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At least 361 records · Page 20Linked to original sources
PubMed1994

3,5,5-Trimethylhexanoylferrocene induction of heme oxygenase activity in normal hepatocytes.

Recent work showed that the combination of 50 microM glutethimide plus 50 microM ferric nitrilotriacetate (FeNTA) synergistically induces heme oxygenase (HO) activity in cultured chick embryo liver cells (Cable et al., Biochem Biophys Res Commun 168: 176-181, 1990). This synergistic induction is due to increased heme synthesis, which then acts to increase HO gene transcription. The aim of the current studies was to characterize the effects on hepatic heme metabolism of (3,5,5-trimethylhexanoyl)ferrocene (TMH-ferrocene), which causes hepatic iron-loading in rats. Unlike FeNTA, TMH-ferrocene alone maximally induced HO activity at 5-10 microM TMH-ferrocene. At higher concentrations, HO activities declined, as did total cellular protein synthesis. Induction of HO was maximal after a 12-hr exposure to TMH-ferrocene, similar to induction by glutethimide plus FeNTA. The effect of TMH-ferrocene on HO could not be ascribed to greater cellular uptake of iron, since cell-associated iron levels were higher after FeNTA than after TMH-ferrocene treatment. TMH-ferrocene (up to 20 microM) did not induce delta-aminolevulinic acid synthase activity. Uroporphyrin accumulation in cells treated with TMH-ferrocene was minimal, but the combination of TMH-ferrocene and glutethimide caused a synergistic increase in uroporphyrin accumulation, similar to treatment with glutethimide plus FeNTA. 4,6-Dioxoheptanoic acid, an inhibitor of heme synthesis, blocked the induction of HO caused by glutethimide and FeNTA, but did not decrease the induction of HO by TMH-ferrocene. TMH-ferrocene-mediated induction of HO does not appear to be due to lipid peroxidation, since malondialdehyde formation was greater for ferrocene (a structural analog of TMH-ferrocene that does not induce HO) than for TMH-ferrocene. Furthermore, the anti-oxidant, butylated hydroxyanisole, which prevented lipid peroxidation, decreased HO induced by glutethimide plus FeNTA, but butylated hydroxyanisole did not affect HO induced by TMH-ferrocene. We conclude that, unlike the combination of glutethimide plus FeNTA, TMH-ferrocene induces HO activity by a mechanism that is independent of cellular heme synthesis.

Animals↗
PubMed1996

N-(2-ferrocene-ethyl)maleimide: a new electroactive sulphydryl-specific reagent for cysteine-containing peptides and proteins.

We report the synthesis and application of a specific electroactive label, N-(2-ferrocene-ethyl)maleimide, which provides new redox properties to organic compounds and proteins possessing sulphydryl groups. Its reaction conditions with the cysteine-containing peptide, glutathione, and a terminal monooxygenase enzyme, cytochrome P450cam are presented. The labelled peptide and enzyme acquired reversible electrochemical properties due to the attached ferrocene moiety.

Bacillus cereus↗
PubMed1993

Non-transferrin-bound-iron in serum and low-molecular-weight-iron in the liver of dietary iron-loaded rats.

1. The feeding of 0.5% (3,5,5-trimethylhexanoyl)ferrocene (TMH-ferrocene) in rats resulted in a severe and progressive liver siderosis (total liver iron, 30 mg/g liver wet weight, after 30 weeks). 2. High concentrations of an iron-rich ferritin (up to 250 mg/l) were detected in serum of heavily iron-loaded rats forming a large fraction of non-transferrin-bound-iron (5000 micrograms/dl in maximum). 3. Ferritin and not haemosiderin was the major iron storage protein in the liver. 4. The total liver iron concentration (from 0.4 to > 30 mg Fe/g wet wt) but not the cytosolic low-molecular-weight-iron fraction (from 0.5 to 2.5 microM) was extremely increased during iron-loading.

Animals↗
PubMed1992

Electrochemical enzyme immunoassay for detection of toxic substances.

Sensors that provide reliable, rapid measurement of toxic substances are needed to solve significant human health and safety problems. We developed a new biosensor design that combines the advantages of immunoassay with electrochemical response. We established that this enzyme-linked immunosensor measures toxic substances in biological samples. The biosensor consists of two major elements: (1) an electrical conducting layer having immobilized enzyme, polyclonal or monoclonal antibodies, and other necessary reagents, and (2) the electronic components used in the signal readout. The result is an amperometric immunoassay based on coupling the immunochemical reaction to the enzyme electrode response by using a soluble, electrochemically active mediator. The specific question addressed was: Does the system's immunochemical detection reliably respond at sufficiently low analyte concentrations? We present our results in these areas: (1) enzyme immobilization on colloidal gold; (2) colloidal gold-enzyme deposition on the electrode surface; (3) mediator-antigen conjugate synthesis; (4) antibody incorporation at the electrode surface; (5) bioelectrode characterization and optimization; and (6) immunosensor demonstration to detect antigen. Sensors that employ immunochemical detection will have broad applicability to detect/diagnose toxic substances in biological samples such as blood and urine and in environmental samples such as wastewater and drinking water.

Biosensing Techniques↗
PubMed1986

Potentially-implantable, ferrocene-mediated glucose sensor.

We describe the construction and in vitro testing of a new potentially-implantable amperometric glucose sensor which is based on mediated electron transfer between immobilized glucose oxidase and a graphite base electrode. Under potentiostatic control, entrapped 1,1'-dimethylferrocene acts as an alternative electron acceptor to oxygen and provides a sensing strategy which is relatively unaffected by possible fluctuations in in vivo oxygen tension. Simple 1 mm wide electrodes with a polyurethane membrane gave linear current responses to at least 20 mmol/l glucose with a mean response time of 68 s. An acceptable proportion (17%) of electrodes had low or zero drift over 17 h at 37 degrees C. With plasma samples from diabetic and non-diabetic subjects, glucose concentrations measured by the sensor were significantly correlated with values obtained by a reference laboratory glucose analyser but were proportionally lower. Extension of this study to in vivo testing and further miniaturization of electrodes is justified.

Blood Glucose↗
PubMed1984

Ferrocene-carbamate as prophylaxis against soman poisoning.

The effect of a carbamate derivative of ferrocene as a prophylactic agent toward soman poisoning was studied in mice. A sixfold decrease of the acute toxicity (24-hr LD50) of soman was obtained when the carbamate (5.5 mg/kg = 1/30 X LD50) was given intraperitoneally 30 min before soman. In this experiment atropine (20 mg/kg ip) was given 10 min before soman as support. The protection was lower when atropine or atropine plus toxogonin were given as therapy (1 min after soman). At these protective doses of the ferrocene -carbamate, a 30% inhibition of blood acetylcholinesterase activity was seen. Like physostigmine, the ferrocene -carbamate inhibited the brain acetylcholinesterase, suggesting that the compound entered the brain tissue.

Animals↗
PubMed1987

Toxicological evaluation of substituted dicyclopentadienyliron (ferrocene) compounds.

The acute toxicity of 3 substituted ferrocenes: acetylferrocene, ethylferrocene, and 2,2-bis(ethylferrocenyl)propane (Catocene) were studied in rats, rabbits and monkeys. Acetylferrocene was found to be the most toxic. The oral lethal dose was less than 5 mg/kg for female rats, between 5 and 50 mg/kg for male rats, and between 10 and 100 mg/kg for monkeys. The toxicity of acetylferrocene appeared to be delayed, with most mortality occurring on the third day after dosing. Acetylferrocene was also highly toxic by skin or eye exposure. Gross pathological examination revealed signs of pneumonopathy in both the rats and monkeys. The mechanism by which monkeys are less susceptible than rats to the toxicity of acetylferrocene is not clear.

Administration, Oral↗
PubMed1987

Sensitive ferrocene reagents for derivatization of thiol compounds in high-performance liquid chromatography with dual-electrode coulometric detection.

Three N-substituted maleimides possessing ferrocene as an electrophore were prepared and evaluated for pre-column derivatization of thiol compounds in high-performance liquid chromatography with dual-electrode coulometric detection. The utility of these reagents was investigated by employing N-acetyl-L-cysteine as a model compound. Among the three, N-(ferrocenyl) maleimide was the most favourable reagent with respect to reactivity, stability and electrochemical properties. The dual-electrode coulometric detection of the adduct showed high selectivity and sensitivity with a detection limit of 0.06 pmol. The proposed method is applicable to the determination of glutathione in biological specimens.

Adult↗
PubMed1994

Liver iron quantification: studies in aqueous iron solutions, iron overloaded rats, and patients with hereditary hemochromatosis.

For the noninvasive liver iron quantification by MRI in human iron overload diseases, fundamental proton relaxation mechanisms were studied in aqueous solutions with ferritin and other iron compounds, in experimentally iron overloaded rats, and in patients with iron overload diseases. MR-relaxation rates as a function of iron concentrations in the range of 0-7.5 mg Fe/g aqueous iron solutions, 0-5.4 mg Fe/g rat liver in vivo, and 0.16-4.9 mg Fe/g human liver in vivo were determined from multi- and sets of single-spin echo sequences (1.5 T imager). As predicted by theory, transverse relaxation rates (1/T2) in aqueous iron solutions, in liver tissue of rats, and in human liver tissue increased linearly with the iron concentration. A preliminary calibration for the liver iron quantification by MRI was performed from in vivo measurements of liver 1/T2-relaxation rates and liver iron quantification by atomic absorption spectroscopy in biopsies from 13 patients. With the single spin-echo method, precise in vivo liver iron quantification in humans also above 2.0 mg Fe/g liver tissue (T2 < 15 ms) should be accomplished on any imager with shortest spin-echo time available, at least TE < 20 ms.

Adult↗
PubMed1993

Chronic feeding of carbonyl-iron and TMH-ferrocene in rats. Comparison of two iron-overload models with different iron absorption.

1. The use of carbonyl-iron and (3,5,5-trimethylhexanoyl)-ferrocene (TMH-ferrocene) as a dietary iron-overload model was studied in rats using 59Fe-labelled compounds. 2. The intestinal absorption of carbonyl-iron but not from the TMH-ferrocene-iron was dependent upon the dosage and downregulated in iron-loaded rats. 3. In both models, and similar to hereditary haemochromatosis in humans, the storage of excess iron in the liver started in hepatocytes, whereas the range of iron-loading was strikingly different. 4. Because of the fast and progressive iron-loading, the TMH-ferrocene-model is the most encouraging animal model for experimental haemochromatosis.

Administration, Oral↗
PubMed1988

[Ferrocene, ruthenocene and rhodocene analogs in haloperidol synthesis and organ distribution after labeling with 103Ru and 103mRh].

Ferrocene-Haloperidol was synthesized by N-alkylation of 4-(4'-chlorophenyl)- 4-hydroxypiperidine with 1-ferrocenyl-4-chlor-butan-1-on. By heating the ferrocene-haloperidol with 103RuCl3 the 103Ru-labelled ruthenocene-haloperidol was obtained. This compound showed a high affinity for lung but not for brain in rats and mice. The decay of the 103Ru labelled compound results in the formation of the 103mRh labelled rhodocene-haloperidol, which is rapidly oxidized by air to the corresponding rhodocinium-haloperidol. This compound can be separated by extraction and TLC.

Animals↗
PubMed1988

[Improved diagnosis using deuterated radiopharmaceuticals?--A comparison of the brain affinity of amphetamine analogs].

Ruthenocene amphetamine analogues have the same brain uptake as iodo-labelled amphetamines. This paper compares the organ-distribution of 103Ru labelled ruthenocene- or ferrocene-amphetamine analogues in mice and rats with the same amphetamine in which H-atoms were partly substituted by D-atoms. The uptake in the brain is increased up to 180-200% for deuterium substituted compounds. The pattern of excreted metabolites leads to the conclusion that the deuterated amphetamines are more slowly metabolised than normal (H) compounds.

Amphetamine↗
PubMed1991

An approach to the use of stable isotopes for DNA sequencing.

The sequencing of DNA by current procedures involves the use of radioisotopic or fluorescent labels. We propose that stable isotopes can be used as such labels and that the large number of stable isotopes available would allow multiplexing so that many DNA segments could be sequenced simultaneously. We have developed methods to use 57Fe2O3 to synthesize ferrocene and to attach the ferrocene to the 5' end of oligonucleotides. The 57Fe-labeled M13 universal primer functioned normally in a Sanger sequencing procedure. When a 57Fe-labeled oligonucleotide had migrated on a polyacrylamide gel it was readily located on the dried gel by scanning with resonance ionization spectroscopy (RIS) coupled with mass spectrometry. Using a 57Fe-labeled primer in a PCR reaction a 2000-bp DNA was produced that was detected by RIS on nylon membrane after agarose electrophoresis. The rapid analysis features of RIS coupled with the multispectral multiplexing possibilities of stable isotopes should significantly increase the rate of determination of DNA sequences.

Base Sequence↗
PubMed1993

Local monitoring of proton spin diffusion in static and rotating samples via spy detection.

A method is described for investigating local proton "spin diffusion" by means of a 13C spin probe. The procedure does not require spectral resolution of proton resonance lines and can be applied in the laboratory frame of reference as well as in the rotating frame. Experimental results are presented for a static single crystal of ferrocene and for a powder sample under magic-angle spinning. The spin-diffusion rate constant is found to be proportional to the spinning speed in the range from 1 to 8 kHz.

Carbon↗
PubMed1994

Cross-polarization dynamics and spin diffusion in some aromatic compounds.

The inversion-recovery cross-polarization (IRCP) magic-angle spinning experiment has been applied to study the 13C-1H cross-polarization dynamics of protonated aromatic carbons in ferrocene, 5,6-dimethoxyindole (DMI) and some indole derivatives. Using the 13C-detected proton spin diffusion (SD) experiment recently developed by Zhang et al. [Solid State Nucl. Magn. Reson., 1 (1992) 313], the slow decaying or incoherent stage of the IRCP experiment is shown to be controlled by the spin diffusion process at the directly bound proton. Moreover, a simple phenomenological model treating spin diffusion as a relaxation process provides an excellent agreement with both the IRCP and SD experimental data for all the different C-H pairs of DMI and its derivatives. The resulting time constants of the non-exponential spin diffusion decays are related to the local intra- and intermolecular network of dipolar interactions. This model is nevertheless found to be inadequate for ferrocene because intramolecular spin diffusion then has an inhomogeneous character.

Diffusion↗
PubMed1992

Mediated amperometric determination of xylose and glucose with an immobilized aldose dehydrogenase electrode.

An enzyme electrode was constructed for amperometric determination of xylose and glucose. The electrode is based on the PQQ-dependent membrane-bound aldose dehydrogenase (ALDH) from Gluconobacter oxydans. ALDH was covalently immobilized on a graphite electrode. Immobilized dimethylferrocene, soluble ferrocene carboxylic acid and phenazine methosulphate were used as electron transfer mediators. When xylose was measured electrochemically using an electrode modified with ALDH and dimethylferrocene, the linear measurement range extended to 100 mM. For glucose measurement the linear measurement range was about one-tenth of that for xylose. The electrode showed fairly good stability; 50% of the original electrode response was still obtained after 5 days of intermittent use. The effect of possible leakage of adsorbed mediator was determined by measuring the response of an electrode with soluble mediator as a function of time. The reproducibility of the electrode was good, the standard deviation of the electrode response in ten measurements with the same electrode being only 2.7%.

Biosensing Techniques↗