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PubMed1995

The effect of chemical pretreatment on the aerobic microbial degradation of PCB congeners in aqueous systems.

A series of experiments was conducted to examine the effects of chemical pretreatment on biodegradation of 14C-labeled PCB congeners in aqueous systems. Fenton's reagent was used to generate hydroxyl radicals (OH) which were successful in partially oxidizing/transforming otherwise recalcitrant molecules of tetrachlorinated PCB, but had little or no impact on the biodegradation of a monochlorinated congener. Application of Fenton's reagent (1% H2O2, 1 mM FeSO4) followed by inoculation with pure cultures Pseudomonas sp, strain LB 400 and Alcaligenes eutrophus, strain H850 resulted in the removal of approximately 38% of 2-chlorobiphenyl and 51% of 2,2',4,4'-tetrachlorobiphenyl in the form of 14CO2. Comparison of the rate and extent of biodegradation of 2,2',4,4'-tetrachlorobiphenyl after the application of Fenton's reagent with the dynamic and final level of radioactivity in the aqueous phase of experimental system suggests two possible means of microbial utilization of tetrachlorinated PCB congener altered by chemical oxidation: (a) consumption of the partially oxidized chemical dissolved in the aqueous phase, and (b) direct microbial attack on the transformed compound, which may still be adhered to the solid surface.

Bacteria, Aerobic↗

PubMed1987

An interaction of benzene metabolites reproduces the myelotoxicity observed with benzene exposure.

Benzene-induced myelotoxicity can be reproduced by the coadministration of two principal metabolites, phenol and hydroquinone. Coadministration of phenol (75 mg/kg) and hydroquinone (25-75 mg/kg) twice daily to B6C3F1 mice for 12 days resulted in a significant loss in bone marrow cellularity in a manner exhibiting a dose-response. One explanation for this potentiation is that phenol stimulates the peroxidase-dependent metabolism of hydroquinone. Addition of phenol to incubations containing horseradish peroxidase, H2O2, and hydroquinone resulted in a stimulation of both hydroquinone removal and benzoquinone formation. Stimulation occurred with phenol as low as 100 microM and with very low concentrations of horseradish peroxidase. When boiled rat liver protein was added to identical incubations containing [14C]hydroquinone, the level of radioactivity recovered as protein bound increased by 37% when phenol was added. Similar results were observed when [14C]hydroquinone was incubated in the presence of activated human leukocytes. Hydroquinone binding was increased by approximately 70% in the presence of phenol. Phenol-induced stimulation of hydroquinone metabolism and benzoquinone formation represents a likely explanation for the bone marrow suppression associated with benzene toxicity.

Animals↗

PubMed1995

[Hematological dispensary care for the participants in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station].

Standard (hemogram, routine biochemical indices) and non-standard hematological parameters reflecting monocytic-macrophagal system (MMS) function and antioxidant defense were investigated in 140 subjects who had worked in radionuclide-contaminated zone after the Chernobyl accident. As shown by measurements of iron serum metabolism, lysozyme, total interferon, CIC, chemiluminescence of venous blood mononuclear leukocytes, MMS in 50% of them underwent negative changes in suppressed antioxidant defense. Standard hematological findings registered abnormalities only in 8-27% of the examinees.

Adult↗

PubMed2004

The source of heme for vascular heme oxygenase II: de novo heme biosynthesis in rat aorta.

Heme is an essential prosthetic group or substrate for many proteins, including hemoglobin, and hemo enzymes such as nitric oxide synthase, soluble guanylyl cyclase, and heme oxygenase (HO). HO is responsible for the breakdown of heme into equimolar amounts of biliverdin, iron, and carbon monoxide, the latter of which is thought to play a role in the regulation of vascular tone. It is not clear whether the source of heme for cardiovascular functions is derived from uptake from the extracellular milieu or synthesis. In this study, we tested the hypothesis that blood vessels obtain their supply of heme for HO through de novo synthesis. Adult male Sprague-Dawley rat aorta was incubated at 37 degrees C in Krebs' solution with 1 micro M [14C]delta-aminolevulinic acid (ALA). [14C]ALA uptake was linear for about 30 min and reached a plateau at approximately 100 min. The radioactivity was incorporated into porphyrins and heme as determined by esterification of 14C-labelled metabolites and thin-layer chromatography. The first and rate-limiting step of heme biosynthesis is catalyzed by ALA synthase (ALA-S), the activity of which was determined in rat aorta using a radiometric assay, approximately 250 nmol x (g wet mass)(-1) x h(-1). Inducing HO-1 in rat aorta with S-nitroso-N-acetylpenicillamine (500 micro M) did not increase ALA-S activity as compared with basal activity levels of the enzyme. It appears that there is a sufficient amount of heme available under basal ALA-S activity conditions to meet the increased demand for heme resulting from HO-1 induction. These observations indicate that the complete enzymatic pathway for de novo heme biosynthesis resides in rat aorta and furthermore indicate that de novo heme synthesis is capable of supplying a substantial portion of the heme substrate for HO in the aorta.

5-Aminolevulinate Synthetase↗

PubMed2003

Optimization of low activity spectrometric gamma-gamma probes for ash determination in coal stockpiles.

A stockpile probe based on backscattered gamma-gamma-ray technique was tested for the determination of coal ash. A centralized tool employing a gamma-ray source of very low radioactivity (1.85 MBq) was used. This logging tool was tested using 137Cs and 133 Ba sources with a 37 mm (diameter) by 75 mm NaI (TI) scintillation detector. Ten source-detector configurations were analyzed using 137Cs, and another nine source-detector configurations are analyzed, using 133Ba source, both for four geophysical models, having a borehole diameter of 90 mm. Regression analysis on the laboratory logging data for each studied configuration was carried out in order to establish calibration equations for ash prediction. The optimum configuration for the logging stockpile probe using 137Cs source was determined to be 80 mm source to detector spacing, and 80 mm iron thickness shielding. This configuration gives the best results for ash prediction. The root mean square (rms) deviation for ash is 1.52%. The optimum configuration for the logging stockpile probe using 133 Ba source is determined to be 85 mm source to detector spacing, and 50mm iron thickness shielding. This configuration gives the best results for ash prediction, where the rms deviation for ash is 1.47%.

Journal Article↗

PubMed1990

Uptake of ascorbic acid by freshly isolated cells and secretory granules from the intermediate lobe of ox hypophyses.

Mechanically isolated cells from the intermediate lobe of ox hypophyses contained 40.6 +/- 3.7 nmol mg-1 protein (mean +/- SE, n = 5) of ascorbic acid. They accumulated radioactivity time dependently, on incubation with L-[14C]ascorbic acid in ionic medium dominated by NaCl. No definite saturation of uptake occurred when mechanically isolated cells were incubated with increasing ascorbic acid concentrations up to 0.6 mM. But if such cells were purified on a Percoll gradient, a clear saturation of uptake could be observed. Acetylsalicylic acid reduced the uptake markedly. When cells loaded with L-[14C]ascorbic acid were homogenized and placed on a Percoll gradient, the radioactivity was recovered in several subcellular fractions. Decrease of the Na+ concentration or presence of ouabain in the medium did not cause noticeable changes in uptake by non-purified cells, whereas uptake by purified cells was clearly sodium-dependent. Phloridzin inhibited uptake. Secretory granules from pars intermedia contained 40.0 +/- 3.8 nmol mg-1 protein of ascorbic acid (mean +/- SE, n = 3) and could accumulate L-[14C]ascorbic acid rapidly in a KCl-dominated medium. The uptake was not saturable with ascorbic acid concentration and was not influenced by the presence of I mM ATP + I mM Mg2+ in the medium. The concentration of copper and iron in isolated cells was comparable to that in isolated neurohypophysial nerve terminals, whereas the concentration of zinc was considerably higher in the pars intermedia cells. The concentration of Cu, Zn, Fe and Co in secretory granules from pars intermedia was higher than in secretory granules from neurohypophyses.

Animals↗

PubMed2005

Identification of heme binding protein complexes in murine erythroleukemic cells: study by a novel two-dimensional native separation -- liquid chromatography and electrophoresis.

In the current postgenomic era there is a growing interest in analysis of protein complexes in their native state. Here we present a novel two-dimensional separation technique for assessment of native protein complexes. The method combines native chromatography with native electrophoresis. The approach was used to study heme-binding protein complexes in murine erythroleukemia cells. The cells were metabolically labeled with [(59)Fe]-heme and cellular lysates were separated by anion-exchange chromatography. Fractions containing the (59)Fe isotope were collected, concentrated and further separated by native gel electrophoresis. A total of 13 radioactive protein bands were detected and analyzed by liquid chromatography-tandem mass spectrometry. Thirty-three individual proteins were identified and attributed to four novel multiprotein complexes representing four different 'snapshots' of cellular events involved in hemoglobin biosynthesis.

Animals↗

PubMed1968

Magakaryocyte quantitation.

A method is described for the quantitation of megakaryocytes. In this technic bone marrow sections obtained at the time of maximal marrow uptake of previously injected plasma bound (59)Fe are counted for radioactivity as well as the number of megakaryocytes and nucleated red cells. We calculated the total megakaryocytes by relating the ratio of megakaryocyte: radioactivity with the total marrow (59)Fe activity at the time of sampling. A multiple counting correction factor which is related to cell diameter and section thickness is required for quantitation of cell numbers from section material. The normal megakaryocyte number for the rat is 11.0 x 10(6)/kg, and 6.1 x 10(6)/kg for man.

Animals↗

PubMed1979

Mineral metabolism of the healing arterial wall.

The mineral metabolism of healing arterial walls was studied by measuring the accumulation of several radioisotopes at the site of vascular repair in rats. Each rat was subjected to a 1-cm full-thickness aortotomy and then immediately injected by tail vein with c 5 muCi of one of the following radioisotopes: chromic chloride Cr 51 or sodium chromate Cr 51; ferrous chloride Fe 59 or ferric chloride Fe 59; manganous chloride Mn 54; selenious acid Se 75; strontium chloride Sr 85; or zinc chloride Zn 65. At intervals of 1, 2, 4, 6, and 10 days after operation and injection, groups of four rats for each radioisotope were killed, aortas dissected, and the specific radioactivity of healing vascular tissue compared with that of adjacent normal artery. There were sharp and statistically significant differences in the preferential accumulation of the radioisotopes in healing compared with normal aorta. Zinc appeared to be the element most involved in vascular repair, followed by selenium and chromium.

Animals↗

PubMed1997

ECAT ART - a continuously rotating PET camera: performance characteristics, initial clinical studies, and installation considerations in a nuclear medicine department.

Advances in fully three-dimensional (3D) image reconstruction techniques have permitted the development of a commercial, rotating, partial ring, fully 3D positron emission tomographic (PET) scanner, the ECAT ART. The system has less than one-half the number of bismuth germanate detectors compared with a full ring scanner with the equivalent field of view, resulting in reduced capital cost. The performance characteristics, implications for installation in a nuclear medicine department, and clinical utility of the scanner are presented in this report. The sensitivity (20 cm diameterx20 cm long cylindrical phantom, no scatter correction) is 11400 cps.kBq-1.ml-1. This compares with 5800 and 40500 cps.kBq-1.ml-1 in 2D and 3D respectively for the equivalent full ring scanner (ECAT EXACT). With an energy window of 350-650 keV the maximum noise equivalent count (NEC) rate was 27 kcps at a radioactivity concentration of approximately 15 kBq.ml-1 in the cylinder. Spatial resolution is approximately 6 mm full width at half maximum on axis degrading to just under 8 mm at a distance of 20 cm off axis. Installation and use within the nuclear medicine department does not appreciably increase background levels of radiation on gamma cameras in adjacent rooms and the dose rate to an operator in the same room is 2 microSv. h-1 for a typical fluorine-18 fluorodeoxyglucose (18F-FDG) study with an initial injected activity of 370 MBq. The scanner has been used for clinical imaging with18F-FDG for neurological and oncological applications. Its novel use for imaging iron-52 transferrin for localising erythropoietic activity demonstrates its sensitivity and resolution advantages over a conventional dual-headed gamma camera. The ECAT ART provides a viable alternative to conventional full ring PET scanners without compromising the performance required for clinical PET imaging.

Equipment Design↗

PubMed2005

Modelling of geochemical reactions and experimental cation exchange in MX 80 bentonite.

Bentonites are widely used for waste repository systems because of their hydrodynamic, surface and chemical-retention properties. MX 80 bentonite (bentonite of Wyoming) contains approximately 85% Na/Ca-montmorillonite and 15% accessory minerals. The dominant presence of Na/Ca-montmorillonite in this clay mineral could cause it to perform exceptionally well as an engineered barrier for a radioactive waste repository because this buffer material is expected to fill up by swelling the void between canisters containing waste and the surrounding ground. However, the Na/Ca-montmorillonite could be transformed to other clay minerals as a function of time under repository conditions. Previous modelling studies based on the hydrolysis reactions have shown that the Na/Ca-montmorillonite-to-Ca-montmorillonite conversion is the most significant chemical transformation. In fact, this chemical process appears to be a simple cation exchange into the engineered barrier. The purpose of the present study was two-fold. Firstly, it was hoped to predict the newly formed products of bentonite-fluid reactions under repository conditions by applying a thermokinetic hydrochemical code (KIRMAT: Kinetic Reactions and Mass Transport). The system modelled herein was considered to consist of a 1-m thick zone of water-saturated engineered barrier. This non-equilibrated system was placed in contact with a geological fluid on one side, which was then allowed to diffuse into the barrier, while the other side was kept in contact with iron-charged water. Reducing initial conditions ( [P(O)2 approximately equals 0] ; Eh=-200 mV) and a constant reaction temperature (100 degrees C) were considered. Secondly, it was hoped to estimate the influence of inter-layer cations (Ca and Na) on the swelling behaviour of the MX 80 bentonite by using an isothermal system of water vapour adsorption and an environmental scanning electron microscope (ESEM) coupled with a digital image analysis (DIA) program. Here, the MX 80 bentonite was previously treated with concentrated solutions (1N) of calcium and sodium chlorides. The results confirmed that the Na/Ca-montmorillonite-to-Ca-montmorillonite conversion was the main chemical transformation in the bentonite barrier under repository conditions. A simplified method (based on volume balance) has shown that the swelling capacity of the engineered barrier would be slightly affected after 1000 years of diffusion-reaction because the volume of neo-formed swelling clays is almost directly proportional to the volume of transformed initial-montmorillonite. Minimal neo-formation of saponites, vermiculites and chlorites was also observed. In addition, an isothermal system of water adsorption and ESEM-DIA methods showed that in the raw-bentonite-to-Ca-bentonite exchange there is a small decrease in the amount of adsorbed water and the swelling potential.

Adsorption↗

PubMed1998

Temporal and spatial variation of waterborne point-of-use 222Rn in three water distribution systems.

Three water supply systems in Iowa were studied to examine temporal variation of 222Rn at the point of entry and the point of use. For the three towns, 71, 9, and 0% of the maximum point-of-use 222Rn concentrations were significantly higher than the point-of-entry 222Rn concentrations. Homes connected to older water mains in two of the towns had higher 222Rn concentrations than those connected to newer water mains. In one town, the waterborne 222Rn concentrations in the home were related to the home's location along an old water main. The increase in 222Rn concentrations, after the water leaves the water plant, were attributed to radium deposits in the water distribution system. In addition, the water plant's radium laden iron filters contributed 7 Bq L-1 and 60 Bq L-1 of 222Rn to the finished water in What Cheer, Iowa, and Wellman, Iowa, respectively. Backwashing schedules in the water treatment systems greatly affected point-of-entry 222Rn concentrations. The results of this study have important implications for 222Rn sampling, required for regulatory compliance.

Fresh Water↗

PubMed1975

Comparison of the effects of zinc deprivation and actinomycin D on ribonucleic acid synthesis by stimulated lymphocytes.

1. EDTA inhibited incorporation of [3H]uridine into RNA of lymphocytes, but did not decrease uptake into the cold-acid-soluble fraction of the cells. The inhibition by EDTA was largely reversible by simultaneous addition of Zn2+. 2. Low concentrations pf actinomycin D (3 ng/ml) added at the time of stimulation of the cells inhibited [3H]uridine incorporation into RNA, but concentrations of 50-100 ng/ml were required to produce the same degree of inhibition if addition of actinomycin D was delayed until just before the incorporation was measured. This difference in sensitivity did not reg within the cells. 3. When added immediately before phytohaemagglutinin, actinomycin D (3 ng/ml) and EDTA produced similar time-courses of inhibition of uridine incorporation. 4. Uridine incorporation at 32h was inhibited when actinomycin D (3 ng/ml) or EDTA was added just before stimulation of the cells, but was only slightly affected when they were added at 32h. At intermediate times the incorporation of uridine remained sensitive to addition of EDTA for longer than it was sensitive to actinomycin D. 5. Polyacrylamide-gel separation of RNA synthesized in EDTA-treated cultures in the presence or absence of added Zn2+ showed that lower availability of Zn2+ resulted in a decreased rate of transfer of radioactivity from 32S to 28S rRNA and decreased survival of 28S rRNA relative to 18S rRNA. 6. Close similarities have been shown to exist between the effects of EDTA and low concentrations of actinomycin D. Not all the effects of EDTA could be explained by postulating that Zn2+ was a constituent of RNA polymerase I, nor were the effects of actinomycin D readily explained by previously suggested mechanisms of action of this antibiotic.

Animals↗

PubMed1969

Subunit dissociation of certain abnormal human hemoglobins.

The extent of dissociation of various hemoglobins into subunits was estimated from their elution volumes (V(e)) on G-100 Sephadex. Under the same controlled conditions carboxyhemoglobins A, A3 (A(1)), F, S, and C all had the same elution volumes. The carboxy and cyanmet derivatives of hemoglobin Kansas (a variant with very low oxygen affinity) had a relatively high V(e), indicating a decreased mean molecular weight and therefore an increased tendency to form dimers and even monomers. Conversely, the liganded derivatives of hemoglobin Chesapeake (a variant with high oxygen affinity) had a relatively low V(e), suggestive of an impaired degree of subunit dissociation. Deoxyhemoglobin Chesapeake had a V(e) identical with that of deoxyhemoglobin A. Cat hemoglobin, known to have an unusually low oxygen affinity, was found to have a higher V(e) than human, dog, rabbit, rat, or guinea pig hemoglobins. Haptoglobin is thought to bind alphabeta dimers in preference to the alpha(2)beta(2)-tetramer. The comparative haptoglobin affinities of the human hemoglobins were measured by competition between the test hemoglobin and radioactive reference hemoglobin for haptoglobin binding sites. Hemoglobins A, F, S, and C all seemed to bind equally readily, but hemoglobin Kansas and cat hemoglobin showed a higher affinity, and hemoglobin Chesapeake a lower affinity. These results are in accord with recently proposed models which predict that hemoglobins which have an increased degree of subunit dissociation will have a low oxygen affinity, and vice versa.

Animals↗

PubMed2002

Instrumental neutron activation analysis of minor and trace elements in food in the Russian region that suffered from the Chernobyl disaster.

The control of food quality, using the analysis of essential and toxic element contents, assumes an urgent importance within the regions that suffered from the Chernobyl disaster. Instrumental neutron activation analysis was used to study contents of 17 chemical elements (calcium, chlorine, cobalt, chromium, cesium, iron, mercury, potassium, magnesium, manganese, sodium, rubidium, antimony, scandium, selenium, strontium, and zinc) in foods within the south and southwest territories of the Kaluga Region that was exposed to radionuclide contamination. The radionuclide contamination ranges up to 15 Ci/km2 there. Flesh and meat products, dairy products, bread, vegetables, legumes, roots, fruits, and mushrooms were analyzed. The concentration of essential and toxic elements in the different foods were in the normal ranges.

Diet↗

PubMedDate not supplied

[The results of a hematological examination of the population living in an area of intense radiological control in Bryansk Province].

As many as 1492 residents of populated areas in Zlynka District of Bryansk Province were studied. There were 628 children and 864 adults in the series. Contamination with radionuclides in the territory of residence was of the order of 40/km2 and above; the level of cesium deposition in the body of the examinees ranged between 0.4 to 3.4. Deviations from the norm in the peripheral blood were detected in 15% of adults and 36% of children. These were manifest by hypochromic anemia, by eosinophil- and lymphoid-type leukemoid reactions, and by other disorders that resulted from nutritional imbalance, deficiency of iron of varying genesis, helminthic invasion, allergic states. Concurrent cellular and humoral immunity shifts coupled with the deviations from the norm in the indices for the thioldisulphide system attest to the need for designing of measures to secure long term observation over health state of the population residing in the contaminated territories.

Adolescent↗

PubMed1982

Spectral and other studies on the intestinal haem receptor of the pig.

We recently demonstrated the presence of a Triton-solubilized high-affinity haem binder on the pig duodenal brush border membrane. The association of haem to the binding factor was determined using radioactive haem and is now studied by a spectrophotometric technique. The binding alters the Soret absorption band of haem from 395 nm to 413 nm. The dissociation constant for the binding of haem to the solubilized binding factor was estimated to be about 10(-9) M by difference spectroscopy. Human serum albumin could not prevent the solubilized binding factor from binding haem. Trypsin digestion destroyed the binder.

Animals↗

PubMedDate not supplied

[Features of immune disorders in miners who took part in cleaning up after the accident at Chernobyl Atomic Energy Station].

The condition was studied of the immune and nervous system in 72 miners who took part in the elimination of the aftermaths of the Chernobyl accident and in 30 miners of the control group. Ascertained in the miners-liquidators was the presence of imbalance of T-cells of the immune system and disorder of the humoral immunity. The patients displayed changes in the blood content of sodium, increased concentrations of iron, zink, and lead, and diminished amounts of cuprum. In this group pathology of the vegetative nervous system, vascular and vestibular abnormalities were found with high frequency. The findings secured attest to the need for taking account of particular features of disordered immunity, abnormalities of metabolism and nervous regulation in instituting a complex therapy in miners-liquidators.

Antibody Formation↗