PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Ferrocyanides”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1978

Ultrastructural localization of nonheme celluar iron with ferrocyanide.

The Prussian blue reaction was evaluated at the ultrastructural level as a cytochemical method to identify ferric and ferrous iron in rat bone marrow and splenic macrophages. Satisfactory tissue preservation and staining were achieved after fixation for 1 hr in 3% glutaraldehyde and exposure for 30 min to Perls's ferrocyanide solution before routine osmication and embedding. The acid ferrocyanide solution formed cuboidal and irregular electron-opaque deposits which localized ferric iron in the macrophage siderosomes and hyaloplasm. When thin sections were directly stained with the acid ferrocyanide, the stain deposits were much less distinct. The size and number of cytes exhibited sparse evenly distributed stain deposits. Several cells displayed abundant precipitates on the inner surface of the plasmalemma. Prussian blue precipitates were occasionally seen in mitochondria and nuclear euchromatin. Although osmium tetroxide post-fixation improved tissue preservation, it did not enhance the density of the ferri-ferrocyanide precipitate. The ferrocyanide solution yielded cuboidal deposits also in clots impregnated with ferritin, and electron diffraction analysis confirmed the symmetrical crystal structure of these stain precipitates. Smaller irregular precipitates were formed in clots impregnated with FeCl3, or Fe2 (SO4)3 solutions, despite the equally interpreted as indicating that the iron hydroxide core or protein structure of ferritin and hemosiderin contributed to the formation of the ultrastructurally evident cuboidal precipitates, but were not necessary for the formation of a colored reaction product. The acid ferrocyanide solution failed to stain clots formed in FeCI2, CuCI2 or CuCI solutions. Staining with a ferricyanide solution identified only sparse foci of ferrous iron in some siderosomes. This study demonstrates that the Prussian blue reaction can be used ultrastructurally to localize iron cations bound to some nonheme iron binding proteins.

Animals↗
PubMed1977

Ferric ion, ferrocyanide, and inorganic phosphate as cytochemical reactants at peripheral nodes of Ranvier.

Ferric ion (Fe3+) and ferrocyanide (Fe(CN)64-) were used under a variety of conditions to stain nodes of Ranvier in mammalian peripheral nerves. Principal findings are: 1. Ferric ion will bind to the extracellular nodal gap substance if nerves are pretreated with a phosphate buffer; or, it will bind to the cytoplasmic surface of the nodal axolemma if pretreatment is with cacodylate or veronal--acetate buffer. 2. Ferrocyanide will bind to the inner surface of the nodal axolemma, where it may react with ferric ion to form a blue stain, or with an osmium compound to form a black stain. 3. Ferric ion and ferrocyanide are bound to nodes as colloidal precipitates, and may migrate away from their sites of formation. 4. Not all nodes in a single piece of tissue, or in a single fibre have identical staining properties. It is concluded that ferric ion, ferrocyanide, and inorganic phosphate are valuable as cytochemical reactants for peripheral nodes of Ranvier, but they must be used in carefully controlled experimental situations in order to avoid spurious results.

Animals↗
PubMed1975

Vanadium compounds and ferrocyanide as ionic redox agents in photosynthesis.

The effect of such ionic redox agents as ferrocyanide and several vanadium compounds was determined on photosynthetic reactions of spinach chloroplasts. It was found that: 1. Vanadyl sulfate like ferrocyanide in moderately high concentrations (0.03 M) donates electrons to Photosystem II. 2. Decavanadate in the presence of 2,5-dibromothymoquinone accepts electrons in Photosystem II. 3. In the absence of a block between the two photosystems, decavanadate accepts electrons in Photosystem I in the vicinity of plastocyanin or beyond. 4. Vanadite and ferrocyanide in high concentrations (0.32 M) donate electrons to Photosystem I. 5. On the basis of chelator inhibition and polyoxyethylene sorbitan monolaureate treatment, the vanadite oxidation site is located near plastocyanin while the ferrocyanide site is between plastocyanin and P-700.

Chloroplasts↗
PubMed1979

Ferrocyanide enhancement of concanavalin A-ferritin and cationized ferritin staining blood cell surface glycoconjugates.

Ferrocyanide was used to enhance cationized ferritin and concanavalin A-ferritin (Con A-ferritin) staining of surface glycoconjugates of peripheral blood and bone marrow cells from rabbits and humans. The glutaraldehyde-fixed cells were stained with Con A-ferritin or cationized ferritin and then exposed to a ferrocyanide solution. The resulting cuboidal and irregular stain deposits averaged 50 nm in diameter when viewed with the transmission (TEM) and scanning electron microscope (SEM). Rabbit blood cells demonstrated more Con A binding sites than human blood cells and the decrease in binding sites observed with maturation of human granulocytic and erythrocytic cells was not evident in rabbit cells. Differences in binding of cationized ferritin to rabbit and human cell surfaces were less prominent than that observed for Con A. These results extend previous studies of blood cell surface glycoconjugates and demonstrate that ferrocyanide enhancement significantly facilitates SEM evaluation of Con A-ferritin and cationized ferritin bound to cell surfaces.

Animals↗
PubMed1979

Ferrocyanide as electron donor to cytochrome aa3. Cytochrome c requirement for oxygen uptake.

1. In the absence of cytochrome c, ferrocyanide or ferrous sulphate reduces cytochrome c oxidase (EC 1.9.3.1), but no continuous oxygen uptake ensues, as it does with N,N,N',N'-tetramethyl-p-phenylenediamine or reduced phenazine methosulphate as reductants, unless a substoichiometric amount of cytochrome c or an excess of clupein is present. Cytochrome c cannot be replaced by porphyrin cytochrome c. 2. Cytochrome c, porphyrin cytochrome c and clupein all stimulate the reduction of cytochrome aa3 by ferrocyanide. 3. A model is proposed to explain these findings in which a high-affinity site for cytochrome c on the oxidase regulates the access of hydrophilic electron donors to a low-affinity site, and reduction via the high-affinity site is required for continuous oxygen uptake. 4. Furthermore, it is shown that upon reaction of oxidase with ferrocyanide, cyano-oxidase is formed.

Cyanides↗
PubMed1978

Ionic strength dependence of the oxidation of iodide and ferrocyanide by compound I of horseradish peroxidase.

The kinetics of the oxidation of iodide and ferrocyanide by compound I of horseradish peroxidase have been studied at 25 degrees C as a function of ionic strength and pH. The ionic strength dependencies of the second-order rate constants are tested with an extended form of the Debye-Hückel equation for the activity coefficients of the reacting species. For the reaction of iodide with compound I it is shown that the pH variation of the rate constant at zero ionic strength is caused mainly by titrating a catalytically important acid group and not mainly by the varying charge of the protein. The ferrocyanide reaction rate with compound I does not correlate with enzyme net charge, at all pH values. The influence of electrostatic interactions on reaction rates is discussed.

Ferrocyanides↗
PubMed1979

Ferrocyanide staining of transferrin and ferritin-conjugated antibody to transferrin.

To evaluate the ultrastructural distribution of transferrin on the surface of L1210 ascites tumor cells, we used ferrocyanide to stain ferric iron (Prussian blue reaction) in transferrin, as well as in ferritin conjugated to antibody that was immunologically attached to the transferrin. Small deposits averaging 5 nm in diameter identified transferrin iron, whereas large cuboidal deposits averaging 50 nm in diameter stained ferritin conjugated-antibody that was bound to both transferrin and apotransferrin on the cell surface. The ability of transferrin to deliver iron to ascites tumor cells was confirmed by kinetic studies of transferrin labeled with 59Fe and 125I. These preliminary results are consistent with release of transferrin iron at the cell surface and demonstrate additional uses for ferrocyanide in ultrastructural cytochemical techniques.

Animals↗
PubMed1978

Intra-axonal ferric ion-ferrocyanide staining of nodes of Ranvier and initial segments in central myelinated fibers.

Ferric ion and ferrocyanide were used to stain central nervous tissue from the spinal cords of rats following fixation in cacodylate-buffered aldehydes. At the nodes of Ranvier in myelinated fibers, the stain was localized primarily on the inner surface of the unmyelinated nodal axolemma, as had been reported previously for peripheral nodes. Unmyelinated initial segments of myelinated neurons were similarly stained, but the axon hillock, cell body and dendrites were not stained. Synapses also exhibited no staining. Details of stain localization and comparison of these results with other ultrastructural data suggest that the stain is specific for the node of Ranvier and the axon initial segment, and are consistent with the idea that the axolemma at these sites may be structurally different from the cell membrane in other regions of the neuron, including paranodal and internodal regions of the axon. The electron-dense substance underlying the cytoplasmic surface of the membrane at the nodes and initial segments may represent a substrate that serves to bind together membrane structures in specialized regions of the axolemma.

Animals↗
PubMedDate not supplied

Specific staining of the axon membrane at nodes of Ranvier with ferric ion and ferrocyanide.

Ferric ion and ferrocyanide were used as stains for light and electron microscopy of peripheral nerves. In rat sciatic nerves, it was found that ferric ion preferntially binds to the cytoplasmic surface of the axon membrane at nodes of Ranvier but not at internodal regions. In myelinated axons in the electric organ of the gymnotid fish, Sternarchus albifrons, the small excitable nodes are similarly stained, but the larger inexcitable nodes are not stained by ferric ion. Staining of the inner surface of the nodal membrane appears to be related to a structural specialization of this membrane, rather than accessibility to stain. Our data thus show a chemical differentiation of the inner surface of the axon membrane between nodes and internodes in normal peripheral nerve fibers and between the inner surface of the axon membrane at active nodes, and the internodes in the Sternarchus electrocyte axons.

Animals↗
PubMed1977

Ultrastructure of leydig cells as revealed by secondary tissue treatment with a ferrocyanide-osmium mixture.

Leydig cells prepared routinely (glutaraldehyde--osmium) for ultrastructural studies are generally found to be lacking in subcellular detail as a result of poor membrane preservation and a dense cytoplasmic matrix. A method modified after that of Karnovsky (1971), utilizing a ferrocyanide--osmium mixture for post-treating glutaraldehyde fixed tissued, was found to yield routinely excellent preservation of Leydig cells. The primary advantages of this method were the enhancement of contrast within the Leydig cell and greatly improved membrane preservation. In addition, the smooth endoplasmic reticulum always appeared as an extensive network of interconnected tubules of uniform diameter; mitochondria, lysosomes, peroxisomes, multivesicular bodies, and Golgi were especially prominent. Glycogen and microfilaments, not readily seen in routine preparations, were found to be abundant in these cells. New observations on the numbers and distributions of subcellular organelles are described and are discussed in relation to their possible role in the steroidogenic process. In view of the greatly improved tissue preservation observed in this study, it is suggested that this treatment be used routinely for preservation of rat Leydig cells.

Animals↗
PubMed1977

Kinetic studies on redox reactions of hemoproteins. I. Reduction of thermoresistant cytochrome c-552 and horse heart cytochrome c by ferrocyanide.

The oxidation-reduction reaction of horse heart cytochrome c and cytochrome c (552, Thermus thermophilus), which is highly thermoresistant, was studied by temperature-jump method. Ferrohexacyanide was used as reductant. (Formula: see text.) Thermodynamic and activation parameters of the reaction obtained for both cytochromes were compared with each other. The results of this showed that (1) the redox potential of cytochrome c-552, + 0.19 V, is markedly less than that of horse heart cytochrome c. (2) deltaHox of cytochrome c-552 is considerably lower than that of horse heart cytochrome c. (3) deltaSox and deltaSred of cytochrome c-552 are more negative than those of horse heart cytochrome c. (4) kred of cytochrome c-552 is much lower than that of horse heart cytochrome c at room temperature.

Animals↗