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At least 235 records · Page 13Linked to original sources
PubMed1997

Selenophosphate synthetase: enzyme labeling studies with [gamma-32P]ATP, [beta-32P]ATP, [8-14C]ATP, and [75Se]selenide.

Selenophosphate synthetase catalyzes a reaction in which ATP and selenide are converted to H3SeP03, H3P04, and AMP in a 1:1:1 ratio. Selenophosphate is derived from the gamma phosphoryl group and orthophosphate from the beta phosphoryl group of ATP. In the absence of selenide, a slow reaction in which ATP is converted quantitatively to 2 H3P04 and AMP occurs. Labeling experiments carried out to detect a putative enzyme-bound pyrophosphate intermediate in the overall reaction showed that up to 0.6 equivalent of the 32P label from [gamma-32P]ATP was bound to protein under enzyme turnover conditions, but only a negligible amount of 32P from [beta-32P]ATP was present. Thus, no Enz-PP intermediate was present in a detectable amount under the experimental conditions used. Isolated enzyme samples contained 75Se from 75Se-labeled selenide and [14C]AMP from [8-14C]ATP in amounts similar to the bound 32P from [gamma-32P]ATP, suggesting that two of the final products, selenophosphate and AMP, were the radioactive compounds detected in these experiments.

Adenosine Triphosphate↗
PubMed2006

Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements.

This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (CSH) with low Ca/Si ratios or aluminosilicate gel at room temperature; CSH, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH)(2) and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement.

Alkalies↗
PubMed1996

Pleuroperitoneal migration of intraperitoneal phosphorus-32-chromic phosphate therapy for stage I ovarian carcinoma.

A patient with postoperative Stage I ovarian carcinoma received 15 mCi of 32P-chromic phosphate suspension in normal saline intraperitoneally as part of her therapy. The following day, a portion of the infused radiopharmaceutical and normal saline had passed transdiaphragmatically into the patient's right pleural cavity. Thoracentesis removed as much fluid as possible and this fluid contained radioactive material. In the ensuing 4 yr, the patient has not manifested any detectable pleural or pulmonary abnormalities attributable to the radioactivity. Retrospective review of 100 consecutive patients receiving 32P-chromic phosphate intraperitoneal therapy resulted in 43 patients in whom the hemithoraces could be evaluated scintigraphically. Three of the 43 patients (7%) had right pleural fluid radioactivity. This is similar to the percentages reported in patients with cirrhosis with ascites in whom hepatic hydrothorax is identified.

Chromium Compounds↗
PubMed1975

Phosphonopyruvic acid: A probable precursor of phosphonic acids in cell-free preparation of Tetrahymena.

1. In cell-free preparations of Tetrahymena, doubly labelled [32P]phosphoenol-[3-14C]pyruvate gives rise to 2-aminoethylphosphonate and 2-amino-3-phosphonopropionate, labelled with the two isotopes in the same ratio as the starting compound. The result is consistent with an intra-molecular rearrangement of phosphoenolpyruvate in the biosynthetic sequence of carbon-phosphorus bond formation. 2. Incubation of [32P]phosphoenolpyruvate with the same preparation, followed by treatment with 2,4-dinitrophenylhydrazine, yielded labelled hydrazones. When these were subjected to hydrogenolysis, the radioactivity was recovered in 2-aminoethylphosphonate and 2-amino-3-phosphonopropionate, suggesting that 2-phosphonoacetaldehyde and 3-phosphonopyruvic acid were probable precursors of the aminoalkylphosphonic acids. 3. Radioactivity from 2-amino-3-phosphono-[3-14C]propionic acid was incorporated into 2-aminoethylphosphonic acid, but incorporation of the radioactivity into lipids was negligible.

Animals↗
PubMed1978

A chemiluminescent effect encountered in the liquid scintillation counting of 32P phosphate.

During the course of a kinetic enzyme study of bisphosphoglyceromutase (EC 2.7.5.4.) a chemiluminescent effect was encountered in the liquid scintillation counting of the beta-emission from 32Pi. A method is described for overcoming the effect, thereby permitting the accurate determination of the radioactive compounds. It is important to check for chemiluminescent effects early in the development of new procedures that involve liquid scintillation counting.

Hydrogen-Ion Concentration↗
PubMed1981

32P-labeling test for DNA damage.

Covalent adducts formed by the reaction of DNA with chemical carcinogens and mutagens may be detected by a 32P-labeling test. DNA preparations exposed to chemicals known to bind covalently to DNA [N-methyl-N-nitrosourea, dimethyl sulfate, formaldehyde, beta-propiolactone, propylene oxide, streptozotocin, nitrogen mustard, and 1,3-bis(2-chloroethyl)-1-nitrosourea] were digested to a mixture of deoxynucleoside 3'-monophosphates by incubation with micrococcal endonuclease (EC 3.1.31.1) and spleen exonuclease (EC 3.1.16.1). The digests were treated with [gamma-32P]ATP and T4 polynucleotide kinase (ATP:5'-dephosphopolynucleotide 5'-phosphotransferase, EC 2.7.1.78) to convert the monophosphates to 5'-32P-labeled deoxynucleoside 3',5'-bis-phosphates. These compounds were then separated on polyethyleneimine-cellulose thin layers in ammonium formate and ammonium sulfate solutions. Autoradiograms of the chromatograms obtained by this high-resolution procedure showed the presence of nucleotides derived from chemically altered, as well as normal, DNA constituents. Maps from DNA exposed to any of the chemicals used exhibited a spot pattern typical for the particular chemical. This method detected a single adduct in 10(5) DNA nucleotides without requiring that the compound under investigation be radioactive and thus provides a useful test to screen chemicals for their capacity to damage DNA by covalent binding.

Animals↗
PubMed1993

Some safety procedures for handling 32P during postlabelling assays.

32P is a high-energy (1.7 MeV) beta-emitter. Its handling is therefore subject to regulation and very strict control. During the postlabelling procedure, numerous steps involve exposure to 32P. The main risk from exposure is through irradiation, but direct accidental contamination can occur. The various manipulation steps (ATP synthesis, labelling, chromatography, quantification) have been analysed for their contribution to potential radiation exposure. Several measures have been taken in the IARC laboratories to minimize exposure of all personnel involved, including those who handle radioactive wastes, since most of the initial radioactivity is eventually discarded. The various steps to be taken for minimizing exposure, such as the training of personnel using fluorescent compounds instead of radioactivity, the use of protective screens and of equipment specially adapted for this work, are reviewed.

Equipment and Supplies↗
PubMed1976

Complete retention of phospholipid acyl groups by mammalian cells in culture.

Radiolabeled phosphate, acetate, and glycerol are incorporated into strain L-fibroblast phospholipids. The acetate and glycerol specifically label the fatty acid and glycerol moieties, respectively, of the phospholipids. To study the metabolic fate of the various moieties of phospholipids, cells incubated with the above radiolabeled compounds were transferred to unlabeled medium, and the rate at which phospholipid radioactivity per 10(6) cells decreased was determined. The rate of decrease expected on the basis of cell division alone was estimated either by monitoring increases in cell number, or by measuring the rate at which radiolabeled DNA per 10(6) cells decreased. Both phospholipid phosphorus and glycerol are lost at a rate greater than can be accounted for by cell division alone. By contrast, nearly all phospholipid acyl chains were retained by the cell to the same extent as radiolabeled DNA. While presence of nonradioactive glycerol in the medium increased the rate at which glycerol was lost from phospholipid, the addition of exogenous fatty acid was without effect on the retention of phospholipid acyl groups. The acyl-glycerol bond of phosphatidylcholine is metabolically more labile than that of phosphatidylethanolamine. Together the data suggest that although L-fibroblast phospholipids undergo deacylation-reacylation reactions, the acyl chains do not equilibrate with either extracellular or intracellular pools of unesterified fatty acid.

Acetates↗
PubMed2004

Biosynthesis of 32P-labelled hydroxocobalamin and a study of its behaviour in rats.

Using Propionibacterium freudenreichii and 32P-ATP, batches of 32P-labelled cobalamin (Cbl) were biosynthesized with a maximum specific activity of 61 microCi/mg, i.e. about 100 times higher than previously reported. Pharmacological doses mixed with 57Co-Cbl were injected subcutaneously in the form of hydroxo-Cbl into rats subsequently killed 5-20 days later. The two labelled Cbls were distributed in approximately the same way, the highest concentration being found in kidney (typical for rats) and about one-fifth of that in liver. These findings tallied with previous observations with radioactive cyano-Cbl and microbiological assay. In all injected rats, the 57Co/32P ratio was lower in liver than in kidney. Drugs eradicating the intestinal flora had no influence. In rats receiving the vitamin orally, the ratio was higher in liver than in kidney. All of our findings could be due to formation of a cobinamide-like compound lacking phosphorus. It is concluded that we have produced radiophosphorus-labelled Cbl that enables studies in vivo.

Administration, Oral↗
PubMed1991

Improved reversed-phase high-performance liquid chromatographic separation of 32P-labelled nucleoside 3',5'-bisphosphate adducts of polycyclic aromatic hydrocarbons.

32P-Postlabelling is a sensitive technique for the detection and analysis of carcinogen-DNA adducts. In this paper we describe the development of an improved high-performance liquid chromatography (HPLC) method for the separation of 32P-labelled 3',5'-bisphosphates of nucleosides modified by reactive derivatives of carcinogenic polycyclic aromatic hydrocarbons (PAH). Optimal resolution of the major 32P-postlabelled DNA adducts formed by the anti-diol-epoxides of ten PAH was achieved using a phenyl-modified silica gel column with a gradient of methanol in phosphate buffer at low pH and high ionic strength. Use of a radioactivity flow detector coupled to the HPLC apparatus allowed detection of subfemtomole quantities of labelled adducts.

Carcinogens↗
PubMed1991

Prevention of radioactive indicator and viral particle transmission with an ointment barrier.

OBJECTIVE: To determine the efficacy of a lanolin-based gel in preventing radioactive particle and viral penetration. DESIGN: Paired, stacked filter discs were held in a stainless steel support, and the gel was applied manually to the upper surface of the upper filter. Indicator solution containing either radioactive viral particles (3H-labeled simian virus 40 or 3H-labeled woodchuck hepatitis virus) or 20 microliters or 100 microliters of 32P-labeled radioactive compounds of much lower molecular weight then were applied to the upper filter. The filter discs were separated after 30 minutes, and the lower disc was examined for radioactivity in a liquid scintillation counter. RESULTS: Transmission of radioactive particles was statistically significantly reduced by the application of the ointment on the upper filter (from 6.7 +/- 0.1 x 10(5) counts per minute [cpm] to 88 +/- 38 cpm). Transmission of both labeled viral particles also was reduced to a similar degree. CONCLUSIONS: Application of protective ointment to the filters significantly reduces transmission of radioactive viral particles and smaller radioactive compounds through filter discs. Use of this ointment may offer similar mechanical protection against the transmission of viruses between patient and healthcare provider.

Equipment Contamination↗
PubMed1995

Effects of OPC-18790, a new positive inotropic agent, on energetics in the ischaemic canine heart: a 31P-MRS study.

OBJECTIVE: Effects of OPC-18790, a novel positive inotropic agent, on cardiohaemodynamics and cardiac energetics were assessed simultaneously in dogs with cardiac ischaemia using phosphorus-31 magnetic resonance spectroscopy (31P-MRS) and compared with those of amrinone, a pure cGMP-inhibited PDE inhibitor. METHODS: Cardiac ischaemia was produced by partial stenosis of the coronary artery. Dogs with cardiac ischaemia were instrumented for the determination of regional coronary blood flow (non-radioactive coloured microsphere method), regional contractile function (sonomicrometry), and haemodynamics. Myocardial phosphate compounds were measured simultaneously by 31P-MRS. RESULTS: Coronary stenosis produced regional dyskinesis, a slight decrease in cardiac output (CO), intracellular acidosis, an increase in the inorganic phosphate (Pi)/creatine phosphate (PCr) ratio concomitantly with a decrease in regional coronary blood flow (CBF) in the ischaemic region. OPC-18790 dose-dependently produced an increase in contractility (measured by peak LVdP/dt) and CO, with only slight changes in heart rate (HR) and mean blood pressure (mBP). OPC-18790 did not change regional dyskinesis, but improved the Pi/PCr ratio at the high dose compared with ischaemic values (before drug administration). Amrinone produced an increase in CO comparable to that of OPC-18790; however, the increase in peak LVdP/dt was smaller while the increase in HR and decrease in mBP were larger than those seen with OPC-18790. Amrinone worsened the Pi/PCr ratio and intracellular acidosis only at the high dose. CONCLUSION: These observed differences in energy metabolism between OPC-18790 and amrinone at the high dose may be due to the ability of OPC-18790 to increase CBF in the ischaemic region and which may attributed to its differing effect on overall haemodynamics. Thus, OPC-18790 may be useful in the management of ischaemic heart failure.

Amrinone↗