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PubMed2002

Role of gas chromatography-mass spectrometry with negative ion chemical ionization in clinical and forensic toxicology, doping control, and biomonitoring.

This paper reviews procedures for the detection or quantification of drugs, pesticides, pollutants, and/or their metabolites relevant to clinical and forensic toxicology, doping control, or biomonitoring using gas chromatography-mass spectrometry with negative ion chemical ionization (GC-MS-NICI). Papers written in English between 1995 and 2000 are reviewed. Procedures are included for the analysis of the following halogen-containing or derivatizable compounds in common biosamples, such as whole blood, plasma, or urine, and in alternative matrices such as sweat, hair, bone, or muscle samples of humans or rats: benzodiazepines, cannabinoids, opioids, acetylsalicylic acid, angiotensin-converting enzyme inhibitors, ketoprofen, methylphenidate enantiomers, tegafur, zacopride, anabolic steroids, chlorophenols, chlorpyrifos, hexachlorocyclohexanes, organochlorines, and polychlorinated biphenyls. The principal information on each procedure is summarized in three tables to facilitate the selection of a method suitable for a specific analytic problem.

Doping in Sports↗
PubMed1953

Skin disinfection.

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Anti-Infective Agents, Local↗
PubMed1983

Correlations of alkylating activity and mutagenicity in bacteria of cytostatic drugs.

Alkylating activity of cytostatic drugs was studied in relation to their mutagenicity and toxicity in E. coli WP2 uvrA. Four classes of directly acting cytostatic drugs were studied: nitrogen mustards (nitrogen mustard, melphalan, chlorambucil and phosphoramide mustard, a metabolite of cyclophosphamide), ethyleneimine derivatives (Thio-TEPA, TEPA and triethylenemelamine), busulfan, and halogenated nitrosoureas. The reference compounds included methyl methanesulfonate, ethyleneimine and methylnitrosourea. Guanosine alkylation was determined by fluorometry. The rate of guanosine and nitrobenzylpyridine alkylation agreed well. Nitrogen mustard derivatives and triethylenemelamine were the most potent alkylating agents among the cytostatic drugs; nitrogen mustard was 5 to 10 times more active than methyl methanesulfonate. Ethyleneimine derivatives, busulfan and the nitrosoureas were relatively weak alkylating agents. Nitrogen mustard and triethylenemelamine were the most potent mutagens to bacteria; they were also among the most toxic drugs studied.

Alkylating Agents↗
PubMed1973

Energy coupling of the hexose phosphate transport system in Escherichia coli.

The active transport of hexose phosphates in Escherichia coli was inhibited by many uncouplers or inhibitors of oxidative metabolism. Fluoride and the lipid soluble cation, triphenylmethylphosphonium, had little effect. The uninduced level of transport was sensitive to fluoride, but not to azide. After energy uncoupling of active transport, the cells could equilibrate their intracellular water with the glucose-6-phosphate in the medium and displayed exit counter-flow suggesting the existence of carrier-mediated transport in the energy-uncoupled cells. The uncoupled transport of glucose-6-phosphate was inhibited by fructose-6-phosphate; the uninduced level of glucose-6-phosphate transport was not inhibited by fructose-6-phosphate. After energy uncoupling, the influx had a low affinity suggesting that, unlike the transport of beta-galactosides, the energy coupling for the active transport of hexose phosphate involved a change in the affinity of influx.

Azides↗
PubMed2000

DNA polymerase I is essential for growth of Methylobacterium dichloromethanicum DM4 with dichloromethane.

Methylobacterium dichloromethanicum DM4 grows with dichloromethane as the unique carbon and energy source by virtue of a single enzyme, dichloromethane dehalogenase-glutathione S-transferase. A mutant of the dichloromethane-degrading strain M. dichloromethanicum DM4, strain DM4-1445, was obtained by mini-Tn5 transposon mutagenesis that was no longer able to grow with dichloromethane. Dichloromethane dehalogenase activity in this mutant was comparable to that of the wild-type strain. The site of mini-Tn5 insertion in this mutant was located in the polA gene encoding DNA polymerase I, an enzyme with a well-known role in DNA repair. DNA polymerase activity was not detected in cell extracts of the polA mutant. Conjugation of a plasmid containing the intact DNA polymerase I gene into the polA mutant restored growth with dichloromethane, indicating that the polA gene defect was responsible for the observed lack of growth of this mutant with dichloromethane. Viability of the DM4-1445 mutant was strongly reduced upon exposure to both UV light and dichloromethane. The polA'-lacZ transcriptional fusion resulting from mini-Tn5 insertion was constitutively expressed at high levels and induced about twofold after addition of 10 mM dichloromethane. Taken together, these data indicate that DNA polymerase I is essential for growth of M. dichloromethanicum DM4 with dichloromethane and further suggest an important role of the DNA repair machinery in the degradation of halogenated, DNA-alkylating compounds by bacteria.

Carbon↗
PubMed1997

Microphysics and heterogeneous chemistry of polar stratospheric clouds.

Liquid and solid particles in polar stratospheric clouds are of central importance for the depletion of stratospheric ozone. Surface-catalyzed reactions on these particles, and diffusion-controlled processes in the bulk of the particles, convert halogens, which derive from compounds of mainly anthropogenic origin, from relatively inert reservoir species into forms that efficiently destroy ozone. The microphysics of these particles under cold stratospheric conditions is still uncertain in many respects, in particular concerning phase transitions such as freezing nucleation and deposition nucleation. Furthermore, there are indications that the rates of key heterogeneous reactions have not yet been established with sufficient accuracy to enable a reliable diagnosis of observed ozone losses by means of global models. The present paper reviews the current (late 1996) knowledge of the physico-chemistry of polar stratospheric clouds and evaluates the remaining uncertainties with respect to their ozone depletion potential.

Journal Article↗
PubMedDate not supplied

Toxicological investigations in the semiconductor industry: III: Studies on prenatal toxicity caused by waste products from aluminum plasma etching processes.

The prenatal toxic effects of contaminated vacuum pump oil (Sample A) and solid waste products (Samples B and C) originating from aluminum plasma etching processes in semiconductor manufacturing were investigated. Three strains of pregnant mice with different degrees of sensitivity during organogenesis (days 6-15 of gestation) were treated daily with 1000 mglkg b.w. (Sample A), 500 or 750 mg/kg b.w. (Sample B), and 250, 500, or 750 mg/kg b.w. (Sample C). On day 18 of pregnancy, the animals were killed and examined for gross changes, number and weight of live fetuses, as well as the number of postimplantation losses and malformations. Analytical data showed that the investigated wastes contained various halogenated hydrocarbons and inorganic compounds. Sample A revealed no signs of prenatal toxic action. In contrast, administration of Samples B and C caused strong prenatal toxic effects. The number of live fetuses declined in a dose--related manner, and evidence of intrauterine growth retardation was noted in fetuses that survived to day 18. The number of fetuses with malformations (only cleft palates) rose significantly in accordance with the doses and sensitivity of the strains (> 95 % of the fetuses of the most sensitive strain after 750 mg/kg; 85% after 500 mg/kg).

Aluminum↗
PubMed2002

Potent inhibition of estrogen sulfotransferase by hydroxylated metabolites of polyhalogenated aromatic hydrocarbons reveals alternative mechanism for estrogenic activity of endocrine disrupters.

Polyhalogenated aromatic hydrocarbons (PHAHs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenylethers, and bisphenol A derivatives are persistent environmental pollutants, which are capable of interfering with reproductive and endocrine function in birds, fish, reptiles, and mammals. PHAHs exert estrogenic effects that may be mediated in part by their hydroxylated metabolites (PHAH-OHs), the mechanisms of which remain to be identified. PHAH-OHs show low affinity for the ER. Alternatively, they may exert their estrogenic effects by inhibiting E2 metabolism. As sulfation of E2 by estrogen sulfotransferase (SULT1E1) is an important pathway for E2 inactivation, inhibition of SULT1E1 may lead to an increased bioavailability of estrogens in tissues expressing this enzyme. Therefore, we studied the possible inhibition of human SULT1E1 by hydroxylated PHAH metabolites and the sulfation of the different compounds by SULT1E1. We found marked inhibition of SULT1E1 by various PHAH-OHs, in particular by compounds with two adjacent halogen substituents around the hydroxyl group that were effective at (sub)nanomolar concentrations. Depending on the structure, the inhibition is primarily competitive or noncompetitive. Most PHAH-OHs are also sulfated by SULT1E1. We also investigated the inhibitory effects of the various PHAH-OHs on E2 sulfation by human liver cytosol and found that the effects were strongly correlated with their inhibitions of recombinant SULT1E1 (r = 0.922). Based on these results, we hypothesize that hydroxylated PHAHs exert their estrogenic effects at least in part by inhibiting SULT1E1-catalyzed E2 sulfation.

Cytosol↗
PubMed1995

Workshop on perinatal exposure to dioxin-like compounds. VI. Role of biomarkers.

Studies of perinatal exposures to dioxin-like compounds (DLCs), coplanar polycyclic halogenated aromatics whose prototype is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), have employed a variety of outcome measures to investigate effects on the reproductive/developmental, endocrine, immune, and neurobehavioral systems. The effects include infertility, growth retardation, fetal loss, changed sexual differentiation, reduced cognitive/motor function, dermatologic and other ectodermal effects, and decreased immune response. Significant biomarkers have included sperm count; CD4/CD8 ratio; and levels of testosterone, T4, and dopamine. Using specific dioxin or PCB congeners, these and other markers were used to investigate the mechanisms of the observed effects. The DLCs, which include some PCB congeners, are characterized by high-affinity binding to the Ah receptor; most biological effects are thought to be mediated by the ligand-Ah receptor complex. Other PCB congeners have low affinity for the Ah receptor, and operate by non-Ah receptor mechanisms. The biologic activity of a PCB mixture is the sum of the agonist and antagonist activities of the different constituents in the mixture. Animal studies with specific PCB congeners can help to clarify these activities. With similar approaches, biologic markers of effect can be developed and applied in epidemiologic studies to monitor for, and predict, adverse effects in humans.

Animals↗
PubMed1992

A brief review of the Ah locus.

The Ah locus, first described as a functional polymorphism among inbred strains of mice, encodes the Ah receptor--a ligand dependent transcriptional activator. This paper reviews the work on the Ah receptor and its importance in the expression of cytochrome P-450IA1 and the pleiotropic effects of halogenated aromatic hydrocarbons.

Animals↗
PubMed1998

Formulation and evaluation of albuterol metered dose inhalers containing tetrafluoroethane (P134a), a non-CFC propellant.

This study was undertaken to evaluate tetrafluoroethane (P134a) as a possible chlorofluorocarbon (CFC) replacement for albuterol metered dose inhaler (MDI) formulations. Preformulation studies using three conventional (oleic acid, sorbitan trioleate, lecithin) and a nonconventional (oleyl alcohol) surfactant indicated that P134a is a poor solvent for these surfactants. A slight improvement in the solubility of oleic acid and oleyl alcohol was observed by the addition of low concentrations of a nonconventional cosolvent diethyl ether (< or = 0.5% w/w). Formulation screening of the prepared albuterol formulations indicated that suspensions containing oleyl alcohol and diethyl ether had a slower rate of separation. Product performance of four albuterol formulations containing oleyl alcohol, diethyl ether, and P134a was evaluated and compared to a leading commercial formulation containing CFC propellants (Ventolin). Ventolin showed excellent agreement between the emitted dose and the expected dose but only a reasonable agreement was observed with one of the better P134a-containing formulations. P134a formulations showed higher internal pressure in comparison to the CFC formulation. The concentrations of the surfactant, drug, and cosolvent appeared to have a significant impact on the uniformity of the emitted dose. Determination of particle size using the time-of-flight and the laser diffraction analyzer revealed that P134a formulations had equal or smaller particle size than the formulation containing CFC. However, the CFC formulation showed a higher respirable fraction than the P134a formulation when measured by the two inertial impaction methods. The observed particle size distribution of the formulation appeared to depend on the measuring method used.

Aerosol Propellants↗