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• Pub. Date : 2025
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AbstractMultidrug-resistantStaphylococcus aureusis a major global health threat, with the VraTSR three-component system playing a key role in sensing and conferring resistance to cell-wall active antibiotics, particularly vancomycin. VraTSR comprises the membrane histidine kinase VraS, the cytoplasmic response regulator VraR, and the uncharacterized membrane protein VraT, which regulate the cell wall stress stimulon. However, the molecular signals sensed by VraTSR remain unknown. To elucidate the activation mechanism of this regulatory system, we investigated interactions with β-lactams and glycopeptides. Using a transcriptional reporter strain, we confirmed VraTSR activation by β-lactams, glycopeptides, a vancomycin-derived photoprobe (VPP), and the previously unreported activators A47934 and moenomycin A. Photo-crosslinking assays with VPP and full-length VraS expressed in membranes revealed a direct interaction with vancomycin, which was further confirmed in purified VraS reconstituted in liposomes. VPP binding was concentration-dependent, saturable, and displaced by vancomycin. Saturation transfer difference (STD) Nuclear Magnetic Resonance (NMR) experiments confirmed vancomycin binding to VraS and demonstrated ampicillin interaction, highlighting the involvement of aryl protons from both antibiotics. These findings establish VraS as a receptor for vancomycin and ampicillin. In contrast, assays with membrane vesicles expressing only VraT or co-expressing VraS/VraT did not show covalent adduct formation between VraT and VPP. While VraT’s exact role remains unclear, its participation in antibiotic sensing or signal transduction cannot yet be excluded. These results demonstrate that vancomycin and ampicillin directly activate VraS, providing critical insights into the activation of the cell wall stress stimulon and the mechanisms underlying antibiotic resistance. Disrupting VraTSR signaling is a promising strategy to combat multidrug resistance inS. aureus,and we provide invaluablein vitroplatforms for identifying potential VraS inhibitors.Author SummaryMultidrug-resistantStaphylococcus aureusposes a major global health threat due to its resistance to cell-wall active antibiotics. Our study focuses on the VraTSR three-component system, a key regulator of the cell wall stress response inS. aureus, whose activation signals have remained unknown.We demonstrate that VraS, the membrane histidine kinase of the system, acts as a direct receptor for vancomycin and ampicillin—two structurally distinct antibiotics. These findings uncover the activation mechanism of VraTSR and position VraS as a central player in antibiotic sensing and resistance.By identifying VraS as a direct antibiotic receptor, we provide a promising target for developing inhibitors to disrupt VraTSR signaling and restore antibiotic efficacy. Additionally, thein vitroplatforms we established enable the identification and testing of potential VraS inhibitors.This study highlights the importance of understanding bacterial stress-response pathways to combat antibiotic resistance, offering critical insights for developing new therapeutic strategies against multidrug-resistantS. aureus, a growing global health challenge.

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• Pub. Date : 2025
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The luminescence properties of BaMgF4 ceramics synthesized using electron beam-assisted synthesis were investigated under vacuum ultraviolet (VUV) synchrotron excitation at a cryogenic temperature of T = 9 K. Their excitation spectra, measured over the 4–10.8 eV range, and corresponding luminescence spectra revealed a complex multicomponent structure with emission maxima at 3.71, 3.55, 3.33, 3, and ~2.8 eV. The primary luminescence band at 330 nm was attributed to self-trapped excitons (STE) excited near the band edge (9.3–9.7 eV), indicating interband transitions and subsequent excitonic relaxation. Bands at 3 and ~2.8 eV were associated with defect states efficiently excited at 6.45 eV, 8 eV and high-energy transitions near 10.3 eV. The excitation spectrum showed distinct maxima at 5, 6.45, and 8 eV, which were interpreted as excitations of defect-related states. These results highlight the interplay between interband transitions, excitonic processes, and defect-related luminescence, which defines the complex dynamics of BaMgF4 ceramics. These findings confirm that radiation synthesis introduces defect centers influencing luminescent properties, making BaMgF4 a promising material for VUV and UV applications.

• Book : 15(2)
• Pub. Date : 2025
• Page : pp.127-127
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Solvents are particularly hazardous among the mixture of pollutants found in the air, as their low vapor pressure allows them to reach the atmosphere, causing damage to ecosystems, and producing secondary deleterious effects on living organisms through a wide variety of possible reactions. In response, innovative, sustainable, and ecological methods are being developed to recover solvents from industrial wastewater, which is typically contaminated with other organic compounds. This study describes the procedure for recovering acetone from a residue from the pharmaceutical industry. This compound contains a high amount of solid organic compounds, which are generated during the manufacture of medicines. The treatment consisted of performing a simple solar distillation using a single-slope glass solar still, which separated the acetone from the mother solution. Under ideal circumstances, the use of solar radiation allowed an efficiency rate of 80% using solar concentration by means of mirrors to increase the temperature and 85% without the use of mirrors in the production of distilled acetone, which was characterized to evaluate its quality using instrumental analytical techniques: NMR, IR, and GC. The results obtained indicate that the acetone recovered by this procedure has a good quality of 84%; however, due to this percentage obtained, its reuse is limited for certain applications where a high degree of purity is required, such as its reuse for pharmaceutical use; for this reason, it was proposed to use said compound to eliminate the organic impurities contained in the catalyst waste granules used in a Mexican oil refinery. The resulting material was examined by SEM and EDS, revealing a high initial carbon content that decreased by 29% after treatment. Likewise, as an additional study, a study was carried out to evaluate the characteristics of the residues obtained at the end of the distillation where rubidium, silicon, carbon, nitrogen, oxygen, and chlorine contents were observed.

• Book : 13(2)
• Pub. Date : 2025
• Page : pp.361-361
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Hysteretic nonlinear elasticity is often observed in consolidated granular media, including concrete, mortar, sandstones, or rocks. Nonlinearity is frequently quantified using Nonlinear Resonant Ultrasonic Spectroscopy (NRUS), which provides tools to define nonlinear parameters for both fast and slow dynamic effects, often observed when analyzing the propagation velocity dependence on strain in such materials. The dependence of these parameters on temperature was studied with the aim of using NRUS to quantify the induced thermal damage; thus, experiments were performed spanning a wide temperature range. However, since most of these materials are used in construction (concrete and sandstone, mostly), it is of interest to understand how sensitive the measured nonlinear parameters are to small environmental temperature fluctuations. In this paper, the dependence on temperature of elastic parameters is investigated, both linear (wave velocity and damping) and nonlinear (the slope and hysteresis of the curves describing the strain dependence of wave velocity and residual conditioning effect on wave velocity), separating the slow from the fast dynamic properties of nonlinearity. The observations reported here denote a different behavior for concrete and Berea sandstone.

• Book : 15(3)
• Pub. Date : 2025
• Page : pp.1230-1230
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Abstract Objective Chemotherapy plays an important role in the treatment of optic pathway hypothalamic gliomas (OPHGs). Commonly used regimens include carboplatin and vincristine and monotherapy with vinblastine weekly. In this retrospective study, we used a monthly regimen of carboplatin and vinblastine to treat progressive/recurrent OPHGs and evaluated its effectiveness, visual preservation, and toxicity. Methods The study involved patients with OPGH who were treated with carboplatin and vinblastine once per month. The response, disease progression, overall survival, vision changes, and toxicity were recorded according to their medical charts at our institute, and survival was analyzed. Results A total of 25 patients were included, including 15 males (60%) and 10 females (40%). The response rate was 11/25 (44%), and the stabilization rate (complete response rate + partial response rate + minor response rate + and stable disease rate) was 21/25 (84%). The 3-year progression-free survival rate was 54.6%, and the 5-year progression-free survival rate was 46.8%. The 5-year overall survival rate was 100%. There were 6 patients who showed improved visual acuity (28.6%). Stable vision was found in 52.4% of patients. Only 2 patients experienced severe allergic reactions to carboplatin. Conclusions The results showed that extending the dosing interval of carboplatin and vinblastine to every month can be seen as a similar response compared with previous regimens. The toxicity of this regimen is milder, and patients benefit from a lower frequency of hospital visits. The regimen can be considered as a choice of the first line of chemotherapy for OPHG patients.

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• Pub. Date : 2025
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The work is devoted to studying the composition for grain (barley and wheat) by terahertz (THz) high-resolution gas spectroscopy. The comparison of the set of chemical compounds formed during thermal decomposition of grain and cereals produced from grain was carried out with using a high-resolution spectrometer with phase-switching of radiation in the range of 115-175 GHz acting on studied gas developed by the authors. Free online spectroscopy databases were used for identification of substances. The results of comparison of molecular profiles of gas mixtures of thermal decomposition products of two varieties of barley, pearl barley and one variety of wheat are presented. Good agreement of the molecular composition for barley and pearl barley and some difference from the composition of the mixture obtained by heating wheat are shown.

• Book : 2025(1)
• Pub. Date : 2025
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