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At least 973 records · Page 54Linked to original sources
PubMed2000

Rapid separation of nitroaromatic compounds by solvating gas chromatography.

Nitroaromatic compounds such as 2,4,6-trinitrotoluene are used in the production of explosive and munitions, and are environmental contaminants as a result of such use. Conventional methods to detect these compounds have relied on liquid and gas chromatography to isolate the individual compounds which may be present at low levels in complex environmental matrices before final detection and identification. A new method, solvating gas chromatography, was used to rapidly separate 8 nitroaromatic compounds, showing improved speed relative to conventional liquid and gas chromatography methods. Solvating gas chromatography allows near real-time detection for these energetic compounds, providing improvements in their detection as environmental contaminants, and as compounds of interest to law enforcement and military organizations.

Chromatography, Gas↗
PubMedDate not supplied

Toxicology of Astragalus lusitanicus Lam.

Astragalus lusitanicus is a toxic legume grown in Morocco and in some other Mediterranean countries. In small ruminants, poisoning by this plant is dominated by nervous signs characterized by many cycles of excitement-depression. Macroscopic examination of poisoned animals showed congestive lesions and oedema in the brain and lungs. Microscopic lesions consisted mainly of vacuolar degeneration in neurons, hepatocytes and in spleen and kidney cells. Serum activity of AST and CK as well as blood glucose and urea were increased as a result of poisoning. However, serum activity of alpha-mannosidase was not modified as is the case in locoism. Chemical investigations showed that A. lusitanicus does not contain swainsonine or miserotoxin and its selenium concentration is very low. However, this legume contains indolizidin alkaloids and a first compound was purified and identified.

Acute Disease↗
PubMed1991

3-Nitropropionic acid-exogenous animal neurotoxin and possible human striatal toxin.

3-Nitropropionic acid (3-NPA)--a suicide inhibitor of succinate dehydrogenase--is a widely distributed plant and fungal neurotoxin known to induce a damage to basal ganglia, hippocampus, spinal tracts and peripheral nerves in animals. Recent reports from Northern China indicate that 3-NPA is also likely to be responsible for the development of putaminal necrosis with delayed dystonia in children after ingestion of mildewed sugar cane. This article discusses the role of 3-NPA in the causation of the disease in China, its neurotoxic effects in animals and the potential role for this compound as a probe of selective neuronal vulnerability.

Animal Diseases↗
PubMed1993

An approach for evaluating and increasing the informational content of mutagenicity and clastogenicity data bases.

A method is described for using the fragments identified by the CASE structure-activity relational expert system to identify the type of chemicals that require further testing in mutagenicity and clastogenicity assays. Inclusion of such chemicals will increase the informational content of databases with respect to structural features that are under-represented in currently available data bases. The method is applied to existing databases (mutagenicity in Salmonella, chromosomal aberrations in Chinese hamster ovary cells, unscheduled DNA synthesis in rat hepatocytes, in vivo induction of micronuclei, somatic mutations in Drosophila melanogaster) to identify structural determinants that are absent.

Aniline Compounds↗
PubMed2004

UR-3216: a new generation oral platelet GPIIb/IIIa antagonist.

Various oral platelet GPIIb/IIIa receptor antagonists have undergone clinical investigations, but to date without success. Various factors have been proposed to explain their failure such as low affinity for the receptor, large peak/trough ratio, low bioavailability, partial agonist activity and pro-aggregatory effect. Efforts to discover a truly effective, safe, oral antagonist led to the discovery of UR-3216 (Fig. 1). The active form of UR-3216, UR-2922, possessed a high affinity for the human platelet receptor (K(d) <1 nM) with a slow dissociation rate (k(off)= 90 min) in vitro. UR-2922 induced no ligand-induced binding sites (LIBS) expression or prothrombotic activity in human platelets, distinctly different from orbofiban and other small molecule antagonists. To date, UR-2922 is the only high affinity GPIIb/IIIa antagonist without LIBS expression. In vivo characteristics of UR-3216 showed prolonged duration of efficacy (>24 h) with its favorable pharmacokinetic profile, superior to all the other oral GPIIb/IIIa antagonists. UR-3216 showed high bioavailability, rapid bioconversion to the active form and biliary excretion. UR-3216 is a novel, orally active GPIIb/IIIa antagonist of a new generation, which has substantially improved the crucial compounding factors and will be useful for the treatment of cardiovascular diseases.

Administration, Oral↗
PubMed2001

Chemical evaluation of compounds as nitric oxide or peroxynitrite donors using the reactions with serotonin.

The aim of this work was to assess the capacities of some .NO-donors to release .NO, and consequently NOx in aerobic medium, or to give peroxynitrite. The method was based on the differential reactivity of serotonin (5-HT) with either NO(x) or peroxynitrite, leading in phosphate-buffered solutions to 4-nitroso- and 4-nitro-5-HT formation, respectively. Yields and formation rates of 5-HT derivatives with .NO-donor were compared to those obtained with authentic .NO or peroxynitrite in similar conditions. Aside from the capacity of diazenium diolates (SPER/NO and DEA/NO) to release .NO spontaneously, converting 5-HT exclusively to 4-nitroso-5-HT, all other .NO donors must undergo redox reactions to produce .NO. S-nitrosoglutathione (GSNO) and sodium nitroprusside (SNP) modified 5-HT only in the presence of Cu2+, GSNO yielding 6 times more 4-nitroso-5-HT than SNP. Furthermore, in the presence of Cu+, the yield of .NO-release from GSNO was 45%. The molsidomine metabolite (SIN-1), which was presumed to release both .NO and O2(7-) at pH 7.4, reacted with 5-HT differently, depending on the presence of reductant or oxidant. Under aerobic conditions, SIN-1 acted predominantly as a 5-HT oxidant and also as a poor .NO and peroxynitrite donor (15% yield of .NO-release and 14 % yield of peroxynitrite formation). The strong oxidant Cu2+, even in the presence of air oxygen, accelerated oxidation and increased .NO release from SIN-1 up to 86%. Only a small part of SIN-1 gave simultaneously .NO and O2(7-) able to link together to give peroxynitrite, but other oxidants could enhance .NO release from SIN-1.

Aerobiosis↗
PubMed2005

Crystal structure, thermal decomposition mechanism and explosive properties of [Na(H2TNPG)(H2O)2]n.

The new coordination polymer of sodium trinitrophloroglucinate, [Na(H2TNPG)(H2O)2]n, was synthesized by reacting trinitrophloroglucinol (H3TNPG) with NaHCO3 in aqueous solution and [Na(H2TNPG)(H2O)2]n was recrystallized to be yellow single crystal. The title compound was characterized by using elemental analysis and Fourier transform infrared (FT-IR) spectrum. Its crystal structure was determined by single crystal X-ray diffraction analysis. The crystalline belongs to monoclinic system and C2/c space group. Each Na+ ion is six-coordinated to one H2TNPG- anion and four water molecules in which the oxygen atoms in the water molecules act as bridging atoms. Coordination bonds, electrostatic interaction and intermolecular hydrogen bonds assemble the ions into network structures. The thermal decomposition mechanism of the complex was studied by using differential scanning calorimetry (DSC), thermogravimetry/derivative thermogravimetry (TG/DTG) and FT-IR techniques. Under nitrogen atmosphere with a heating rate of 10 degrees C/min the thermal decomposition of the complex contained one endothermic and five exothermic processes. Two intense exothermic decomposition processes were observed in the range of 173-228 degrees C suggesting its energetic nature and the solid decomposition residue at 500 degrees C was sodium isonitrile. Explosive properties revealed that the compound is sensitive to mechanical stimuli. All properties data observed show that the title compound has explosive properties and can act as components of ecologically clean initiating compositions.

Calorimetry, Differential Scanning↗
PubMed2006

Synthesis, characterization and thermolysis studies on new derivatives of 2,4,5-trinitroimidazoles: potential insensitive high energy materials.

This paper reports the synthesis of three new derivatives of 2,4,5-trinitroimidazole namely, 1-methyl-2,4,5-trinitroimidazole (III), 1-carboethoxy-2,4,5-trinitroimidazole (V) and 1-picryl-2,4,5-trinitroimidazole (VII). The title compounds (III) and (V) were synthesized by the nitration of 1-methyl-/1-carboethoxy-(2,4,5-triiodoimidazole) (II and IV) with fuming nitric acid at 0 degrees C and (VII) was synthesized by condensation of 2,4,5-triiodoimidazole (I) with picryl chloride to obtain 1-picryl-2,4,5-triiodoimidazole (VI) followed by its nitration with fuming nitric acid at 0 degrees C. The synthesized compounds have been characterized by elemental analysis, spectral and thermal techniques. The thermolysis studies using TG-DTA revealed exothermic decomposition of the nitroimidazoles (III, V and VII) with T(max) in the temperature range of 196-225 degrees C. The energy of activation obtained for these compounds was in the range 150-170 kJ/mol. The sensitivity data obtained for the newly synthesized compounds (III, V and VII) indicated their safe nature towards external stimuli (h(50%)>100 cm; friction>36 kg) and could be potential candidates for low vulnerable applications in the futuristic systems. The theoretically predicted performance parameters suggest that 1-methyl-2,4,5-trinitroimidazole (III), exhibits higher velocity of detonation (VOD: 8.8 km/s) compared to compounds V and VII (VOD: 7.6 and 8.41 km/s, respectively).

Calorimetry, Differential Scanning↗
PubMed2005

Spatial and temporal distribution of imidacloprid and thiamethoxam in citrus and impact on Homalodisca coagulata populations.

Titers of two systemic neonicotinoid insecticides in citrus trees were measured in conjunction with conventional evaluations of their impact on glassy-winged sharpshooter (Homalodisca coagulata (Say); GWSS) populations. Xylem fluid samples were collected at regular intervals and from multiple locations within field-grown citrus trees to determine imidacloprid and thiamethoxam concentrations using commercial ELISA kits. Uptake profiles varied considerably with peak mean titers of imidacloprid occurring 6-8 weeks after application compared with 2 weeks for thiamethoxam. The persistence of each compound also varied as near-peak levels of imidacloprid were sustained for another 6-10 weeks before gradually declining. In contrast, thiamethoxam titers declined more rapidly after the initial peak, possibly reflecting an application rate only one-quarter of that used for imidacloprid. Within-tree distributions were more similar for the two compounds, with no significant effect due to height of the sample (upper or lower half) or to the quadrant location within the tree, with the exception of one quadrant in the thiamethoxam-treated trees. Substantial reductions in GWSS nymphs and adults were observed in imidacloprid-treated trees during the 2001 trial and were sustained for 4-5 months after treatment. Treatment effects on nymphs were not as well pronounced in the 2002 trial, when overall GWSS infestations were much reduced from the previous year. However, consistently lower adult infestations were still observed in 2002 for both treatments compared with untreated trees. Information on the spatial and temporal profiles in citrus trees was obtained for both compounds to complement field impact data and improve understanding of their pest management potential.

Animals↗