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PubMed1985

Radioactive methionine: determination, and distribution of radioactivity in the sulfur, methyl and 4-carbon moieties.

A simple and inexpensive method is described for isolation and determination of [14C]methionine in the non-protein fraction of tissues extensively labeled with 14C. The effectiveness of the method was demonstrated by isolation of non-protein [14C]methionine (as the carboxymethylsulfonium salt) of proven radiopurity from the plant Lemna which had been grown for a number of generations on [U-14C]sucrose and contained a 2000-fold excess of 14C in undefined non-protein compounds. To our knowledge, this is the first reported assay for radioactive methionine under these demanding conditions. This method also offers an attractive alternative to the use of more expensive and sophisticated equipment for assay of radioactive methionine under less demanding conditions. An advantage is that the isolated methioninecarboxymethylsulfonium salt is readily degraded to permit separate determination of radioactivity in the 4-carbon, methyl and sulfur moieties of methionine. During this work, a facile labilization of 3H attached to the (carboxy)methylene carbon of methioninecarboxymethylsulfonium salt was observed. This labilization is ascribed to formation of a sulfur ylid.

Carbon↗
PubMed2004

Degradation of the radioactive and non-labelled branched 4(3',5'-dimethyl 3'-heptyl)-phenol nonylphenol isomer by sphingomonas TTNP3.

The degradation of the 4(3',5'-dimethyl-3'-heptyl)-phenol (p353NP) nonylphenol isomer in cultures of Sphingomonas TTNP3 supplemented with the technical mixture of nonylphenol was first assessed. Then the radioactive and non-labelled form of these diastereomers were both synthesised. The radioactive isomers were synthesised using [ring-U-14C]-labelled phenol and 3,5-dimethyl-3-heptanol by Friedel and Crafts alkylation. The time-course of degradation was performed with and without 14C-p353NP; balancing of radioactivity was calculated from different soluble fractions (organic, aqueous), bacterial biomass, and 14CO2 evolved as mineralization product. The noticeable portion of 14C bound to biomass showed that at least the aromatic ring of 14C-p353NP was degraded and served as energy source and probably as carbon source for bacterial growth. In addition, the appearance of 3,5-dimethyl-3-heptanol, the nonanol corresponding with the side-chain of p353NP, was demonstrated in the bacterial media, and its concentration determined during the course of fermentation. Besides the parent 14C-p353NP, no other radioactive compounds, i.e. metabolites of 14C-p353NP were detected in the media.

Biodegradation, Environmental↗
PubMed1969

Assimilation and metabolism of exogenous organic compounds by the strict autotrophs Thiobacillus thioparus and Thiobacillus neapolitanus.

The assimilation and utilization of the individual carbon atoms of pyruvate and acetate by cells of Thiobacillus thioparus and T. neapolitanus, in the presence and absence of an energy source, were studied by use of radioactive substrates. Both organisms produced (14)CO(2) from (14)C-labeled pyruvate, but more came from carbon 1 than from carbons 2 or 3. The conversion of the carbons of acetate to CO(2) by both organisms was much less than that from any of the pyruvate carbons. When labeled pyruvate and acetate were incubated with these organisms, small amounts of radioactivity were found in the tricholoacetic acid-soluble material, nucleic acids, and lipids, and larger amounts were found in the protein fraction. The composition of the incubation medium affected the amount of utilization and incorporation of labeled substrates by both organisms. The presence of an exogenous energy source (Na(2)S(2)O(3)) suppressed incorporation of the labeled substrates into various cellular components by T. thioparus, but enhanced incorporation by T. neapolitanus. When (14)C-pyruvate was used as a substrate, as many as 12 radioactive compounds were found in the water-soluble fraction in the experiments with T. neapolitanus, whereas no more than three radioactive compounds were detected in this fraction in the experiments with T. thioparus. Of the total (14)C activity found in the water-soluble fractions, malic acid contained the highest percentage. These findings are discussed in light of the overall metabolism of these two sulfur-oxidizing obligate chemoautotrophs, as well as in relation to the biochemical basis of chemoautotrophy.

Acetates↗
PubMed1989

Uptake and utilization of lipids by Paramecium tetraurelia.

Uptake rates of a variety of 14C-labeled fatty acids and complex lipids by Paramecium tetraurelia during 48 h of log-phase growth varied. Fatty acid uptake was maximal during lag phase of growth when phagosome (food vacuole) formation was minimal. Food vacuole formation was shown to be suppressed by the presence of exogenous lipids and by starvation. The rates of uptake of lipids were significantly greater than those of small organic compounds such as amino acids, cyclitols, fatty acid precursors and metabolic intermediates. Significant amounts of radioactivity from 14C-labeled fatty acids were metabolized to 14CO2. The uptake rates of different saturated, straight-chain fatty acids of even carbon numbers were different and were not correlated with chain length, results suggesting that the primary mechanism for uptake of these compounds was neither by bulk transport nor simple diffusion and that carrier-mediated processes could possibly be involved.

Animals↗
PubMedDate not supplied

Abrasiveness evaluation of silica and calcium carbonate used in the production of dentifrices.

Our purpose was to apply a radiometric method to an abrasiveness evaluation in samples of silica and calcium carbonate used as an abrasive in a dentifrice, to help in a prudent selection of materials by dentifrice producers. The results of RDA (radioactive dentin abrasion) abrasiveness indices obtained for these compounds varied from 136 to 19. The relative standard deviations of these RDA results varied from 5.9% to 11.8%, showing a good precision in the method. Also, the results obtained indicated that the abrasiveness indices increase with the particle size of the material. A comparison between different abrasives with similar particle sizes showed that silica presents higher RDA values than calcium carbonate.

Calcium Carbonate↗
PubMed1990

Distribution and binding of 1, 3, 5 [U14C]-trioxane in maternal and fetal rats.

The tissue distribution and binding of 14C activity were studied at different time intervals following a single oral administration of 1,3,5[U14C]-trioxane (14C-TOX) (40 mg/kg: 1.6 MBq/kg) to pregnant rats. Animals were killed on the 21st day of gestation 3, 24, or 48 hours after administration of TOX. In maternal rats, 3 hours after administration, the highest levels of total radioactivity were found in the liver and plasma, followed by a slow, gradual decline with time. The level of 14C-activity in the whole fetus was comparable to that of the maternal kidney through the study. The radioactivity in the fetal kidney and liver at the end of 48 hours after single administration was higher than at 3 hours after administration. Slow decline in radioactivity was observed with time in the fetal brain, skin and carcass. However, after 48 hours the level of total radioactivity in the fetal kidney and brain was more than twice as high as in the corresponding maternal organs. Three hours following 14C-TOX administration 35-41% of the respective total 14C radioactivity in maternal liver and kidney was firmly bound to the macromolecules, while the fetal liver and kidney showed 100-72% binding with respect to their total radioactivity.

Animals↗
PubMed2004

Radiocarbon behaviour in seawater and the brown algae Fucus serratus in the vicinity of the COGEMA La Hague spent fuel reprocessing plant (Goury)--France.

Extensive studies of the radiocarbon (14C) distribution and transfer in the marine environment of the North-Cotentin peninsula and along the English Channel have been carried out. The main aims of these studies have been to estimate the spatial and temporal variation of the 14C concentration in seawater and to calculate 14C concentration factors for some biological species. Such information will be helpful in order to calculate precisely radiation doses to humans. First results obtained in the vicinity of the COGEMA La Hague nuclear plant (Goury) indicate a 14C labelling of the dissolved inorganic carbon (DIC) in seawater (8.0-26.2 Bq.m(-3)) and a tight relationship between the 14C in the liquid releases from the plant and the 14C concentrations in DIC. The particulate organic carbon (POC) is also labelled. The concentration factor calculations for the brown algae (Fucus serratus) sampled from Goury, and also along the English Channel, give 14C values around 3000 Bq.kg(-1) fresh weight / Bq.L(-1).

Atlantic Ocean↗
PubMed1970

Intermediates of photosynthesis in Acetabularia mediterranie chloroplasts.

The chloroplast fraction isolated from Acetabularia mediterranie was exposed to (14)CO(2) as NaH(14)CO(3) in light and darkness, and soluble radioactive compounds were analyzed at frequent intervals. The behavior of Calvin cycle intermediates indicates that this cycle was responsible for much of the carbon fixation in the chloroplasts. However, a substantial part of recently fixed carbon was metabolized via glycolic and glyceric acids. Possible pathways for their metabolism are discussed. Some carboxylation of C(3) acids was suggested by the behavior of phosphoenolpyruvate and malate. A number of amino acids were formed. Small amounts of such compounds as citrate, succinate, and fumarate not usually associated with photosynthesis might have been derived from a low level of mitochondrial contamination. About one-third of the carbon fixed in light was present in acid-labile insoluble compounds other than polysaccharides or proteins. Dark fixation of CO(2) was very small compared with photosynthesis.

Autoradiography↗
PubMed1976

[Study of the biosynthesis of phleic acids, polyunsaturated fatty acids synthesised by Mycobacterium phlei (author's transl)].

Because of their structures, phleic acids (general formula: CH3-(CH2)m-(CH=CH-CH2-CH2)n-CO2H; main component: m = 14, n = 5) cannot be synthesized by the same kinds of enzymatic systems as other natural polyunsaturated fatty acids. By using specifically labelled 14C compounds, we have tested the ability of different molecules to be incorporated in the phleate skeletons by Mycobacterium phlei. The localisation of radioactive carbon atoms has been studied by chemical degradation of labelled phleates, isolation and purification of the degradation products, and determination of their specific radioactivity. When M. phlei cells are incubated with labelled acetate, the unsaturated and saturated parts of the molecules of phleic acids are unequally labelled. The radioactivity of succinate monoester on the one hand and fatty acids (mixture of myristic and palmitic acids) on the other hand, measured after oxidative degradation of phleate esters, shows a constant ratio under definite conditions. Whether [1-14C]acetate or [2-14C]acetate is used for incubation, the same ratio is observed. Therefore acetate is the precursor of the unsaturated part as well as of the saturated part of the phleate molecules. By using labelled fatty acid esters, it has been found that palmitic acid is the precursor of phleates with m = 14, while myristic acid is the precursor of phleates with m = 12. Stearic and eicosanoic acids are not incorporated without degradation. The hypothesis of a condensation of a saturated fatty acid with a preformed polyunsaturated molecule was examined. Search for such a molecule in the lipids of M. phlei gives negative results. Pentaunsaturated phleate arising from palmitate is more abundant than pentaunsaturated phleate arising from myristate, while the reverse is true for hexaunsaturated phleates. These observations make very unlikely such an hypothesis. An elongation process fits well with the observed facts provided that this process involves elongation by two acetate units simultaneously, making elongation by four carbon atoms at a time. Such a requirement would be easily satisfied if two molecules of acetate are condensed together before their utilization in the elongation process. In such a hypothetical process, crotonate would be the most probable substrate of the elongation reaction.

Acetates↗
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↗
PubMed1987

The disposition and metabolism of acrylic acid and ethyl acrylate in male Sprague-Dawley rats.

Following oral dosing of [2,3-14C]acrylic acid (AA; 4, 40, or 400 mg/kg) and [2,3-14C]ethyl acrylate (EA; 2, 20, or 200 mg/kg), the dosed radioactivity was rapidly excreted, with 50-75% of the dose for both compounds eliminated within 24 hr. The primary excretory metabolite for both compounds is carbon dioxide, accounting for 44-68% of the dose. HPLC analysis of the urine of AA- and EA-dosed animals indicated the presence of 3-hydroxypropionic acid. The detection of this metabolite suggests the incorporation of AA into propionic acid metabolism and may explain the rapid evolution of carbon dioxide from AA and EA. HPLC analysis of urine from EA-dosed rats revealed the presence of two metabolites derived from glutathione conjugation, N-acetyl-S-(carboxyethyl)cysteine and N-acetyl-S-(carboxyethyl)cysteine ethyl ester. The excretion of the N-acetyl cysteine derivatives of EA, expressed as a percentage of the dosed compound, decreased in a dose-dependent manner that may be attributed to the depletion of glutathione in organs primarily responsible for glutathione conjugation. No significant decrease in hepatic nonprotein sulfhydryl (NPSH) content was observed following oral dosing with EA at 2-200 mg/kg. However, the depletion of NPSH content at the dosing site, forestomach, and glandular stomach, decreased significantly between 0.02 and 0.2% EA in the dose solution (2 and 20 mg/kg). This observation would suggest that the dosing site represents a significant site of conjugation for relatively low doses of EA. Treatment with the carboxylesterase inhibitor, tri-o-cresyl phosphate (TOCP), 18 hr prior to acrylate dosing potentiated the depletion of hepatic nonprotein sulfhydryls, emphasizing the dominance of hydrolysis as a systemic detoxifying mode in this species. In contrast to EA, AA did not significantly decrease NPSH content in the liver, blood, or forestomach at oral doses of less than 8% AA in the dose solution (400 mg/kg), although a significant depletion of NPSH was observed in the glandular stomach at doses greater than 0.08% (4 mg/kg). No conjugation involving the double bond of AA could be detected in in vitro reactions with glutathione or in the in vivo metabolites, suggesting a secondary effect of AA on NPSH content in these organs. The weights of the forestomach and glandular stomach increased with AA dose, reflecting gross edema and inflammation. With EA this effect on organ weight was only demonstrated in the forestomach, and the response was increased when hydrolysis of EA was inhibited with TOCP.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrylates↗
PubMed1990

Visualization of histamine H1 receptors in dog brain by positron emission tomography.

Histamine H1 receptors were visualized in the living dog brain using [11C]pyrilamine or [11C]doxepin by positron emission tomography (PET). The regional distribution of these carbon-11 labeled compounds in the brain corresponded well with that of the histamine H1 receptors separately determined by in vitro binding assay. The radioactivity in the brain was reduced by treatment with triprolidine (1 mg/kg), a histamine H1 antagonist. The results of our study indicate that it is feasible to visualize histamine H1 receptors in human brain using these 11C-labeled compounds and PET.

Animals↗
PubMed1993

Evaluation of potential strontium chelators in an octanol-water system.

90Sr has a physical half-life of sufficient duration to make it a potentially dangerous contaminant from nuclear accidents and radioactive wastes. In the present study, the efficacy of 16 compounds as potential chelators of strontium was tested in vitro. Strontium solubilization from strontium carbonate and its distribution in an octanol-water system (Do/w) was determined in the absence and presence of alpha-ketoglutaric acid, Kryptofix 222, ethylenglycol-bis-(beta-amino-ethylether)-N,N-tetraacetic acid, diethylentriamine pentaacetic acid, Kryptofix 5, disodium chlodronate, disodium ethidronate, oxaloacetic acid, fumaric acid, D-gluconic acid, succinic acid, citric acid, D,L-2,3-diaminopropionic acid, 1,1-cyclohexanediacetic acid, tartaric acid, and trans-1,2-cy-clohexanediol. Kryptofix 222 and Kryptofix 5 significantly increased solubilized strontium, suggesting strontium chelation potential. Since in previous in vivo studies both compounds were also effective in the removal of strontium following internal contamination, it is concluded that the octanol-water system may be useful screening compounds with strontium chelation potential.

Bridged Bicyclo Compounds↗