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PubMed1987

Prenatal exposure to alcohol alters the Golgi apparatus of newborn rat hepatocytes: a cytochemical study.

The effect of prenatal exposure to ethanol on the Golgi apparatus of newborn rat hepatocytes has been studied cytochemically using several trans-Golgi markers (thiamine pyrophosphatase, uridine diphosphatase, inosine diphosphatase, acid phosphatase, and 5'-nucleotidase) as well as a cis-side marker (osmium impregnation). The amount of cerium phosphate formed in the cytochemical reactions was roughly quantitated by stereologic methods. The Golgi apparatus of about 40% of the hepatocytes appeared disorganized after alcohol treatment, and in the other 60%, the electron density of reaction product deposits for all phosphatases investigated was decreased. 5'-Nucleotidase was completely absent in cisternae of Golgi apparatus of treated cells. In control cells impregnated with osmium tetroxide, reduced osmium compounds were observed in most Golgi cisternae and in nearby vesicles. In contrast, only small vesicles appeared positive in treated hepatocytes. These results suggest that prenatal alcohol exposure alters some Golgi functions. Thus, the decrease in nucleoside diphosphatase and 5'-nucleotidase cytochemical activities after ethanol exposure strongly suggests that this treatment could affect glycosylation in the Golgi apparatus of newborn rat hepatocytes.

5'-Nucleotidase↗
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↗
PubMed2005

A multianalyte flow electrochemical cell: application to the simultaneous determination of carbohydrates based on bioelectrocatalytic detection.

A multianalyte flow electrochemical cell (MAFEC) for bioanalysis is constructed, characterised and used for simultaneous carbohydrate analysis incorporating mediated amperometric enzyme electrodes. Although multidetection schemes can be addressed with microfabricated systems, it is demonstrated that a "meso" analytical device of low cost can give answers to traditional simultaneous multianalysis problems, being robust, and easy to construct and operate. The cell operates as a radial flow thin-layer device and can achieve mass transport controlled response for fast electrochemical reactions. When appropriate enzymatic electrodes are used the response becomes kinetically limited, but still shows a better than 5% R.S.D. for response to different sugars analysed. All the enzymatic sensors are mediated with different osmium compounds appropriate for each enzyme's mechanism (NAD or PQQ dehydrogenases) in some cases combining multienzyme sensors. All sensors were optimised so that different sugars do not produce interferences to other sensors. Matrix interferences were kept low by operating all sensors at or below 150 mV versus Ag/AgCl. The integrated system was used for the simultaneous detection of fructose, sucrose, glucose, galactose, and lactose, fully characterising the system for these analytes (sensitivity, dynamic range). Cross referenced calibration curves were used for signal treatment and interpretation and it was possible to analyse real juice and milk samples with results agreeing with the standard enzymatic methods for the same analyses with a sampling frequency of more than 100 h(-1).

Biosensing Techniques↗
PubMed2001

Tmtacn, tacn, and triammine complexes of (eta 6-arene)OsII: syntheses, characterizations, and photosubstitution reactions (tmtacn = 1,4,7-trimethyl-1,4,7-triazacyclononane; tacn = 1,4,7-triazacyclononane).

A series of (eta 6-arene)OsII complexes containing the saturated nitrogen donor ligands tmtacn, tacn, and NH3 are prepared and characterized. The electrochemical properties and photochemical reactions of these complexes are studied, and the solid-state structures for [(eta 6-p-cymene)Os(tacn)](PF6)2 (1) and [(eta 6-p-cymene)Os(tmtacn)](PF6)2 (2) are determined. Single-crystal X-ray data: 1, orthorhombic, space group Pbca-D2h15 (No. 61), with a = 14.716(3) A, b = 17.844(3) A, c = 18.350(4) A, V = 4819(2) A3, and Z = 8; 2, monoclinic, space group C2-C2(3) (No. 5), with a = 17.322(4) A, b = 10.481(3) A, c = 15.049(4) A, beta = 98.72 degrees, V = 2701(1) A3, and Z = 4.

Electrochemistry↗
PubMed2004

Spectrophotometric studies of the interaction of noble metals with quercetin and quercetin-5'-sulfonic acid.

Results of some studies on the interaction of noble metals with quercetin (Q) and quercetin-5'-sulfonic acid (QSA), the compounds of flavonoid group, are presented. The reactions of chloride complexes of the metals: RuOHCl5(2-), PdCl4(2-), OsCl6(2-), PtCl6(2-) and AuCl4- with both reagents were examined. The redox reactions of ruthenium and gold with Q and QSA have been identified. The reaction of the metals with both reagents results in the formation of the oxidized form of Q that exhibits maximum absorbance at 291 nm. Ruthenium and gold react with the examined reagents under similar conditions: 0.04 M HCl and 1 x 10(-4) M Q (or QSA). The CH3OH + H2O (1:1) (Q) and pure aqueous (QSA) media can be used. The reaction of gold with Q is slow at room temperature. It can be accelerated by heating the solution being examined. The reaction proceeds significantly faster when the water-soluble sulfonic derivative of quercetin, quercetin-5'-sulfonic acid, is used as a reagent. The new species formed can make the basis of spectrophotometric methods for the determination of ruthenium and gold. The molar absorptivities at 291 nm are equal to 5.0 x 10(3) and 2.2 x 10(4) L mol(-1) cm(-1) for Ru and Au, respectively, independently of the reagent used. Some methods for the determination of the content of gold (0.04%) in a cosmetic cream were developed.

Cosmetics↗
PubMed1994

Determination of intracytoplasmic filaments in the chondrocytes of articular cartilage.

Intracytoplasmic filaments were demonstrated in the chondrocytes of articular cartilage of cattle at 82 days post partum and at 3 and 4 years of age using transmission electron microscopy and immunocytochemistry. Samples of cartilage for electron microscopy were processed in a standard way. Immunocytochemical procedures were performed with semithin sections made from the material prepared for electron microscopy after embedding medium and osmium compounds had been eliminated. Vimentin filaments were demonstrated by means of anti-vimentin monoclonal antibody visualized by peroxidase-labelled immunoglobulin. Both techniques showed that intracytoplasmic filaments were situated around the nucleus and only occasionally at the cell periphery, e.g. in cell projections.

Aging↗
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↗
PubMed1996

In vitro activity and biochemical effectiveness of new organometallic complexes of osmium(III) against Leishmania donovani and Trypanosoma cruzi.

In the present paper, the in vitro activities of 10 osmium(III) complexes with [OSIII(L)] degrees structure against promastigote forms of Leishmania donovani and epimastigote forms of Trypanosoma cruzi haven been assayed. The complexes OSIII-2,4dinitroimidazole dithiocarbamate, OSIII-4-nitroimidazole dithiocarbamate, OSIII-benznidazole dithiocarbamate and OSIII-2-amino-6-Br-benzothiazole dithiocarbamate induced high percentages of growth inhibition in the parasites. The four compounds showed moderate cell toxicity. The inhibitory effects of these complexes on macromolecule synthesis have been evaluated using [3H]-thymidine, [3H]-uridine and [3H]-leucine incorporation. These metal-drug complexes clearly inhibit the DNA, RNA and protein synthesis, as well as the enzymatic activities of succinate dehydrogenase, malate dehydrogenase and pyruvate kinase.

Animals↗
PubMed2000

A practical technique to postfix nanogold-immunolabeled specimens with osmium and to embed them in Epon for electron microscopy.

Nanogold is a tiny gold probe, freely diffusible in cells and tissues, and is suitable for pre-embedding immunohistochemistry. However, it is necessary to develop Nanogold to a larger size so that it can be observed by conventional transmission electron microscopy. Silver enhancement is usually used for visualizing Nanogold, but the silver shell produced is unstable in OsO(4) and often becomes invisible after OsO(4) postfixation, which is necessary for good visualization of ultrastructure. We used silver enhancement with silver acetate, followed by gold toning with chloroauric acid, to replace the silver shell with a more stable gold in order to observe Nanogold after osmium fixation and Epon embedding. This technique is applicable to various intra- and extracellular antigens. For correlative observation of immunolabled specimens by light and electron microscopy, specimens adhered to slideglasses were embedded in Epon under non-adhesive plastic film. By heating the Epon sheets after polymerization, these supports were removed without difficulty and provided easy correlative observation.

Animals↗
PubMed1989

Structure of undecacarbonyl[tris(pentafluorophenyl)phosphine]-triangulo- triosmium, a substituted osmium cluster containing a fluorinated triphenylphosphine ligand.

[Os3(CO)11[P(C6F5)3]], Mr = 1410.87, monoclinic, P2(1)/n, a = 19.058 (1), b = 9.109 (1), c = 20.424 (2) A, beta = 105.53 (1) degree, V = 3416 (1) A3, Z = 4, Dm = 2.74 (2), Dx = 2.743 g cm-3, mu(Mo K alpha, lambda = 0.71073 A) = 113.3 cm-1, F(000) = 2560, T = 297 (1) K, RF = 0.022 for 3529 reflections. The Os atoms form an approximate isosceles triangle. Each Os atom exhibits a distorted octahedral coordination geometry. The carbonyl groups are all terminal and the bulky phosphine ligand is coordinated equatorially.

Ligands↗
PubMed2002

Interactions of glucose oxidase with various metal polypyridine complexes as mediators of glucose oxidation.

The interaction between glucose oxidase (GOx) and a typical metal complex, which is chemically stable in both oxidized and reduced forms, has been investigated by a voltammetric method. The evaluation of an electron-transfer mediator useful for glucose oxidation is discussed from thermodynamic and kinetic points of view, i.e. the redox potentials of various metal complexes and the second-order rate constants for the electron transfer between GOx in reduced form and the metal complexes in oxidized form. No mediation of glucose oxidation by [Co(bpy)(3)](2+) (bpy=2,2'-bipyridine) or [Cu(bpy)(2)](2+) occurred, in spite of their appropriate redox potentials. This was attributed mainly to the lower electron-self-exchange rates of the mediator and the reaction with GOx. All three types of osmium(II) complexes, [Os(PP) (n)](2+) ( n=2 or 3; PP=polypyridine), [OsL(2)(PP)(2)](2+) (L=imidazole and its derivatives), and [OsClL(bpy)(2)](+), acted as excellent electron-transfer mediators for the glucose oxidation. Mixed ligand complexes, [OsL(2)(PP)(2)](2+) and [OsClL(bpy)(2)](+), have been concluded to be more efficient electron-transfer mediators. The electron-transfer rates between the mediator and GOx have been found to be accelerated by intermolecular electrostatic interactions or hydrogen bonds.

Electrochemistry↗
PubMed2006

Oxidation-reduction dynamics in layer-by-layer self-assembled redox polyelectrolyte multilayer modified electrodes.

The oxidation-reduction dynamics of layer-by-layer (LbL) self-assembled redox polyelectrolyte multilayer films on electrodes has been studied by cyclic voltammetry, chrono-amperometry, electrochemical quartz crystal microbalance (EQCM), ellipsometry, and Fourier transform reflection-absorption infrared spectroscopy (FT-IRRAS). Thin layer electrochemistry with fast electron transfer at the underlying metal-film interface and charge propagation by electron hopping between adjacent redox sites in the finite thin film has been observed. An almost ideal cyclic voltammetry for a fixed number of redox sites in the thin surface film suggests that the multilayer can be fully oxidized and reduced in the time scale of the experiment (RT/vF > or = 0.05 sec). The electron hopping diffusion coefficient 3 x 10(-10) cm2 s(-1) was obtained from the chronoamperometric current transient and the ellipsometric thickness. Both cyclic voltammetry and potential step yield a surface osmium bipyridyl redox concentration of gamma Os = 4 x 10(-10) mol x cm(-2) for (PAH-Os)5(PVS)4 film. Exchange of ions and solvent occur simultaneously to the charge injection as revealed by the EQCM mass change and the ellipsometric thickness change. From the end-to-end mass-to-charge linear relationship, the molar mass of the ionic and neutral species exchanged largely exceeds the molar mass of any ions or solvent which suggests an important flux of solvent during redox switching. An initial "break in" effect is observed for the first oxidation-reduction cycles when a newly self-assembled film equilibrates with the electrolyte as charge is injected during the electrochemical perturbation.

Electrochemistry↗
PubMed1994

Distribution of DNA, nuclear micro-heterogeneities and compaction of the chromatin in rabbit epididymal spermatozoa. Ultrastructural evaluation of the Feulgen-like technique using osmium ammine.

An adaptation of the Feulgen procedure to visualise DNA at the ultrastructural level, using osmium ammine instead of Schiff reagent, was applied to ultrathin sections of rabbit epididymal spermatozoa, known to display increasing chromatin compaction as they progress through the epididymis. In contrast with the somatic cell nuclei of the epididymal epithelium, which display classical staining, the chromatin of spermatozoa is partly or fully destroyed during the hydrolysis step of the technique. The sperm chromatin resistance towards destruction is a function of the initial sperm nuclear compaction and of the duration of hydrolysis prior to Feulgen-like staining. For a given nucleus, the maximum staining intensity is only obtained after an optimal duration of hydrolysis. However, because of this duration and local differences in chromatin compaction, the total DNA of a section is never completely visualized. The most compact parts of the nuclei are not yet stained, when the less compact parts have already been destroyed. This gives rise to a sperm-specific pattern which corresponds to the enhancement of microheterogeneities present in all sperm nuclei and to the local depolymerisation of the nuclear material during hydrolysis. The depolymerised parts of nuclei sit over the sections, and they also bind uranyl acetate, ethidium bromide and anti-protamine antibodies. Therefore, in sperm nuclei, the Feulgen-like staining at the ultrastructural level does not reveal the true DNA distribution. However, the amount of staining can be quantified to evaluate sperm chromatin compaction.

Animals↗
PubMed1995

Imaging of DNA in human and plant chromosomes by high-resolution scanning electron microscopy.

We describe a DNA-specific staining procedure, using a blue platinum organic dye, which allows DNA imaging of chromosomes by detection of back-scattered electrons in the scanning electron microscope. DNA distribution is visualized within chromosomal details of the centromeric and satellite regions, or in interphase chromatin, with high-resolution (10-15 nm) for comparison with the corresponding secondary electron image representing DNA plus protein.

Centromere↗
PubMed2005

[Os(bpy)2(CO)(enIA)][OTf]2: a novel sulfhydryl-specific metal-ligand complex.

The synthesis and physical-chemical characterization of the metal-ligand complex [Os(bpy)2(CO)(enIA)][OTf]2 (where enIA = ethylenediamine iodoacetamide) with a sulfhydryl-specific functional group is described. The UV and visible absorption and luminescence emission, including lifetime and steady-state anisotropy, are reported for the free probe and the probe covalently linked to two test proteins. The spectroscopic properties of the probe are unaffected by chemical modification and subsequent covalent linkage to the proteins. The luminescence lifetime in aqueous buffer is approximately 200 ns and the limiting anisotropy is greater than 0.125, suggesting a potentially useful probe for biophysical investigations.

Cysteine↗
PubMed2005

Density functional calculation of the electronic circular dichroism spectra of the transition metal complexes [M(phen)3]2+ (M = Fe, Ru, Os).

The circular dichroism spectra of the tris-bidentate metal complexes Lambda-[M(phen)3]2+, with M = Fe, Ru, Os and phen = 1,10-tris-phenanthroline, are investigated computationally, employing time-dependent density functional theory. Good agreement with experimental spectra is obtained for Ru and Os. The Lambda-[Os(phen)3]2+ spectrum is analyzed in detail. It is shown how relativistic effects red shift CD bands where the Os 5d-orbital participates to a large extent in the excitations. Further, the participation of the metal in the ligand pi --> pi exciton CD is determined to be of the order of 10%. Though solvent effects can have a noticeable effect on individual transitions and rotatory strengths, they are demonstrated to have only a very small overall effect on the resulting simulated CD spectra. For Lambda-[Fe(phen)3]2+, the results are shown to be rather sensitive to the choice of the applied hybrid and nonhybrid density functionals, and the optimized geometries based thereupon. In particular, the sign pattern of the lower-energy part (up to 33 x 10(3) cm(-1)) of the Lambda-[Fe(phen)3]2+ CD spectrum is difficult to reproduce. Some combinations of functionals and geometries yield good agreement with experiment, but no "best" approach can be devised based on the available results. Possible sources of errors in the spectrum of Lambda-[Fe(phen)3]2+ due to deficiencies in the functionals and the exchange-correlation kernels are investigated.

Circular Dichroism↗
PubMed1983

Metal compound intensification of the electron-density of diaminobenzidine.

Diaminobenzidine (DAB), commonly used in immunocytochemistry as the substrate for peroxidase, has a low electron density. DAB has a known affinity for the salts of some metals and therefore an examination of the ability of six metal compounds (including osmium tetroxide) to increase the electron density associated with DAB deposits has been undertaken. Ultra-thin sections of unosmicated rat pituitary gland, embedded in L. R. White resin, were immunostained by a hapten sandwich immunoperoxidase method, using antibodies to ACTH and TSH. The unintensified electron density of the DAB polymer reaction product on the specific endocrine granules was compared with the electron density resulting from the use of each of the six metal compounds. Lead and silver nitrate gave unsatisfactory results, while phosphotungstic acid and uranyl acetate produced a limited increase in specific electron density under the conditions used. Gold chloride was found to give the highest electron density to the specific endocrine granules, followed closely by osmium tetroxide. Background staining was greater when osmium was used. We conclude that several metal compounds may be used to intensify the electron density of DAB, but of the ones tested, gold chloride, which is safer, more stable, and cheaper than osmium tetroxide, was clearly the best. This approach not only increases the electron density of the DAB reaction product, but allows of the possibility of quantitation using energy dispersive X-ray analysis.

3,3'-Diaminobenzidine↗