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PubMed2006

Solid-phase microextraction: investigation of the metabolism of substances that may be abused by inhalation.

Purified liquefied petroleum gas (LPG), a mixture of butane, isobutane, and propane, is commonly abused by inhalation. Little is known about the mammalian metabolism of these substances. Metabolism of other hydrocarbons, including n-hexane and cyclohexane, has been studied in vitro using a range of liver preparations, with metabolites analyzed by static headspace techniques. Solid-phase microextraction (SPME) for sampling metabolites in the headspace of incubates of volatile compounds with activated rat liver microsomes is investigated. Cyclohexanol and cyclohexanone were formed from cyclohexane and 1-, 2-, and 3-hexanol and 2-hexanone from n-hexane as predicted. Secondary alcohols are found for the other compounds studied, except for propene and isobutane, together with 2-propanone and 2-butanone from propane and n-butane, respectively. Samples from three individuals who died following LPG abuse contained a range of putative n-butane metabolites: n-butanol, 2-butanol, 2,3-butanediol, 3-hydroxy-2-butanone, and 2,3-butanedione. To our knowledge, the last three compounds have not been proposed as metabolites of n-butane in man. These might be produced through similar metabolic pathways to those of n-hexane and n-heptane. The findings indicate the value of SPME for investigating the metabolism of volatile substances and for detecting and monitoring exposure to these compounds.

Animals↗
PubMed1987

Physiological significance of the alcohol dehydrogenase polymorphism in larvae of Drosophila.

This study deals with biochemical and metabolic-physiological aspects of the relationship between variation in in vivo alcohol dehydrogenase activity and fitness in larvae homozygous for the alleles Adh71k, AdhF, AdhS, of Drosophila melanogaster, and for the common Adh allele of Drosophila simulans. The Adh genotypes differ in the maximum oxidation rates of propan-2-ol into acetone in vivo. There are smaller differences between the Adh genotypes in rates of ethanol elimination. Rates of accumulation of ethanol in vivo are negatively associated with larval-to-adult survival of the Adh genotypes. The rank order of the maximum rates of the ADHs in elimination of propan-2-ol, as well as ethanol, is ADH-71k greater than ADH-F greater than ADH-S greater than simulans-ADH. The ratio of this maximum rate to ADH quantity reveals the rank order of ADH-S greater than ADH-F greater than ADH-71k greater than simulans-ADH, suggesting a compensation for allozymic efficiency by the ADH quantity in D. melanogaster. Our findings show that natural selection may act on the Adh polymorphism in larvae via differences in rates of alcohol metabolism.

Alcohol Dehydrogenase↗
PubMed2001

Toxicokinetics of methyl tert-butyl ether and its metabolites in humans after oral exposure.

Methyl tert-butyl ether (MTBE) is widely used as an additive to gasoline, to increase oxygen content and reduce tailpipe emission of pollutants. Widespread human exposure to MTBE may occur due to leakage of gasoline storage tanks and a high stability and mobility of MTBE in ground water. To compare disposition of MTBE after different routes of exposure, its biotransformation was studied in humans after oral administration in water. Human volunteers (3 males and 3 females, identical individuals, exposures were performed 4 weeks apart) were exposed to 5 and 15 mg 13C-MTBE dissolved in 100 ml of water. Urine samples from the volunteers were collected for 96 h after administration in 6-h intervals and blood samples were taken in intervals for 24 h. In urine, MTBE and the MTBE-metabolites tert-butanol (t-butanol), 2-methyl-1,2-propane diol, and 2-hydroxyisobutyrate were quantified, MTBE and t-butanol were determined in blood samples and in exhaled air in a limited study of 3 male volunteers given 15 mg MTBE in 100 ml of water. MTBE blood concentrations were 0.69 +/- 0.25 microM after 15 mg MTBE and 0.10 +/- 0.03 microM after 5 mg MTBE. MTBE was rapidly cleared from blood with terminal half-lives of 3.7 +/- 0.9 h (15 mg MTBE) and 8.1 +/- 3.0 h (5 mg MTBE). The blood concentrations of t-butanol were 1.82 +/- 0.63 microM after 15 mg MTBE and 0.45 +/- 0.13 microM after 5 mg MTBE. Approximately 30% of the MTBE dose was cleared by exhalation as unchanged MTBE and as t-butanol. MTBE exhalation was rapid and maximal MTBE concentrations (100 nmol/l) in exhaled air were achieved within 10-20 min. Clearance of MTBE by exhalation paralleled clearance of MTBE from blood. T-butanol was cleared from blood with half-lives of 8.5 +/- 2.4 h (15 mg MTBE) and 8.1 +/- 1.6 h (5 mg MTBE). In urine samples, 2-hydroxyisobutyrate was recovered as major excretory product, t-butanol and 2-methyl-1,2-propane diol were minor metabolites. Elimination half-lives for the different urinary metabolites of MTBE were between 7.7 and 17.8 h. Approximately 50% of the administered MTBE was recovered in urine of the volunteers after both exposures, another 30% was recovered in exhaled air as unchanged MTBE and t-butanol. The obtained data indicate that MTBE-biotransformation and excretion after oral exposure is similar to inhalation exposure and suggest the absence of a significant first-pass metabolism of MTBE in the liver after oral administration.

Adult↗
PubMed1994

Suicide by environmental hypoxia (forced depletion of oxygen).

Suicidal suffocation by forced oxygen depletion (environmental hypoxia) with carbon dioxide (CO2) and with propane is discussed in two cases. No toxicologic proof was available with the former and circumstantial evidence weighed heavily. The latter case demonstrated inhaled propane by an on-scene transthoracic aspirate; all other toxicology specimens, including brain, liver, blood, kidney, fat, and vitreous, did not contain hydrocarbons. This second fatality was complicated by multi-agent overdose, including diphenhydramine, fluoxetine (Prozac), and nordiazepam. The designation of these deaths as due to oxygen depletion involved careful scrutiny of the autopsy, toxicologic, and scene findings. Complete analysis of all factors surrounding these rarely encountered suffocation deaths is stressed.

Adult↗
PubMed1990

Occurrence of 222Rn and progeny in natural gas processing plants in western Canada.

In Western Canada, there are many plants that process natural gas to remove impurities (CO2, H2S, H2O) and recover natural gas liquids (propane, butane, etc.). Trace quantities of 222Rn present in the inlet stream are concentrated in streams rich with propane. Potential hazards to plant operators include direct inhalation of 222Rn and progeny; exposure to gamma radiation from short-lived progeny deposited inside equipment; or inhalation of 210Pb when contaminated equipment is opened for repair. Twenty-four plants operated by seven companies cooperated to assess these potential hazards. The findings indicate a substantial flux of 222Rn and progeny passing through the plants, but little accumulation of radionuclides. In no case was there evidence of significant exposure of plant operators or maintenance personnel to ionizing radiation. Further investigation of pipeline operations, and chemical operations using natural gas liquids as feed stock, is recommended.

Bismuth↗
PubMed1995

Investigation of alternate droplet material bubble dosimeters.

Past theoretical research involving superheated liquid droplet (bubble) neutron dosimeters has shown the possibility of using alternate droplet materials in order to give the dosimeter improved temperature stability. Based on that research testing was conducted on HFC-134a, propylene, propane, and hexafluoropropylene to determine (1) the compatibility of the novel superheated liquid material with the detector gel matrix material; (2) the gamma sensitivity of the detector droplets; (3) the response of the dosimeters as a function of neutron energy; and (4) the response of the dosimeters as a function of temperature. These tests were conducted at the Armed Forces Radiobiology Research Institute using a 60Co source, the Naval Surface Warfare Center using a tandem neutron accelerator, and the United States Naval Academy using an unmoderated 252Cf source. The response of the alternate droplet material dosimeters was compared to the response of the original Freon 12 droplet material dosimeter. The data indicated that the propane and propylene materials were chemically incompatible with the gel material and that the hexafluoropropylene dosimeters were sensitive to gamma radiation, thus making these types of dosimeters unsuitable. However, the HFC-134a superheated liquid droplets were stable in the gel material, responded uniformly over varying neutron energies, and had a predictable temperature response.

Biophysical Phenomena↗
PubMed1993

Catabolism of isonicotinate by Mycobacterium sp. INA1: extended description of the pathway and purification of the molybdoenzyme isonicotinate dehydrogenase.

Catabolism of isonicotinate by Mycobacterium sp. INA1 has been shown to proceed via 2-hydroxyisonicotinate, 2,6-dihydroxyisonicotinate (citrazinate), citrazyl-CoA and 2,6-dioxopiperidine-4-carboxyl-CoA. An extended pathway involving propane-1,2,3-tricarboxylate as a further intermediate is presented in this paper. Propane-1,2,3-tricarboxylate was oxidized stepwise to 2-oxoglutarate involving an oxidase, aconitase and isocitrate dehydrogenase. Isonicotinate dehydrogenase catalyses the first step of isonicotinate metabolism in Mycobacterium sp. INA1. The enzyme was purified to apparent homogeneity by a three-step procedure. Enrichment was accompanied by partial loss in specific activity. The native enzyme had a molecular mass of either 125 kDa or 250 kDa, when estimated by native gradient PAGE or gel filtration, respectively. SDS-gel electrophoresis revealed three types of subunits with molecular masses of approximately 83, 31 and 19 kDa. N-Terminal amino acid sequences of all three subunits have been determined. Molybdenum, iron, acid-labile sulphur and FAD were present at molar ratios of 1, 4, 4, 1 per protomer (125 kDa). The molybdenum-complexing cofactor was shown to be molybdopterin cytosine dinucleotide. Besides isonicotinate, only quinoline-4-carboxylate was found to be oxidized at appreciable rates.

Amino Acid Sequence↗
PubMed2000

Azole. 44. Uber morpholinonitroimidazolderivate

The structure analyses of racemic 3-chloro-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-ol, C(10)H(15)ClN(4)O(4), (II), and 3-chloro-1-(5-morpholino-4-nitroimidazol-1-yl)propan-2-ol, C(10)H(15)ClN(4)O(4), (III), have been undertaken in order to determine the position of the morpholine residue in these two isomers. The morpholine residue in (II) is connected at the 4-position, while in (III), it is connected at the 5-position of the imidazole ring. The morpholine mean planes and nitro groups in the two compounds deviate from the imidazole planes to different extents. The nitro groups in (II) and (III) take part in the conjugation system of the imidazole rings. In consequence, the exocyclic C-N bonds are significantly shorter than the normal single Csp(2)-NO(2) bond and the nitro groups in (II) and (III) show an extraordinary stability on treatment with morpholine and piperidine [Gzella, Wrzeciono & Poppel (1999). Acta Cryst. C55, 1562-1565]. In the crystal lattice, the molecules of both compounds are linked by O-H.N and C-H.O intermolecular hydrogen bonds.

Journal Article↗
PubMed2001

[Azole. 45(1). Uber 2,4-Dinitrophenylhydrazone von Morpholinonitroimidazolderivaten].

The three title compounds, namely (Z)-1-(4,5-dinitroimidazol-1-yl)-3-morpholinopropan-2-one 2,4-dinitrophenylhydrazone, C(16)H(17)N(9)O(9), (IV), (Z)-3-morpholino-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-one 2,4-dinitrophenylhydrazone, C(20)H(25)N(9)O(8), (Va), and (E)-3-morpholino-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-one 2,4-dinitrophenylhydrazone tetrahydrofuran solvate, C(20)H(25)N(9)O(8).C(4)H(8)O, (Vb), have been prepared and their structures determined. In (IV), the C-4 nitro group is nearly perpendicular to the imidazole ring and the C-4-NO(2) bond length is comparable to the value for a normal single Csp(2)-NO(2) bond. In (IV), (Va) and (Vb), the C-5 nitro group deviates insignificantly from the imidazole plane and the C-5-NO(2) bond length is far shorter in all three compounds than C-4-NO(2) in (IV). In consequence, the C-4 nitro group in (IV) is easily replaced by morpholine, while the C-5 nitro group in (IV), (Va) and (Vb) shows an extraordinary stability on treatment with the amine. The E configuration in (Vb) is stabilized by a three-centre hydrogen bond.

Journal Article↗
PubMed2003

A semi-synthetic analog of the cembranoid sarcophine.

The title molecule, 2(R)-[(1E,3E,7S,8S,11E,13R)-13-hydroxy-4,8,12-trimethyl-7,8-epoxycyclotetradeca-1,3,11-trien-1-yl]propane-1,2-diol, C(20)H(32)O(4), is a semi-synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14-membered ring differs substantially from that of sarcophine. The two OH groups of the propane-1,2-diol moiety form an unusual weak intramolecular hydrogen bond with an O...O distance of 2.788 (2) A, and the molecules are linked into double chains by intermolecular hydrogen bonds with O...O distances of 2.772 (2) and 2.849 (2) A.

4-Butyrolactone↗
PubMed2003

A chloride ion contained in a cobalt 'claw': [Co3(DADIT)3]Cl(PF6)2.

A trimeric compound containing Co(II) is described, namely tris[mu-2-[3-(dimethylamino)propylimino]propane-1-thiolato]tricobalt(II) chloride bis(hexafluorophosphate), [Co(3)(C(10)H(21)N(2)S)(3)]Cl(PF(6))(2). Each Co atom is ligated by one 2-[3-(dimethylamino)propylimino]propane-1-thiolate ligand, an amine group and an imine group. The thiolate groups bridge the Co atoms, forming a six-membered ring that encloses the chloride ion in a well defined binding pocket.

Chlorides↗
PubMed2006

A second polymorph of [H3N(CH2)3NH3][V4O10].

The title compound, propane-1,3-diammonium tetravanadate, (C3H12N2)[V4O10], represents a second polymorph of composition beta-[H3N(CH2)3NH3][V4O(10)]. It differs from the alpha polymorph [Riou & Ferey (1995). J. Solid State Chem. 120, 137-145] in the conformation of the propane-1,3-diammonium dication which, in the present example, lies on a twofold axis and adopts a syn-syn rather than a syn-anti conformation. The twofold symmetry of this conformation thus co-operates with the vanadium oxide framework to result in a higher symmetry for the resultant crystal, viz. C2/c versus P2(1)/n. The overall unit-cell parameters for the two polymorphs are similar, and the inorganic layer within each is topologically identical, comprising edge-sharing V(IV)O5 square pyramids linked together via corner-sharing with V(V)O4 tetrahedra. A key difference between the two polymorphs is a ;head-to-head' versus ;head-to-tail' stacking of the vanadyl groups in adjacent layers.

Journal Article↗
PubMed2006

Purification, crystallization and preliminary crystallographic study of an IDS-epimerase from Agrobacterium tumefaciens BY6.

The initial degradation of all stereoisomers of the complexing agent iminodisuccinate (IDS) is enabled by an epimerase in the bacterial strain Agrobacterium tumefaciens BY6. This protein was produced in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method. Crystals of IDS-epimerase were obtained under several conditions. The best diffracting crystals were grown in 22% PEG 3350, 0.2 M (NH4)2SO4 and 0.1 M bis-Tris propane pH 7.2 at 293 K. These crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 55.4, b = 104.2, c = 78.6 angstroms, beta = 103.3 degrees, and diffracted to 1.7 angstroms resolution. They contain two protein molecules per asymmetric unit. In order to solve the structure using the MAD phasing method, crystals of the L-selenomethionine-substituted epimerase were grown in the presence of 20% PEG 3350, 0.2 M Na2SO4 and 0.1 M bis-Tris propane pH 8.5.

Agrobacterium tumefaciens↗
PubMed1986

Microtubule structure studied by quick freezing: cryo-electron microscopy and freeze fracture.

Microtubules have been quickly frozen and examined by electron microscopy using several techniques: (1) freezing of a thin layer of solution by plunging into cryogen, followed by cryoelectron microscopy of the unstained vitrified samples; (2) freezing by the propane-jet method, followed by freeze fracturing and metal replication. The unstained frozen-hydrated microtubules show a structure in agreement with X-ray diffraction data; they differ from negatively stained particles mainly by the better preservation of cylindrical shape. Secondly, they reveal a supertwist of the profilaments that is not detected reliably by other methods. This allows a determination of the number of protofilaments and the polarity. The structural resolution of unstained microtubules is similar to that of stained ones (about 2-3 nm); it is limited by low contrast and lack of crystalline order. Propane-jet or cryo-block freezing followed by freeze fracturing reveals the structures of the inner and outer surfaces of the microtubule wall at a resolution of 4 nm or better. The outside is dominated by the longitudinal protofilaments whereas on the inside one observes tilted cross-striations. Although the freezing temperatures of the two methods are different (liquid nitrogen or helium) they yield similar results for the case of thin layers of protein solution.

Animals↗
PubMed1985

Alterations of the eicosanoid synthetic capacity of rat brain microvessels following ischemia: relevance to ischemic brain edema.

To know the mechanism underlying ischemic brain edema, a time-course analysis of the eicosanoid synthetic capacity of brain microvessels was carried out using unilateral, middle cerebral artery (MCA)-occluded rats. Concomitant with the development of brain edema the synthetic capacity of all products, including cyclooxygenase and lipoxygenase products, increased significantly. Next the effects of 15-hydroperoxyarachidonic acid (15-HPAA) on the synthetic capacity of microvessels were examined. The drug caused a generalized increase of each product, the profile of which was similar to that obtained with ischemic hemispheres, although the ratios of each product differed somewhat among them. The enhanced synthesis of eicosanoids by 15-HPAA was markedly suppressed by radical scavengers such as alpha-tocopherol, hydroquinone, and 1,2-bis(nicotineamide)-propane. Furthermore, the evolution of brain edema was virtually suppressed by the systemic administration of 1,2-bis(nicotineamide)-propane. The above result suggests that the enzyme activity of the arachidonic acid (AA) cascade of microvessels is stimulated by its own products. Such a mechanism will form a vicious cycle that accelerates the accumulation of free radicals within microvessels and thus may play a role in the progressing disruption of the blood-brain barrier (BBB) following ischemia.

Animals↗
PubMed1993

Solubilization of high-affinity, guanine nucleotide-sensitive mu-opioid receptors from 7315c cell membranes.

High-affinity mu-opioid receptors have been solubilized from 7315c cell membranes. Occupancy of the membrane-associated receptors with morphine before their solubilization in the detergent 3-[(3-cholamidopropyl) dimethyl]-1-propane sulfonate was critical for stabilization of the receptor. The solubilized opioid receptor bound [3H]-etorphine with high affinity (KD = 0.304 +/- 0.06 nM; Bmax = 154 +/- 33 fmol/mg of protein). Of the membrane-associated [3H]etorphine binding sites, 40 +/- 5% were recovered in the solubilized fraction. Both mu-selective and non-selective enkephalins competed with [3H]etorphine for the solubilized binding sites; in contrast, delta- and kappa-opioid enkephalins failed to compete with [3H]etorphine for the solubilized binding sites at concentrations of < 1 microM. The mu-selective ligand [3H][D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin also bound with high affinity (KD = 0.79 nM; Bmax = 108 +/- 17 fmol/mg of protein) to the solubilized material. Of the membrane-associated [3H][D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin binding sites, 43 +/- 3% were recovered in the solubilized material. Guanosine 5'-O-(3-thiotriphosphate), GTP, and guanosine 5'-O-(2-thiodiphosphate), but not adenylylimidodiphosphate, diminished [3H][D-Ala2,N-Me-Phe4,Gly5-ol] enkephalin binding in a concentration-dependent manner. Finally, mu-opioid receptors from rat brain membranes were also solubilized in a high-affinity, guanine nucleotide-sensitive state if membrane-associated receptors were occupied with morphine before and during their solubilization with the detergent 3-[(3-cholamidopropyl)dimethyl]-1-propane sulfonate.

Animals↗
PubMed1998

Enantioselectivity of some 1-(benzofuran-2-yl)-1-(1-H-imidazol-1-yl) alkanes as inhibitors of P450Arom.

The low stereospecificity of the enantiomers of 1-[(benzofuran-2-yl)-4-chlorophenylmethyl]imidazole (6, R=H, R'=4'-Cl) and the corresponding 4-fluoro compound as inhibitors of aromatase (P450Arom) has been explored using 1-(5,7-dichlorobenzofuran-2-yl)-1-(1H-imidaz-1-yl)ethane (7, R1=R2=Cl, R=CH3), -propane (7, R1=R2=Cl, R=C2H5), and the corresponding 5,7-dibromo compounds resolved as their dibenzoyl-D (or -L) tartrates. Low enantioselectivity ratios of 4.8 (5,7-diCl) and 12.6 (5,7-diBr) were shown for the ethanes. The values for the corresponding propanes were 8.3 and 5.2, respectively, and for these compounds the stereoselectivity was reversed.

Alkanes↗
PubMed1997

Metathesis of Alkanes Catalyzed by Silica-Supported Transition Metal Hydrides

The silica-supported transition metal hydrides (=Si-O-Si=)(=Si-O-)2Ta-H and (=Si-O-)xM-H (M, chromium or tungsten) catalyze the metathesis reaction of linear or branched alkanes into the next higher and lower alkanes at moderate temperature (25degrees to 200degreesC). With (=Si-O-Si=)(=Si-O-)2Ta-H, ethane was transformed at room temperature into an equimolar mixture of propane and methane. Higher and lower homologs were obtained from propane, butane, and pentane as well as from branched alkanes such as isobutane and isopentane. The mechanism of the step leading to carbon-carbon bond cleavage and formation likely involves a four-centered transition state between a tantalum-alkyl intermediate and a carbon-carbon final sigma-bond of a second molecule of alkane.

Journal Article↗