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Methods in Molecular Biology (Clifton,... 2017Histochemical techniques enable the specific identification of myelin by light microscopy. Here we describe three histochemical methods for the staining of myelin...
Histochemical techniques enable the specific identification of myelin by light microscopy. Here we describe three histochemical methods for the staining of myelin suitable for formalin-fixed and paraffin-embedded materials. The first method is conventional luxol fast blue (LFB) method which stains myelin in blue and Nissl bodies and mast cells in purple. The second method is a LBF-based method called MCOLL, which specifically stains the myelin as well the collagen fibers and cells, giving an integrated overview of the histology and myelin content of the tissue. Finally, we describe the osmium tetroxide method, which consist in the osmication of previously fixed tissues. Osmication is performed prior the embedding of tissues in paraffin giving a permanent positive reaction for myelin as well as other lipids present in the tissue.
Topics: Animals; Fluorescent Antibody Technique; Histocytochemistry; Immunohistochemistry; Microscopy; Myelin Sheath; Nerve Tissue; Rats; Staining and Labeling; Tissue Fixation
PubMed: 28155156
DOI: 10.1007/978-1-4939-6788-9_15 -
National Science Review Mar 2023Aromatic metallacycles are of considerable current interest. Reported aromatic metallacycles are mainly those with carbon, nitrogen, oxygen and sulfur. In this work, we...
Aromatic metallacycles are of considerable current interest. Reported aromatic metallacycles are mainly those with carbon, nitrogen, oxygen and sulfur. In this work, we report the synthesis and characterization of aromatic chloroosmacyclopentatrienes, which represent the first structurally confirmed metallaaromatic with a chlorine atom in its framework. Single-crystal X-ray diffraction studies show that these planar chloroosmacyclopentatrienes possess a very short Os-ClC distance suggesting M=ClC bond character.
PubMed: 37063704
DOI: 10.1093/nsr/nwac237 -
IUCrData Jul 2020The title compound, [Os(CHNP)(CO)], crystallizes in the ortho-rhom-bic space group with = 8. The mol-ecule consists of a triangular triosmium(0) core surrounded by...
The title compound, [Os(CHNP)(CO)], crystallizes in the ortho-rhom-bic space group with = 8. The mol-ecule consists of a triangular triosmium(0) core surrounded by eight carbonyl ligands and four 1,3,5-tri-aza-7-phosphatri-cyclo-[3.3.1.1]decane (or PTA) ligands. One Os atom is coordinated by two PTA ligands and two CO ligands, while the other two Os atoms are each bonded to a single PTA ligand and three CO ligands. There is a small disorder associated with the Os unit so that a minor orientation has an occupancy of 2.17 (4)%. The title compound represents the first structurally characterized triangular Os carbonyl cluster with four monodentate tertiary phosphane ligands.
PubMed: 36339792
DOI: 10.1107/S2414314620009359 -
Chemistry (Weinheim An Der Bergstrasse,... Dec 2022Although osmabenzyne, osmanaphthalyne, osmaphenanthryne, and osmaanthracyne have been previously reported, the synthesis of polycyclic osmaarynes is still a challenge....
Although osmabenzyne, osmanaphthalyne, osmaphenanthryne, and osmaanthracyne have been previously reported, the synthesis of polycyclic osmaarynes is still a challenge. Herein, we report the successful synthesis of the first pentacyclic osmaarynes (pyreno[b]osmabenzynes 1 a and 2 a) and hexacyclic osmaaryne (peryleno[b]osmabenzyne 3 a). Nucleophilic reaction of osmaarynes was used to obtain the corresponding pyreno[b]osmium complexes (1 and 2) and peryleno[b] osmium complex (3), which exhibited near-infrared luminescence and aggregation-induced emission (AIE) properties. Complexes 2 and 3 are resistant to photodegradation, and complex 2 has better photothermal conversion properties than 3.
Topics: Osmium; Luminescence
PubMed: 36198664
DOI: 10.1002/chem.202202334 -
Developmental Neurobiology Sep 2020Tissue and neural engineering for various regenerative therapies are rapidly growing fields. Of major interest is studying the complex interface between cells and...
Tissue and neural engineering for various regenerative therapies are rapidly growing fields. Of major interest is studying the complex interface between cells and various 3D structures by scanning electron microscopy with focused ion beam. Notwithstanding its unrivaled resolution, the optimal fixation, dehydration, and staining protocols of the samples while preserving the complex cell interface in its natural form, are highly challenging. The aim of this work was to compare and optimize staining and sample drying procedures in order to preserve the cells in their "life-like state" for studying the cell interface with either 3D well-like structures or gold-coated mushroom-shaped electrodes. The process involved chemical fixation using a combination of glutaraldehyde and formaldehyde, followed by gentle drying techniques in which we compared four methods: (critical point drying, hexamethyldisiloxane, repeats of osmium tetroxide-thiocarbohydrazide [OTOTO], and resin) in order to determine the method that best preserves the cell and cell interface morphology. Finally, to visualize the intracellular organelles and membrane, we compared the efficacy of four staining techniques: osmium tetroxide, osmium tetroxide and salts, osmium and uranyl acetate, and OTOTO. Experiments were performed on embryonic stem cell-derived photoreceptor precursors, neural cells, and a human retinal pigment epithelial cell line, which revealed that the optimal processing combination was resin drying and OTOTO staining, as manifested by preservation of cell morphology, the lowest percentage of cellular protrusion breakage as well as a high-quality image. The obtained results pave the way for better understanding the cell interface with various structures for enhancing various biomedical applications.
Topics: Animals; Cell Line; Cells, Cultured; Embryonic Stem Cells; Humans; Imaging, Three-Dimensional; Mice; Microscopy, Electron, Scanning; Osmium Tetroxide; Retinal Pigment Epithelium
PubMed: 31228876
DOI: 10.1002/dneu.22707 -
Open Research Europe 2022Precious metal nanoparticles are key for a range of applications ranging from catalysis and sensing to medicine. While gold (Au), silver (Ag), platinum (Pt), palladium... (Review)
Review
Precious metal nanoparticles are key for a range of applications ranging from catalysis and sensing to medicine. While gold (Au), silver (Ag), platinum (Pt), palladium (Pd) or ruthenium (Ru) nanoparticles have been widely studied, other precious metals are less investigated. Osmium (Os) is one of the least studied of the precious metals. However, Os nanoparticles are interesting materials since they present unique features compared to other precious metals and Os nanomaterials have been reported to be useful for a range of applications, catalysis or sensing for instance. With the increasing availability of advanced characterization techniques, investigating the properties of relatively small Os nanoparticles and clusters has become easier and it can be expected that our knowledge on Os nanomaterials will increase in the coming years. This review aims to give an overview on Os and Os oxide materials syntheses and applications.
PubMed: 37645302
DOI: 10.12688/openreseurope.14595.2 -
Chemical Society Reviews Feb 2018Anticancer metallodrugs based on ruthenium and osmium are among the most investigated and advanced non-platinum metallodrugs. Inorganic drug discovery with these agents... (Review)
Review
Anticancer metallodrugs based on ruthenium and osmium are among the most investigated and advanced non-platinum metallodrugs. Inorganic drug discovery with these agents has undergone considerable advances over the past two decades and has currently two representatives in active clinical trials. As many ruthenium and osmium metallodrugs are prodrugs, a key question to be addressed is how the molecular reactivity of such metal-based therapeutics dictates the selectivity and the type of interaction with molecular targets. Within this frame, this review introduces the field by the examples of the most advanced ruthenium lead structures. Then, global structure-activity relationships are discussed for ruthenium and osmium metallodrugs with respect to in vitro antiproliferative/cytotoxic activity and in vivo tumor-inhibiting properties, as well as pharmacokinetics. Determining and validating global mechanisms of action and molecular targets are still major current challenges. Moreover, significant efforts must be invested in screening in vivo tumor models that mimic human pathophysiology to increase the predictability for successful preclinical and clinical development of ruthenium and osmium metallodrugs.
Topics: Antineoplastic Agents; Cell Proliferation; Humans; Neoplasms; Organometallic Compounds; Osmium; Ruthenium; Structure-Activity Relationship
PubMed: 29170783
DOI: 10.1039/c7cs00332c -
Accounts of Chemical Research Feb 2015CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a... (Review)
Review
CONSPECTUS: A current issue in metal-catalyzed reactions is the search for highly efficient transition-metal complexes affording high productivity and selectivity in a variety of processes. Moreover, there is also a great interest in multitasking catalysts that are able to efficiently promote different organic transformations by careful switching of the reaction parameters, such as temperature, solvent, and cocatalyst. In this context, osmium complexes have shown the ability to catalyze efficiently different types of reactions involving hydrogen, proving at the same time high thermal stability and simple synthesis. In the catalytic reduction of C═X (X = O, N) bonds by both hydrogenation (HY) and transfer hydrogenation (TH) reactions, the most interest has been focused on homogeneous systems based on rhodium, iridium, and in particular ruthenium catalysts, which have proved to catalyze chemo- and stereoselective hydrogenations with remarkable efficiency. By contrast, osmium catalysts have received much less attention because they are considered less active on account of their slower ligand exchange kinetics. Thus, this area remained almost neglected until recent studies refuted these prejudices. The aim of this Account is to highlight the impressive developments achieved over the past few years by our and other groups on the design of new classes of osmium complexes and their applications in homogeneous catalytic reactions involving the hydrogenation of carbon-oxygen and carbon-nitrogen bonds by both HY and TH reactions as well as in alcohol deydrogenation (DHY) reactions. The work described in this Account demonstrates that osmium complexes are emerging as powerful catalysts for asymmetric and non-asymmetric syntheses, showing a remarkably high catalytic activity in HY and TH reactions of ketones, aldehydes, imines, and esters as well in DHY reactions of alcohols. Thus, for instance, the introduction of ligands with an NH function, possibly in combination with a pyridine ring, led to a new family of [OsCl2(PP)(NN)] (NN = diamine, 2-aminomethylpyridine; PP = diphosphine) and pincer [OsCl(CNN)(PP)] (HCNN = 6-aryl-2-aminomethylpyridine, 2-aminomethylbenzo[h]quinoline) complexes, which are outstanding catalysts for (asymmetric) HY and TH of carbonyl compounds and DHY of alcohols with turnover numbers and turnover frequencies up to 10(5) and 10(6) h(-1), respectively. In addition, PNN osmium complexes containing the 2-aminomethylpyridine motif have been found to be among the most active catalysts for HY of esters. These complexes have shown catalytic activities that are comparable and in some cases superior to those reported for analogous ruthenium systems. These results give an idea of the potential of Os complexes for the design of new highly productive and robust catalysts for the synthesis of chiral and nonchiral alcohols and amines as well as ketones from alcohols. Thus, we hope that this report will promote increased interest in the chemistry of these metal complexes, opening novel opportunities for new catalytic processes as well as the improvement of existing ones.
Topics: Catalysis; Hydrogenation; Organic Chemicals; Osmium
PubMed: 25650714
DOI: 10.1021/ar5003818 -
Methods in Molecular Biology (Clifton,... 2023Dysfunction in adipocyte expansion during the onset of obesity is associated with metabolic abnormalities. Determination of adipocyte size and number is an important...
Dysfunction in adipocyte expansion during the onset of obesity is associated with metabolic abnormalities. Determination of adipocyte size and number is an important measure for a comprehensive evaluation of the metabolic status of adipose tissue. Here, we describe three methods for the determination of adipocyte size that can be applied to tissue samples obtained from humans and rodent models. While the first method presented is more robust, it does require the use of osmium, a toxic heavy metal, which requires special handling and disposal precautions in addition to specialized equipment. Two additional methods are described that can be of use to most researchers.
Topics: Humans; Adipocytes; Adipose Tissue; Obesity
PubMed: 37076669
DOI: 10.1007/978-1-0716-3167-6_4 -
Histochemistry and Cell Biology Apr 2024One hundred years ago, Robert Feulgen published a landmark paper in which he described the first method to stain DNA in cells and tissues. Although a century has passed... (Review)
Review
One hundred years ago, Robert Feulgen published a landmark paper in which he described the first method to stain DNA in cells and tissues. Although a century has passed since the discovery by Feulgen and Rossenbeck, the chemical reaction still exerts an important influence in current histochemical studies. Its contribution in diverse fields, spanning from biomedicine to plant biology, has paved the way for the most significant studies that constitute our current knowledge. The possibility to specifically explore the DNA in cell nuclei while quantifying its content makes it a contemporary and timeless method. Indeed, many histocytochemical studies following the 1924 paper have led to a deep understanding of genome organization in general as well as several specific mechanisms (e.g. DNA duplication or tumour pathology) that, nowadays, constitute some of the most fundamental pillars in biological investigations. In this review, we discuss the chemistry and application of the Feulgen reaction to both light and electron microscopy.
PubMed: 38609528
DOI: 10.1007/s00418-024-02279-9