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Heliyon Sep 2023Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that...
Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the assessment of novel anti-fibrotic treatments.
PubMed: 37662829
DOI: 10.1016/j.heliyon.2023.e19343 -
Organic Letters Aug 2023A novel stereoselective synthetic approach to pentahydroxyazepane iminosugars is described. The strategy relies on a key osmium-catalyzed aminohydroxylation reaction of...
A novel stereoselective synthetic approach to pentahydroxyazepane iminosugars is described. The strategy relies on a key osmium-catalyzed aminohydroxylation reaction of allylic alcohols obtained via addition of vinylmagnesium bromide to a d-mannose-derived aldehyde, which forms the new C-N bond with complete regio- and stereocontrol according to the tethering approach. Subsequent intramolecular reductive amination afforded the desired azepanes. This method represents the first application of the osmium-catalyzed tethered aminohydroxylation reaction to the synthesis of iminosugars.
PubMed: 37515782
DOI: 10.1021/acs.orglett.3c02087 -
Dalton Transactions (Cambridge, England... Mar 2024In this contribution we report the synthesis, characterization and anticancer activity of novel cyclometalated 4-phenylthiazole-derived ruthenium(II) (2a-e) and...
In this contribution we report the synthesis, characterization and anticancer activity of novel cyclometalated 4-phenylthiazole-derived ruthenium(II) (2a-e) and osmium(II) (3a-e) complexes. Formation and sufficient purity of the complexes were unambigiously confirmed by H-, C- and 2D-NMR techniques, X-ray diffractometry, HRMS and elemental analysis. The binding preferences of these cyclometalates to selected amino acids and to DNA models including G-quadruplex structures were analyzed. Additionally, their stability and behaviour in aqueous solutions was determined by UV-Vis spectroscopy. Their cellular accumulation, their ability of inducing apoptosis, as well as their interference in the cell cycle were studied in SW480 colon cancer cells. The anticancer potencies were investigated in three human cancer cell lines and revealed IC values in the low micromolar range, in contrast to the biologically inactive ligands.
Topics: Humans; Molecular Structure; Models, Molecular; Cell Line, Tumor; Antineoplastic Agents; Cell Cycle; Ruthenium; Coordination Complexes
PubMed: 38426897
DOI: 10.1039/d4dt00245h -
Scientific Reports Dec 2023The Turonian age (~ 90-94 Ma) was the hottest geological interval in the Cretaceous and also marked by the K3 event, a pronounced enrichment of He in pelagic...
The Turonian age (~ 90-94 Ma) was the hottest geological interval in the Cretaceous and also marked by the K3 event, a pronounced enrichment of He in pelagic sediments (i.e., massive input of extraterrestrial materials). Here, we present Os isotopic (Os/Os) and platinum group element (PGE) data from Turonian sedimentary records. After a sharp unradiogenic shift during the end-Cenomanian oceanic anoxic event 2, the Os/Os ratios declined continuously throughout the Turonian, which could be ascribed to the formations of several large igneous provinces (LIPs). Because the interval with the most unradiogenic Os/Os ratios (i.e., enhanced LIP volcanism) does not correspond to the warmest interval during the mid-Cretaceous, additional sources of CO, such as subduction zone volcanism or the kimberlite formation, may explain the Cretaceous Thermal Maximum. As Os isotope ratios do not show any sharp unradiogenic shifts and PGE concentrations do not exhibit a pronounced enrichment, an influx of fine-grained cosmic dust to the Earth's surface, possibly from the long-period comet showers, can be inferred at the time of the He enrichment during the mid-Turonian K3 event. Our findings highlight the different behaviors of He and PGE information in the sedimentary rocks during the input of fined-grained extraterrestrial materials.
PubMed: 38086887
DOI: 10.1038/s41598-023-49252-5 -
Inorganic Chemistry Apr 2024Deprotonation of the thioamidate group of [OsH{κ-,-[NHC(CH)S]}(≡CPh)(IPr)(PPr)]OTf [; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CFSO] results in the...
Deprotonation of the thioamidate group of [OsH{κ-,-[NHC(CH)S]}(≡CPh)(IPr)(PPr)]OTf [; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolylidene; OTf = CFSO] results in the release of acetonitrile and formation of the terminal sulfide complex OsH(S)(≡CPh)(IPr)(PPr) (), which has been transformed into the hydrosulfide [OsH(SH)(≡CPh)(IPr)(PPr)]OTf () and the methylsulfide [OsH(SMe)(≡CPh)(IPr)(PPr)]OTf () through protonation and methylation reactions, respectively. The structure, spectroscopic characteristics, and reactivity of these compounds are compared. Reactions of and with 2-hydroxypyridine and 2-mercaptopyridine afford [OsH{κ-,-[X-py]}(≡CPh)(IPr)(PPr)]OTf [X = O (), S()].
PubMed: 38488723
DOI: 10.1021/acs.inorgchem.4c00596 -
Advanced Healthcare Materials Jun 2024Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase...
Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase (GOx) can be combined with nanozymes (nanomaterials mimic enzymes) to use glucose effectively for purposes. However, there is still room for improvement in these systems, particularly in terms of process simplification, enzyme activity regulation, and treatment effects. Herein, the approach utilizes GOx to directly facilitate the biomineralized growth of osmium (Os) nanozyme (GOx-OsNCs), leading to dual-active centers and remarkable triple enzyme activities. Initially, GOx-OsNCs use vicinal dual-active centers, enabling a self-cascaded mechanism that significantly enhances glucose sensing performance compared to step-by-step reactions, surpassing the capabilities of other metal sources such as gold and platinum. In addition, GOx-OsNCs are integrated into a glucose-sensing gel, enabling instantaneous visual feedback. In the treatment of infected diabetic wounds, GOx-OsNCs exhibit multifaceted benefits by lowering blood glucose levels and exhibiting antibacterial properties through the generation of hydroxyl free radicals, thereby expediting healing by fostering a favorable microenvironment. Furthermore, the catalase-like activity of GOx-OsNCs aids in reducing oxidative stress, inflammation, and hypoxia, culminating in improved healing outcomes. Overall, this synergistic enzyme-nanozyme blend is user-friendly and holds considerable promise for diverse applications.
Topics: Glucose Oxidase; Animals; Osmium; Anti-Bacterial Agents; Wound Healing; Mice; Blood Glucose; Diabetes Mellitus, Experimental; Humans; Glucose; Wound Infection
PubMed: 38507709
DOI: 10.1002/adhm.202303548 -
Molecules (Basel, Switzerland) Apr 2024Membrane materials with osmium nanoparticles have been recently reported for bulk membranes and supported composite membrane systems. In the present paper, a catalytic...
Membrane materials with osmium nanoparticles have been recently reported for bulk membranes and supported composite membrane systems. In the present paper, a catalytic material based on osmium dispersed in n-decanol (nD) or n-dodecanol (nDD) is presented, which also works as an emulsion membrane. The hydrogenation of p-nitrophenol (PNP) is carried out in a reaction and separation column in which an emulsion in the acid-receiving phase is dispersed in an osmium nanodispersion in n-alcohols. The variables of the PNP conversion process and p-aminophenol (PAP) transport are as follows: the nature of the membrane alcohol, the flow regime, the pH difference between the source and receiving phases and the number of operating cycles. The conversion results are in all cases better for nD than nDD. The counter-current flow regime is superior to the co-current flow. Increasing the pH difference between the source and receiving phases amplifies the process. The number of operating cycles is limited to five, after which the regeneration of the membrane dispersion is required. The apparent catalytic rate constant () of the new catalytic material based on the emulsion membrane with the nanodispersion of osmium nanoparticles (0.1 × 10 s for n-dodecanol and 0.9 × 10 s for n-decanol) is lower by an order of magnitude compared to those based on adsorption on catalysts from the platinum metal group. The advantage of the tested membrane catalytic material is that it extracts p-aminophenol in the acid-receiving phase.
PubMed: 38675662
DOI: 10.3390/molecules29081842 -
Dalton Transactions (Cambridge, England... Sep 2023The transition metal frustrated Lewis pair compounds [(Cym)M(κS,P,N-HL1)][SbF] (Cym = η--MeCHiPr; H2L1 = -(-tolyl)-'-(2-diphenylphosphanoethyl)thiourea; M = Ru (5), Os...
The transition metal frustrated Lewis pair compounds [(Cym)M(κS,P,N-HL1)][SbF] (Cym = η--MeCHiPr; H2L1 = -(-tolyl)-'-(2-diphenylphosphanoethyl)thiourea; M = Ru (5), Os (6)) have been prepared from the corresponding dimer [{(Cym)MCl}(μ-Cl)] and H2L1 by successive chloride abstraction with NaSbF and AgSbF and NH deprotonation with NaHCO. Complexes 5 and 6 and the previously reported phosphano-guanidino compounds [(Cym)M(κP,N,N'-HL2)][SbF] [H2L2 = ,'-bis(-tolyl)-''-(2-diphenylphosphanoethyl) guanidine; M = Ru (7), Os (8)] and pyridinyl-guanidino compounds [(Cym)M(κN,N',N''-HL3)][SbF] [H2L3 = ,'-bis(-tolyl)-''-(2-pyridinylmethyl) guanidine; M = Ru (9), Os (10)] heterolytically activate H in a reversible manner affording the hydrido complexes [(Cym)MH(H2L)][SbF] (H2L = H2L1; M = Ru (11), Os (12); H2L = H2L2; M = Ru (13), Os (14); H2L = H2L3; M = Ru (15), Os (16)). DFT calculations carried out on the hydrogenation of complex 7 support an FLP mechanism for the process. Heating 9 and 10 in methanol yields the orthometalated complexes [(Cym)M(κN,N',C-H2L3-H)][SbF] (M = Ru (17), Os (18)). The phosphano-guanidino complex 7 activates deuterated water in a reversible fashion, resulting in the gradual deuteration of the three cymene methyl protons through sequential C(sp)-H bond activation. From DFT calculations, a metal-ligand cooperative reversible mechanism that involves the O-H bond activation and the formation of an intermediate methylene cyclohexenyl complex has been proposed. Complexes 5-10 catalyse the hydrogenation of the CC double bond of styrene and a range of acrylates, the CO bond of acetophenone and the CN bond of -benzylideneaniline and quinoline. The CC double bond of methyl acrylate adds to catalyst 9, affording complex 19 in which a new ligand exhibiting a κN,N',C coordination mode has been incorporated.
PubMed: 37665066
DOI: 10.1039/d3dt02339g -
Angewandte Chemie (International Ed. in... May 2024Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp)-H functionalization, among which the...
Chiral Osmium(II)/Salox Species Enabled Enantioselective γ-C(sp)-H Amidation: Integrated Experimental and Computational Validation For the Ligand Design and Reaction Development.
Herein, multiple types of chiral Os(II) complexes have been designed to address the appealing yet challenging asymmetric C(sp)-H functionalization, among which the Os(II)/Salox species is found to be the most efficient for precise stereocontrol in realizing the asymmetric C(sp)-H amidation. As exemplified by the enantioenriched pyrrolidinone synthesis, such tailored Os(II)/Salox catalyst efficiently enables an intramolecular site-/enantioselective C(sp)-H amidation in the γ-position of dioxazolone substrates, in which benzyl, propargyl and allyl groups bearing various substituted forms are well compatible, affording the corresponding chiral γ-lactam products with good er values (up to 99 : 1) and diverse functionality (>35 examples). The unique performance advantage of the developed chiral Os(II)/Salox system in terms of the catalytic energy profile and the chiral induction has been further clarified by integrated experimental and computational studies.
PubMed: 38499469
DOI: 10.1002/anie.202401498 -
Journal of Lipid Research May 2024Contrast-enhanced computed tomography offers a nondestructive approach to studying adipose tissue in 3D. Several contrast-enhancing staining agents (CESAs) have been...
Contrast-enhanced computed tomography offers a nondestructive approach to studying adipose tissue in 3D. Several contrast-enhancing staining agents (CESAs) have been explored, whereof osmium tetroxide (OsO) is the most popular nowadays. However, due to the toxicity and volatility of the conventional OsO, alternative CESAs with similar staining properties were desired. Hf-WD 1:2 POM and Hexabrix have proven effective for structural analysis of adipocytes using contrast-enhanced computed tomography but fail to provide chemical information. This study introduces isotonic Lugol's iodine (IL) as an alternative CESA for adipose tissue analysis, comparing its staining potential with Hf-WD 1:2 POM and Hexabrix in murine caudal vertebrae and bovine muscle tissue strips. Single and sequential staining protocols were compared to assess the maximization of information extraction from each sample. The study investigated interactions, distribution, and reactivity of iodine species towards biomolecules using simplified model systems and assesses the potential of the CESA to provide chemical information. (Bio)chemical analyses on whole tissues revealed that differences in adipocyte gray values post-IL staining were associated with chemical distinctions between bovine muscle tissue and murine caudal vertebrae. More specific, a difference in the degree of unsaturation of fatty acids was identified as a likely contributor, though not the sole determinant of gray value differences. This research sheds light on the potential of IL as a CESA, offering both structural and chemical insights into adipose tissue composition.
PubMed: 38823780
DOI: 10.1016/j.jlr.2024.100572