Guanidine Hydrochloride Research Articles

Production and immunological characterisation of recombinant flagellin C of <i>Pseudomonas aeruginosa</i>

SCIENTIFIC RELEVANCE. Pseudomonas aeruginosa is one of the main causative agents of focal and diffuse suppurative inflammations in immunocompromised individuals. The multiple antimicrobial resistance of Р. aeruginosa has created an urgent need to develop effective preventive vaccines against this bacterium and to enhance their protective properties by selecting adjuvants. A promising strategy is to use flagellin, a P. aeruginosa flagellum component inducing the innate immune system through interaction with toll-like receptor 5 (TLR5) and activating the T-cell immune response, as a component or adjuvant in vaccine development.AIM. This study aimed to produce recombinant flagellin C (FliC) of P. aeruginosa and investigate its immunogenicity, adjuvanticity, and protective properties.MATERIALS AND METHODS. The fliC nucleotide sequence was obtained by PCR on template DNA of P. aeruginosa PA-103 and was inserted into the pQE-30 plasmid for subsequent expression in Escherichia coli M15. Recombinant FliC purification involved two stages: isolation of inclusion bodies and their dissolution in buffers containing urea and guanidine hydrochloride. Mice were immunised by two intraperitoneal injections with a two-week interval. The immunisation used purified recombinant FliC at a dose of 50 μg per animal and its combination with the Klebsiella pneumoniae surface antigen in a 1:1 ratio. Serum samples from immunised mice were tested for specific antibodies to recombinant FliC by enzyme-linked immunosorbent assay (ELISA). The protective properties of FliC were assessed by intraperitoneal challenge of mice with cultures of P. aeruginosa PA-103 and K. pneumoniae 204.RESULTS. The authors obtained the producing strain, generated recombinant FliC, and purified the protein to a 97.6% purity. The analysis of serum samples from immunised mice by ELISA and the protection assessment in challenge experiments showed that the purified recombinant FliC protein had immunogenic properties. Furthermore, the experimental challenge of FliC-immunised mice with P. aeruginosa confirmed that recombinant FliC had protective properties, as evidenced by the protection index of 3.0. Recombinant FliC exhibited adjuvant properties, as demonstrated by the effectiveness index of 6.1 observed in the experimental challenge of mice immunised with the combination of recombinant FliC and the surface antigen of K. pneumoniae.CONCLUSIONS. The purified recombinant FliC protein of P. aeruginosa demonstrated protective activity in mice challenged with P. aeruginosa and adjuvant properties when combined with the K. pneumoniae surface antigen, increasing the immunogenicity of the latter. The use of recombinant FliC holds promise for the creation of a candidate vaccine against P. aeruginosa infection.

CE-MS/MS and CE-timsTOF to separate and characterize intramolecular disulfide bridges of monoclonal antibody subunits and their application for the assessment of subunit reduction protocols

Characterization at the subunit level enables detailed mass spectrometric characterization of posttranslational modifications (PTMs) of monoclonal antibodies (mAbs). The implemented reduction often leaves the intramolecular disulfide bridges intact. Here, we present a capillary electrophoretic (CE) method based on a neutral-coated capillary for the separation of immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) digested and reduced mAb subunits followed by mass spectrometry (MS), MS/MS identification, and trapped ion mobility mass spectrometry (timsTOF). Our CE approach enables the separation of (i) different subunit moieties, (ii) various reduction states, and (iii) positional isomers of these partly reduced subunit moieties. The location of the remaining disulfide bridges can be determined by middle-down electron transfer higher energy collisional dissociation (EThcD) experiments. All these CE-separated variants show differences in ion mobility in the timsTOF measurements. Applying the presented CE-MS/MS method, reduction parameters such as the use of chaotropic salts were studied. For the investigated antibodies, urea improved the subunit reduction significantly, whereas guanidine hydrochloride (GuHCl) leads to multiple signals of the same subunit in the CE separation. The presented CE-MS method is a powerful tool for the disulfide-variant characterization of mAbs on the subunit level. It enables understanding disulfide bridge reduction processes in antibodies and potentially other proteins.

Antibacterial Effect of Two Novel Sealants: A Laboratory-Based Study.

This research sought to assess the impact of polyhexamethylene guanidine hydrochloride (PHMGH) and 1,3,5-triacryloyl hexahydro-1,3,5-triazine (TAT) on the antibacterial activity of an experimental resin sealant. The two experimental sealants were formulated based on previous research, and Streptococcus mutans (S. mutans) was tested for biofilm and planktonic bacteria's antibacterial properties. In 48 hours, 300 L of frozen S. mutans in skim milk was stored in an oven at 37°C in a microaerophilic atmosphere with 5% of CO2 and put on a petri plate containing brain-heart infusion (BHI) broth with agar at 15 g/L. By combining 100 mL of the subculture broth with 900 mL of a sterile saline solution (0.9%) in an Eppendorf tube, the initial inoculum used for the experiments was evaluated. The colonies were measured in colony-forming units per milliliter (CFU/mL) after being counted visually. To measure the antibacterial activity, log CFU/mL was used to express the number of bacteria in the broth that had been in contact with the samples for 24 hours. Outcomes of antibacterial activity against planktonic bacteria and against biofilm development on polymerized materials. The two innovative sealant materials were found to differ significantly from one another, while group 2's mean and standard deviation values were larger. Dental sealants designed with PHMGH and TCPTAT for anticaries application showed less bacterial growth throughout time the cavity prevention properties of the resin sealant.

Carbon-13 chemical shift tensor measurements for nitrogen-dense compounds.

This paper reports the principal values of the 13 C chemical shift tensors for five nitrogen-dense compounds (i.e., cytosine, uracil, imidazole, guanidine hydrochloride, and aminoguanidine hydrochloride). Although these are all fundamentally important compounds, the majority do not have 13 C chemical shift tensors reported in the literature. The chemical shift tensors are obtained from 1 H→13 C cross-polarization magic-angle spinning (CP/MAS) experiments that were conducted at a high field of 18.8T to suppress the effects of 14 N-13 C residual dipolar coupling. Quantum chemical calculations using density functional theory are used to obtain the 13 C magnetic shielding tensors for these compounds. The best agreement with experiment arises from calculations using the hybrid functional PBE0 or the double-hybrid functional PBE0-DH, along with the triple-zeta basis sets TZ2P or pc-3, respectively, and intermolecular effects modeled using large clusters of molecules with electrostatic embedding through the COSMO approach. These measurements are part of an ongoing effort to expand the catalog of accurate 13 C chemical shift tensor measurements, with the aim of creating a database that may be useful for benchmarking the accuracy of quantum chemical calculations, developing nuclear magnetic resonance (NMR) crystallography protocols, or aiding in applications involving machine learning or data mining. This work was conducted at the National High Magnetic Field Laboratory as part of a 2-week school for introducing undergraduate students to practical laboratory experience that will prepare them for scientific careers or postgraduate studies.

Natural Underwater Bioadhesive Offering Cohesion Modulation via Hydrogen Bond Disruptor: A Highly Injectable and in Vivo Stable Remedy for Gastric Ulcer Resolution.

Injectable bioadhesives are attractive for managing gastric ulcers through minimally invasive procedures. However, the formidable challenge is to develop bioadhesives that exhibit high injectability, rapidly adhere to lesion tissues with fast gelation, provide reliable protection in the harsh gastric environment, and simultaneously ensure stringent standards of biocompatibility. Here, a natural bioadhesive with tunable cohesion is developed based on the facile and controllable gelation between silk fibroin and tannic acid. By incorporating a hydrogen bond disruptor (urea or guanidine hydrochloride), the inherent network within the bioadhesive is disturbed, inducing a transition to a fluidic state for smooth injection (injection force <5N). Upon injection, the fluidic bioadhesive thoroughly wets tissues, while the rapid diffusion of the disruptor triggers instantaneous in situ gelation. This orchestrated process fosters the formed bioadhesive with durable wet tissue affinity and mechanical properties that harmonize with gastric tissues, thereby bestowing long-lasting protection for ulcer healing, as evidenced through in vitro and in vivo verification. Moreover, it can be conveniently stored (≥3m) postdehydration. This work presents a promising strategy for designing highly injectable bioadhesives utilizing natural feedstocks, avoiding any safety risks associated with synthetic materials or nonphysiological gelation conditions, and offering the potential for minimally invasive application.

An all-rounder aminoguanidine based ligand, its unusual anionic zinc(ii) and cadmium(ii) coordination complexes and their biological implications

The versatility of the ligand by protonating and deprotonating in the same medium yields unparallel complexes, one of which is more potent against E. coli than the standard ciprofloxacin, and opens-up new possibilities in coordination chemistry.

Guanidine hydrochloride (GuHCl)-catalysed microwave-mediated solvent- and metal-free synthesis of pyrimido[1,2-a]benzimidazole from aryl aldehyde and aryl methyl ketone

The rapid, eco-friendly, solvent- and metal-free microwave-assisted synthesis of pyrimido[1,2-a]benzimidazole in high yields was achieved using the green organocatalyst guanidine hydrochloride using simple and inexpensive starting materials.

Suitability of Adenosine Derivatives in Improving the Activity and Stability of Cytochrome c under Stress: Insights into the Effect of Phosphate Groups.

It is well known that adenosine and its phosphate derivatives play a crucial role in biological phenomena such as apoptosis and cell signaling and act as the energy currency of the cell. Although their interactions with various proteins and enzymes have been described, the focus of this work is to demonstrate the effect of the phosphate group on the activity and stability of the native heme metalloprotein cytochrome c (Cyt c), which is important from both biological and industrial aspects. In situ and in silico characterizations are used to correlate the relationship between the binding affinity of adenosine and its phosphate groups with unfolding behavior, corresponding peroxidase activities, and stability factors. Interaction of adenosine (ADN), adenosine monophosphate (AMP), adenosine 5'-diphosphate (ADP), and adenosine 5'-triphosphate (ATP) with Cyt c increases peroxidase-like activity by up to 1.8-6.5-fold compared to native Cyt c. This activity is significantly maintained even after multiple stress conditions such as oxidative stress and the presence of a chaotropic agent such as guanidine hydrochloride (GuHCl). With binding affinities on the order of ADN < AMP < ADP < ATP, adenosine derivatives were found to stabilize Cyt c by varying the secondary structural features of the protein. Thus, in addition to being a fundamental study, the current work also proposes a way of stabilizing protein systems to be used for real-time biocatalytic applications.

Engineering application of recyclable guanidine hydrochloride-hexamethylenediamine phytic acid polydopamine supported melamine sponge for the efficient elimination of europium and chromium from industrial wastewater

Synthesis and application of recyclable adsorbents with many available active sites and high adsorption capacity for accomplishing quick kinetics and high removal proportion have been become significant challenges in the purified fields of radionuclides and heavy metals contamination. Herein, regenerative ploy (guanidine hydrochloride hexamethylenediamine-phytic acid)-polydopamine decorated melamine sponges (PGH/HDPA/PDA/MS) were successfully synthesized using melted polymerization approach to remove Eu(III) and Cr(VI). The sorption behaviors and interactive mechanisms of Eu(III) and Cr(VI) by PGH/HDPA/PDA/MS were obtained via macroscopical experiments under various water chemistry factors conditions. The findings of our experimental studies demonstrated that specific sorption performances of Eu(III) and Cr(VI) onto PGH/HDPA/PDA/MS hybrids could achieve equilibrium within 3 h. The maximum adsorption capacities were respectively 2.43 × 10−3 mol/g and 6.75 × 10−3 mol/g for Eu(III) and Cr(VI), which were higher than large numbers of adsorbents reported among the anterior literatures. The interactive mechanism between PGH/HDPA/PDA/MS hybrids and Eu(III) and Cr(VI) was displayed through electrostatic attraction, cation exchange, surface complexation. Besides, the partially trivalent Cr(III) was also adhered to PGH/HDPA/PDA/MS surfaces through reductive reaction. According to our studies, the PGH/HDPA/PDA/MS hybrids are regarded as feasible adsorbents for highly effective purification of trivalent lanthanides and heavy metal ions pollutions from industrial wastewater.

Design, synthesis, chemical and biological evaluation of 2,5,5-trisubstituted-1,2-thiazepan-6-one 1,1-dioxides

In this article, we designed and synthesized a series of novel 2,5,5-trisubstituted (including spirocyclic) 1,2-thiazepan-6-one 1,1-dioxides (put simply, γ,γ-disubstituted β-keto ε-sultams), prepared a number of derivatives and evaluated their cytotoxic activity against MDA-MB-231 breast cancer cell line. In particular, alkylation of N-monosubstituted methanesulfonamides with α,α-disubstituted β-halogenated esters (including cyclic representatives) afforded the corresponding N-mesylated β-amino acid esters. The latters were involved in CSIC (Carbanion-mediated Sulfonamide Intramolecular Cyclization) reaction to give the target γ,γ-disubstituted β-keto ε-sultams (including spirocyclic representatives) in synthetically useful yields. This class of compounds can be considered as valuable building blocks since they possess carbonyl functionality and an EWG-activated methylene group capable of further functionalization. For instance, the condensation with DMFDMA afforded the corresponding α-dimethylaminomethylidene derivatives – the direct precursors for the heterocyclization reactions. Their treatment with hydrazine hydrate or guanidine hydrochloride provided the corresponding pyrazolo- and pyrimidofused ε-sultams. Despite the prepared β-keto ε-sultams showing weak cytotoxicity against the MDA-MB-231 breast cancer cell line, their pyrazolofused derivatives appeared perspective pharmacological templates with stable cytotoxic effects. Moreover, β-keto ε-sultams and their heterofused derivatives form water-soluble conjugates with branched polymers based on dextran-polyacrylamide (D-PAA) that can be used as the transport module for targeted drug delivery in biological media.

Comparative evaluation of disinfectant efficacy against biofilm-residing microorganisms

Introduction. Bacteria in biofilms (BFs) have increased resistance to antibacterial agents, including disinfectants; however, the efficacy level varies depending on the chosen treatment. Therefore, evaluation of efficacy of main disinfectants against BF-residing microorganisms is of scientific and practical interest.&#x0D; The purpose of the study was to explore the effect of disinfectants from various chemical groups on gram-positive and gram-negative bacteria residing in BFs.&#x0D; Materials and methods. The effect of the following disinfectants has been evaluated: alkyldimethylbenzylammonium chloride (ADBAC), tertiary amine (TA), polyhexamethylene guanidine chloride (PHMG), hydrogen peroxide (HP), chloramine (CA), dichloroisocyanuric acid sodium salt (Na DCC), sodium hypochlorite (HC), ethyl alcohol (EA), glutaraldehyde (GA)) against Pseudomonas aeruginosa ATCC 15442 and Staphylococcus aureus ATCC 6538-P BFs. BFs were grown in 96-well plates at 37ºC for 24 hours and then exposed to biocide solutions. The efficacy of disinfectants was evaluated by the number of remaining viable cells and BF relative density.&#x0D; Results. The analyzed bacterial strains formed moderate BFs; the average number of viable cells in BFs was 6.51 ± 0.19 lg. The viable bacterial cell counts in BFs reduced by more than 4 lg when exposed to HP solutions at a concentration of 6%, Na DCC solution — 0.1% (by active chlorine), HC — 1% (by active chlorine), CA – 1% (by product), PHMG — 0.05%, TA — 1.0 %. The BF density decreased by more than 70%. ADBAC solutions at concentrations of 0.1–1.0%, TA — 0.05%, HP — 3%, Na DCC solution — 0.05% (by active chlorine) caused a 2-lg reduction in viable cell counts in BFs. The efficacy of chlorine-active compounds and HP increased when 0.5% sulfonol was added. GA (0.25–1.00%) and EA (40–70%) solutions were ineffective against BF microorganisms.&#x0D; Conclusion. A promising potential in combating microbial biofilms is demonstrated by disinfectants from the group of oxidizing agents (chlorine-active and oxygen-containing), TA and PHMG; using ADBAC as an individual compound is ineffective; aldehydes and alcohols are unable to destroy BFs and eliminate microorganisms in them.

Structural motifs in the early metallation steps of Zn(II) and Cd(II) binding to apo-metallothionein 1a

Many proteins require a metal cofactor to function and these metals are often involved in the protein folding process. The protein metallothionein (MT) has a dynamic structure capable of binding to a variety of metals with different stoichiometries. The most well-understood structure is the seven-metal, two domain structure formed upon metallation using Zn(II) or Cd(II). However, the partially metallated states and the pathways to form these clusters are less well-understood, although it is known that the pathways are pH dependent. Using stopped flow methods, it is shown that the metallation rates of the less cooperative Zn(II) binding pathway is much more impacted by low pH conditions that that of the more cooperative Cd(II) binding pathway. Electrospray ionization mass spectrometry (ESI-MS) methods reveal specific mixtures of bridging and terminally bound MxSy structures form in the first few metallation steps. Using a combination of methods, the data show that the result of unfolding this intrinsically disordered apo-MT structure using guanidinium chloride is that the formation of preliminary bridging structures that form in the first few metallation steps is impeded. The data show that more terminally bound structures form. Our conclusion is that the compact conformation of the native apo-MT at physiological pH allows for rapid formation of complex metal-thiolate structures with high affinity that provides protection from oxidation, a function that is suppressed upon unfolding. Overall, these results highlight both the importance of the apo-MT structure in the metallation pathway, but also the differences in Zn(II) and Cd(II) binding under different conditions.

Effects of glycine 64 substitutions in RNA-dependent RNA polymerase on ribavirin sensitivity and pathogenicity of coxsackievirus A6

Hand, foot, and mouth disease (HFMD) caused by a group of enteroviruses is a global public health problem. In recent years, coxsackievirus A6 (CVA6) has emerged as an important HFMD agent. Previous studies have shown that mutations of glycine 64 in RNA-dependent RNA polymerase (3D polymerase), which is central to viral replication, cause phenotypic changes such as ribavirin resistance, increased replication fidelity, and virulence attenuation in poliovirus and enterovirus A71. In this study, we constructed CVA6 mutants with G64R, G64S, and G64T substitutions by site-directed mutagenesis in full-length cDNA of an infectious CVA6 strain cloned in pcDNA3.1. Viral RNA was obtained by in vitro transcription, and the rescued virus strains were propagated in RD cells. Sequencing after six passages revealed that G64S and G64T mutations were stably inherited, whereas G64R was genetically unstable and reversed to the wild type. Comparison of the biological characteristics of the wild-type and mutant CVA6 strains in an in vivo model (one-day-old ICR mice) revealed that the pathogenicity of CVA6-G64S and CVA6-G64T was significantly reduced compared to wild-type CVA6. In vitro experiments indicated the mutant CVA6-G64S and CVA6-G64T strains had increased resistance to 0.8 mM ribavirin and a decreased replication rate in the presence of 0.8 mM guanidine hydrochloride. Our results show that mutation of residue 64 reduces CVA6 susceptibility to ribavirin and increases CVA6 susceptibility to guanidine hydrochloride, together with increased replication fidelity and attenuated viral pathogenicity, thus laying a foundation for the development of safe and effective live attenuated CVA6 vaccine.

Conformational Stability of the N-Terminal Region of MDM2.

MDM2 is an E3 ubiquitin ligase which is crucial for the degradation and inhibition of the key tumor-suppressor protein p53. In this work, we explored the stability and the conformational features of the N-terminal region of MDM2 (N-MDM2), through which it binds to the p53 protein as well as other protein partners. The isolated domain possessed a native-like conformational stability in a narrow pH range (7.0 to 10.0), as shown by intrinsic and 8-anilinonapthalene-1-sulfonic acid (ANS) fluorescence, far-UV circular dichroism (CD), and size exclusion chromatography (SEC). Guanidinium chloride (GdmCl) denaturation followed by intrinsic and ANS fluorescence, far-UV CD and SEC at physiological pH, and differential scanning calorimetry (DSC) and thermo-fluorescence experiments showed that (i) the conformational stability of isolated N-MDM2 was very low; and (ii) unfolding occurred through the presence of several intermediates. The presence of a hierarchy in the unfolding intermediates was also evidenced through DSC and by simulating the unfolding process with the help of computational techniques based on constraint network analysis (CNA). We propose that the low stability of this protein is related to its inherent flexibility and its ability to interact with several molecular partners through different routes.

A Comprehensive Comparison of Rapid RNA Extraction Methods for Detection of SARS-CoV-2 as the Infectious Agent of the Upper Respiratory Tract using Direct RT-LAMP Assay.

The current COVID-19 pandemic has highlighted the need for faster and more cost-effective diagnostic methods. The RNA extraction step in current diagnostic methods, such as real-time qPCR, increases the cost and time required for testing. Reverse-transcription loop-mediated isothermal amplification (RT-LAMP) is a promising technique for developing diagnostic tests with desired sensitivity and specificity without the need for RNA extraction. An RT-LAMP assay was developed to detect SARS-CoV-2 with a sensitivity of 0.5 copies of positive control plasmid per microliter in 40 min. Several rapid RNA extraction protocols were evaluated using different reagents, including bovine serum albumin, Triton X-100, Tween 20, proteinase K, guanidine hydrochloride, guanidinium isothiocyanate (GITC), and thermal treatment. Finally, the sensitivity and specificity of the developed direct RT-LAMP were determined using 150 upper respiratory tract samples. Method 10 was selected as the most efficient protocol for the RNA extraction step. The sensitivity and specificity of the developed direct RT-LAMP assay with clinical samples were estimated at 98.4% and 88.8%, respectively. These results suggest that the combination of GITC and Triton X-100 detergent is a highly efficient method for RNA extraction and direct RT-LAMP detection of SARS-CoV-2 in clinical samples, providing a valuable tool for the rapid and cost-effective diagnosis of COVID-19.

Effective catalysts for wastewater treatment under sunlight: Gas dependent preparation of mesoporous biphasic N-doped TiO2 nanoparticles

Photocatalysts are playing an indispensable role in tackling environmental and energy crises; however, they are associated with poor solar energy utilization. In this study, N-doped titanium dioxide (N-TiO2) nanocrystals were successfully prepared using benign N-source, guanidine chloride by simple sol-gel technique. The significance of annealing gases environment (air, argon, and nitrogen) on their physicochemical properties and photocatalytic activity under direct sunlight irradiation was investigated. XRD and Raman data revealed that the crystal structure of spheroidal N-TiO2 nanocrystals was transformed from monophase anatase with less crystallinity in argon, and nitrogen to dual-phase anatase/rutile (A/R) with higher crystallinity in air. Importantly, XPS confirmed the successful incorporation of N in interstitial sites of the bare titania structure. Moreover, DRS and PL results revealed that the introduction of N into the TiO2 matrix not only led to a red shift towards visible-light but also lowered the bandgap energy (2.35 eV) and suppressed charge carriers recombination. BET showed a typical IV isotherm of mesoporous N-TiO2 nanomaterials with a high specific surface area in the range of 80–103 m2 g−1. Furthermore, their rhodamine B (RhB) photodegradation performance and thermal-stability were dictated by the annealing gas type. Nobly, the N-TiO2 prepared in air demonstrated the highest degradation performance (99%) with the fastest rate (0.0158 min−1) which is twice faster as the control TiO2 material. Its real textile wastewater removal was 63% and 56.5% COD and TOC, respectively. These improved performances are mainly attributed to its higher crystallinity, A/R mixed phase, aqueous-dispersion character, and lower recombination rate. Such gas driven-synthesis of photocatalysts has practical applications in designing other solar energy conversion systems.

Approaching the extraction of proteins from brewing wastes using deep eutectic solvents

Deep eutectic solvents (DES) are innovative solvents with promising functionalities, including their use for the sustainable extraction of compounds. This work proposes to evaluate the potential of DES for the extraction of proteins from two residues of the brewing industry with high protein content: brewer's spent grain (BSG) and malt rootlets (MR). Fourteen different DES with pHs ranging from 1.3 to 10.2 were employed and the extraction was assisted by high intensity focussed ultrasounds (HIFU). The DES constituted by guanidinium chloride and urea (1:2) at pH 9.1 provided the highest protein yield for both residues. The extraction conditions (amount of waste, HIFU amplitude, temperature, and extraction time) were optimized by a Box-Behnken experimental design. Long extraction times, high ultrasound amplitudes, and low amounts of residue favoured the extraction of proteins. Under optimal conditions, it was possible to recover 13 ± 2 g protein/100 g from BSG and 10.2 ± 0.6 g protein/100 g from MR. Different procedures were evaluated to remove DES from the final extract. This method guaranteed the selective extraction of proteins without the presence of phenolic compounds that are usually co-extracted. Moreover, proteins with different bioactivities were identified in purified extracts by proteomic analysis and RP-UHPLC-Q-Orbitrap-MS/MS.

Fabrication of Multifunctional Cotton Fabrics with Antibacterial, Hydrophobic, and Dyeing Performance.

Cotton fibers have received considerable attention owing to their functional properties. Current research endeavors have shifted toward devising straightforward and versatile approaches for modifying cotton fibers. Herein, a simple and feasible method was proposed for preparing multifunctional cotton fibers. This method entailed subjecting cotton fibers to alkaline conditions, prompting the epoxy group in epoxidized soybean oil to engage in a ring-opening reaction with the hydroxyl group in cotton fibers and the amino group in polyhexamethylene guanidine hydrochloride. Epoxidized soybean oil acted as a bridge, forming a covalent bond between polyhexamethylene guanidine hydrochloride and cotton fibers, thereby facilitating the cationization of cotton fibers. Structural changes in the modified cotton fibers were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The modified cotton fibers were also evaluated for their dyeing, antibacterial, and hydrophobic properties. The results demonstrated that the dye exhaustion and total dye utilization of modified cotton in salt-free dyeing were much higher than those of raw cotton in conventional dyeing. The water contact angle of the modified cotton fiber reached 139.5°, and their antibacterial properties were partially improved. Importantly, this chemical modification was performed under mild conditions, highlighting its simplicity and environmentally friendly nature.

Biological Properties and Antibiotic Resistance of &lt;i&gt;Klebsiella pneumoniae&lt;/i&gt; and Its Role in the Etiological Structure of Community-Acquired Pneumonia Pathogens

Background. In a novel coronavirus pandemic, the most common complications of viral pneumonia are secondary infections of bacterial and fungal etiology. At the same time, the spread of multidrug-resistant bacteria remains a global threat to public health. One of such microorganisms of the Enterobacteriaceae family is Klebsiella pneumoniae, which belongs to dangerous resistant pathogens of the ESKAPE group.The aim of the study was the comparative analysis of the biological properties of classical and hypermucoid strains of K.pneumoniae isolated from patients with community-acquired pneumonia (CAP): characterization of their sensitivity to antibacterial drugs, Klebsiella bacteriophage, and a disinfectant (polyhexamethylene guanidine hydrochloride), as well as assessment of the strains’ virulence in the model of experimental infection in white mice.Material and methods. 56 strains of Klebsiella isolated in diagnostic quantities from patients’ sputum samples were studied. Species identification of cultures was carried out using bacteriological and mass spectrometric methods. The sensitivity of bacteria to antibiotics, bacteriophage, and the disinfectant was determined in accordance with regulatory documents.Results. In the course of the study, 243 gram-negative cultures were isolated, of which 30% were bacteria of the genus Klebsiella spp. An analysis of their species composition showed that K.pneumoniae occupied a dominant place in the structure. Based on colony morphology, Burri-Gins smear staining, and a positive string test, 14 strains with a hypermucoid phenotype were identified. These strains differed from the classic K.pneumoniae strain by the presence of a thicker capsule in smears, virulence in white mice (DCL≤103 mc), and increased resistance to commercial Klebsiella bacteriophage. At the same time, they were characterized by a wider spectrum of sensitivity to antibiotics. There were no significant differences in sensitivity to the disinfectant in strains of both morphotypes.Conclusion. The results obtained demonstrated the important role of K.pneumoniae in the etiological structure of CAP pathogens.

Biochemical Deconstruction and Reconstruction of Nuclear Matrix Reveals the Layers of Nuclear Organization

Nuclear matrix (NuMat) is the fraction of the eukaryotic nucleus insoluble to detergents and high-salt extractions that manifests as a pan-nuclear fiber-granule network. NuMat consists of ribonucleoprotein complexes, members of crucial nuclear functional modules, and DNA fragments. Although NuMat captures the organization of nonchromatin nuclear space, very little is known about components organization within NuMat. To understand the organization of NuMat components, we subfractionated it with increasing concentrations of the chaotrope guanidinium hydrochloride (GdnHCl) and analyzed the proteomic makeup of the fractions. We observe that the solubilization of proteins at different concentrations of GdnHCl is finite and independent of the broad biophysical properties of the protein sequences. Looking at the extraction pattern of the nuclear envelope and nuclear pore complex, we surmise that this fractionation represents easily solubilized/loosely bound and difficultly solubilized/tightly bound components of NuMat. Microscopic analyses of the localization of key NuMat proteins across sequential GdnHCl extractions of in situ NuMat further elaborate on the divergent extraction patterns. Furthermore, we solubilized NuMat in 8M GdnHCl and upon removal of GdnHCl through dialysis, en masse renaturation leads to RNA-dependent self-assembly of fibrous structures. The major proteome component of the self-assembled fibers comes from the difficultly solubilized, tightly bound component. This fractionation of the NuMat reveals different organizational levels within it which may reflect the structural and functional organization of nuclear architecture.