PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “IRON, RADIOACTIVE”

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 325 records · Page 18Linked to original sources
PubMed1985

[Rapid analysis of transferrin-iron complexes by isoelectric focusing and radioactive densitometry on gel].

The analysis of the molecular forms of transferrin-iron complexes with 59Fe, was carried out using an isoelectric focusing method on commercially available polyacrylamide plates (PAG plates pH = 4-6,5, LKB). Depending upon the saturation degree of proteins with iron, apotransferrin (pI = 6,1), transferrin-Fe3+ (pI = 5,8), transferrin-2 Fe3+ (a) (pI = 5,5) and transferrin-2 Fe3+ (b) (pI = 5,3) were put forward. When the protein was saturated with iron, a double band was observed which was assigned to the microheterogeneity of the protein and depends upon the sialic content. The quantitative analysis was carried out by studying 59Fe radioactivity distribution directly on the plate. As a control, a specific staining of proteins was achieved. The interpretation of the results is difficult if such a method is used, as some bands are not attributed. Through an unspecific staining, the UV-visible densitometry is not satisfactory enough. The proposed method allows a fast analysis of transferrin-metal complexes labeled with radioactive metals. Such a method would be adaptable to the study of other complexes as transferrin-67Ga, transferrin 111In in order to determine the binding site of metal on the protein and its metal content.

Densitometry↗
PubMedDate not supplied

Significance of skin metallization in the diagnosis of electrocution.

The differentiation of minute current marks from the faint traces of burns may offer some difficulties. Marcinkowski and Wojciechowski (1973) treated the skin of corpses with the same metal objects either heated to a high temperature or exposed to 250 V of alternating current, and determined (by an electrographic method) that metallization appeared only after applying the electric current. The continuation of these observations is linked with the actual experimental studies of Pankowski. By treating the skin of corpses with alternating and direct current of 10, 50, 100 and 250 V for 0.3 sec, 1 sec, 30 sec and 1 min passing through a radioactive electrode of 60Co, he has shown that the radioactivity of the skin at the site of electrode contact increases with the elevation of the voltage and its duration. In the case of direct current the rise was 630-54000-fold at the site of the positive electrode. Using electrodes of copper, aluminium and iron (not radioactive) it has also been shown (by an electrographic method) that metallization intensifies under the same conditions of time and voltage. Metallization could be detected even when no current marks on the skin were evident. Electrography appears to be extremely useful in the detection of metallization. No metallization was detected at the site of the negative electrode (as refers to direct current).

Electric Injuries↗
PubMed1989

Aqueous ethanol extraction of dietary soy protein isolate improves 59Fe absorption by the rat from a casein-based test meal.

A commercial soy protein isolate (SPI) was further processed in an attempt to understand how a diet based on SPI can cause decreased iron retention by the rat from a separately administered casein-based test meal. Groups of eight rats were fed either a casein-based diet or a diet based on SPI. The acid-precipitated SPI was incorporated into diets as such, after neutralization, after 60% (v/v) ethanol extraction and neutralization, or after 60% ethanol exposure and neutralization. All dietary SPI was heat-treated by exposure to steam at 108 degrees C for 30 min. Rats were fed their respective diets, each containing 25 mg Fe/kg, for 13 d, and then all rats were fed a 59Fe-radiolabeled 2.5-g casein test meal containing 64 micrograms of iron. Ingested radioactivity was determined following the meal, and retained radioactivity over the subsequent 10-d period. Absorption was not distinguishable for groups fed the casein-based (78.3 +/- 3.6%) and the ethanol-extracted, SPI-based diet (80.2 +/- 5.4%). Absorption was lower (P less than 0.01) for groups fed each of the other SPI-based diets: SPI as such (68.3 +/- 8.9%), neutralized SPI (69.8 +/- 5.0%) and ethanol-exposed SPI (67.6 +/- 4.8%). An ethanol-extractable component of SPI may be responsible for decreased iron absorption by animals fed SPI prior to a radiolabeled test meal.

Absorption↗
PubMed1990

Cir and Fiu proteins in the outer membrane of Escherichia coli catalyze transport of monomeric catechols: study with beta-lactam antibiotics containing catechol and analogous groups.

Recently, beta-lactam agents containing iron-chelating moieties, such as E0702, which contains catechol, and pirazmonam and U-78,608, which contain 3-hydroxypyridone, have been developed. By determining the susceptibility to these agents of Escherichia coli mutants lacking various iron-repressible outer membrane proteins, we showed that two of these proteins with hitherto unknown functions, Fiu and Cir, were apparently involved in the transport of monomeric catechol and its analogs. These results confirm the conclusion of Curtis and co-workers, which was obtained by using a different set of catechol-containing antibiotics (N. A. C. Curtis, R. L. Eisenstadt, S. J. East, R. J. Cornford, L. A. Walker, and A. J. White, Antimicrob. Agents Chemother. 32:1879-1886, 1988). E0702 was shown to enhance the uptake of radioactive ferric iron into wild-type cells but not into cir fiu double mutants. By combining the influx of E0702 with its hydrolysis by a periplasmic beta-lactamase, we showed that the wild-type cells transported unliganded E0702 at a rate comparable to or even higher than the rate of transport of the E0702-Fe3+ complex. We postulate that the main function of Cir and Fiu may be to recapture the hydrolytic products of enterobactin, such as 2,3-dihydroxybenzoic acid and 2,3-dihydroxybenzoylserine.

Anti-Bacterial Agents↗
PubMed1982

Transferrin endocytosis in reticulocytes: an electron microscope study using colloidal gold.

The endocytosis of transferrin by rabbit reticulocytes was investigated by electron microscopy using transferrin labelled with colloidal gold. This complex was shown to bind and donate its iron to the cells in a manner comparable to native iron-transferrin. After incubation at 37 degrees C approximately 70% of the transferrin-gold particles were located within endocytotic vesicles. Treatment of the cells with pronase, EDTA, metabolic inhibitors and heating to 46 degrees C inhibited the endocytosis. The uptake of colloidal gold complexes of albumin and concanavalin A were compared with that of transferrin. Little endocytosis of these proteins was observed. It is concluded that colloidal gold is a suitable label for the investigation of transferrin endocytosis and that the endocytosis is specific for transferrin and sensitive to the action of reagents which damage membrane receptors, alter membrane function or impair cell metabolism.

Albumins↗
PubMed1986

Prognostic significance of some clinical, morphological and cytogenetic findings in refractory anaemia (RA) and RA with sideroblasts.

In 27 patients initially diagnosed as refractory anaemia (RA) or RA with sideroblasts (RA-S) according to the FAB-classification a number of clinical, morphological and cytogenetic parameters were correlated for prognostic significance. From these correlations it emerged that severe cytopenia is centrally positioned with regard to clinical course in RA and RA-S. Positive correlations were found to initial diagnosis, clonal cytogenetic abnormalities, progression to RA with an excess of blasts (RAEB) or acute myeloid leukaemia (AML), the percentage of bone marrow blast cells and prolonged half life for radioactively labeled iron. The degree of peripheral blood granulocytopenia, alone, was correlated to bone marrow hypoplasia. Moreover, the frequency of abnormal karyotypes was inversely correlated to bone marrow cellularity and proportional to the frequency of bone marrow blast cells. From these relationships it may be proposed that chromosome abnormalities are associated with prolonged blast cell generation times and inhibition of blast cell maturation resulting in reduced marrow cellularity and blast cell accumulation, and, in the peripheral blood, falling percentages of neutrophil granulocytes. With the blast cell accumulation the bone marrow cellularity again becomes hyperplastic and the preleukaemic condition is transformed into RAEB or AML.

Anemia, Refractory↗
PubMed1975

The role of renal adenosine 3',5'-monophosphate in the control of erythropoietin production.

A regulatory role for adenosine 3',5'-monophosphate (cyclic AMP) in the production of the renal hormone rythropoietin following erythropoietic stimulation with cobaltous chloride hexahydrate is proposed. Studies in rates reveal a temporal relationship between renal cyclic AMP levels and plasma titers of erythropoietin. In addition, cobalt increases the activity of an erythropoietin-generating enzyme (renal erythropoietic factor) with maximal enzyme activity occurring after the rise in cyclic AMP levels but before the increase in erythropoietin titers. This increase in renal cyclic AMP is localized to the renal cortex. Cobalt stimulates renal cortical adenylate cyclase but has no effect on renal cyclic nucleotide phosphodiesterase. The addition of cyclic AMP (3 time 10-6 M) and a partially purified cyclic AMP-dependent protein kinase from rat kidney to an inactive preparation of renal erythropoietic factor increases the ability of renal erythropoietic factor to generate erythropoietin. Data from the polycythemic mouse assay, a bioassay used to quantitate erythropoietic activity of test substances, indicate that dibutyryl cyclic AMP is erythropoietically active with respect to its ability to increase radioactive-labelled iron (59Fe) incorporation into heme of newly formed red blood cells. Theophylline, which by itself is erythropoietically inactive, potentiated the erythropoietic effect of cobalt in polycythemic mice. These results suggest that cyclic AMP plays a significant role in the renal production of erythropoietin following cobalt administration. It is postulated that cobalt stimulates renal cortical adenyoate cyclase, thus increasing renal cyclic AMP levels. Cyclic AMP then activates a protein kinase which subsequently stimulates renal erythropoietic factor to generate erythropoietin. A similar cyclic AMP mechanism may be operative after erythropoietic stimulation by exposure to hypoxia or prostaglandin treatment.

Adenine Nucleotides↗
PubMed1950

Radioiron absorption in anemic dogs; fluctuations in the mucosal block and evidence for a gradient of absorption in the gastrointestinal tract.

The control of iron absorption appears to reside in the mucosa of the gastrointestinal tract. The normal dog absorbs very little iron, but the anemic iron-depleted dog may absorb 10 to 20 times as much. This "mucosal block" of the normal dog probably is due largely to iron stores in the mucosa. "Mucosal block" can be effected in the anemic iron-depleted dog by feeding of iron salts, but the degree of "mucosal block" under these conditions never reaches the high degree of "mucosal block" in the normal dog. Rapid movement of iron through the mucosa may explain the short duration of "mucosal block" due to iron feeding in the anemic iron-depleted dogs (18 to 20 hours, Fig. 1). The colon absorbs very little iron under the conditions described. The stomach and duodenum seem to be most active in its absorption. This suggests the existence of a gradient in the capacity of the gastrointestinal tract to absorb iron.

Anemia↗
PubMed1975

A test of time invariance in models of ferrokinetics.

Application of a particular mathematical property of time-invariant systems to experimental data obtained from injection and infusion of radioactive tracer iron in normal subjects is used to show that the generally applied assumption of time invariance to ferrokinetic systems is unjustified and may lead to substantial errors in analysis.

Adult↗
PubMed1983

Relative toxicity of inhaled metal sulfate salts for pulmonary macrophages.

The effects of metal sulfate aerosols on respiratory defense mechanisms in hamsters were studied. Pulmonary macrophage phagocytic rates were measured by determining the in vivo uptake of radioactive colloidal gold (198Au) 1, 24, or 48 h after a single 4-h exposure. The concentrations of sulfate aerosols causing a 50% inhibition in pulmonary macrophage endocytosis (EC50) were determined. When hamsters were exposed for 4 h to cupric sulfate (greater than or equal to 4.8 mg/m3), zinc sulfate (greater than or equal to 3.1 mg/m3), ferric sulfate (greater than or equal to 7.8 mg/m3), or zinc ammonium sulfate (greater than or equal to 10.0 mg/m3), macrophage endocytosis was significantly reduced 1 h after exposure compared with that in unexposed control animals. Although the response was variable, 24 h after exposures to the higher sulfate concentrations the percent of gold ingested by pulmonary macrophages remained depressed. By 48 h, the rate of macrophage endocytosis in hamsters had returned to normal control values except in hamsters exposed to 4.8 mg/m3 cupric sulfate or 9.8 mg/m3 ferric sulfate. These hamsters showed significant increases in phagocytosis. The EC50 values in milligrams of sulfate per cubic meter for cupric sulfate, zinc sulfate, ferric sulfate, and zinc ammonium sulfate were 2.7, 4.5, 7.5, and 17.9, respectively. These results are negatively correlated with the ranking of sulfates using the criteria of relative irritant potency, as measured by increases in pulmonary flow resistance. Thus, rankings of related chemical structures are not absolute. Their relative toxicities vary depending on the end point selected.

Aerosols↗
PubMed2000

Ruthenium-based compounds and tumour growth control (review).

Heavy metals have often been represented, as an uncertain entity related to renal and other risks of toxicity. In favour of this thought there are several lines of evidence, first of all traffic pollution, other evidence that metals such as arsenite, mercury, cadmium or even iron or radioactive heavy metals, that may be introduced into the body by accident, have been responsible of well known pathologies (for example saturnism with lead) or acute toxicity. Therefore, the biological and medical literature have debated on this subject, mainly from the toxicological point of view, rather than studying possible advantages that might come from compounds based on these metals. Exceptions are represented by studies on the role of metal ions in the biochemistry of enzymes and energy production and, although with less emphasis, on their possible use for correcting metabolic malfunctions. Ruthenium, as a metal, has received an even poorer interest and besides the use in histology, neither ruthenium ions nor ruthenium compounds have a clear place in medicine and biology. Nevertheless, since the middle seventies, many studies have been published, showing in a convincible and repetitive manner, the possible advantages of ruthenium as a base for new competitive drugs. The aim of this review is therefore that of critically examining the past and the actual work on ruthenium compounds with emphasis on their proposed role in cancer therapy.

Animals↗
PubMed1975

The effect of increased particles on the endocytosis of radiocolloids by pulmonary macrophages in vivo: competitive and toxic effects.

We have developed a technique for measuring the rate of particle ingestion by pulmonary macrophages in vivo. This technique has been used to examine the impact of pre-exposure to ferric oxide, colloidal carbon, and coal dust on the endocytosis of a test particle, colloidal gold. Our technique for estimating endocytosis is as follows: Syrian golden hamsters received intratracheal instillations (0.15 cm3/100 g body weight) of a suspension of colloidal 198Au (approximately 30 nm diameter). Two hours following instillation, each hamster was sacrificed and its trachea cannulated. The lungs were lavaged 12 times with saline solutions, and the number of cells and gold particles in each wash determined. Analysis of the washout curves permits the calculation of the fraction, gamma, of the colloidal particles which has been ingested at a time, t. This method was then used to measure the influence of inhaled or intratracheally instilled particles on the endocytosis of the gold particles. Hamsters breathed ferric oxide aerosol spontaneously or were given intratracheal instillations of colloidal carbon or coal dust. Immediately following the exposure, the ability of the macrophages to ingest a test particle was assayed by the technique described above. In all instances, colloidal gold endocytosis measured at 2 h was significantly depressed. However, when challenged by the gold colloid 24 h after exposure to the inhaled or instilled particles, only the coal dust group exhibited depressed endocytosis. We conclude that all dusts studied competitively inhibit endocytosis, but only some exhibit a toxic effect on macrophage function.

Aerosols↗