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At least 631 records · Page 35Linked to original sources

Metabolism of explosive compounds by sulfate-reducing bacteria.

The metabolism of various explosive compounds-1,3,5-trinitrobenzene (TNB), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine (HMX)-by a sulfate-reducing bacterial consortium, Desulfovibrio spp., was studied. The results indicated that the Desulfovibrio spp. used all of the explosive compounds studied as their sole source of nitrogen for growth. The concentrations of TNB, RDX, and HMX in the culture media dropped to below the detection limit (<0.5 ppm) within 18 days of incubation. We also observed the production of ammonia from the nitro groups of the explosive compounds in the culture media. This ammonia served as a nitrogen source for the bacterial growth, and the concentration of ammonia later dropped to <0.5 mg/L. The sulfate-reducing bacteria may be useful in the anaerobic treatment of explosives-contaminated soil.

Ammonia↗

Reconstruction of a case of thallium poisoning using LA-ICP-SFMS.

The unique capabilities of laser ablation in combination with inductively coupled plasma sector field mass spectrometry (LA-ICP-SFMS) were employed to reconstruct details of a homicide by thallium poisoning, which took place 38 years ago in Austria. Thallium was determined in several human bone samples after acid digestion in a microwave oven. The ICP-SFMS results showed that the thallium concentration in the victim's bones was in the range 1.07-2.63 microg g(-1), which is up to 170 times higher compared to concentrations found in bones of persons who have died due to natural causes. The results were in accordance with the values obtained by graphite furnace atomic absorption spectrometry (GF-AAS). Laser ablation ICP-SFMS was applied to assess the time interval between the victim's poisoning and death. Several line scans with a laser spot size of 50 mum were performed on a thumbnail of the poisoned person and on a reference thumbnail by laser ablation ICP-SFMS. Thallium peaks were detected on the nail of the victim at a distance of 2.5 mm from the younger edge of the nail.

Aged↗

A radial-distribution-function approach for predicting rodent carcinogenicity.

Carcinogenic activity has been investigated using the Radial-Distribution-Function (RDF) approach. A discriminant model was developed to predict the carcinogenic and non-carcinogenic activity on a data set of 188 compounds. The percentage of overall classification was 76.4% for the carcinogenic chemicals and 72.5% for the non-carcinogenic chemicals. The predictive power of the model was validated by two tests: a cross-validation by the resubstitution technique and a test set (compounds not used in the development of the model) with 79.3 and 72.5% good classification, respectively. The RDF descriptors were compared with eight other methodologies; Constitutional, Molecular walks counts, Galvez topological charge indices, 2D autocorrelations, Randić molecular profiles, Geometrical, 3D-MORSE, and WHIM, demonstrating that the RDF descriptors are better to the rest of the approaches used.

Animals↗

Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine by novel fungi isolated from unexploded ordnance contaminated marine sediment.

Undersea deposition of unexploded ordnance (UXO) constitutes a potential source of contamination of marine environments by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). Using sediment from a coastal UXO field, Oahu Island, Hawaii, we isolated four novel aerobic RDX-degrading fungi HAW-OCF1, HAW-OCF2, HAW-OCF3 and HAW-OCF5, tentatively identified as members of Rhodotorula, Bullera, Acremonium and Penicillium, respectively. The four isolates mineralized 15-34% of RDX in 58 days as determined by liberated 14CO2. Subsequently we selected Acremonium to determine biotransformation pathway(s) of RDX in more details. When RDX (100 microM) was incubated with resting cells of Acremonium we detected methylenedinitramine (MEDINA), N2O and HCHO. Also we detected hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) together with trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX). Under the same conditions MNX produced N2O and HCHO together with trace amounts of DNX and TNX, but we were unable to detect MEDINA. TNX did not degrade with Acremonium. These experimental findings suggested that RDX degraded via at least two major initial routes; one route involved direct ring cleavage to MEDINA and another involved reduction to MNX prior to ring cleavage. Nitrite was only detected in trace amounts suggesting that degradation via initial denitration did take place but not significantly. Aerobic incubation of Acremonium in sediment contaminated with RDX led to enhanced removal of the nitramine.

Biodegradation, Environmental↗

Uptake and persistence of the vertebrate pesticide, sodium monofluoroacetate (compound 1080), in plants of cultural importance.

Field research was undertaken to determine if naturally occurring plants utilised by a Maori (the indigenous people of New Zealand) community for food and medicine would take up the toxin sodium monofluoroacetate (Compound 1080) from baits used to control the brush-tailed possum Trichosurus vulpecula. Single baits were placed at the base of individual plants of two species, pikopiko (Asplenium bulbiferum) and karamuramu (Coprosma robusta). Plants were sampled at various times up to 56 days, and samples analyzed for 1080 content. No 1080 was detected in any of the pikopiko samples, whereas 1080 was detected in karamuramu, at a maximum concentration of 5 ppb after 7 days, and 2.5 ppb after 14 days. This concentration decreased to zero at 28 days, indicating that while karamuramu was shown to take up 1080, it was not persistent. The results of this study suggest there is negligible risk of humans being poisoned by consuming plants that have taken up 1080 from baits. To allay community concerns that minute concentrations of 1080 might influence the medicinal properties of plants, it is suggested a withholding period of 30 days after 1080 control operations could be adopted.

Animals↗

Biochemical basis of warfarin and bromadiolone resistance in the house mouse, Mus musculus domesticus.

Danish mice (Mus musculus domesticus) genetically resistant to the anticoagulant action of two 4-hydroxycoumarins, warfarin and bromadiolone, were examined to determine their mechanism of resistance. The hepatic vitamin K epoxide reductase in the bromadiolone-resistant mice and in one phenotype of warfarin-resistant mice was highly insensitive to in vitro inhibition by warfarin and bromadiolone. The kinetic constants for the epoxide reductase from bromadiolone-resistant mice were also altered. The Vmax for this enzyme was decreased by 40%, and the Km for the reaction reductant, dithiothreitol, was 70% lower than that of normal mice. This phenotype of Danish resistant mice appears to have a resistance mechanism that is similar to that reported for a Welsh strain of warfarin-resistant rats. The other phenotype of Danish resistant mice had a hepatic epoxide reductase that was only slightly less sensitive to warfarin inhibition than normal. The mechanism of warfarin resistance in these mice is not apparent from the available data.

4-Hydroxycoumarins↗

Peripheral sympathetic function in patients with a polyneuropathy.

Abnormal peripheral vasoconstrictor responses to inspiration were found in the finger tips of 11 out of 20 patients with a suspected polyneuropathy, most of whom had no clinical evidence of autonomic involvement. Among these 11 patients the neuropathy involved both motor and sensory fibers in 9, sensory fibers alone in 1, and autonomic fibers alone in another; it was accompanied by electrical changes suggestive of axonal degeneration in 9 patients, and by normal findings in 1, while the remaining patient was not investigated electrophysiologically. In addition to conventional electrophysiological tests of somatic motor and sensory function, it is suggested that peripheral vasomotor function be evaluated when patients with a polyneuropathy are being investigated, in order to identify the spectrum of nerve fibers that are involved and thereby characterize the disorder more fully.

Adolescent↗

Qualitative and quantitative determination of fluoroacetic acid in Arrabidea bilabiata and Palicourea marcgravii by 19F-NMR spectroscopy.

Qualitative and quantitative examination of Arrabidea bilabiata and Palicourea marcgravii by 19F-NMR spectroscopy has shown the presence of fluoroacetic acid. By acid-base enrichment it is possible to detect amounts of fluoroacetic acid which otherwise are below detection rate. The detection limit (without enrichment) is estimated to be about 4 micrograms/g. Disturbing metal ions of higher oxidation states are also removed by this way. Arrabidea bilabiata contains 64.1 micrograms/g (seeds) and 3.0 micrograms/g (leaves), and Palicourea marcgravii contains 5.4 micrograms/g (leaves).

Fluorine↗

Toxicity and pollution potential of thallium.

Toxicity and pollution potential of thallium are reviewed. Thallium is slightly more acutely toxic to mammals than mercury, and as acutely toxic as copper to fish. Its present industrial uses are too limited to generate pollution, but thallium, discharged in wastes from mines, ore-processing, and coal-burning plants, is contaminating the environment.

Animals↗

Inorganic and organic fluoride concentrations in tissues after the oral administration of sodium monofluoroacetate (Compound 1080) to rats.

Male rats were used to study the inorganic (ionic) and organic fluoride concentrations in plasma, liver, kidneys and stomach content after oral doses of 0, 2.2, 3.5, 4.0, 5.0 and 7.0 mg sodium monofluoroacetate (SMFA, Compound 1080)/kg body weight. Tissue and plasma ionic fluoride concentrations were observed to be higher in all rats given SMFA as compared to rats in the control group. This observation suggests in vivo defluorination of SMFA. Homogenates of liver obtained from SMFA poisoned rats showed significant increases in ionic fluoride concentration during a 6-day storage period at +4 degrees C, with the total fluoride concentration (ionic and organic) remaining constant. The average percentages of distribution of SMFA (organic fluoride) in plasma, liver, and kidneys were 7.05, 5.07 and 1.68, respectively. Plasma and tissue SMFA concentrations were generally lower than the corresponding stomach fluid SMFA concentrations for all dosage groups. Lethal concentration of SMFA in the liquid stomach content was in the range 84.9--189 micrograms/ml, corresponding to total (ionic and organic) fluoride concentrations in the range of 16.1--36 micrograms/ml.

Animals↗