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At least 109 records · Page 6Linked to original sources
PubMed1977

Effect of dietary cholesterol on the pattern of osmium deposition in the symbiote-containing cells of the pea aphid.

Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the per-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.

Animals↗
PubMed1977

Osmium tetroxide/p-phenylenediamine staining of nucleoli and Balbiani Rings in Chironomus salivary glands.

This paper deals with the application of the osmium tetroxide fixation followed by p-phenylenediamine treatment to salivary gland cells from Chironomus larvae. After this procedure, cytoplasm, nucleoli and Balbiani rings show a high degree of staining both in light and electron microscopy, while chromatin remains unstained. Ethanol fixation followed by osmium tetroxide/p-phenylenediamine does not modify the above mentioned staining pattern. Under these conditions, extractive procedures for lipids do not affect the osmiophilia of nucleoli and Balbiani rings, while RNase or trichloroacetic acid treatment decreaes the staining degree of these structures. In osmium tetroxide/p-phenylenediamine treated salivary glands, the highest contrast within nuclei is seen to occur in the pars granulosa from normal or segregated nucleoli, as well as in Balbiani ring granules, which appear either as hollow granules or with a bipartite or horseshoe-like structure.

Animals↗
PubMed1989

Application of the ferrocyanide-reduced osmium method for mineralizing cartilage: further evidence for the enhancement of intracellular glycogen and visualization of matrix components.

The ferrocyanide-reduced osmium (FRO) fixation method was applied to neonatal mouse mandibular condylar cartilage for its processing for electron microscopy. The results were compared to those obtained by the conventional glutaraldehyde-osmium tetroxide fixation method. Three different stages in the life cycle of condylar cartilage cells were examined. FRO enabled the visualization of delicate fibrillar mesh in the matrix of all three zones of the cartilage, resulting in a dense appearance of the intercellular matrix. The classical stellate shape of matric granules seen in cartilage fixed with glutaraldehyde-osmium tetroxide was not observed in FRO-processed tissues. Chondrocytes that were FRO-processed almost entirely filled their lacunar space. In their pericellular area, fibrillar material and electron-dense aggregates could be demonstrated by the FRO method. As a conclusion of this study, it is recommended to supplement a conventional protocol with the FRO fixation method for routine and research purposes.

Animals↗
PubMed2006

Morphological analysis of lamellar structures in mouse type II pneumocytes by quick-freezing and freeze-drying with osmium tetroxide vapor-fixation.

The lamellar body is a membranous structure periodically laminating in vesicles that is known as the most distinctive feature of type II pneumocytes by conventional preparation methods for transmission electron microscopy. The quick-freezing and freeze-drying method, followed by osmium tetroxide vapor-fixation (QF-FD-OsV), was performed to examine the in situ morphology of the lamellar body in type II pneumocytes of living mouse lungs. Typical lamellar structures were rarely seen in vesicles of the type II pneumocytes, but amorphous components and dispersed stripes were often detected in the vesicles, as revealed by the QF-FD-OsV method. To clarify how the lamellar body was formed during the conventional preparation steps, lung tissues of mice were treated with different fixation procedures, such as immersion-fixation with osmium tetroxide or perfusion-fixation with glutaraldehyde followed by osmium tetroxide, in combination with alcohol dehydration or QF-FD-OsV. In addition to lamellar bodies of type II pneumocytes in the specimens with alcohol dehydration, some lamellar structures were also formed even with the QF-FD-OsV method. These findings suggest that the labile lamellar body is easily modified and formed during both chemical fixation and alcohol dehydration steps.

Animals↗
PubMed2004

Multiply osmium-labeled reporter probes for electrochemical DNA hybridization assays: detection of trinucleotide repeats.

In electrochemical DNA hybridization assays target or probe DNAs end-labeled with electroactive compounds have been frequently used. We show that multiple osmium labels yielding faradaic (at carbon or mercury electrodes) and catalytic signals (at mercury electrodes) can be easily covalently bound to DNA molecules. We use (GAA)(7) (T)(n) oligodeoxynucleotides (ODNs) with n ranging between 5 and 50. (T)(n) tails are selectively modified with osmium tetroxide,2,2'-bipyridine leaving the (GAA)(7) repeat intact for the DNA hybridization. These ODNs are applied as reporter probes (RP's) in DNA hybridization double-surface (DS) assay using magnetic beads for the DNA hybridization and pyrolytic graphite (PGE) or hanging mercury drop (HMDE) electrodes for the electrochemical detection. We show that in difference to the usual single-surface methods (where the RP has to be bound to target DNA near to the surface to communicate with the electrode) in the DS assay the RP can be bound to DNA regardless of its position and can used for the determination of the length of DNA repetitive sequences. Several fmols or about a hundred of amol of a RP with osmium-labeled (T)(50) tail can be detected at PGE and HMDE, respectively, at 1-2 min accumulation time.

Biosensing Techniques↗
PubMed2004

Imido-osmium(VIII) compounds in organic synthesis: aminohydroxylation and diamination reactions.

Imido complexes of osmium tetroxide are versatile compounds for olefin functionalisation. This tutorial review offers a brief historical overview on these compounds and discusses the electronic properties and reactivities of isolated imido osmium compounds in what had been the original stoichiometric aminohydroxylation reaction. The recently emerging catalytic Sharpless aminohydroxylation is discussed with special emphasis on mechanistic details. The final section deals with diamination of olefins, which relies on the chemistry of bisimido and trisimido osmium complexes.

Alcohols↗
PubMed1995

Complex of osmium tetroxide with 1,10-phenanthroline binds covalently to double-stranded DNA.

Complex of osmium tetroxide with 1,10-phenanthroline (Os,phen) reacts with double-stranded B-DNA in contrast to osmium tetroxide, pyridine and other osmium structural probes which show a strong preference for single-stranded DNA (ssDNA) (Palecek, E. in Abelson, J.N., and Simon, M.I. (eds), Lilley, D.M.J., and Dahlberg, J.E., (volume eds.), Methods in Enzymology, Vol. 212, DNA Structures, part B., Academic Press, 139-155 (1992)). Modification of negatively supercoiled DNA (scDNA) with Os,phen changes the DNA electrophoretic mobility inducing the DNA relaxation at lower degrees of modification followed by formation of positive supercoils at higher modification extents. Electrophoretic mobility of the Os,phen-modified DNA fragments in agarose gel is almost unchanged while a strong retardation of the same fragments is observed in polyacrylamide gels. Os,phen-modified DNA is hypersensitive to nuclease S1. Cleavage of this DNA by restriction enzymes is selectively inhibited showing a preference of Os,phen for TA and AT dinucleotide steps. DNA modification by Os,phen is inhibited by low and moderate concentrations of MgCl2. The covalent binding of Os,phen to double-stranded DNA (dsDNA) is preceded by noncovalent interactions (probably intercalation) inducing DNA structural changes; the shape of the Os,phen-modified DNA molecule appears to be severely deformed.

Base Composition↗
PubMed1999

Monoclonal antibody against DNA adducts with osmium structural probes.

Osmium tetroxide complexes with nitrogen ligands (Os,L) have been widely used as probes of the DNA structure. A monoclonal antibody OsBP7H8 against DNA adducts with Os,L was produced in mice. OsBP7H8 does not bind to proteins or total yeast RNA modified with Os,2,2'-bipyridine (bipy) nor to the unmodified nucleic acids and proteins. The antibody recognizes DNA modified with Os,bipy (DNA-Os,bipy) or with OsO4,1,10-phenanthroline (DNA-Os,phen) but it does not cross-react with oxidized DNA and with DNA adducts of osmium tetroxide complexes with other ligands (such as pyridine, TEMED and bathophenanthroline disulfonic acid). The affinity of OsBP7H8 to DNA-Os,phen is about five-fold higher as compared to DNA-Os,bipy. The antibody can be thus applied either for recognition of single-stranded and distorted regions in DNA (after DNA modification with Os,bipy) or for detection of both single-stranded and double-stranded DNAs (after DNA modification with Os,phen). A new simplified procedure for the dot-blot analysis is proposed, not requiring the purification of DNA-osmium adduct prior to its application to the membrane.

Animals↗
PubMed1970

Osmium staining of endoplasmic reticulum and mitochondria in the rat adrenal cortex.

The zona fasciculata of the rat adrenal cortex synthesizes and secretes glucocorticoids. As observed after aldehyde fixation, the cells in this zone contain an extensive endoplasmic reticulum (ER), a small Golgi apparatus, a moderate number of lipid droplets, and abundant mitochondria with tubulovesicular cristae. Numerous areas within the endoplasmic reticulum and mitochondrial cristae appear clear. In addition, a small percentage of mitochondria encompasses large, clear areas. After immersion of finely minced adrenal cortex in unbuffered 2% OsO(4) (40-48 hr at 40 degrees C), deposits of osmium are seen within the Golgi apparatus, the entirety of the ER, and occasionally within mitochondria. In some mitochondria, the deposits are within cristae; in others, within vacuoles; in still others, in both cristae and vacuoles. These localizations correspond best to the clear areas found in aldehyde-fixed tissue. Osmium is not deposited in lipid droplets, in bar-containing inclusions, in mitochondrial matrix inclusions, or in the peripheral, outer mitochondrial spaces. Addition of zinc-iodide to OsO(4) increases the amount of Golgi apparatus and mitochondrial staining. Adrenocorticotropin (ACTH) does not affect the localization of deposits; hypophysectomy decreases mitochondrial staining. This study (a) emphasizes the necessity for electron microscopic confirmation of osmium localization when this technique is used as a Golgi apparatus stain; and (b) suggests that the ER-staining pattern may be consistent in cells actively synthesizing steroids or steroid-like compounds.

Adrenal Glands↗
PubMed1996

Antimicrobial activities in vitro and in vivo of transition element complexes containing gold(I) and osmium(VI).

Metal compounds have been used as antibacterial agents for centuries. The in-vitro activity of two metal containing complexes, one gold, the other osmium, was investigated using a panel of clinically isolated bacteria and Candida albicans. Twenty strains of each organism were used and MIC and MBC values determined using the agar plate dilution method. Protein binding effects on the activity of the compounds were also investigated using media supplemented with 5% human blood. In-vivo activity of the two compounds was subsequently determined in a hairless-obese mouse skin-surface activity model. Both compounds were highly active against the Gram-positive organisms and Candida albicans in vitro. The gold compound had some Gram-negative activity but the osmium complex was inactive against these organisms. Both were extensively protein bound. In the in-vivo experiment the gold compound achieved a 2-3 log reduction for all the test organisms and was at least as good as or superior to mupirocin in its eradication rate. The osmium compound was inactive.

Animals↗
PubMed2000

Spontaneous and osmium tetroxide-induced mutagenesis in an Escherichia coli strain deficient in both endonuclease III and endonuclease VIII.

Thymine glycol, uracil glycol, 5-hydroxycytosine and 5-hydroxyuracil are common base lesions produced by cellular metabolism as well as ionizing radiation and environmental carcinogens. Escherichia coli DNA glycosylase, endonuclease III and endonuclease VIII recognize and remove these lesions from DNA. In this study, we assessed the mutagenic potential of these lesions in the supF gene as a forward mutation target in double-stranded plasmid DNA using an E.coli strain deficient in both endonuclease III and endonuclease VIII. These lesions were introduced into pTN89 DNA by the chemical oxidant osmium tetroxide. Spontaneous supF mutations occurred at a frequency of 3.03x10(-7) and osmium tetroxide-induced at a frequency of 8. 25x10(-7). Sequence analysis of supF mutants revealed that mutations occurred at cytosine sites rather than thymine sites, suggesting that thymine glycol is not the principal premutagenic lesion. In contrast, G:C-->A:T transitions were dominantly detected in the spontaneous and osmium tetroxide-induced mutations in the endonuclease III and endonuclease VIII double defective host. In this case, products of cytosine oxidation such as 5-hydroxycytosine, which are the substrate for endonuclease III and endonuclease VIII, were the principal mutagenic lesions.

Base Sequence↗
PubMed1997

Potassium permanganate and tetraethylammonium chloride are a safe and effective substitute for osmium tetroxide in solid-phase fluorescent chemical cleavage of mismatch.

Whilst chemical cleavage of mismatch (CCM) detects all point mutations in DNA, its widespread use has been hampered by the complex multistage methodology and the need for toxic chemicals, in particular osmium tetroxide. Here we show that osmium tetroxide can be replaced by potassium permanganate, giving the same spectrum of mutation detection, but with greater sensitivity. The use of potassium permanganate is compatible with solid phase capture and fluorescent detection, giving a safer method of mutation detection. We present here a comparison of CCM with osmium tetroxide and with potassium permanganate, tested on a complete set of single base pair mismatches and a number of small insertion/deletions.

DNA, Bacterial↗
PubMed1996

Lipiodol accumulation in hepatic hemangioma. Detection with osmium postfixation.

Lipiodol has been used to increase the detectability of small primary neoplasms in the liver. We report a patient who was found to have lipiodol deposits in the liver one month after intra-arterial injection. The region was resected, under ultrasound control, because of the impression that the lesion was malignant. The specimen contained two small hemangiomas as well as many small dysplastic nodules (adenomatous hyperplasia) in a noncirrhotic parenchyma. To locate the lipiodol deposit in this case, the tissue was radiographed, postfixed in osmium tetroxide, and embedded in paraffin. Black osmium-stained deposits were found within the cavities of the hemangiomas but not in the dysplastic nodules. Most of the deposits were extracellular multivesiculated bodies with a small focus of lipid droplets engulfed by multinucleated foreign-body type giant cells. This report reinforces that hepatic lipiodol retention is not specific for hepatocellular carcinoma. We present, for the first time, the histologic appearance of lipiodol accumulation in an hemangioma. The value of osmium tetroxide postfixation for the detection of lipiodol is also demonstrated.

Adult↗
PubMed1987

Measurement of increased uptake of osmium in skin and in a gelatin model 'tissue' treated with tannic acid.

The effect of tannic acid (TA) on the deposition of osmium was studied in discs of hamster skin and in fixed gelatin. Pieces of skin treated with 1.0% TA before OsO4 fixation absorbed almost twice as much as untreated pieces. Gelatin, used here as a model 'tissue' showed an even greater degree of enhancement. Treated gelatin capsule halves and strips took up 4-6 times as much osmium as untreated ones. The deposition of osmium was verified by neutron activation analysis.

Animals↗
PubMed1978

Tissue fixation and staining with osmium tetroxide: the role of phenolic compounds.

It has been postulated that phenol-containing areas of plant and animal tissues were osmiophilic, but proof of direct interaction between osmium tetroxide and phenolic materials, or the nature of such reactions, has been lacking. We find that, under conditions similar to those of normal tissue fixation, osmium tetroxide reacts rapidly with those phenols containing o-dihydroxy groups (including such species found in plant tissues) to give very stable chelate complexes. We conclude that these complexes are responsible for the observed electron-density in phenol-containing areas of tissue treated with osmium tetroxide, so that such phenols are indeed osmiophilic.

Histocytochemistry↗
PubMed1980

Use of osmium-ferrocyanide treatment for improved lysosomal acid trimetaphosphatase reaction and subcellular detail in thyroid follicular cells.

The histochemical reaction for acid trimetaphosphatase in addition to secondary tissue treatment with an osmium-ferrocyanide mixture was used to study lysosomes and phagolysosomes in the mouse thyroid gland. The osmium-ferrocyanide postfixation enhanced reaction product localization, reduced diffuse reaction, and improved membrane contrast. In addition, the ultrathin tissue sections did not require heavy metal staining, thus eliminating potential stain artifacts due to precipitation. In view of the improved tissue preservation and enzyme localization, it is suggested that osmium-ferrocyanide postfixation be used after the acid trimetaphosphatase method.

Acid Anhydride Hydrolases↗
PubMed1996

The osmium tetroxide-p-phenylenediamine procedure reveals the chromatid cores and kinetochores of meiotic chromosomes by light and electron microscopy.

We analyzed first-metaphase meiotic chromosomes of the grasshopper Chorthippus jucundus by two different methods, i.e., a silver impregnation technique and the osmium tetroxide-p-phenylenediamine (Os-PPD) procedure. The former was applied on squashed testes previously fixed in ethanol-acetic acid, whereas for Os-PPD the material was not subjected to any previous extraction treatment but was fixed in OsO4, treated with PPD, and embedded in Epon 812. Both techniques revealed chromatid cores and kinetochores regardless of the processing of the material (squashed or sectioned). Unstained Os-PPD sections were analyzed by light microscopy and transmission electron microscopy (TEM). The Os-PPD technique provided a high contrast of chromatid cores and kinetochores in relation to the chromatin, which revealed a low electron density. To determine the Os-PPD reaction mechanism, the PAS procedure, as well as scanning electron microscopy (SEM) backscattering and SEM X-ray microanalysis, was performed on sections. By use of the Os-PPD-PAS procedure, glycol groups formed by oxidation of osmium bound to aromatic substrates were detected in chromatid cores and kinetochores by brightfield and fluorescence microscopy. A high Z contrast was detected in these structures by backscattered electron imaging. SEM X-ray microanalysis showed osmium and phosphorus to be the main elements present on the chromatid cores. Taking into account the known reactivity of OsO4 and the present results, the possible participation of nucleic acids as well as proteins in the Os-PPD reaction mechanism and in the composition of chromatid cores and kinetochores is discussed.

Animals↗
PubMed1976

Post-yersinotic Reiter's disease in a physician treated with osmium tetroxide.

A case of general yersinosis in a male physician is described. Most probably the infection was acquired nosocomially in a paediatric ward. The infection affected several organs including the liver, but osmium tetroxide was nevertheless used to perform chemical synovectomy in a knee joint suffering from active arthritis. The arthritis was cured, and the already existing liver affection did not progress. The only complaint from the patient, months after the osmic acid injection, was a strong metallic taste on the tongue. More than a year after the intra-articular injection, the metallic taste disappeared. The amount of osmium in the patient's blood was then calculated to be less than 100 molecules of osmium per ml blood.

Adult↗