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PubMed1993

Catabolism of heme moiety of hemoglobin.haptoglobin in rat liver cells in vivo.

After intravenous administration of [3H-heme,14C-globin]hemoglobin.haptoglobin or [59Fe-heme]hemoglobin.haptoglobin to rats, the radioactive materials extracted from the liver homogenate or its subcellular fractions were subjected to a gel filtration column. In addition to the 82-kDa component, we found three metabolites of heme moiety of the complex in the subcellular fractions. Intact hemoglobin.haptoglobin complex with 3H, 14C, and 59Fe radioactivities, an 82-kDa component with 3H, 14C, and 59Fe radioactivities, a 40-kDa component with 3H and 59Fe radioactivities, a lower molecular weight component with 3H and 59Fe radioactivities, and a component with 3H and 59Fe radioactivities bound to the microsome, which are referred to as peaks A, B, C, D, and E, respectively. Using a differential centrifugation technique, most of peak B was found in the mitochondria-lysosomal fraction. Peaks C and D were in the 82,500 x g supernatant fraction, while peak D was also found in the mitochondria-lysosomal fraction. The molecular weight of peak C was approximately 40 kDa, and the 3H radioactivity of peak C was eluted at the same fraction as glutathione S-transferases using both gel filtration and ion exchange chromatography. Peak E that was solubilized from the microsomes was found at the microsomal heme protein fraction on gel filtration chromatogram. Some of the 3H radioactivity in the microsomes was partially co-purified with cytochrome b5 fraction. These results indicate that there are at least four metabolites of heme moiety of hemoglobin.haptoglobin complex in rat liver cells during its catabolism and suggest that some of the heme derived from catabolized hemoglobin.haptoglobin complex binds to glutathione S-transferases in the cytosol and is incorporated into apoheme proteins in the microsomes or at least apocytochrome b5.

Animals↗

PubMed1997

Acid leaching studies of neutron-irradiated chyrsotile asbestos.

Samples of chrysotile from Quebec (UICC B and Jeffrey 4T-30) and from the Coalinga region of California (Calidria RG-144) were irradiated with thermal neutrons in a reactor. The main activation products induced were 46Sc, 51Cr, 59Fe and 60Co. Accurately weighed samples of the irradiated materials were dispersed in N HCl by hand shaking for 10 s. After leaching for predetermined periods at 25 degrees C, the samples were filtered and the concentrations of Mg determined in the filtrates by inductively-coupled plasma atomic emission spectrometry (IPC-AES) and the activities of the four radionuclides by high resolution gamma-ray spectrometry. Similar measurements were made on solutions obtained by refluxing samples of irradiated chrysotile with 2N HCl for 2 h. The specific activities of each of the four activation products were calculated in arbitrary units and, as the concentrations of Sc, Cr, Fe and Co in the UICC B sample had already been determined, it was possible to estimate the concentrations of these elements in the other two samples. Similarities in the leaching patterns of magnesium and of the activation products showed that with all samples, high proportions of the parent trace elements were present in the form of isomorphous substitutes for magnesium in structural brucite. Agreement was closest with the Calidria chrysotile in which all the radionuclides had a similar pattern. With the Jeffrey and UICC B samples, the presence of a high proportion of the iron as relatively insoluble magnetite accounted for the observed discrepancy in behaviour between 59Fe and Mg. More detailed calculation of leaching rates over specific time intervals showed that, initially, 51Cr and 60Co dissolved more rapidly than Mg but that this was followed by a period in which the opposite was the case. It was concluded that the Calidria RG-144 sample is an ideal candidate for studies of magnesium dissolution in vivo.

Asbestos, Amphibole↗

PubMed2005

Influence of addition order and contact time on thorium(IV) retention by hematite in the presence of humic acids.

The influence of addition order and contact time in the system hematite (alpha-Fe2O3)-humic acid (HA)-thorium(IV) (Th(IV)) was studied in batch experiments. Th(IV) is considered here as a chemical analogue of other actinides (IV). The sorption isotherms were acquired varying pH in the range 2-10 and HA concentration in the range 1-100 mg/L. As already observed by numerous authors, Th(IV) retention was hindered when HA and hematite were equilibrated beforehand during 24 h. As it has been observed in a previous study, this effect was drastic when the ratio between humic and surface (iron oxide) sites exceeds a critical value. However, when HA was added after a 24-h equilibration of the hematite-Th(IV) system, Th(IV) was barely desorbed from the iron oxide surface. Furthermore, no drastic effect of the ratio between humic and surface sites could be evidenced, as the increase of HA concentration only results in a slight monotonic decrease in Th(IV) retention. Increasing contact time between components of the systems only indicated slight Th(IV) retention variation. This was interpreted as a consequence of slow kinetic controls of both the Th(IV)-HA complexation and HA-hematite sorption.

Adsorption↗

PubMedDate not supplied

Natural attenuation reactions at a uranium mill tailings site, western U.S.A.

This paper presents a modeling analysis of the geochemical evolution of a contaminated sandy aquifer at a uranium mill tailings site in the western United States. The tailings pond contains fluids having a pH of 1.5 to 3.5 and high levels of As, Be, Cd, Cr, Pb, Mo, Ni, Se, 226Ra, 228Ra, 230Th, 238U, and 234U. Seepage of tailings fluids into the aquifer has formed a low-pH ground water plume. The reclamation plan is to install a low-permeability cover on the tailings pond to stop the seepage and allow the plume to be attenuated by reactions with the aquifer matrix and flushed by uncontaminated upgradient ground water. To evaluate this reclamation scenario, ground water and sediment core samples were analyzed along one flowpath. Speciation-solubility and mass-transfer modeling revealed two sets of chemical reactions for acid seepage and flushing, respectively. The current concentrations and distribution of ground water constituents can be interpreted as being controlled by stepwise pH-buffer reactions with calcite, amorphous aluminum hydroxide, and amorphous iron hydroxides. These buffer reactions divide the aquifer into zones of near-constant pH, separated by interface zones. For the flushing stage, it is predicted that reactions with surface-bound species will dominate the reaction paths, and more pore volumes are required to neutralize the plume than predicted by models that do not consider surface reactions. Direct mineralogical and surface analysis is needed to substantiate this assertion.

Environmental Monitoring↗

PubMed1999

Radionuclide concentrations in underground waters of Mururoa and Fangataufa Atolls.

In 1997 an expedition to Mururoa and Fangataufa Atolls was carried out to sample underground waters from cavity-chimneys and carbonate monitoring wells. The aim of this study was to determine the prevailing concentration and distribution status of radionuclides. Elemental analysis of interstitial waters was carried out in the water fraction as well as in particles collected at 11 underground monitoring wells. 238Pu, 239,240Pu, 241Am, 137Cs, 90Sr, 3H, 125Sb, 155Eu and 60Co were analyzed in both fractions by alpha-, beta- and gamma-spectrometry. Measurements showed that at 60% of the sites, pH and Eh seemed to be related to tidal cycles; in contrast HTO was constant during the sampling time. Interstitial waters from carbonates and transition zones shared similar chemical composition that were not different from that of the surrounding seawater. Waters collected from basalt cavities left after nuclear tests, (Aristee and Ceto) have a different chemical signature characterized by a deficiency in Mg, K and SO4 as well as enrichment in Sr, Si, Al and Cl compared to the rest of the stations. Radionuclide concentrations present in both, water and particulate fractions, were significantly higher at Ceto and Aristee than at any other monitoring wells, except for Fuseau and Mitre monitoring wells (Fangataufa) where values similar to Ceto were found (e.g. 239,240Pu: > 20 mBq g-1). Considering that Pu isotopes showed high Kd values compared to non-sorbing radionuclides such as 3H, 90Sr and 137Cs it is very unlikely that migration from cavities to monitoring wells accounts for the concentration of Pu isotopes and Am at Fuseau 30 and Mitre 27. Perhaps the contact of lagoon waters with the well before sealing could be a possible source of the transuranics found at these sites. The 238Pu/239,240Pu ratios measured in the particles were similar to that of the lagoon (0.38), thus supporting this hypothesis. The fact that transuranics were found only in the particle fraction, in the water (colloids included) these radionuclides were below detection limits, may be accounted for the conspicuous quantity of iron oxy-hydroxides present in the particulate fraction that under the appropriate redox conditions may be interacting selectively with elements in solution (scavenging) resulting in the enhanced transuranic signal. While transuranics have been found in places of their origin, radionuclides with low Kd values (3H, 90Sr, 137Cs) have already been transported to monitoring wells, as well as to the atolls' lagoons and the open ocean.

Nuclear Warfare↗

PubMed1982

Biochemical characterization of the OXI mutants of the yeast Saccharomyces cerevisiae.

OXI mutants in Saccharomyces cerevisiae lack a functional cytochrome c oxidase. Wild type and OXI mutants were grown in the presence of radioactive delta-amino[14C]levulinic acid, a precursor of porphyrin and heme, and [3H]mevalonic acid, a precursor of the alkyl side-chain of heme a. SDS polyacrylamide gel electrophoresis of the delipidated mitochondria showed that delta-amino[14C]levulinic acid was distributed into three bands migrating in the regions of Mr 28 000, 13 500, and 10 000, while [3H]mevalonic acid was found in a single band with apparent Mr of 10 000. The immunoprecipitates obtained by incubating the solubilized mitochondria of any OXI mutant with antibodies against cytochrome c oxidase, showed, after delipidation, a high specific radioactivity due to delta-amino[14C]levulinic acid and [3H]mevalonic acid. This suggested that a prophyrin a was present in all these OXI mutants. HCl fractionation confirmed the presence of porphyrin a in the apooxidase of these mutants. Atomic absorption spectra of the immunoprecipitate of cytochrome c oxidase showed that copper was not detectable in the mutant OXI IIIa which lacked subunit 1, but was present in the mutant OXI IIIb, which exhibited a minor alteration in the electrophoretic mobility of subunit 1. In OXI I and II mutants there was a 50% reduction in the amount of copper in the immunoprecipitated cytochrome c oxidase. These observations may be interpretable as follows: (1) alterations in polypeptide biosynthesis due to the OXI mutations lead to an improper configuration of cytochrome c oxidase, so that ferrochelatase cannot transfer iron into porphyrin a; (2) subunit I is the binding site for copper, but the mutations in subunits II and III alter the binding site of one of the two copper atoms in subunit I.

Aminolevulinic Acid↗

PubMed1976

Synthesis of apoferritin in mouse peritoneal macrophages. Characterization of 20 S particles.

Apoferritin particles were found in mouse peritoneal macrophages cultured in vitro. They were found as 20S particles in the "ribosomal fraction" of macrophages labeled with L-[14C]glutamic acid. Possibilities that they were breakdown products of ribosomes or of other well-known contaminants of the ribosomal fraction were excluded because they did not incorporate [5-3H]uridine. They were resistant to RNase and were relatively resistant to detergent. The antibody against horse spleen apoferritin precipitated about 70% of the particles in the 20S region, judging by measurement of radioactivity. On in vitro incubation with Fe2+ and suitable oxidizing agents the sedimentation coefficient of 80% of the 20S particles changed to about 60S, which corresponds to that of ferritin. SDS-polyacrylamide gel electrophoresis revealed the presence of subunit structures with the same molecular size as that of mouse liver apoferritin. Under the electron microscope, the particles appeared spherical with a relatively uniform diameter of about 130 A.

Animals↗

PubMed1976

Bone blood flow in the rat determined by the uptake of radioactive particles.

1. Two different suspensions of radioactive particles, 99Tcm-labelled microspheres and 59Fe-labelled resin particles, were injected into the rat central circulation in order to study the distribution of blood flow to the skeleton. 2. Measurements of particle uptake showed that the mean proportion of cardiac output flowing to the skeleton was 3-1%, a figure much lower than the valve of 27% found by Brookes (1970) in a similar experiment. 3. The blood flow per unit mass to individual bones covered a wide range.

Animals↗

PubMed1983

Interaction of rhodanese with mitochondrial NADH dehydrogenase.

NADH dehydrogenase is an iron-sulfur flavoprotein which is isolated and purified from Complex I (mitochondrial NADH: ubiquinone oxidoreductase) by resolution with NaClO4. The activity of the enzyme (followed as NADH: 2-methylnaphthoquinone oxidoreductase) increases linearly with protein concentration (in the range between 0.2 and 1.0 mg/ml) and decreases with aging upon incubation on ice. In the present work a good correlation was found between enzymic activity and labile sulfide content, at least within the limits of sensitivity of the assays employed. Rhodanese (thiosulfate: cyanide sulfurtransferase (EC 2.8.1.1) purified from bovine liver mitochondria was shown to restore, in the presence of thiosulfate, the activity of the partly inactivated NADH dehydrogenase. Concomitantly, sulfur was transferred from thiosulfate to the flavoprotein and incorporated as acid-labile sulfide. Rhodanese-mediated sulfide transfer was directly demonstrated when the reactivation of NADH dehydrogenase was performed in the presence of radioactive thiosulfate (labeled in the outer sulfur) and the 35S-loaded flavoprotein was re-isolated by gel filtration chromatography. The results indicated that the [35S]sulfide was inserted in NADH dehydrogenase and appeared to constitute the structural basis for the increase in enzymic activity.

Animals↗

PubMed1979

An improved method for the measurement of red cell survival using non-radioactive chromium.

An improved technique for the measurement of red cell survival is described in which non-radioactive 50Cr is used in patients for whom radioactive labels are not advisable. The 50Cr was measured by neutron activation analysis using a high resolution germanium (lithium) diode gamma-ray spectrometer. In adult controls, the values obtained were in the range accepted as normal for the 51Cr method, and double labelling experiments showed close agreement. The application of this technique to the measurement of red cell survival in pregnant women suspected of having haemolytic anemia is described.

Adolescent↗

PubMed1980

Isotope decay range distribution curves for use in the analysis of electron microscope autoradiographs.

Analysis of autoradiographs at the electron microscope level requires special procedures, since the size of the radioactive structures visualized are comparable to the range of the radioactive decay particles emitted. Quantitative analysis in these circumstances requires that the sizes, shapes, and juxtaposition of the various structures be taken into account in relation to the range distribution of silver grains, produced by the decays, from a point source for the particular isotope and autoradiographic conditions employed. We present the distribution of silver grains about a point source for the four electron capture isotopes 51Cr, 55Fe, 111In, and 125I. Thin radioactive line sources were constructed and the distribution of autoradiographic grains measured. The grain distributions are discussed in relation to the number of particles per disintegration and their energy and range. A simple calculation enables these line source distributions to be converted into point source distributions, which can then be used for whichever method of quantitative analysis is considered appropriate for a particular problem. An outline is given of some of the more important aspects of various methods of analysis.

Autoradiography↗

PubMedDate not supplied

Exogenous and endogenous DNA modifications as monitored by 32P-postlabeling: relationships to cancer and aging.

32P-postlabeling analysis, a highly sensitive method for the detection and measurement of covalent carcinogen-DNA adducts and other DNA modifications, does not require radioactive test substances and, therefore, can be applied to DNA of mammals, including humans exposed to low doses of environmental or occupational genotoxicants. The basic procedure entails the enzymatic incorporation of 32P-label into hydrolysis products of DNA, followed by chromatographic mapping and autoradiography of the 32P-labeled digestion products and quantitative scintillation spectrometry. Microgram amounts of DNA are analyzed: Thus the assay is suited for limited amounts of cells or tissues. Various versions of the assay afford different sensitivities of adduct detection. A single aromatic or bulky/hydrophobic adduct in 10(8)-10(10) nucleotides can be detected and measured (corresponding to 0.3-30 amol adduct/micrograms DNA or 0.1-10 nmol adduct/mol DNA-P). In animal models, the assay has been successfully applied to a variety of mutagenic (genotoxic) as well as nonmutagenic carcinogens. In humans, DNA specimens from cigarette smokers, iron foundry workers, and coke oven workers whose total aromatic adduct levels ranged from 1 adduct in 10(6)-10(8) DNA nucleotides have been examined by 32P-postlabeling. The assay also detects DNA modifications--Indigenous (I)-compounds--that increase with age in untreated animals. I-compound profiles and levels are highly species-, strain-, sex-, and tissue-specific, and also depend on diet composition. Caloric restriction, a highly efficient method for improving resistance to carcinogenesis and extending life span, increased rather than decreased I-compound levels in various tissues of male rats. Nonmutagenic hepatocarcinogens reduced levels of I-compounds in the target organ. Because of the specificity of this effect, reduction of I-compound levels appears to represent a novel biomarker for the action of nonmutagenic carcinogens. DNA from various hepatomas was found largely devoid of I-compounds. The results support a possible antineoplastic and antiaging role of these DNA modifications.

Aging↗

PubMed1984

Metabolism of 7,12-dimethylbenz(a)anthracene by alveolar macrophages containing ingested ferric oxide, aluminum oxide or carbon particles.

Rat alveolar macrophages with ingested aluminum oxide (Al2O3), ferric oxide (Fe2O3) or carbon particles were incubated for 24 hours with 3H-7, 12-dimethylbenz(a)anthracene (DMBA). Essentially the same amounts and types of metabolites were produced by and released from macrophages with ingested Fe2O3 and Al2O3 particles. Smaller quantities of DMBA and its metabolites could be extracted with ethyl acetate from the culture media and cell lysates of macrophages with ingested carbon particles than from those with Fe2O3 and Al2O3 particles. Also, more of the intracellular radioactivity was associated with insoluble material in macrophages with ingested carbon than in those with the other two types of particles. The results suggest that the inability of Al2O3 to act as a co-carcinogenic carrier for polycyclic aromatic hydrocarbons (PAH) is not related to its effect on PAH metabolism. However, adsorption of PAH and their nonpolar metabolites to carbon may alter the exposure pattern of pulmonary tissues to PAH and their metabolites.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1985

Molecular structures involved in 67Ga and 59Fe binding by placenta and tumors.

The binding of 67Ga and 59Fe by placenta and tumors was compared. After sonification, about 50% of the total radioactivity was present in the insoluble fraction consisting of heavy subcellular particles (mitochondria, fragments of membranes, nuclei, etc.) and known to be rich in lipo- and glycoproteins. Heat denaturation and gel filtration were used to study transferrin and ferritin distribution in the supernatant. The differences between 59Fe and 67Ga uptake in this supernatant seemed to indicate that the transferrin-ferritin system plays a less important role in 67Ga binding than in 59Fe binding.

Animals↗

PubMed1977

Isotopic exchange in 59Fe labeled rice-based meals.

The process of isotopic exchange between extrinsic 59Fe tracer and native nonheme Fe in a rice-based meal was studied by performing Sephadex G-50 column chromatography of soluble supernatant of (1) 59Fe-labeled meal after in vitro pepsin digestion and (2) duodenal aspirate obtained from a human subject fed a similarly labeled meal. The elution patterns of radioactivity and chemically determined nonheme Fe differed markedly when the supernatant of in vitro digested meal at pH 1.8 was analyzed, whereas the patterns were similar when pH was adjusted to 6.2 and also for duodenal aspirate at pH 7. Our results imply that complete isotopic exchange between 59Fe tracer and native nonheme Fe in rice-based meal does not take place in vitro or even during gastric digestion but that it is probably completed in the duodenum.

Chromatography, Gel↗

PubMed1975

Technetium-99m-pyrophosphate: studies in vivo and in vitro.

In rats with induced rickets, the uptake of 99mTcO4 and 99mTc-pyrophosphate per gram of bone was increased as compared with weight-matched controls. However, the uptake of radioactive calcium and 32P-pyrophosphate was similar in both rachitic and control animals, suggesting that the 99mTc label conferred specificity and favored the rachitic lesions. Employing the rat tibia in an in vitro system, 99mTcO4 uptake was predominantly in the organic bone matrix; radioactive calcium, 32P-pyrophosphate, or 14C-diphosphonate uptake was mainly in the bone mineral; and 99mTc-pyrophosphate, 99mTc-diphosphonate, and 99mTc-polyphosphate were found in both mineral and organic phases. By removal of both mineral and polysaccharide and by using agents that altered the degree of collagen fibril cross-linking, evidence was obtained suggesting the 99mTcO4 and 99mTc-pyrophosphate are preferentially bound by immature collagen.

Animals↗

PubMed1986

67Ga binding to sulfated proteoglycan in normal and CCl4-damaged liver.

The binding of 67Ga and 59Fe to sulfated proteoglycan in the normal and CCl4-damaged mouse livers have been studied by means of Sepharose CL-4B column chromatography in guanidine hydrochloride. 67Ga uptake in the liver was elevated to approximately 1.8 times that of the control 2 days after a single administration of CCl4. 67Ga was bound to two types of sulfated proteoglycan (average mol. wt 1,700,000 and 35,000) in the normal and CCl4-damaged liver. However, the percentage of 67Ga bound to sulfated proteoglycan (mol. wt about 1,700,000) in the CCl4-damaged liver was increased as compared with that in the normal liver. Papain digestion of these sulfated proteoglycan fractions caused the 67Ga radioactivities to shift to a low molecular weight fraction (about 10,000). Cellulose acetate electrophoresis of this fraction (mol. wt about 10,000) isolated from the normal and CCl4-damaged livers resulted in identifying heparan sulfate (HS). The 35SO4 incorporation into HS band isolated from the CCl4-damaged liver, as an indicator of HS synthesis, was increased compared with that of the normal liver. 59Fe was not bound to sulfated proteoglycan and its gel filtration pattern was evidently different from that of 67Ga.

Animals↗

PubMed1991

Targeting radiopharmaceuticals--II. Evaluation of new trivalent metal complexes with different overall charges.

Three new multidentate ligands designed to have high affinity for Ga3+, In3+ and Fe3+ have been synthesized. N-(2-hydroxybenzyl)-N'-pyridoxylethylenediamine-N,N'-diacetic acid (HBPLED), N-(2-hydroxy-3,5-dimethylbenzyl)-N'-(3-hydroxy-1,2,5-trimethyl-4- pyridylmethyl)ethylenediamine-N,N'-diacetic acid (Me4HBPLED) and N,N'-bis(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl) ethylenediamine-N,N'-diacetic acid (DMPLED). These ligands give metal-ligand (M-L) complexes with (M = Ga3+, In3+, Fe3+) overall charges of -1.0 and +1, respectively. The 67Ga, 68Ga and 111In complexes of each of the three ligands and the 59Fe complex of Me4HBPLED were prepared, characterized and their biodistributions determined in rats after intravenous injection. Despite the differences in overall charge, the biological behavior of all three 111In complexes were similar, in that the radioactivity cleared rapidly via the kidney. The biodistributions of the 68Ga and 67Ga complexes were comparable to that of the 111In complex counterpart. Also, the 59Fe-Me4HBPLED biodistribution was not significantly different from those of the 68Ga- and 111In-Me4HBPLED. The renal clearance rate seems insensitive to the overall M-L charge; suggesting that the hydrophilic periphery of the ligand rather than the overall molecular charge determines the biological fate (with respect to renal clearance).

Animals↗