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An affinity label for the anion binding site in ovotransferrin. Implications for iron release to reticulocytes.

Bromopyruvate has been found to be an affinity label for the anion binding site in ovotransferrin. Spectral and radioactive labeling studies indicate that the bromopyruvate first forms a reversible ternary complex with ovotransferrin and iron and then reacts to yield the covalently bound product. This derivative is partially resistant to iron loss by protonation and suggests that protonation and loss of anion is a requisite first step for iron release to reticulocytes.

Affinity Labels↗

The clinical use of radionuclide bone marrow imaging.

Bone marrow aspiration and biopsy are excellent techniques for evaluating bone marrow, but this evaluation is limited to a small part of the total blood-forming organ. With the introduction of radionuclide bone marrow imaging, a simple technique became available that overcomes marrow sampling errors by giving a total body view of functioning marrow. Furthermore, the procedure is noninvasive and provides an atraumatic method for evaluating a number of clinical problems including a discrepancy between bone marrow histology and clinical status (possible marrow sampling error), the determination of amount of active marrow after radiation and chemotherapy when further therapy is being considered, detection of sites of extramedullary hematopoiesis, location of the optimal sites for bone marrow biopsy, the diagnosis and staging of diffuse hematologic disorders, detection of metastases, the diagnosis of bone marrow infarcts in hemolytic anemias, and detecting avascular necrosis of the femoral heads. There are two major classes of bone marrow agents: (1) those that are incorporated into the erythroid precursors such as radioiron and (2) colloids that are taken up by the reticuloendothelial system (RES). Indium-111 chloride was originally considered to be an erythropoietic agent but appears to share some properties of RES labels. The best label to use is dependent on the disease being evaluated.

Anemia, Aplastic↗

Perrhenate uptake by iron and aluminum oxyhydroxides: an analogue for pertechnetate incorporation in Hanford waste tank sludges.

Perrhenate (ReO4-), a nonradioactive surrogate for pertechnetate (99TcO4-), was partitioned during precipitation and aging of iron and aluminum oxyhydroxide solids from aqueous simulants of high-level nuclear waste stored at Hanford, WA. Neutralization of acidic metal nitrate solutions (Al/Fe mole ratio 0.25 and 13.5; 40 ppm Re) to a final pH > 13, followed by aging at 90 degrees C for up to 18 weeks, resulted in substantial amounts of reversibly sorbed Re (approximately 1-10 ppm). Irreversibly sorbed Re increased in the Fe-dominated system with aging, reaching a final value of approximately 83 ppb after 168 h, in a mixture of hematite with minor goethite. Irreversibly sorbed Re in the Al-dominated system generally decreased with time to approximately 30 ppb after 18 weeks in solids dominated by boehmite. Increasing the total amount of Re to 1000 ppm increased the extent of irreversible sorption. The presence of 100 ppm Si prevented transformation of and irreversible Re uptake by ferrihydrite in Fe-dominated systems. In Al-dominated systems, 200 ppm Ni prevented hematite formation but did not affect perrhenate uptake. Results suggest that 5% of the 99Tc inventory in the Hanford waste tanks may be associated with the sludges, and approximately 0.5% incorporated into the solids under oxidizing conditions.

Aluminum Hydroxide↗

Absorption and retention studies of trace elements and minerals in rats using radiotracers and whole-body counting.

A description is given of a whole-body counting technique using radiotracers, permitting the determination of true absorption and endogenous excretion of trace elements and minerals in the rat in vivo. This non-invasive counting method involves oral and intraperitoneal administration of tracer doses of a radioisotope in a cross-over fashion and subsequent measurement of the whole-body retention in a whole-body counter. Thus, true absorption can be determined in one animal which contributes to the reduction of animal use. To study the variations in counting response due to radioisotope distribution, to size or shape of the animal body, the influence of the position of a point source and distribution over different phantoms to simulate various body sizes are experimentally evaluated for 64Cu, 65Zn, 59Fe and 28Mg. Results from 2 studies, with 64Cu and 28Mg, as an example for a trace element and a mineral respectively, are presented and illustrate that absorption as measured by apparent absorption does not necessarily reflect true absorption. True absorption as determined by the whole-body retention method using radioisotopes corrects for faecal losses of endogenous origin.

Absorption↗

[Production of 52Fe by the 55Mn(p,4n)52Fe reaction and milking of 52mMn from 52Fe].

The excitation functions were measured for the nuclear reactions of 55Mn(p,4n)52Fe and 55Mn(p,n)55Fe by using thin manganese disks, specially prepared under a pressure of 200-250 kg/cm2 at 400-500 degrees C for 0.5-1 hour. The maximum cross section in the excitation function for the 55Mn(p,4n)52Fe reaction was found to be 1.4mb at Ep = 54 MeV. From the yield curve, 24.8 MBq/microA h (670 muCi/microA h) of 52Fe was estimated to be produced with 0.45% 55Fe contamination in the energy region between 73 and 39 MeV. Iron-52 was produced in the yield of 85-93% to the expected value from the yield curve in the energy region of 44-60 MeV. For the separation of 52Fe, the radiochemical yield of 52FeCl3 was 70-92% and its radionuclidic purity was higher than 99%. Manganese-52m was obtained repeatedly by eluting the anion exchange column adsorbing 52Fe with 6N-HC1 in 99.9% radionuclidic purity and 86% yield to the expected value. The amount of 55Fe in a large quantity of 52Fe could be determined in 1-2 days from end of bambardment (EOB) by analyzing decay curve of Mn-Ka-X ray from 52Fe and 55Fe.

Drug Contamination↗

Generation of polluted waters from mining wastes in a uranium deposit.

Dump consisting of 9500 tons of rich-in-pyrite mining wastes located in the uranium deposit Curilo, Western Bulgaria, was, after rainfall, an intensive source of acid drainage waters. These waters had a pH in the range of about 1.7-4.5 and contained radionuclides (uranium, radium), heavy metals (copper, zinc, cadmium, lead, nickel, cobalt, iron, and manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The generation of these polluted waters was studied under real field conditions for a period of about seven years during different climatic seasons. It was found that the dump was inhabited by a diverse microflora in which some acidophilic chemolithotrophic bacteria were the prevalent microorganisms. The solubilization of the above-mentioned pollutants from the dump material was connected mainly with the oxidation of pyrite and other sulphide minerals by these bacteria. Their activity depended on some essential environmental factors such as temperature, pH, and water, oxygen and nutrient contents in the dump.

Acid Rain↗

Biochemistry of metalocenes. I. Distribution of 59Fe or 103Ru-labeled metalocene carboxylic acid in mice.

Metalocene carboxylic acids labeled with 59Fe or 103Ru were administered to mice and the organ distributions and amounts of label excreted were determined. Both metalocenes were excreted approximately 90 times faster than the respective inorganic chlorides 59FeCl3 or 103RuCl3. The metalocenes showed an extremely high kidney-to-muscle ratio (up to 1,000). 99mTc-labeled renal agents, tested for comparison, showed lower ratios. Retention of radioactivity in blood and the presence of free iron in urine indicate that the ferrocene derivative is degraded in vivo, but the ruthenocene analog is not.

Animals↗