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Inorganic Chemistry Dec 2023Herein, we disclose a unique method of oxidation of a 1,4-naphthoquinone ring in air. We report that (1,4-naphthoquinone)-NH-N=C(OH)Ph (HL) coordinated to octahedral...
Herein, we disclose a unique method of oxidation of a 1,4-naphthoquinone ring in air. We report that (1,4-naphthoquinone)-NH-N=C(OH)Ph (HL) coordinated to octahedral ruthenium(II) and osmium(II) ions activates an O molecule spontaneously. Hydrogen atom transfer (HAT) from the -NH- function of HL to O and subsequent (2e + 2H) oxidation forming (1,3,4-trioxonaphthalen)=N-N=C(OH)Ph (HL) have been established. The HL → HL transformation occurs via (3-hydroperoxy-1,4-naphthoquinone)=N-N=C(O)Ph (HL) as an intermediate. The primary step is HAT generating HL and hydroperoxide (OOH) radicals. HL is delocalized over the aromatic ring and incites coupling reactions via ortho carbon and produces coordinated HL. In solution, the homolytic cleavage of the peroxo bond leads to aromatic ring oxidation, affording L. Ruthenium(II) and osmium(II) complexes of the types [M(HL)(PPh)X], [M(HL)(PPh)X], and -[M(L)(PPh)X] were successfully isolated in good yields. Notably, the cyclic voltammograms of all of the complexes exhibit reversible anodic waves due to M/M redox couples. The rate constants of the [M(HL)(PPh)X] → [M(HL)(PPh)X] conversions determined by time-driven UV-vis spectroscopy in dry CHCl, wet CHCl, and DO wet CHCl in air at 298 K follow the order > > . It is established that the rate constants are dependent on the O content of the solution but not on the concentration of the complex.
PubMed: 38047920
DOI: 10.1021/acs.inorgchem.3c03038 -
ACS Omega Feb 2024To study transcriptome dynamics without harming cells, it is essential to convert chemical bases. 4-Thiouridine (4sU) is a biocompatible uridine analogue that can be...
To study transcriptome dynamics without harming cells, it is essential to convert chemical bases. 4-Thiouridine (4sU) is a biocompatible uridine analogue that can be converted into a cytidine analogue. Although several reactions can convert 4sU into a cytidine analogue, few studies have compared the features of these reactions. In this study, we performed three reported base conversion reactions, including osmium tetroxide, iodoacetamide, and sodium periodate treatment, as well as a new reaction using 2,4-dinitrofluorobenzene. We compared the reaction time, conversion efficacy, and effects on reverse transcription. These reactions successfully converted 4sU into a cytidine analogue quantitatively using trinucleotides. However, the conversion efficacy and effect on reverse transcription vary depending on the reaction with the RNA transcript. OsO treatment followed by NHCl treatment showed the best base-conversion efficiency. Nevertheless, each reaction has its own advantages and disadvantages as a tool for studying the transcriptome. Therefore, it is crucial to select the appropriate reaction for the target of interest.
PubMed: 38434802
DOI: 10.1021/acsomega.3c08516 -
Bioinorganic Chemistry and Applications 2024X-ray crystallography, spectroscopy, computational methods, molecular docking studies, and DNA-binding studies have been useful in the investigations of intermolecular...
Molecular Structure, Spectroscopic, Frontier Molecular Orbital Analysis, Molecular Docking Studies, and DNA-Binding Studies of Osmium(II)-Cymene Complexes with Aryl Phosphine and Aryl Phosphonium Assemblies.
X-ray crystallography, spectroscopy, computational methods, molecular docking studies, and DNA-binding studies have been useful in the investigations of intermolecular and intramolecular interactions of osmium-cymene oxalato complexes with aryl phosphine and aryl phosphonium groups in both primary and secondary coordination spheres, respectively. Molecular structures of the novel complexes PPh[Os(--cymene)Br(--CO)] () and [Os(--cymene) (--CO)PPh] () were resolved by single-crystal X-ray diffraction (XRD). Primary and secondary coordination sphere contacts were investigated using Hirshfeld surface analysis which was supported by molecular docking (MD) studies. The MD data obtained predicted significant differences in binding energy across three receptors for the two osmium complexes. An DNA-binding study was accomplished using UV-Vis spectroscopy which showed that both and bond with DNA through an intercalation approach. The optimized molecular geometry, frontier molecular orbital (E and E) energies, global electrophilicity index (), chemical hardness (), chemical potential (), and the energy band gap (E-E) were calculated utilizing density functional theory (DFT) methods. Computed structural parameters (bond lengths and angles) support the experimental single-crystal XRD data.
PubMed: 38840845
DOI: 10.1155/2024/6697523 -
Ecology and Evolution Apr 2024Comparative anatomy is an important tool for investigating evolutionary relationships among species, but the lack of scalable imaging tools and stains for rapidly...
Comparative anatomy is an important tool for investigating evolutionary relationships among species, but the lack of scalable imaging tools and stains for rapidly mapping the microscale anatomies of related species poses a major impediment to using comparative anatomy approaches for identifying evolutionary adaptations. We describe a method using synchrotron source micro-x-ray computed tomography (syn-μXCT) combined with machine learning algorithms for high-throughput imaging of Lepidoptera (i.e., butterfly and moth) eyes. Our pipeline allows for imaging at rates of ~15 min/mm at 600 nm resolution. Image contrast is generated using standard electron microscopy labeling approaches (e.g., osmium tetroxide) that unbiasedly labels all cellular membranes in a species-independent manner thus removing any barrier to imaging any species of interest. To demonstrate the power of the method, we analyzed the 3D morphologies of butterfly crystalline cones, a part of the visual system associated with acuity and sensitivity and found significant variation within six butterfly individuals. Despite this variation, a classic measure of optimization, the ratio of interommatidial angle to resolving power of ommatidia, largely agrees with early work on eye geometry across species. We show that this method can successfully be used to determine compound eye organization and crystalline cone morphology. Our novel pipeline provides for fast, scalable visualization and analysis of eye anatomies that can be applied to any arthropod species, enabling new questions about evolutionary adaptations of compound eyes and beyond.
PubMed: 38571794
DOI: 10.1002/ece3.11137 -
Faraday Discussions Jul 2023Noble metal elements are focal catalytic candidates for many chemical processes, but have received little attention in the field of nitrogen fixation except ruthenium...
Noble metal elements are focal catalytic candidates for many chemical processes, but have received little attention in the field of nitrogen fixation except ruthenium and osmium. Iridium (Ir), as a representative, has been shown to be catalytically inactive for ammonia synthesis because of its weak nitrogen adsorption and severe competitive adsorption of H over N that strongly inhibits the activation of N molecules. Here we show that, upon compositing with lithium hydride (LiH), iridium can catalyze ammonia formation at much enhanced reaction rates. The catalytic performance of the LiH-Ir composite can be further improved by dispersion on a MgO support with a high specific surface area. At 400 °C and 10 bar, the MgO-supported LiH-Ir (LiH-Ir/MgO) catalyst shows a 100-fold increase in activity compared to the bulk LiH-Ir composite and the MgO-supported Ir metal catalyst (Ir/MgO). The formation of a lithium-iridium complex hydride phase was identified and characterized, and this phase may be responsible for the activation and hydrogenation of N to NH.
PubMed: 37010013
DOI: 10.1039/d2fd00142j -
Microscopy (Oxford, England) Nov 2023Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we...
Biological nanoparticles, such as bacterial outer membrane vesicles (OMVs), are routinely characterized through transmission electron microscopy (TEM). In this study, we report a novel method to prepare OMVs for TEM imaging. To preserve vesicular shape and structure, we developed a dual fixation protocol involving osmium tetroxide incubation prior to negative staining with uranyl acetate. Combining osmium tetroxide with uranyl acetate resulted in preservation of sub-50 nm vesicles and improved morphological stability, enhancing characterization of lipid-based nanoparticles by TEM.
Topics: Microscopy, Electron; Coloring Agents; Osmium Tetroxide; Bacterial Outer Membrane; Microscopy, Electron, Transmission; Staining and Labeling; Osmium
PubMed: 37148329
DOI: 10.1093/jmicro/dfad027 -
BioRxiv : the Preprint Server For... Sep 2023Scanning electron microscopy (SEM) offers an unparalleled view of the membrane topography of mammalian cells by using a conventional osmium (OsO) and ethanol-based...
Scanning electron microscopy (SEM) offers an unparalleled view of the membrane topography of mammalian cells by using a conventional osmium (OsO) and ethanol-based tissue preparation. However, conventional SEM methods limit optimal resolution due to ethanol and lipid interactions and interfere with visualization of fluorescent reporter proteins. Therefore, SEM correlative light and electron microscopy (CLEM) has been hindered by the adverse effects of ethanol and OsO on retention of fluorescence signals. To overcome this technological gap in achieving high-resolution SEM and retain fluorescent reporter signals, we developed a freeze-drying method with gaseous nitrogen (FDGN). We demonstrate that FDGN preserves cyto-architecture to allow visualization of detailed membrane topography while retaining fluorescent signals and that FDGN processing can be used in conjunction with a variety of high-resolution imaging systems to enable collection and validation of unique, high-quality data from these approaches. In particular, we show that FDGN coupled with high resolution microscopy provided detailed insight into viral or tumor-derived extracellular vesicle (TEV)-host cell interactions and may aid in designing new approaches to intervene during viral infection or to harness TEVs as therapeutic agents.
PubMed: 37808646
DOI: 10.1101/2023.09.28.559906 -
Asian Biomedicine : Research, Reviews... Oct 2023Hemolysis, elevated liver enzymes, low platelet count (HELLP) syndrome is generally considered to be a variant or complication of preeclampsia. It is a life-threatening...
BACKGROUND
Hemolysis, elevated liver enzymes, low platelet count (HELLP) syndrome is generally considered to be a variant or complication of preeclampsia. It is a life-threatening obstetric complication.
OBJECTIVES
To evaluate the immunohistochemistry and ultrastructural of syncytiotrophoblastand Hoffbauer cells in placental villi of patients with HELLP syndrome.
METHODS
Two groups of patients with a total of 50 full-term human placentas (n = 25 in each group) were assigned as the control (normotensive) and HELLP syndrome. Placental tissue samples were fixed in 10% neutral formalin and paraffin-embedding protocol was performed. We prepared 5 μm sections for histological and immunohistochemical staining. Sections were immunostained with Hoffbauer cell marker CD68. For transmission electron microscopy (TEM), placental tissue samples were fixed in 2.5% buffered glutaraldehyde and then, in 1% osmium tetroxide for routine ultrastructural examinations.
RESULTS
When the HELLP group fetal placental sections were examined, intracytoplasmic edema in syncytiotrophoblast, degenerative vacuoles, and degenerative findings on cell surface membranes were observed. Moreover, villous edema was remarkable. The number of CD68-positive Hoffbauer cells per villus control group sections was 0.23 ± 0.02 and the number of CD68-positive cells per villus in HELLP group placenta sections was 0.83 ± 0.12. The increase in the number of Hoffbauer cells per villus in the HELLP group was significant ( < 0.001). Compared with the control group, there was a significant increase in the number of Hoffbauer cells and syncytiotrophoblasts in the HELLP group, and degenerative changes were also observed in the ultrastructure of these cells.
CONCLUSIONS
Pathology of the HELLP syndrome is in relation to CD68-positive placental macrophages.
PubMed: 37899759
DOI: 10.2478/abm-2023-0065 -
Veterinary World Mar 2024The pathogenesis of staphylococcal infections is mediated by virulence factors, such as enzymes, toxins, and biofilms, which increase the resistance of microorganisms to...
BACKGROUND AND AIM
The pathogenesis of staphylococcal infections is mediated by virulence factors, such as enzymes, toxins, and biofilms, which increase the resistance of microorganisms to host immune system evasion. Testing and searching for standardized multi-level algorithms for the indication and differentiation of biofilms at the early stages of diagnosis will contribute to the development of preventive measures to control the critical points of technology and manage dangerous risk factors for the spread of infectious diseases. This research aimed to study the main stages of s biofilm formation in experiments and to analyze the dynamics of respiratory syndrome development in chickens infected with these bacteria.
MATERIALS AND METHODS
Experimental reproduction of the infectious process was performed using laboratory models: 10-day-old White Leghorn chickens (n = 20). Before the experiments, the birds were divided into two groups according to the principle of analogs: Group I (control, n = 10): the birds were intranasally inoculated with 0.5 cm of 0.9% NaCl solution; Group II (experiment, n = 10): the birds were intranasally inoculated with a suspension of bacteria, 0.5 cm, concentration 1 billion/cm.
RESULTS
Colonization of individual areas of the substrate under study occurred gradually from the sedimentation and adhesion of single motile planktonic cells to the attachment stage of microcolony development. Staining preparations with gentian violet due to the "metachromosia" property of this dye are a quick and fairly simple way to differentiate cells and the intercellular matrix of biofilms. Fixation with vapors of glutaraldehyde and osmium tetroxide preserves the natural architecture of biofilms under optical and scanning electron microscopy. Pure cultures of microorganisms were isolated from the blood, lungs, small intestine, liver, kidneys, and spleen after 5-10 days during experimental infection of chickens. Clinical signs of respiratory syndrome developed within 5-6 days after infection. Acute and subacute serous-fibrinous airsacculitis, characterized by edema and thickening of the membranes of the air sacs and the presence of turbid, watery, foamy contents in the cavity, was the most characteristic pathomorphological sign. The signs of acute congestive hyperemia and one-sided serous-fibrinous pneumonia developed with significant thickening of fibrinous deposits. In Garder's gland, there was an increase in the number of secretory sections, indicating hypersecretion of the glands. In the lymphoid follicles of Meckel's diverticulum, leukocytes, usually lymphocytes, and pseudoeosinophils were detected.
CONCLUSIONS
Hydration and heteromorphism of the internal environment of biofilms determine the localization of differentiated cells in a three-dimensional matrix for protection against adverse factors. The most characteristic pathomorphological sign was the development of acute and subacute serous-fibrinous airsacculitis when reproducing the infectious process in susceptible models. There was a significant thickening of fibrinous deposits and signs of acute congestive hyperemia and one or two serous-fibrinous pneumonia developed.
PubMed: 38680142
DOI: 10.14202/vetworld.2024.612-619 -
Advanced Healthcare Materials Mar 2024Acute kidney injury (AKI) is a common adverse event in chemotherapy patients. AKI is accompanied by the generation of reactive oxygen species (ROS) and inflammation....
Acute kidney injury (AKI) is a common adverse event in chemotherapy patients. AKI is accompanied by the generation of reactive oxygen species (ROS) and inflammation. Therefore, the management of ROS and inflammation is a potential strategy for AKI mitigation. Herein, polyethylene glycol-coated osmium nanozyme-based antidotes (Os) are developed for imaging-guided photothermal therapy (PTT) in combination with cisplatin (Pt); while, avoiding AKI induced by high-dose Pt. Os nanoantidotes can enhance the efficiency of tumor treatment during combined PTT and chemotherapy and inhibit tumor metastasis by improving the hypoxic and inflammatory tumor microenvironment. Os nanoantidotes preferentially accumulate in the kidney because of their 2-nm size distribution; and then, regulate inflammation by scavenging ROS and generating oxygen to alleviate Pt-induced AKI. Os nanoantidotes can be cleared from the kidneys by urine excretion but can be degraded under hydrogen peroxide stimulation, reducing the bio-retention of these compounds. By integrating PTT with inflammatory regulation, Os nanoantidotes have the potential to reduce the side effects of chemotherapy, offering an alternative route for the clinical management of cancer patients with chemotherapy-induced AKI.
Topics: Humans; Osmium; Reactive Oxygen Species; Acute Kidney Injury; Neoplasms; Inflammation; Antineoplastic Agents; Cell Line, Tumor; Tumor Microenvironment
PubMed: 38097368
DOI: 10.1002/adhm.202302729