipocyte differentiation plays an important role in bone remodeling due to secretory factors that can directly modulate osteoblast and osteoclast, thus affecting overall bone mass and skeletal integrity. Excessive adipocyte differentiation within bone marrow microenvironment can lead to decreased bone mass, eventually causing osteoporosis. Mechanical microenvironment of bone marrow, including fluid shear, maintains the balance of adipocyte and osteoblast differentiation during bone remodeling. However, how mechanical cues interact with long noncoding RNA (lncRNA) and regulating adipocyte differentiation remains unexplored. In this study, we investigated the mechanosensitive role of lncRNA MALAT1 during mesenchymal stem cells (MSCs) adipocyte differentiation. By applying physiologically relevant shear stress, MSCs experienced morphological changes and adipocyte differentiation differences. Shear stress inhibits MSCs adipocyte differentiation with reduced oil-red-o-stained lipid droplets. Silencing MALATs results in reduced adipocyte differentiation. By leveraging a novel gapmer double stranded locked nuclei acid (dsLNA) nanobiosensor, we showed that shear stress inhibits MALAT1 expression with significantly reduced fluorescence intensity. Our findings suggest that shear stress influences adipocyte differentiation primarily through the downregulation of MALAT1, highlighting a significant interplay between biophysical cues and lncRNAs. This interaction is crucial for understanding the complexities of bone remodeling and the potential therapeutic targeting of lncRNAs to treat bone-related disorders.

bioengineering↗

bioRxiv2025

A post-assembly conformational change makes the SARS-CoV-2 polymerase elongation-competent

Coronaviruses (CoV) encode sixteen non-structural proteins (nsps), most of which form the replication-transcription complex (RTC). The RTC contains a core composed of one nsp12 RNA-dependent RNA polymerase (RdRp), two nsp8s and one nsp7. The core RTC recruits other nsps to synthesize all viral RNAs within the infected cell. While essential for viral replication, the mechanism by which the core RTC assembles into a processive polymerase remains poorly understood. We show that the core RTC preferentially assembles by first having nsp12-polymerase bind to the RNA template, followed by the subsequent association of nsp7 and nsp8. Once assembled on the RNA template, the core RTC requires hundreds of seconds to undergo a conformational change that enables processive elongation. In the absence of RNA, the (apo-)RTC requires several hours to adopt its elongation-competent conformation. We propose that this obligatory activation step facilitates the recruitment of additional nsps essential for efficient viral RNA synthesis and may represent a promising target for therapeutic interventions.

biophysics↗

bioRxiv2025

AAVone: A Cost-Effective, Single-Plasmid Solution for Efficient AAV Production with Reduced DNA Impurities

Currently, the most common approach for manufacturing GMP-grade adeno-associated virus (AAV) vectors involves transiently transfecting mammalian cells with three plasmids that carry the essential components for production. The requirement for all three plasmids to be transfected into a single cell and the necessity for high quantities of input plasmid DNA, limits AAV production efficiency, introduces variability between production batches, and increases time and labor costs. Here, we developed an all-in-one, single-plasmid AAV production system, called AAVone. In this system, the adenovirus helper genes (E2A, E4orf6, and VA RNA), packaging genes (rep and cap), and the vector transgene cassette are consolidated into a single compact plasmid with a 13-kb backbone. The AAVone system achieves a two- to four-fold increase in yields compared to the traditional triple-plasmid system. Furthermore, the AAVone system exhibits low batch-to-batch variation and eliminates the need for fine-tuning the ratios of the three plasmids, simplifying the production process. In terms of vector quality, AAVs generated by the AAVone system show similar in vitro and in vivo transduction efficiency, but a substantial reduction in sequences attributed to plasmid backbones and a marked reduction in non-functional snap-back genomes. In Summary, the AAVone platform is a straightforward, cost-effective, and highly consistent AAV production system - making it particularly suitable for GMP-grade AAV vectors.

bioengineering↗

bioRxiv2024

A new class of penicillin-binding protein inhibitors to address drug-resistant Neisseria gonorrhoeae

{beta}-Lactams are the most widely used antibiotics for the treatment of bacterial infections because of their proven track record of safety and efficacy. However, susceptibility to {beta}-lactam antibiotics is continually eroded by resistance mechanisms. Emerging multidrug-resistant (MDR) Neisseria gonorrhoeae strains possessing altered penA alleles (encoding PBP2) pose a global health emergency as they threaten the utility of ceftriaxone, the last remaining outpatient antibiotic. Here we disclose a novel benzoxaborinine-based penicillin-binding protein inhibitor series (boro-PBPi) that is envisioned to address penA-mediated resistance while offering protection against evolution and expansion of {beta}-lactamases. Optimization of boro-PBPi led to the identification of compound 21 (VNRX-14079) that exhibits potent antibacterial activity against MDR N. gonorrhoeae achieved by high affinity binding to the PBP2 target. Boro-PBPi/PBP2 complex structures confirmed covalent interaction of the boron atom with Ser310 and the importance of the {beta}3-{beta}4 loop for improved affinity. 21 elicits bactericidal activity, a low frequency of resistance, a good safety profile, suitable pharmacokinetic properties, and in vivo efficacy in a murine infection model against ceftriaxone-resistant N. gonorrhoeae. 21 is a promising anti-gonorrhea agent poised for further advancement.

microbiology↗

bioRxiv2024

A Palette of Bridged Bicycle-Strengthened Fluorophores

Organic fluorophores are the keystone of advanced biological imaging. The vast chemical space of fluorophores has been extensively explored in seek of molecules with ideal properties. However, within the current molecular constraints, there appears to be a trade-off between high brightness, robust photostability, and tunable biochemical properties. Herein we report a general strategy to systematically boost the performance of donor-acceptor-type fluorophores by leveraging SO2 and O-substituted azabicyclo[3.2.1] octane auxochromes. These bicyclic heterocycles give rise to a collection of Bridged dyes (BD) spanning the UV and visible range with top-notch quantum efficiencies, enhanced water solubility, and tunable cell-permeability. Notably, these azabicyclic fluorophores showed remarkable photostability than its tetramethyl or azatidine analogue, at the same time completely resistant to oxidative photobluing rendered by the Bredts rule. Functionalized BD dyes are tailored for applications in single-molecule imaging, super-resolution imaging (STED and SIM) in fixed or live mammalian cells and plant cells, and live zebrafish imaging or chemigenetic voltage imaging. Synergizing with advanced imaging methods, the bridge bicycle dyes represent a versatile palette for biological researches.

biophysics↗

bioRxiv2024

Deciphering the thiolactonization mechanism in thiolactomycin biosynthesis

Thiolactomycin (1), which features a unique{gamma} -thiolactone ring, is a promising antibiotic candidate that specifically targets bacterial type II fatty acid synthase. Despite extensive studies on its pharmacological activities, modes of action, and chemical synthesis, the enzymatic processes responsible for forming the activity-determining{gamma} -thiolactone ring have remained largely unknown. Here, we resolve this problem by revealing that the condensation and heterocyclization (Cy) domain of the nonribosomal peptide synthetase (NRPS) TlnC (TlnCCy), along with the cytochrome P450 enzyme TlnA, cooperatively enable the{gamma} -thiolactone assembly. TlnCCy mediates an unusual sulfurtransfer reaction to sulfurate the polyketide intermediate, generating a thiocarboxylate intermediate. Subsequently, TlnA acts as a{gamma} -thiolactone synthase, converting the linear thiocarboxylate intermediate into 1 via a distal radical-based cyclization mechanism. These findings not only expand the functional and catalytic repertoires of NRPS Cy domains and P450 enzymes, but also highlight a special enzymatic strategy for{gamma} -thiolactone biosynthesis in nature. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/629141v2_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@7e0ad2org.highwire.dtl.DTLVardef@f86b80org.highwire.dtl.DTLVardef@159d136org.highwire.dtl.DTLVardef@1b633ff_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Unexpected Activities of CYP152 Peroxygenases towards Non-carboxylic Substrates Reveal Novel Substrate Recognition Mechanism and Catalytic Versatility

Exploring and exploiting the catalytic promiscuity of enzymes is a central topic and captivating challenge in enzymology. CYP152 peroxygenases are attractive biocatalysts for diverse reactions under mild conditions using H2O2 as cofactor. However, their substrate scope is limited by a carboxyl group required for acid-base catalysis, following the well-accepted principle that heme-dependent H2O2-utilizing enzymes employ a carboxyl group within their active sites to facilitate H2O2 activation. Herein, we reveal for the first time that several CYP152 family members can directly degrade various aromatic pollutants without any carboxyl group, exhibiting novel aromatic hydroxylation and dehalogenation activities. Through crystal structure analysis, isotope tracing experiments, and QM/MM calculations, we elucidate that the phenolic hydroxyl group activated by electron-withdrawing substituent(s) functionally replaces the carboxyl group, forming hydrogen bonds with the conserved arginine leading to Compound I formation. The oxygen atom of the newly formed hydroxyl group originates from water, bypassing the conventional oxygen rebound step. These findings provide first insights into the mechanisms of P450 peroxygenases towards non-carboxylic substrates, expanding our knowledge of biological C-H activation and C-halogen bond cleavage beyond canonical P450 reactions. This discovery holds immense potential for harnessing these enzymes in innovative strategies for industrial biocatalysis and environmental remediation.

biochemistry↗

bioRxiv2024

MorphoDiff: Cellular Morphology Painting with Diffusion Models

Understanding cellular responses to external stimuli is critical for parsing biological mechanisms and advancing therapeutic development. High-content image-based assays provide a cost-effective approach to examine cellular phenotypes induced by diverse interventions, which offers valuable insights into biological processes and cellular states. In this paper, we introduce MorphoDiff, a generative pipeline to predict high-resolution cell morphological responses under different conditions based on perturbation encoding. To the best of our knowledge, MorphoDiff is the first framework capable of producing guided, high-resolution predictions of cell morphology that generalize across both chemical and genetic interventions. The model integrates perturbation embeddings as guiding signals within a 2D latent diffusion model. The comprehensive computational, biological, and visual validations across three open-source Cell Painting datasets show that MorphoDiff can generate high-fidelity images and produce meaningful biology signals under various interventions. We envision the model will facilitate efficient in silico exploration of perturbational landscapes towards more effective drug discovery studies.

bioinformatics↗

bioRxiv2024

Neuropeptide-mediated temporal sensory filtering in a primordial nervous system

Sensory filtering - prioritizing relevant stimuli while ignoring irrelevant ones - is crucial for animals to adapt and survive in complex environments. While this phenomenon has been primarily studied in organisms with complex nervous systems, it remains unclear whether simpler organisms also possess such capabilities. Here, we studied temporal information processing in Schmidtea mediterranea, a freshwater planarian flatworm with a primitive nervous system. Using long-term behavioral imaging and oscillatory ultraviolet (UV) light stimulations with rhythms matching the timescale of the animals short-term memory ([~]minutes), we observed that planarians initially ignored rhythmic oscillations in UV intensity but eventually began tracking them after several cycles, demonstrating sensory filtering. We identified two neuropeptides, knockdown of which eliminated the initial ignoring phase and led to immediate stimulus-tracking, suggesting that these neuropeptides mediate an active sensory gating mechanism preventing response to transient fluctuations in stimuli. Notably, when UV stimulation was coupled with synchronous visible light oscillations, the planarians tracked the combined signals immediately, indicating that coherence across sensory modalities can override the initial gating. Our findings demonstrate that even simple nervous systems can filter temporal information and that this mechanism is mediated by neuropeptides. Unlike classical fast-acting small-molecule neurotransmitters, neuropeptides provide a slower, sustained, and global form of modulation that allows for more sophisticated control of sensory processing. Significance statementWe show that simple nervous systems can use specific neuropeptides to achieve sensory filtering, a behavior previously thought to require complex brain architecture. This neuropeptide-mediated sensory gating mechanism reveals a fundamental role for neuropeptides in temporal information processing, offering insights into the mechanistic and evolutionary origins of attention-like behaviors.

animal behavior and cognition↗

bioRxiv2024

Potential mechanisms and effects of melatonin-regulated Nrf2/HO-1 pathway on acute lung injury due to formaldehyde exposure

Acute lung injury is a topic of great interest in critical care medicine due to its high mortality rates. The lungs are the immediate target organ for formaldehyde inhalation damage. Lung damage and fibrosis are the most important outcomes of severe and acute lung disease and pose a serious threat to human health. Melatonin (MT), a natural bioactive compound with anti-inflammatory and antioxidant properties, However, it is not clear whether MT can prevent FA-induced acute lung injury (ALI). Therefore, in this study, we aimed to evaluate the protective effects of MT and the potential mechanisms against FA-induced ALI. An environmental exposure bin was used to inhale 3 mg{middle dot}m3 FA-induced ALI, which was given intraperitoneally with different doses of MT (5/10/20 mg/kg) after successful modeling. In addition, rats were treated with Nrf2 inhibitor (ML385) to validate the signaling pathway. Lung function was measured, histopathological/morphological changes in lung tissue were assessed, and inflammatory expression and oxidation levels in lung tissue were detected. We observed that MT greatly alleviated the lung dysfunction, pathological lung injury, pulmonary edema and inflammatory response after successful modeling of FA. In additional, MT played a role in modulating the Nrf2/HO-1 signaling pathway, which effectively inhibit oxidative stress caused by FA-induced lung tissue injure. Moreover, we found that activation of the NF-{kappa}B pathway is associated with inflammation caused by this injury. Overall, our data suggest that MT inhibits the expression of oxidative stress and inflammation in lung tissue through the institutional or Nrf2/HO-1 pathway, alleviating FA-induced ALI.

developmental biology↗

bioRxiv2024

Exploring Genetic Interactions with Rare Variants Reveals Gene Networks Susceptible to Complex Diseases

Genetic interactions play a crucial role in understanding the susceptibility and etiology of complex human diseases. However, existing methods for analyzing gene-gene interactions are often limited to common variants and may not capture the effects of rare variants. In this study, we propose a novel method called GGI-RUNNER that is specifically designed for analyzing gene-gene interactions of rare variants. GGI-RUNNER evaluates the enrichment of rare variant interaction burden in patients relative to baselines in the general population. The baselines are estimated for pairwise genes by a recursive truncated negative-binomial regression model on multiple genomic features available from public data. Intensive simulations demonstrate that GGI-RUNNER exhibits substantially higher statistical power than alternative epistasis tests and maintains reasonable type I error rates even in stratified populations. Applied to real data, GGI-RUNNER identified significant rare variant interactions associated with Alzheimers disease, Hirschsprungs disease, Ulcerative colitis and Crohns disease. Furthermore, we found that these identified genes for each trait can form interconnected networks, which may provide valuable insights into the underlying molecular mechanisms.

bioinformatics↗

bioRxiv2024

Selection of Bone-Targeting Peptides for Therapeutic Intervention: An In Vivo Evaluation and Comparison Study

Hydroxyapatite (HA)-binding peptides are emerging as promising candidates for bone-targeted therapies due to their strong affinity for mineralized tissues and biocompatibility. However, most studies to date have focused on in vitro characterization, providing limited insight into their in vivo performance. This study bridges that gap by evaluating the in vivo behavior of HA-binding peptides D8, E8, YD8, and YE8 using fluorescence imaging to assess their biodistribution in healthy and pathological bone environments. In healthy animal models, D8 demonstrated the strongest binding across mineralized tissues, including the skull, femur, and tibia, while YD8 showed moderate binding. In contrast, E8 and YE8 exhibited limited localization influenced by peptide dosage and binding kinetics. Pathological models, including defective tibia and osteogenesis imperfecta (OIM) mice, revealed preferential accumulation of D8 and YD8 in structurally compromised regions, underscoring their potential for targeting diseased bone microenvironments. Fluorescence imaging, enhanced by spectral unmixing algorithms, proved effective for assessing peptide localization and distribution. These findings highlight the utility of HA-binding peptides for bone-targeted therapies and emphasize the importance of in vivo studies in advancing their therapeutic and diagnostic applications. This work provides a foundation for optimizing peptide designs to improve specificity and efficacy in bone repair and regeneration.

bioengineering↗

bioRxiv2024

Dysregulation of cellular iron predisposes chemotherapy resistant cancer cells to ferroptosis

Despite centuries of research, metastatic cancer remains incurable due to resistance against all conventional cancer therapeutics. Alternative strategies leveraging non-proliferative vulnerabilities in cancer are required to overcome cancer recurrence. Ferroptosis is an iron dependent cell death pathway that has shown promising pre-clinical activity in several contexts of therapeutic resistant cancer. However, ferroptosis sensitivity is highly variable across tissue types and cell state posing a challenge for clinical translation. We describe a convergent phenotype induced by chemotherapy where cells surviving chemotherapy have similar transcriptomic signatures and dysregulated iron homeostasis, regardless of initial cell type or chemotherapy used. Elevated labile iron levels are counteracted by NRF2 signaling that does not alleviate the amount of labile iron. Selectively inhibiting GPX4 leads to uniform susceptibility to ferroptosis in surviving cells, highlighting the common reliance on lipid peroxidation defenses. Cellular iron dysregulation is a vulnerability of chemoresistant cancer cells that can be leveraged by triggering ferroptosis. STATEMENT OF SIGNIFICANCEWe show that cells surviving chemotherapy are uniformly sensitive to ferroptosis, despite different sensitivity in untreated cells. Ferroptosis sensitivity surprisingly occurs alongside NRF2 signaling, likely due to loss of PCBP1 and accumulated labile iron. Labile iron accumulation as a driver of ferroptosis sensitivity constitutes another starting point for translation of ferroptosis.

cancer biology↗

bioRxiv2024

Enantioselective photoenzymatic C(sp3)-H functionalization via single-electron oxidation of carbanions

Established strategies for enantioselective hydroalkylation for C(sp3)-C(sp3) bond formation usually require pre-functionalized substrates as radical precursors in both transition-metal and photoenzymatic catalysis. Based on a sequential proton transfer/electron transfer (PT/ET) strategy, here we show a cooperative photoenzymatic system consisting of a flavin-dependent ene-reductase (ER) and an organophotoredox catalyst fluorescein (FI) to achieve atom-economic enantiodivergent hydroalkylation of electron-deficient C(sp3)-H with olefins. Mechanistic studies revealed a pathway for radical intermediate formation via excited-state FI*-induced single-electron oxidation of carbanions under alkaline conditions. The overall catalytic efficiency is enhanced by the electron transfer (ET) between FMNox and FI-*, while the stereoselectivity is controlled by ERs through enantioselective hydrogen atom transfer (HAT). We anticipate that this mode of photoenzymatic catalysis will inspire new pathways for generating free radical intermediates and foster innovative strategies for achieving photoenzymatic new-to-nature reactions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/627421v2_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@11b6c1eorg.highwire.dtl.DTLVardef@1575346org.highwire.dtl.DTLVardef@1c24a2org.highwire.dtl.DTLVardef@1a93c0d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Convergence of autism proteins at the cilium

Hundreds of high-confidence autism genes have been identified, yet the relevant etiological mechanisms remain unclear. Gene ontology analyses have repeatedly identified enrichment of proteins with annotated functions in gene expression regulation and neuronal communication. However, proteins are often pleiotropic and these annotations are inherently incomplete. Our recent autism functional genetics work has suggested that these genes may share a common mechanism at the cilium, a membrane-bound organelle critical for neurogenesis, brain patterning, and neuronal activity-all processes strongly implicated in autism. Moreover, autism commonly co-occurs with conditions that are known to involve ciliary-related pathologies, including congenital heart disease, hydrocephalus, and blindness. However, the role of autism genes at the cilium has not been systematically investigated. Here we demonstrate that autism proteins spanning disparate functional annotations converge in expression, localization, and function at cilia, and that patients with pathogenic variants in these genes have cilia-related co-occurring conditions and biomarkers of disrupted ciliary function. This degree of convergence among genes spanning diverse functional annotations strongly suggests that cilia are relevant to autism, as well as to commonly co-occurring conditions, and that this organelle should be explored further for therapeutic potential. One-Sentence SummaryAutism genes of diverse functional annotations converge at cilia, deepening our understanding of underlying autism biology and co-occurring conditions.

cell biology↗

bioRxiv2024

Synergistic Multi-Pronged Interactions Mediate the Effective Inhibition of Alpha-Synuclein Aggregation by the Chaperone HtrA1

The misfolding, aggregation, and the seeded spread of alpha synuclein (-Syn) aggregates are linked to the pathogenesis of various neurodegenerative diseases, including Parkinsons disease (PD). Understanding the mechanisms by which chaperone proteins prevent the production and seeding of -Syn aggregates is crucial for developing effective therapeutic leads for tackling neurodegenerative diseases. We show that a catalytically inactive variant of the chaperone HtrA1 (HtrA1*) effectively inhibits both -Syn monomer aggregation and templated fibril seeding, and demonstrate that this inhibition is mediated by synergistic interactions between its PDZ and Protease domains and -Syn. Using biomolecular NMR, AFM and Rosetta-based computational analyses, we propose that the PDZ domain interacts with the C-terminal end of the monomer and the intrinsically disordered C-terminal domain of the -Syn fibril. Furthermore, in agreement with sequence specificity calculations, the Protease domain cleaves in the aggregation-prone NAC domain at site T92/A93 in the monomer. Thus, through multi-pronged interactions and multi-site recognition of -Syn, HtrA1* can effectively intervene at different stages along the -Syn aggregation pathway, making it a robust inhibitor of -Syn aggregation and templated seeding. Our studies illustrate, at high resolution, the crucial role of HtrA1 interactions with both the intrinsically disordered -Syn monomers and with the dynamic flanking regions around the fibril core for inhibition of aggregation. This inhibition mechanism of the HtrA1 chaperone may provide a natural mechanistic blueprint for highly effective therapeutic agents against protein aggregation. Significance StatementPD and other synucleinopathies are marked by misfolding and aggregation of -Syn, forming higher-order species that propagate aggregation in a prion-like manner. Understanding how chaperone proteins inhibit -Syn aggregation and spread is essential for therapeutic development against neurodegeneration. Through an integrative approach of solution-based NMR, AFM, aggregation kinetics, and computational analysis, we reveal how a catalytically inactive variant of the chaperone HtrA1 effectively disrupts aggregation pathways. We find that the inactive Protease and PDZ domains of HtrA1 synergistically bind to key intrinsically disordered sites on both -Syn monomers and fibrils, thereby effectively inhibiting both aggregation and templated seeding. Our work provides a natural and unique blueprint for designing inhibitors to prevent the formation and seeding of aggregates in neurodegenerative diseases.

biophysics↗

bioRxiv2024

Molecular epidemiology of carbapenem-resistant hypervirulent Klebsiella pneumoniae: Risk factors and resistance mechanism of ceftazidime/avibactam in China

The high morbidity and mortality rates associated with carbapenem-resistant hypervirulent Klebsiella pneumoniae have become a global public health problem. We analyzed the whole genome sequence and epidemiological data of 81 carbapenem-resistant Klebsiella pneumoniae strains and conducted sensitivity experiments to explore the optimal concentration of carbapenem-resistant Klebsiella pneumoniae. We verified the resistance and virulence genes of carbapenem-resistant Klebsiella pneumoniae using polymerase chain reaction and compared virulence between carbapenem-resistant hypervirulent Klebsiella pneumoniae a ndcarbapenem-resistant-non-hypervirulent Klebsiella pneumoniae through Galleria mellonella assays.The prevalent types of multilocus sequence typing in our carbapenem-resistant Klebsiella pneumoniae strains were ST11 (69.14%, 56/81). ST11-K64-O1/O2v1 has become an epidemic type in our hospital, with drug-resistance genes dominated by blaKPC-2 (90.12%, 73/81). Ceftazidime/avibactam has better antibacterial effects on carbapenem-resistant Klebsiella pneumoniae, and its resistance is mainly mediated by a resistance plasmid containing the blaKPC-2 gene. 52 carbapenem-resistant hypervirulent Klebsiella pneumoniae strains carry the blaKPC-2, with a high detection rate of siderophore. Further research has shown that the genetic environment of the blaKPC-2 contains TnpR_Tn3 and ISKpn27 upstream and ISKpn6 insertion sequences downstream. Galleria mellonella revealed that the survival rate of carbapenem-resistant hypervirulent Klebsiella pneumoniae was lower than that of carbapenem-resistant-non-hypervirulent Klebsiella pneumoniae, and the survival rate of carbapenem-resistant hypervirulent Klebsiella pneumoniae-K64 was lower than that of carbapenem-resistant hypervirulent Klebsiella pneumoniae-K47.The spread of carbapenem-resistant hypervirulent Klebsiella pneumoniae strains is alarming, necessitating molecular monitoring of hypervirulent strains and strengthening the nosocomial infection prevention and control measures. Antibiotics should be used reasonably based on patients infection status and local epidemiological data. ImportanceCarbapenem-resistant Klebsiella pneumonia is a global public health concern. We conducted a molecular epidemiological analysis of 81 carbapenem-resistant hypervirulent Klebsiella pneumoniae strains from our hospital and explored the resistance mechanism of ceftazidime/avibactam. We identified the blaKPC-2 gene to be primarily responsible for carbapenem resistance in our hospital, and ST11-K64 was the dominant clone. A high-risk clone, ST307-K102, was detected, necessitating strengthened surveillance to prevent its spread. This studys findings contribute to the optimization of antimicrobial management and indicate that genomic research can assist with the tracking of hospital infection outbreaks and the improvement of infection-control measures.

microbiology↗

bioRxiv2024

Frequency-dependent and capacitive tissue electrical properties in spinal cord stimulation models

BackgroundModels of spinal cord stimulation (SCS) simulate the electric fields (E-fields) generated in targeted tissues, which in turn can predict physiological and then behavioral outcomes. Notwithstanding increasing sophistication and use in optimizing therapy, SCS models typically calculate E-fields using the quasi-static approximation (QSA). QSA, as implemented in neuromodulation models, neglects the frequency dispersion of tissue conductivity, as well as propagation, capacitive, and inductive effects on the E-field. The reliability of QSA specifically for SCS has not been considered in detail, especially for higher-frequency SCS. MethodsWe implemented a frequency-dependent finite element method (FEM) and solved a high- resolution RADO-SCS model with voltage-controlled (VC) and current-controlled (CC) stimulation to assess the impact of frequency-dependent conductivity (dispersion) and permittivity of spinal tissues on E-fields generated at three different spinal column locations (epidural space, spinal cord, and root) for frequencies spanning from 1 Hz to 10 MHz. Results were compared with predictions of QSA method, with varied conductivity values of purely resistive tissues. We further assessed the impact of frequency-dependent and capacitive tissue properties on spinal heating and distortion of the E-field waveform. ResultsTissue-specific electric properties around the energized leads and mode of stimulation-control impacted the magnitude of E-fields. In the spinal cord, the VC-SCS E-field generated with the frequency-dependent and capacitive properties was comparable to the QSA with 2X epidural fat conductivity, whereas the CC-SCS generated E-field was minimally impacted by frequency- dependent and capacitive properties up to 10 kHz. Spinal cord heating predicted by frequency- dependent and capacitive tissue properties was comparable to the QSA conditions with VC-SCS, whereas with CC-SCS, there was no impact of the frequency-dependent and capacitive tissue properties in spinal cord heating. E-field waveform distortion in the spinal cord, with CC-SCS at 1 kHz-specific electrical properties, was significant when fat capacitance (permittivity) was increased by 10X, whereas with VC-SCS, there was no effect of tissue capacitance. ConclusionRegardless of the mode of SCS, QSA was still valid in predicting SCS-induced E-field and heating at the spinal tissues- across and {beta} dispersion region of spinal tissues dielectric spectrum for VC-SCS and up to 10 kHz for CC-SCS.

bioengineering↗