The chemistry and biogenesis of the S-containing metabolites of vinyl chloride in rats.

In order to determine whether vinyl chloride yields chloroethylene oxide in vivo, the biogenesis of the various urinary S-containing metabolites in rats has been investigated.N-Acetyl-S-(2-hydroxyethyl)cysteine is a major vinyl chloride metabolite in rats, but according to the method of protective esterification that is used, so either N-acetyl-S-(2-chloroethyl)cysteine or N-acetyl-S-(2-hydroxyethyl)cysteine may be isolated from the body fluids. N-Acetyl-S-vinylcysteine is a second related metabolite. These S-containing vinyl chloride metabolites are not mutagenic in S. typhimurium. Neutral methanol methylates N-acetyl-S-(2-hydroxyethyl)cysteine. N-Acetyl-S-(2-methoxyethyl)cysteine plus N-acetyl-S-vinylcysteine degrade to give the volatile S-(2-methoxyethyl)(prop-1 or 2-enyl)sulphide.Administration of several vinyl chloride metabolites and closely related compounds to rats shows that chloroacetaldehyde and S-(carboxymethyl)cysteine, but not chloroacetic acid, lie on a pathway or pathways connecting vinyl chloride with thiodiglycollic acid. The fact (a) that chloroacetaldehyde affords both thiodiglycollic acid and N-acetyl-S-(2-hydroxyethyl)cysteine in the animal and (b) that S-(carboxymethyl)cysteine has been identified amongst the hydrolytic products from an hepatic extract prepared from vinyl chloride-treated animals is consistent with the formation of chloroacetaldehyde, and with the reaction of chloroethylene oxide or chloroacetaldehyde with glutathione in the presence of a glutathione S-epoxide transferase to give the identified S-containing metabolites.     

Influence of external chloride concentration on the kinetics of mobile charges in the cell membrane of Valonia utricularis: Evidence for the existence of a chloride carrier

Charge pulse relaxation studies were performed on cells of the giant marine alga Valonia utricularis. Two exponential voltage relaxations were recorded as found previously (Benz, R., and U. Zimmermann. 1983. Biophys. J. 43:13-26.). The parameters of the two exponential voltage decays were studied as a function of the chloride concentration in the artificial sea water. Replacement of external chloride by 2(N-morpholino)ethanesulfonate (Mes^-) had a dramatic influence on the four relaxation parameters. This chloride dependence could not be satisfactorily explained by the simplified model used earlier. Accordingly, additional reaction steps had to be included in the model. Only two relaxation processes could be resolved under all experimental conditions. This means that the heterogeneous complexation reactions, k_R (association), and k_D (dissociation) were too fast to be resolved. Therefore a carrier model with equilibrium heterogeneous surface reactions was used to fit the experimental results. From the charge pulse data at different chloride concentrations the translocation rate constants of the free and complexed carriers, k_S and k_AS, through the membrane, as well as the total surface concentration of carrier systems, N₀, could be evaluated. The results described here indicate that the cell membrane of Valonia utricularis contains an electrogenic transport system for chloride.     

Heme-linked ionization and chloride binding in intestinal peroxidase and lactoperoxidase.

Hog intestinal peroxidase and bovine lactoperoxidase exhibited similar spectral shifts upon pH alteration. From spectrophotometric titrations, it was found that there are hemelinked ionizations of pK_a = 4.75 in intestinal peroxidase and pK_a = 3.5 in lactoperoxidase. The apparent pK_a (pK_a′) increased with the increase in chloride concentration. The pK_a′ vs log[Cl^?] plots showed that the chloride forms complex with the acid forms of these enzymes with a dissociation constant (pK = 2.7). Although the dissociation constant (K_d) of the peroxidase-cyanide complexes is nearly independent of pH, cyanide competed with chloride in the acidic pH region. The slopes of logK_d vs log[Cl^?] were 1.0 for intestinal peroxidase and 0.5 for lactoperoxidase. The reaction of hydrogen peroxide with these peroxidases was also affected by chloride, similarly as the reaction with cyanide was. The results were explained by assuming that protonation occurs at the distal base and destroys the hydrogen bond between the base and a water molecule at the sixth coordinate position of the heme iron.     

Chlorination and phosphorylation of cotton cellulose by reaction with phosphoryl chloride in N,N-dimethylformamide

Native cotton yarn reacts rapidly with phosphoryl chloride in N,N-dimethylformamide to produce highly chlorinated cellulose (degree of substitution of 0.5 or greater), phosphorylated cellulose, and cellulose formate. The ratio of chlorination to phosphorylation was readily controlled by varying the concentration of phosphoryl chloride in N,N-dimethylformamide.Reaction variables studied were the reagent concentration, reaction temperature, and reaction time. The effect that each of these variables has on the tensile and flammability properties of the resultant yarns was investigated. Yarns containing large proportions of chlorine have high tensile-strength and are unusually extensible, whereas yarns containing phosphorus have high flame-resistance. A mechanism for the selective chlorination or phosphorylation of the cotton cellulose is advanced.     

Active transport of chloride by Anacystis nidulans

Chloride uptake by the cyanobacterium Anacystis nidulans at 38°C is energy dependent showing maximum rate (around 5.10^-7 mol Cl^-xml cell water^-1xmin^-1) and accumulation (up to 160 fold) in light and air. The respective values in air and darkness were 40–70% lower. In the dark under N₂ no uptake was found. Chloride transport had an optimum at pH 6.7 and a K _M of 2.10^-5 M which was pH-independent. It was inhibited by carbonyl cyanide m-chlorophenylhydrazone and N,N′-dicyclohexylcarbodiimide in the light and in the dark, and also to a lesser extent by valinomycin. 3-(3,4-dichlorophenyl)-1,1-dimethylurea in the light caused a moderate stimulation. To obtain information about the energy source of active chloride transport the action of the four inhibitors on membrane potential (determined through the distribution of triphenylmethylphosphonium) and ATP level (determined by the firefly method) was examined. It was found that a high negative membrane potential was unfavorable for chloride accumulation probably by stimulating passive efflux. On the other hand a good correlation between ATP level and chloride transport activity was obtained. Attempts to induce chloride uptake by sudden acidification of the external medium in presence of N,N′-dicyclohexyl-carbodiimide or during anaerobiosis were not successful. Two mechanisms of chloride uptake are discussed:

1. primary active transport by an ATP-dependent pump, and
2. “chemiosmotic” secondary active transport linked to a proton gradient, the present data favoring mechanism a.

     

Development of sensitive high-performance liquid chromatography with fluorescence detection using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride as a labeling reagent for determination of bisphenol A in plasma samples

A sensitive HPLC method for determination of bisphenol A (BPA) in plasma samples using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) as a fluorescence labeling reagent was developed. The fluorescence labeling reaction was completed within 10 min at room temperature. DIB-Cl reacts with the phenolic hydroxyl group of BPA in the presence of triethylamine (TEA). The DIB-Cl derivative of BPA (DIB-BPA) was separated within 30 min with an ODS column using acetonitrile–water (90:10, v/v) as the isocratic eluent. Calibration graphs were linear over the range of 1.0–100 ng/ml (r=0.999). The detection limit of DIB-BPA was 0.05 ng/ml (2.5 pg) at a signal-to-noise ratio of 3. The relative standard deviations (RSDs) of the method for between-run were 1.0–5.0%. The analytical recoveries of known amounts (1.0 and 100 ng/ml) of BPA-spiked rabbit plasma were around 95%.     

Evaluation of the Versant CT/GC DNA 1.0 Assay (kPCR) for the Detection of Extra-Genital Chlamydia trachomatis and Neisseria gonorrhoeae Infections

Screening for extra-genital Chlamydia trachomatis and Neisseria gonorrhoeae infections is a crucial component for sexually transmitted diseases management, even if at present days no commercial methods have been approved for use on pharyngeal and rectal specimens by the US FDA or have received the conformity CE marking. Here we report the analytical sensitivities of the Versant CT/GC 1.0 assay (Siemens Healthcare Diagnostics, Tarrytown, NY, USA) on rectal and pharyngeal swabs, and an evaluation about the suitability for this assay with two widely used swab collection devices (E-Swab and eNAT, Copan, Brescia, Italy). The limits of detection for rectal and pharyngeal specimens with the Versant assay were 10 copies/ml and 1.0 copies/ml, for C. trachomatis and N. gonorrhoeae, respectively. False positive results due to the presence of non-gonococcal Neisseria species were excluded when clinical rectal and pharyngeal samples containing organisms identified as N. meningitidis, N. sicca, N. flavescens and N. subflava were tested. Due to its sensitivity and specificity, the Versant assay represents a good choice for the diagnosis of chlamydial and/or gonococcal infections not only in genito-urinary samples, but also on rectal and pharyngeal swabs.     

Effect of calcium chloride on heavy metal induced alteration in growth and nitrate assimilation of Sesamum indicum seedlings

In the early growth phase of Sesamum indicum cv. PB-1, the decrease in fresh and dry mass was higher with 1.0 mM Cd²⁺ than with the same level of Pb²⁺ and Cu²⁺. Recovery from the metal stress was considerable in the root fresh weight and almost completely in the root dry weight when 10.0 mM (1.9 EC), calcium chloride was supplied to the growing seedlings along with the metal salts in various combinations. Accumulation of Pb²⁺, Cd²⁺ and Cu²⁺ was differential to the metals and the plant parts when supplied without or with 10.0 mM calcium chloride. The order of endogenous metal accumulation was Cu²⁺Cd²⁺Pb²⁺ and roots accumulated more metal than the leaves in the absence, as well as in the presence, of calcium chloride. Calcium chloride could recover loss of in vivo NRA in roots caused by either of the metal combinations, whereas the salt could recover the loss in leaf NRA caused only by Pb²⁺Cd²⁺ (1.0 mM each). Response of root and leaf NRA was on the other hand, different when the enzyme was assayed directly using an in vitro assay method, and the salt accelerated the loss in enzyme activity drastically. The organic-N content of root and leaf was, however, increased significantly (p < 0.001) with calcium chloride alone and with the metals supplied in various combinations. Our data indicate that instead of a high endogenous accumulation of Cu²⁺, Cd²⁺ and Pb²⁺ in roots and leaves the metal toxicity is recovered to a great extent in the presence of 10.0 mM calcium chloride in the root environment regarding growth and nitrate reduction of the roots and leaves of young sesame seedlings.     

Microbial metabolism of pyridinium compounds. Metabolism of 4-carboxy-1-methylpyridinium chloride, a photolytic product of paraquat

1. A bacterium, Achromobacter D, isolated from garden soil by elective culture, utilized N-methylisonicotinic acid (4-carboxy-1-methylpyridinium chloride) as sole carbon source. 2. Extracts of N-methylisonicotinate-grown cells oxidized this substrate only after supplementation with a source of nicotinamide nucleotides and then consumed 1 mol of O₂ and released 1 mol of CO₂/mol of N-methylisonicotinate supplied. 3. The N-methyl group of the substrate was released as methylamine whereas the five C atoms of the pyridine ring were accounted for as succinate and formate. The CO₂ evolved by extracts was believed to derive from the carboxyl group on C-4 of the heterocyclic ring. 4. The immediate precursor of the succinate end-product was succinic semialdehyde; the inducible nature of succinic semialdehyde dehydrogenase in N-methylisonicotinate-grown cells supported this finding. 5. There was no evidence for monohydroxylation of the ring, but the time sequence of the appearance of the end-products indicated that the oxygen-requiring, NADH-requiring and decarboxylation steps clearly preceded the formation of methylamine and succinate. 6. The results are consistent with the oxidative cleavage of a partially reduced heterocyclic ring followed by several hydrolytic and dehydrogenase steps resulting in the appearance of the end-products.     

Synthesis of a β-D-linked disaccharide from dimeric tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride

Condensation of dimeric 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride with benzyl alcohol in the presence of N,N,2,4,6-pentamethylaniline or N,N,2,6-tetramethylaniline gave an oximino glycoside that was reduced with lithium aluminum hydride to benzyl 2-amino-2-deoxy-α-D-gluco- and -mannopyranoside hydrochloride that were identified as the N-acetyl derivatives.     

Determination of chloride procedure based upon diffusion of hydrogen chloride

We describe a simple, inexpensive sample preparation method that involves the isolation of chloride as hydrogen chloride from serum and urine prior to chloride analysis with the chloride ion-selective electrode. Chloride analyses of clinical chemistry standards with the present method were found to be in good agreement with analyses reported by the manufacturer. Reliability of the method is also evident by complete recovery of chloride added to serum and urine, minimal day-to-day variation of analyses, and a coefficient of variation that generally is less than 2%. An evaluation of factors influencing the procedure is also reported. The usefulness of the chloride ion-selective electrode to determine chloride in serum or urine is greatly enhanced by the sample preparation method described since matrix interference by other sample components is removed prior to analysis.     

Disinfection of Microorganisms by Use of Electrochemically Regenerated Periodate

A new method for disinfection of microorganisms by electrochemically regenerated periodate was developed. Oxidation of iodate to periodate was observed at 1.25 V versus a silver/silver chloride electrode in a cyclic voltammogram of potassium iodate. When 1.25 V was applied in 1.0 mM potassium iodate, approximately 4-log inactivation of Escherichia coli was observed in 30 min.     

Diagnostics of a nonequilibrium nitrogen plasma from the emission spectra of the second positive system of N2

A method is proposed for determining the electron density N _e and the electric field E in the non-equilibrium nitrogen plasma of a low-pressure discharge from the spectra of the second positive system of N₂. The method is based on measuring the specific energy deposition in the plasma and the distribution of nitrogen molecules over the vibrational levels of the C ³Π _u state, as well as on modeling this distribution for a given energy deposition. The fitting parameters of the model are the values of N _e and E. A kinetic model of the processes governing the steady-state density of the C ³Π _u nitrogen molecules is developed. The testing of this method showed it to be quite reliable. The method is of particular interest for diagnosing electrodeless discharges and provides detailed information on the processes occurring in the discharge plasma. Preliminary data are obtained on the plasma parameters in a cavity microwave discharge and an electrode microwave discharge. In particular, it is found that the electric field in an electrode microwave discharge in nitrogen is lower than that in a hydrogen discharge. This effect is shown to be produced by stepwise and associative processes with the participation of excited particles in nitrogen.     

Determination of nicotinamide N-oxide—a human excretory product

A method for the determination of nicotinamide N-oxide has been developed. It is based on the ability of the N-oxide to function as an electron acceptor in the xanthine oxidase catalyzed oxidation of xanthine. In simple mixtures the N-oxide can be converted quantitatively to nicotinamide and the latter determined by the cyanogen bromide method. The conversion is not always quantitative in complex mixtures, such as urine; an isotope dilution variation on the basic method permits the determination of the N-oxide in such situations. The basic method is applicable over the range 0.02–0.3 μmole of nicotinamide N-oxide.The new method has been used to verify the prominent excretory role of nicotinamide N-oxide in rodents. Application of the method to a study of human urines has permitted the detection of the N-oxide as an excretory metabolite in man. Only vanishingly small quantities of the N-oxide are excreted under normal conditions. However after the ingestion of 200 mg of nicotinamide, significant quantities of the N-oxide are detectable in human urine. Urine samples obtained from a number of other mammalian species contained little or no detectable nicotinamide N-oxide.     

Chemical modification of polyvinyl chloride and silicone elastomer in inhibiting adhesion of Aeromonas hydrophila

Disease-causing bacteria of the genus Aeromonas are able to adhere to pipe materials, colonizing the surfaces and forming biofilms in water distribution systems. The aim of our research was to study how the modification of materials used commonly in the water industry can reduce bacterial cell attachment. Polyvinyl chloride and silicone elastomer surfaces were activated and modified with reactive organo-silanes by coupling or co-crosslinking silanes with the native material. Both the native and modified surfaces were tested using the bacterial strain Aeromonas hydrophila, which was isolated from the Polish water distribution system. The surface tension of both the native and modified surfaces was measured. To determine cell viability and bacterial adhesion two methods were used, namely plate count and luminometry. Results were expressed in colony-forming units (c.f.u.) and in relative light units (RLU) per cm². Almost all the chemically modified surfaces exhibited higher anti-adhesive and anti-microbial properties in comparison to the native surfaces. Among the modifying agents examined, poly[dimethylsiloxane-co-(N,N-dimethyl-N-n-octylammoniopropyl chloride) methylsiloxane)] terminated with hydroxydimethylsilyl groups (20 %) in silicone elastomer gave the most desirable results. The surface tension of this modifier, was comparable to the non-polar native surface. However, almost half of this value was due to the result of polar forces. In this case, in an adhesion analysis, only 1 RLU cm^?2 and less than 1 c.f.u. cm^?2 were noted. For the native gumosil, the results were 9,375 RLU cm^?2 and 2.5 × 10⁸ c.f.u. cm^?2, respectively. The antibacterial activity of active organo-silanes was associated only with the carrier surface because no antibacterial compounds were detected in liquid culture media, in concentrations that were able to inhibit cell growth.     

Investigations about dissolution of cellulose in the 1-allyl-3-alkylimidazolium chloride ionic liquids

In this work, the 1-allyl-3-alkylimidazolium chloride ionic liquids were synthesized and characterized by increasing carbon atoms (n ≤ 6) of alkyl chains on a cationic 3-imidazole ring. The results indicated that 1-allyl-3-alkylimidazolium chloride with asymmetrical structure on the two sides of a cationic 3-imidazole ring (i.e., n = 1, 2, 6) exhibited alkalinity and lower thermal stabilities, and showed better solubility to the cellulose samples at 60-120 °C than those with symmetrical structures (n = 3, 4). The cellulose samples treated by 20% (w/w) ethylenediamine solution showed better solubility in 1-allyl-3-ethyl, hexyl-imidazolium chloride ionic liquids than that treated with 20% (w/w) NaOH solution at 5 °C for 72 h. XRD and TG analysis indicated that 0 0 2 plane apparent crystallite size as well as thermal stability of the regenerated cellulose samples from the ionic liquids decreased significantly compared with the untreated cellulose samples.     

Preparation of a manganese titanate nanosensor: Application in electrochemical studies of captopril in the presence of para-aminobenzoic acid

This study reports the synthesis and characterization of a novel nanostructure-based electrode for electrochemical studies and determination of captopril (CP). At first manganese titanate nanoceramics were synthesized by the sol–gel method. The structural evaluations of the pure nanopowders were investigated by different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Then it was used to prepare a new nanostructured manganese titanate carbon paste electrode (MnTiO₃/CPE). The characterization of the modified sensor was carried out by comprehensive techniques such as electrochemical impedance spectroscopy (EIS), SEM, and voltammetry. Subsequently, the modified electrode was used for CP catalytic oxidation in the presence of para-aminobenzoic acid (PABA) as a mediator. The results showed that PABA has high catalytic activity for CP oxidation. The electrochemical behavior of CP was studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and differential pulse voltammetry (DPV) techniques. Under the optimized conditions, the catalytic oxidation peak current of CP showed two linear dynamic concentration ranges of 1.0 × 10⁻⁸ to 1.0 × 10⁻⁷ and 1.0 × 10⁻⁷ to 1.0 × 10⁻⁶, with a detection limit of 1.6 nM (signal/noise = 3), using the DPV technique. Finally, the proposed method was successfully applied for determination of CP in pharmaceutical and biological samples.     

Liquid chromatographic–mass spectrometric determination of the novel,recently identified thioTEPA metabolite,thioTEPA-mercapturate,in urine

An assay for the quantitative determination of the mercapturic acid conjugate of N,N′,N″-triethylenethiophosphoramide (thioTEPA-mercapturate) in human urine has been developed. ThioTEPA-mercapturate, a recently identified metabolite of the alkylating anticancer agent thioTEPA, was analyzed using LC–MS and with direct sample injection. Sulphadiazine was used as internal standard. Linearity was accomplished in the therapeutic relevant range of 1–25 μg/ml; recovery was 84% and both accuracy and precision were less than 20% for the lower limit of quantification (1.0 μg/ml) and less than 10% for the other concentration levels. The stability of thioTEPA-mercapturate proved to be satisfactory over a period of 2 months, when kept at −80°C. ThioTEPA-mercapturate urine concentrations of two patients treated with thioTEPA are presented demonstrating the applicability of the assay for clinical samples.     

Role of chloride ion as an allosteric activator of angiotensin-converting enzyme

The nature of chloride ion as an activator of angiotensin-converting enzyme was studied by a series of kinetic experiments with hog plasma enzyme preparation. The enzyme required the presence of chloride ion for its full catalytic activity, but its requirement of monovalent anion was not absolute. The K_A value for the enzymechloride binding was estimated to be about 150 mm in all cases regardless of the peptide substrates employed. In the presence of chloride ion, the activity of the enzyme was increased, but its optimum pH was shifted gradually to the alkaline region up to pH 8.2 depending on the concentration of chloride ion. In addition, in the presence of chloride ion, the apparent K_m values were reduced markedly while the V_max values were not much altered; for example, for the hydrolysis of angiotensin I decapeptide, the K_m value decreased by a factor of 50 while only an 18% increase in V_max was observed when the enzyme was saturated with chloride ion. The result suggests that chloride ion acts as a conformational modifier inducing the affinity of synergistic binding of substrate.     

N,N-dimethylacetamide/lithium chloride plasticized starch as solid biopolymer electrolytes

In this study, N, N-dimethylacetamide (DMAc) with certain concentration ranges of lithium chloride (LiCl) was used to plasticize starch by melting extrusion. Solid state ionic conductors, DMAc-plasticized starch containing LiCl also had a potential application as solid biopolymer electrolytes. Scanning electron microscope (SEM) showed that many remanent starch granules embed in DMAc-plasticized starch matrix. With increasing LiCl content, the number of remanent starch granules decreased dramatically and homogeneous thermoplastic starch (TPS) could be achieved. Moreover, Fourier Transform infrared (FT-IR) spectroscopy revealed that LiCl could increase the interaction between starch and plasticizers. In addition, the supermolecular structure of starch was destructed by LiCl detected by wide-angle X-ray scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Finally, LiCl not only could increase the water absorption of TPS, but also improved the conductance of TPS. The conductance of TPS with 18 wt% LiCl content could achieve to 10^?0.5 S cm^?1 at 18 wt% water content.