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The Israel Medical Association Journal... Oct 2007OsO4 is a powerful oxidizer. It affects mainly the skin and mucous membranes. Although unsuitable for a large-scale terrorist attack, mainly due to its scarcity, it... (Review)
Review
OsO4 is a powerful oxidizer. It affects mainly the skin and mucous membranes. Although unsuitable for a large-scale terrorist attack, mainly due to its scarcity, it could be used in small-scale attacks. The small quantity contained in a vial would cause irritation to the eyes, nose, throat and skin. Combining the agent with an explosive material will probably destroy most of it, chemically. Thus, releasing the chemical without using explosives may be considerably more dangerous. Medical management is mainly symptomatic. As soon as the chemical enters the body, it rapidly reacts with the tissues in contact. Medical personnel should be aware of its poisonous effects and be equally familiar with the necessary self-protection measures and the treatment protocols.
Topics: Chemical Terrorism; Chemical Warfare Agents; Emergency Treatment; Environmental Exposure; Humans; Mucous Membrane; Osmium Tetroxide; Oxidants; Skin
PubMed: 17987767
DOI: No ID Found -
RNA (New York, N.Y.) Apr 2017Structured RNAs have a central role in cellular function. The capability of structured RNAs to adopt fixed architectural structures or undergo dynamic conformational...
Structured RNAs have a central role in cellular function. The capability of structured RNAs to adopt fixed architectural structures or undergo dynamic conformational changes contributes to their diverse role in the regulation of gene expression. Although numerous biophysical and biochemical tools have been developed to study structured RNAs, there is a continuing need for the development of new methods for the investigation of RNA structures, especially methods that allow RNA structure to be studied in solution close to its native cellular conditions. Here we use osmium tetroxide (OsO) as a chemical probe of RNA structure. In this method, we have used fluorescence-based sequencing technologies to detect OsO modified RNA. We characterized the requirements for OsO modification of RNA by investigating three known structured RNAs: the M-box, glycine riboswitch RNAs, and tRNA Our results show that OsO predominantly modifies RNA at uracils that are conformationally exposed on the surface of the RNA. We also show that changes in OsO reactivity at flexible positions in the RNA correlate with ligand-driven conformational changes in the RNA structure. Osmium tetroxide modification of RNA will provide insights into the structural features of RNAs that are relevant to their underlying biological functions.
Topics: Base Sequence; Molecular Probes; Nucleic Acid Conformation; Osmium Tetroxide; RNA, Transfer, Asp; Riboswitch; Staining and Labeling; Uracil
PubMed: 28115596
DOI: 10.1261/rna.057539.116 -
Cytometry. Part a : the Journal of the... Jan 2017Mass cytometry offers the advantage of allowing the simultaneous measurement of a greater number parameters than conventional flow cytometry. However, to date, mass...
Mass cytometry offers the advantage of allowing the simultaneous measurement of a greater number parameters than conventional flow cytometry. However, to date, mass cytometry has lacked a reliable alternative to the light scatter properties that are commonly used as a cell size metric in flow cytometry (forward scatter intensity-FSC). Here, we report the development of two plasma membrane staining assays to evaluate mammalian cell size in mass cytometry experiments. One is based on wheat germ agglutinin (WGA) staining and the other on Osmium tetroxide (OsO ) staining, both of which have preferential affinity for cell membranes. We first perform imaging and flow cytometry experiments to establish a relationship between WGA staining intensity and traditional measures of cell size. We then incorporate WGA staining in mass cytometry analysis of human whole blood and show that WGA staining intensity has reproducible patterns within and across immune cell subsets that have distinct cell sizes. Lastly, we stain PBMCs or dissociated lung tissue with both WGA and OsO ; mass cytometry analysis demonstrates that the two staining intensities correlate well with one another. We conclude that both WGA and OsO may be used to acquire cell size-related parameters in mass cytometry experiments, and expect these stains to be broadly useful in expanding the range of parameters that can be measured in mass cytometry experiments. © 2016 International Society for Advancement of Cytometry.
Topics: Animals; Cell Membrane; Cell Size; Flow Cytometry; Humans; Osmium Tetroxide; Wheat Germ Agglutinins
PubMed: 27768827
DOI: 10.1002/cyto.a.23000 -
Membranes Oct 2022Liquid membranes based on nanoparticles follow a continuous development, both from obtaining methods and characterization of techniques points of view. Lately, osmium...
Liquid membranes based on nanoparticles follow a continuous development, both from obtaining methods and characterization of techniques points of view. Lately, osmium nanoparticles have been deposited either on flat membranes, with the aim of initiating some reaction processes, or on hollow fiber membranes, with the aim of increasing the contact surface with the phases of the membrane system. This paper presents the obtainment and characterization of a liquid membrane based on osmium nanoparticles (Os-NP) dispersed in decanol (Dol) for the realization of a membrane system with a large contact surface between the phases, but without using a liquid membrane support. The dispersion of osmium nanoparticles in -decanol is carried out by the method of reducing osmium tetroxide with 1-undecenoic acid (UDA). The resulting membrane was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy analysis (EDAX), thermoanalysis (TG, DSC), Fourier transform infra-red (FTIR) spectroscopy and dynamic light scattering (DLS). In order to increase the mass transfer surface, a design for the membrane system was realized with the dispersion of the membrane through the receiving phase and the dispersion of the source phase through the membrane (DBLM-dispersion bulk liquid membrane). The process performance was tested for the reduction of -nitrophenol (pNP) from the source phase, using sodium tetra-borohydride (NaBH), to -aminophenol (pAP), which was transported and collected in the receiving phase. The obtained results show that membranes based on the dispersion of osmium nanoparticles in -decanol can be used with an efficiency of over 90% for the reduction of -nitrophenol and the separation of -aminophenol.
PubMed: 36295782
DOI: 10.3390/membranes12101024 -
Molecules (Basel, Switzerland) Mar 2023Sharpless asymmetric dihydroxylation is an important reaction in the enantioselective synthesis of chiral vicinal diols that involves the treatment of alkene with osmium... (Review)
Review
Sharpless asymmetric dihydroxylation is an important reaction in the enantioselective synthesis of chiral vicinal diols that involves the treatment of alkene with osmium tetroxide along with optically active quinine ligand. Sharpless introduced this methodology after considering the importance of enantioselectivity in the total synthesis of medicinally important compounds. Vicinal diols, produced as a result of this reaction, act as intermediates in the synthesis of different naturally occurring compounds. Hence, Sharpless asymmetric dihydroxylation plays an important role in synthetic organic chemistry due to its undeniable contribution to the synthesis of biologically active organic compounds. This review emphasizes the significance of Sharpless asymmetric dihydroxylation in the total synthesis of various natural products, published since 2020.
Topics: Hydroxylation; Biological Products; Alkenes; Stereoisomerism
PubMed: 36985698
DOI: 10.3390/molecules28062722 -
Beilstein Journal of Nanotechnology 2016Osmium tetroxide 2,2'-bipyridine (OsBp) is known to react with pyrimidines in ssDNA and preferentially label deoxythymine (T) over deoxycytosine (C). The product,...
Osmium tetroxide 2,2'-bipyridine (OsBp) is known to react with pyrimidines in ssDNA and preferentially label deoxythymine (T) over deoxycytosine (C). The product, osmylated DNA, was proposed as a surrogate for nanopore-based DNA sequencing due to OsBp's "perfect" label attributes. Osmylated deoxyoligos translocate unassisted and measurably slow via sub-2 nm SiN solid-state nanopores, as well as via the alpha-hemolysin (α-HL) pore. Both nanopores discriminate clearly between osmylated and intact nucleobase; α-HL was also shown to discriminate between osmylated T and osmylated C. Experiments presented here confirm that the kinetics of osmylation are comparable for short oligos and long ssDNA and show that pyrimidine osmylation is practically complete in two hours at room temperature with less than 15 mM OsBp. Under the proposed labeling conditions: deoxyoligo backbone degradation measures less than 1/1,000,000; false positives such as osmylated deoxyadenine (A) and osmylated deoxyguanine (G) measure less than 1/100,000; false negatives, i.e., unosmylated C measure less than 1/10,000; and unosmylated T must measure substantially lower than 1/10,000 due to the 27-fold higher reactivity of T compared to C. However, osmylated C undergoes degradation that amounts to about 1-2% for the duration of the labeling protocol. This degradation may be further characterized, possibly suppressed, and the properties of the degradation products via nanopore translocation can be evaluated to assure base calling quality in a DNA sequencing effort.
PubMed: 27826518
DOI: 10.3762/bjnano.7.135 -
Basic & Clinical Pharmacology &... Apr 2021
Topics: Osmium; Osmium Tetroxide; Skin
PubMed: 33459507
DOI: 10.1111/bcpt.13562 -
Accounts of Chemical Research May 2016The standard method of screening ligands for selectivity in asymmetric, transition metal-catalyzed reactions requires experimental testing of hundreds of ligands from...
The standard method of screening ligands for selectivity in asymmetric, transition metal-catalyzed reactions requires experimental testing of hundreds of ligands from ligand libraries. This "trial and error" process is costly in terms of time as well as resources and, in general, is scientifically and intellectually unsatisfying as it reveals little about the underlying mechanism behind the selectivity. The accurate computational prediction of stereoselectivity in enantioselective catalysis requires adequate conformational sampling of the selectivity-determining transition state but has to be fast enough to compete with experimental screening techniques to be useful for the synthetic chemist. Although electronic structure calculations are accurate and general, they are too slow to allow for sampling or fast screening of ligand libraries. The combined requirements can be fulfilled by using appropriately fitted transition state force fields (TSFFs) that represent the transition state as a minimum and allow fast conformational sampling using Monte Carlo. Quantum-guided molecular mechanics (Q2MM) is an automated force field parametrization method that generates accurate, reaction-specific TSFFs by fitting the functional form of an arbitrary force field using only electronic structure calculations by minimization of an objective function. A key feature that distinguishes the Q2MM method from many other automated parametrization procedures is the use of the Hessian matrix in addition to geometric parameters and relative energies. This alleviates the known problems of overfitting of TSFFs. After validation of the TSFF by comparison to electronic structure results for a test set and available experimental data, the stereoselectivity of a reaction can be calculated by summation over the Boltzman-averaged relative energies of the conformations leading to the different stereoisomers. The Q2MM method has been applied successfully to perform virtual ligand screens on a range of transition metal-catalyzed reactions that are important from both an industrial and an academic perspective. In this Account, we provide an overview of the continued improvement of the prediction of stereochemistry using Q2MM-derived TSFFs using four examples from different stages of development: (i) Pd-catalyzed allylation, (ii) OsO4-catalyzed asymmetric dihydroxylation (AD) of alkenes, (iii) Rh-catalyzed hydrogenation of enamides, and (iv) Ru-catalyzed hydrogenation of ketones. In the current form, correlation coefficients of 0.8-0.9 between calculated and experimental ee values are typical for a wide range of substrate-ligand combinations, and suitable ligands can be predicted for a given substrate with ∼80% accuracy. Although the generation of a TSFF requires an initial effort and will therefore be most useful for widely used reactions that require frequent screening campaigns, the method allows for a rapid virtual screen of large ligand libraries to focus experimental efforts on the most promising substrate-ligand combinations.
Topics: Alkenes; Alkylation; Amides; Catalysis; Hydrogenation; Hydroxylation; Ketones; Models, Chemical; Osmium Tetroxide; Palladium; Quantum Theory; Rhodium; Stereoisomerism
PubMed: 27064579
DOI: 10.1021/acs.accounts.6b00037 -
Scientific Reports Oct 2022Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of...
Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of brain lesions was performed using two techniques: (1) histological methods, such as TTC (Triphenyltetrazolium chloride), a time-consuming and inaccurate process; or (2) MRI imaging, a faster, 3D imaging method, that comes at a high cost. In the last decade, high-resolution micro-CT for 3D sample analysis turned into a simple, fast, and cheaper solution. Here, we successfully describe the application of brain contrasting agents (Osmium tetroxide and inorganic iodine) for high-resolution micro-CT imaging for fine location and quantification of ischemic lesion and edema in mouse preclinical stroke models. We used the intraluminal transient MCAO (Middle Cerebral Artery Occlusion) mouse stroke model to identify and quantify ischemic lesion and edema, and segment core and penumbra regions at different time points after ischemia, by manual and automatic methods. In the transient-ischemic-attack (TIA) mouse model, we can quantify striatal myelinated fibers degeneration. Of note, whole brain 3D reconstructions allow brain atlas co-registration, to identify the affected brain areas, and correlate them with functional impairment. This methodology proves to be a breakthrough in the field, by providing a precise and detailed assessment of stroke outcomes in preclinical animal studies.
Topics: Animals; Mice; Osmium Tetroxide; X-Ray Microtomography; Stroke; Infarction, Middle Cerebral Artery; Disease Models, Animal; Iodine
PubMed: 36261475
DOI: 10.1038/s41598-022-21494-9 -
Nanomaterials (Basel, Switzerland) Sep 2021Composite membranes play a very important role in the separation, concentration, and purification processes, but especially in membrane reactors and membrane...
Composite membranes play a very important role in the separation, concentration, and purification processes, but especially in membrane reactors and membrane bioreactors. The development of composite membranes has gained momentum especially through the involvement of various nanoparticles, polymeric, oxide, or metal, that have contributed to increasing their reactivity and selectivity. This paper presents the preparation and characterization of an active metal nanoparticle-support polymer type composite membrane, based on osmium nanoparticles obtained in situ on a polypropylene hollow fiber membrane. Osmium nanoparticles are generated from a solution of osmium tetroxide in butyl alcohol by reduction with molecular hydrogen in a contactor with a polypropylene membrane. The composite osmium-polypropylene hollow fiber obtained membranes (Os-PPM) were characterized from the morphological and structural points of view: scanning electron microscopy (SEM), high resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX), X-ray diffraction analysis (XRD), Fourier transform Infrared (FTIR) spectroscopy, thermal gravimetric analysis, and differential scanning calorimetry (TGA, DSC). The process performance was tested in a redox process of nitrophenol and 10-undecylenic (10-undecenoic) acid, as a target substance of biological or biomedical interest, in solutions of lower aliphatic alcohols in a membrane contactor with a prepared composite membrane. The characteristics of osmium nanoparticles-polypropylene hollow fiber membranes open the way to biological and biotechnological applications. These membranes do not contaminate the working environment, operate at relatively low temperatures, provide a large contact area between reactants, allow successive oxidation and reduction operations in the same module, and help to recover the reaction mass by ultrafiltration. The results obtained show that the osmium-polypropylene composite membrane allows the reduction of nitrophenol or the oxidation of 10-undecylenic acid, the conversion depending on the concentration in the lower aliphatic alcohol, the nature of the lower aliphatic alcohol, and the oxidant or reducing flow through the membrane contactor.
PubMed: 34684968
DOI: 10.3390/nano11102526