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PubMed1996

The effect of sustained release boli with ammoniumiron(III)-hexacyanoferrate(II) on radiocesium accumulation in sheep grazing contaminated pasture.

Sustained release boli with the cesium binder ammonium iron(III)-hexacyanoferrate(II) (AFCF) were tested under practical conditions for sheep grazing on pastures contaminated with radiocesium (134Cs+137Cs) from the Chernobyl fallout. Two types of AFCF boli were developed: boli without a protective surface coating intended to last 4-8 wk; and boli coated by a wax-mixture with an extended duration of 10-12 wk. From 1989 to 1993 we measured the effect of wax-coated and uncoated boli administered at various times during the grazing season to a total of 3,248 animals. Reductions in radiocesium levels in meat of sheep were measured by in vivo monitoring. Administration of AFCF boli without a wax-coating reduced the mean radiocesium levels in lambs by 43-75% over a 4-8 wk period, and administration of the wax-coated AFCF boli reduced the mean radiocesium levels by 48-65% over a 9-11 wk period. The coefficients of variation in meat radiocesium levels were similar in treated and control groups at the end of the observation period, showing that the reduction of meat radiocesium values was homogenous throughout the treated groups. The boli giving sustained release of AFCF is a labor-saving and cost effective countermeasure for sheep grazing radiocesium contaminated pastures.

Animals↗

PubMed1986

Treatment of rheumatoid synovitis of the knee with intraarticular injection of dysprosium 165-ferric hydroxide macroaggregates.

One hundred eight knees of 93 patients with seropositive rheumatoid arthritis and persistent synovitis of the knee were treated with an intraarticular injection of 270 mCi of dysprosium 165 bound to ferric hydroxide macroaggregate. Leakage of radioactivity from the injected joint was minimal. Mean leakage to the venous blood 3 hours after injection was 0.11% of the injected dose; this corresponds to a mean whole body dose of 0.2 rads. Mean leakage to the liver 24 hours after injection was 0.64% of the injected dose; this corresponds to a mean liver dose of 3.2 rads. In 7 additional patients examined, there was negligible or near negligible activity found in the draining inguinal lymph nodes. One-year followup was possible for 74 knees (63 patients). Sixty-one percent of the knees had good results, 23% had fair results, and 16% had poor results. There was a direct correlation between the radiographic stage and response to treatment. In knees with stage I radiographic changes, 72% showed good results; 93% showed improvement. In knees with stage II changes, 59% showed good results; 81% showed improvement. These preliminary results indicate that dysprosium 165-ferric hydroxide macroaggregate is an effective agent for radiation synovectomy. The low leakage rates observed offer a definite advantage over agents previously used.

Adult↗

PubMedDate not supplied

Isolation, cloning, sequence analysis and X-ray structure of dimethyl sulfoxide/trimethylamine N-oxide reductase from Rhodobacter capsulatus.

The periplasmic enzyme dimethyl sulfoxide/trimethylamine N-oxide reductase (DMSOR/TMAOR) from the photosynthetic purple bacterium Rhodobacter capsulatus functions as the terminal electron acceptor in its respiratory chain. The enzyme catalyzes the reduction of highly oxidized substrates like dimethyl sulfoxide (DMSO) or trimethylamine N-oxide (TMAO). At a molybdenum redox centre, two single electrons are transferred from cytochrome c556 to the substrate, e.g. DMSO, generating dimethyl sulfide (DMS) and water. The operon encoding this enzyme was isolated, cloned and sequenced, and its chromosomal location determined. It was shown by analytical and crystallographic data that DMSOR and TMAOR are identical enzymes. Degenerate primers were derived from short peptide sequences and a 700 bp fragment was amplified by nested PCR, subsequently cloned and radioactively labeled to screen a prepared lambda DASH library. Positive lambda clones were subcloned into pBluescript and subsequently transformed into Escherichia coli to sequence the DMSOR/TMAOR operon. By an optimized protein purification high yields (5 mg protein/l culture) with a specific activity of 30 U/mg were obtained. The molecular mass was experimentally determined by electrospray mass spectroscopy (MS) to be 85034 Da and from the deduced amino acid sequence of the apoenzyme to be 85033 Da. The enzyme was crystallized in space group P4(1)2(1)2 with unit cell dimensions of a = b = 80.7 A and c = 229.2 A diffracting beyond 1.8 A. The three-dimensional structure was solved by a combination of multiple isomorphous replacement (MIR) and molecular replacement techniques. The atomic model was refined to an R-factor of 0.169 for 57394 independent reflections. The spherical protein consists of four domains with a funnel-like cavity that leads to the freely accessible metal-ion redox center. The sole bis(molybdopterin guanine dinucleotide)molybdenum cofactor (1541 Da) of the single chain protein has the molybdenum ion bound to the cis-dithiolene group of only one molybdopterin guanine dinucleotide (MGD) molecule. In addition, two oxo ligands and the oxygen of a serine side chain are bound to the molybdenum ion.

Cloning, Molecular↗

PubMed1975

Secondary specific immune response in vitro to MSV tumor cells.

The interactions which occur between antigenic tumor cells and normal or immune lymphoid cells in a 3-day in vitro culture, have been studied with a murine sarcoma virus (MSV)-induced tumor. The 3H-thymidine incorporation of lymphoma cells growing in suspension, and the radioactive-chromium release of freshly sampled lymphoma cells regularly added to the culture, have been compared to determine the part played by immune lymphoid cells in cytolysis and cytostasis of the tumor-cell population. The cytolytic activity increases in the culture from day 0 to day 3. It is due, predominantly, to T-cells, and remains specific to antigens shared by MSV tumors and related lymphomas. This activity would be difficult to detect unless freshly sampled ascitic cells were used as targets, since the lymphoma cells spontaneously lose a part of their sensitivity to immune cytolysis during in vitro culture. The method used in the present experiments is a secondary chromium release test (SCRT), which measures the invitro secondary stimulation of cytotoxic T-lymphocytes (CTL) by tumor cells. In the absence of stimulatory cells, the CTL activity would have rapidly fallen in vitro. The cytostatic activity also increases during the 3 days in vitro, in parallel to the cytolytic activity: it is due to non-T-cells and remains mainly non-specific. The significance of these data for the interpretation of invitro demonstrated cell-mediated anti-tumor immune reactions is briefly discussed, as well as their relevance in the in vivo role of immune CTL.

Animals↗

PubMed2006

Pilot-scale in situ bioremedation of uranium in a highly contaminated aquifer. 2. Reduction of u(VI) and geochemical control of u(VI) bioavailability.

In situ microbial reduction of soluble U(VI) to sparingly soluble U(IV) was evaluated at the site of the former S-3 Ponds in Area 3 of the U.S. Department of Energy Natural and Accelerated Bioremediation Research Field Research Center, Oak Ridge, TN. After establishing conditions favorable for bioremediation (Wu, et al. Environ. Sci. Technol. 2006, 40, 3988-3995), intermittent additions of ethanol were initiated within the conditioned inner loop of a nested well recirculation system. These additions initially stimulated denitrification of matrix-entrapped nitrate, but after 2 months, aqueous U levels fell from 5 to approximately 1 microM and sulfate reduction ensued. Continued additions sustained U(VI) reduction over 13 months. X-ray near-edge absorption spectroscopy (XANES) confirmed U(VI) reduction to U(IV) within the inner loop wells, with up to 51%, 35%, and 28% solid-phase U(IV) in sediment samples from the injection well, a monitoring well, and the extraction well, respectively. Microbial analyses confirmed the presence of denitrifying, sulfate-reducing, and iron-reducing bacteria in groundwater and sediments. System pH was generally maintained at less than 6.2 with low bicarbonate level (0.75-1.5 mM) and residual sulfate to suppress methanogenesis and minimize uranium mobilization. The bioavailability of sorbed U(VI) was manipulated by addition of low-level carbonate (< 5 mM) followed by ethanol (1-1.5 mM). Addition of low levels of carbonate increased the concentration of aqueous U, indicating an increased rate of U desorption due to formation of uranyl carbonate complexes. Upon ethanol addition, aqueous U(VI) levels fell, indicating that the rate of microbial reduction exceeded the rate of desorption. Sulfate levels simultaneously decreased, with a corresponding increase in sulfide. When ethanol addition ended but carbonate addition continued, soluble U levels increased, indicating faster desorption than reduction. When bicarbonate addition stopped, aqueous U levels decreased, indicating adsorption to sediments. Changes in the sequence of carbonate and ethanol addition confirmed that carbonate-controlled desorption increased bioavailability of U(VI) for reduction.

Bacteria↗

PubMed1992

Blood flow to bone marrow during development of anemia or polycythemia in the rat.

We applied the radioactive microsphere method to follow the magnitude and time course (0 to 96 hours) of blood flow changes during development and recovery from anemia in awake rats. Blood flow was also monitored during a 96-hour period after polycythemia was induced (erythropoietin administered subcutaneously [SC]). The possible influence of innervation was also examined. After a blood loss of approximately 50% (hypovolemia), blood flow to the femoral marrow tripled within 12 hours and remained elevated for the entire 96-hour period. The relative increase in blood flow to the femoral bone was even greater. Similar findings were obtained in rats with phenylhydrazine (PHZ) hemolytic anemia (normovolemia). Denervation had no detectable effect on the increased blood flow to either marrow or bone. The augmented blood flow during hemolytic anemia was accompanied by a doubling of the oxygen consumption rate by the marrow, while the glucose uptake was not detectably altered. Erythropoietin supplements (3 x 1,000 IU/kg, SC, 6-hour intervals) increased blood flow to the marrow by approximately 25% after 48 hours, and at 72 hours the blood flow had reached a value twice that obtained under control conditions. These results indicate that blood flow to bone marrow is highly variable and hormonally and/or locally regulated. This may have practical consequences for marrow transplantation technology and for administration of drug therapy to patients with insufficient bone marrow hematopoiesis.

Anemia↗

PubMed1982

The effect of heat treatment and particle size of bran on mineral absorption in rats.

The effect of heat treatment of bran on the true zinc absorption was measured using an isotope-dilution technique. A bran-based breakfast cereal (heated to 204 degrees for 40 min during manufacture) was incorporated into a semi-synthetic diet at a level of 180 g/kg. A parallel diet was formulated containing an identical weight of untreated bran from the same source plus other ingredients used to make the cereal. 2. Young male Wistar rats (mean weight 80 g) were injected intramuscularly with 65Zn to label body Zn. They were given the heat-treated- and untreated-bran diets for 9 d. During the last 6 d of this period Zn intakes and faecal and urinary Zn were measured in order to calculate apparent Zn retention. True Zn retention was measured by taking into account losses of Zn of endogenous origin (labelled with 65Zn), by measuring faecal and urinary radioactivity of endogenous origin. 3. Heat treatment of bran removed approximately one-third of the phytate, but this was not enough to improve Zn absorption from the diet. True Zn retention measured by isotope dilution was significantly higher (P less than 0.02) than apparent Zn retention measured by the conventional balance technique. 4. The hypothesis that a reduction in particle size of bran would improve mineral availability was tested by feeding coarse and milled bran (100 mg/kg diet) in a semi-synthetic diet to rats and measuring true Fe and apparent Zn absorptions. The importance of phytate was also investigated by feeding a diet containing dephytinized bran. 5. Male Wistar rats (mean weight 172 g) were given diets containing coarse, milled or dephytinized bran for 9 d. Fe and Zn intakes were measured and faeces and urine collected for Fe and Zn analysis. 6. Rhe mean (+/- SE) particle size of the bran was reduced on milling from 3.5 (+/- 1.8) to 0.2-0.5 mm. There were no differences in the fraction of Fe retained between the three groups. Particle size had a small effect on Zn retention which was marginally higher in rats on the milled-bran diet (0.126 (+/- 0.023)) than in those on the coarse-bran diet (0.087 (+/- 0.012)). Total removal of phytate had a greater effect and apparent Zn retention from the dephytinized-bran diet was significantly higher (0.182 (+/- 0.027), P less than 0.001).

Animals↗

PubMed2005

Chemical reduction of U(VI) by Fe(II) at the solid-water interface using natural and synthetic Fe(III) oxides.

Abiotic reduction of 0.1 mM U(VI) by Fe(II) in the presence of synthetic iron oxides (biogenic magnetite, goethite, and hematite) and natural Fe(III) oxide-containing solids was investigated in pH 6.8 artificial groundwater containing 10 mM NaHCO3. In most experiments, more than 95% of added U(VI) was sorbed to solids. U(VI) was rapidly and extensively (> or = 80%) reduced in the presence of synthetic Fe(III) oxides and highly Fe(II) oxide-enriched (18-35 wt % Fe) Atlantic coastal plain sediments. In contrast, long-term (20-60 d) U(VI) reduction was less than 30% in suspensions of six other natural solids with relatively low Fe(III) oxide content (1-5 wt % Fe). Fe(II) sorption site density was severalfold lower on these natural solids (0.2-1.1 Fe(II) nm(-2)) compared tothe synthetic Fe(lII) oxides (1.6-3.2 Fe(II) nm(-2)), which may explain the poor U(VI) reduction in the natural solid-containing systems. Addition of the reduced form of the electron shuttling compound anthrahydroquinone-2,6-disulfonate (AH2DS; final concentration 2.5 mM) to the natural solid suspensions enhanced the rate and extent of U(VI) reduction, suggesting that AH2DS reduced U(VI) at surface sites where reaction of U(VI) with sorbed Fe(II) was limited. This study demonstrates that abiotic, Fe(II)-driven U(VI) reduction is likely to be less efficient in natural soils and sediments than would be inferred from studies with synthetic Fe(III) oxides.

Adsorption↗

PubMed1992

Monoclonal antibody-coated magnetite particles as contrast agents for MR imaging and laser therapy of human tumors.

Attempts to improve human tumor detection by non-radioactive magnetic resonance techniques have led several investigators to develop antibody-linked paramagnetic contrast agents. Initial studies focused on gadolinium conjugated to monoclonal antibodies. However, very high levels of this contrast agent were needed to significantly reduce proton relaxation times and obtain improved MR images. The use of magnetite (Fe 3O 4) as an MR contrast agent provides a magnetic moment that is approximately one order of magnitude larger than gadolinium. In this study monoclonal antibodies 44 x 14 (specific for squamous cell carcinoma) and 436G10 (specific for melanoma) were obtained from ammonium sulfate precipitation of tumor ascitic fluid. Equal volumes of magnetite solution (1.87 mg Fe/ml) and antibody solution 44 x 14 (5.24 mg protein/ml) and 436G10 (0.64 mg protein/ml) were mixed and sonicated. The 44 x 14-magnetite and 436G10-magnetite solutions were then added to equal volumes of M20 and P3 squamous cell carcinoma cell lines. T1 and T2 values were obtained on a Praxis II NMR spectrometer equipped with a 10 mm probe and 0.25 Tesla permanent magnet. The T2 relaxation times of the magnetite-antibody-cell mixtures were 31 ms with an R = 0.985 for both experimental samples. Our results demonstrate a significant decrease in T2 by binding of the magnetite-coated antibodies to these melanoma and carcinoma cells in vitro. The possibility of detecting subclinical local and metastatic disease with magnetite linked to monoclonal antibodies followed by MRI guided laser tumor ablation therapy may render this technique clinically attractive for treatment of deep-seated tumors.

Antibodies, Monoclonal↗

PubMed1965

ISOTOPIC STUDIES OF UREA METABOLISM IN RABBITS.

1. The half-life of [(15)N]urea was found to be significantly longer than that of [(14)C]urea injected at the same time, the differences being due to endogenous catabolism of urea, which is accompanied by little or no reutilization of (14)C but is approx. 20% for (15)N. [(15)N]Urea therefore appears to be valueless as an indicator of nitrogen metabolism unless the extents of endogenous catabolism of urea and of fractional reutilization of (15)N can be separately estimated. 2. Though measurements of the radioactivity of expired (14)CO(2) confirmed the existence of considerable urea catabolism these could not be used for quantitative assessments. 3. Alternative graphical methods based on [(14)C]urea specific activities in plasma and urine samples were used to calculate the fraction of urea production that is excreted. Values by the two methods were in good agreement and showed that some animals excrete less than half the urea that they produce. 4. Specific activity differences between simultaneous samples of urinary and plasma urea reflect the presence of a pool of urea in the kidney that is not in equilibrium with the body urea pool. Calculations indicate the presence of urea in the kidney that in some cases may represent as much as 15% of the body pool, and in two animals in which post-mortem renal analyses were performed the masses of urea found agreed closely with the calculated values. 5. A model for urea metabolism is proposed that includes this pool in the excretory pathway. The related theory is shown to be adequate to explain the shape of the specific activity curves of urinary urea from the time of injection and the constant delay of the specific activity of urinary urea, relative to that of plasma urea, that is observed after a short preliminary equilibration period. 6. The body urea pool was calculated from the activity retained at 1.5hr. by excluding renal activity and the corrected specific activity of plasma urea at the same time. The urea pool was calculated to be distributed at the plasma concentration in a substantially smaller water volume than that found by injecting tritiated water in five animals. Reasons for this are discussed. 7. Urea synthesis rates calculated from the pool values are in close agreement with rates calculated from the mass of urea recovered in the urine and the fraction of newly synthesized urea that is excreted.

Animals↗

PubMed2004

Depleted uranium dust from fired munitions: physical, chemical and biological properties.

This paper reports physical, chemical and biological analyses of samples of dust resulting from munitions containing depleted uranium (DU) that had been live-fired and had impacted an armored target. Mass spectroscopic analysis indicated that the average atom% of U was 0.198 +/- 0.10, consistent with depleted uranium. Other major elements present were iron, aluminum, and silicon. About 47% of the total mass was particles with diameters <300 microm, of which about 14% was <10 microm. X-ray diffraction analysis indicated that the uranium was present in the sample as uranium oxides-mainly U3O7 (47%), U3O8 (44%) and UO2 (9%). Depleted uranium dust, instilled into the lungs or implanted into the muscle of rats, contained a rapidly soluble uranium component and a more slowly soluble uranium component. The fraction that underwent dissolution in 7 d declined exponentially with increasing initial burden. At the lower lung burdens tested (<15 microg DU dust/lung) about 14% of the uranium appeared in urine within 7 d. At the higher lung burdens tested (~80-200 microg DU dust/lung) about 5% of the DU appeared in urine within 7 d. In both cases about 50% of that total appeared in urine within the first day. DU implanted in muscle similarly showed that about half of the total excreted within 7 d appeared in the first day. At the lower muscle burdens tested (<15 microg DU dust/injection site) about 9% was solubilized within 7 d. At muscle burdens >35 microg DU dust/injection site about 2% appeared in urine within 7 d. Natural uranium (NU) ore dust was instilled into rat lungs for comparison. The fraction dissolving in lung showed a pattern of exponential decline with increasing initial burden similar to DU. However, the decline was less steep, with about 14% appearing in urine for lung burdens up to about 200 microg NU dust/lung and 5% at lung burdens >1,100 microg NU dust/lung. NU also showed both a fast and a more slowly dissolving component. At the higher lung burdens of both DU and NU that showed lowered urine excretion rates, histological evidence of kidney damage was seen. Kidney damage was not seen with the muscle burdens tested. DU dust produced kidney damage at lower lung burdens and lower urine uranium levels than NU dust, suggesting that other toxic metals in DU dust may contribute to the damage.

Air Pollutants, Radioactive↗