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PubMed1991

Quality control program on biological monitoring by Japan Federation of Occupational Health Organizations.

Since 1980, the Japan Federation of Occupational Health Organizations has been conducting an external quality control survey for biological monitoring under a contract with the Ministry of Labour of the Japanese Government. The number of participating organizations has increased from 91 in 1980 to 179 in 1987. The items in the program were lead and free erythrocyte protoporphyrin concentrations in blood, and lead, coproporphyrin, delta-aminolevulinic acid, chromium, hippuric acid, methylhippuric acid, total trichloro-compounds, mandelic acid, and phenol concentrations in urine. Evaluation was based on a scoring system. The scores were on the slope of major axis for probable ellipse, the slope of regression line, square root of error mean square for regression, performance indices, and the difference between 'true' and observed values of each sample. There was a gradual improvement in the evaluation scores as a function of time. The improvement was paralleled by the adoption of modern analytical methods such as flameless atomic absorption spectrometry for blood-lead measurement and high-performance liquid chromatography for urinary hippuric acid determination in many participants. These methods are simple in operation and reliable in performance. It was considered very probable that the program promoted the adoption.

Environmental Monitoring↗
PubMed1991

Metabolism of inhaled styrene in acetone-, phenobarbital- and 3-methylcholanthrene-pretreated rats: stimulation and stereochemical effects by induction of cytochromes P450IIE1, P450IIB and P450IA.

1. The effect of various cytochrome P-450 inducers, namely acetone, phenobarbital (PB) and 3-methylcholanthrene (MC), on the pharmacokinetics of styrene metabolism was studied. 2. Styrene metabolism in vivo was studied measuring phenylglyoxylic acid (PGA), the enantiomers of mandelic acid (MA), and total thioethers excreted in the urine during a 24 h period of airborne exposure to styrene at 500 cm3/m3 (2100 mg/m3). In acetone-pretreated rats, PGA and MA and thioether formation were elevated 30-50%. The R/S ratio of MA enantiomers was about two in all styrene-exposed groups except PB-pretreated rats, which showed a ratio of four. 3. Styrene metabolism in liver microsomes measured in vitro was increased by styrene 140%, acetone plus styrene by 190%, methylcholanthrene plus styrene by 180% and phenobarbital plus styrene by 250%. 4. N-Nitrosodimethylamine demethylation (NDMAD) and 7-pentoxyresorufin dealkylation (PROD) in liver microsomes were enhanced 100-150% by styrene inhalation. The metabolism of 7-ethoxyresorufin was not significantly enhanced. 5. Monoclonal antibodies to P-450 IA1, IA2, IIB1 and IIE1 were utilized to identify cytochrome P-450s by Western blot analysis. These studies showed clearly that styrene inhalation induced principally cytochrome P450IE1, whereas styrene given by gavage at a high narcotic dosage induced both P450IIE1 (NDMAD, 60%) and P450IIB (PROD, 3000%). 6. Our conclusions are that styrene metabolism in vivo in both autoinduced and induced by other foreign compounds, that cytochrome P450IIE1 induction has a major impact on styrene metabolism and that P450IIB1 induction yields an altered MA metabolite enantiomer ratio.

Acetone↗
PubMed1990

Production of benzoylformic acid from phenylglycine by Saccharomycopsis lipolytica.

Microbial production of benzoylformic acid (BF), which can be used as a substrate of enzymatic synthesis of (R)-(-)-mandelic acid, was investigated. Among 145 strains of yeasts and actinomycetes, Saccharomycopsis lipolytica (IAM 4964) was the best producer of BF from DL-phenylglycine (DL-PG). Culture conditions for BF production by the organism were optimized. When 0.2% fructose as a carbon source and 0.7% Bacto-tryptone as a nitrogen source were used in the presence of 4% DL-PG, 14.5 mg/ml of BF was produced (about 37% molar yield) in 4 days of cultivation. BF was synthesized from the L-form of PG, but not from the D-form. The BF was isolated from culture broth in a crystalline form and physicochemically identified.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1984

Metabolism of inhaled ethylbenzene in rats.

Male Wistar rats were exposed to ethylbenzene (0, 300, or 600 ppm for 6 h), and the metabolic fate of the compound was elucidated on the basis of the biotransformation products found in the urine. Fourteen different compounds thought to originate from ethylbenzene were identified. The main metabolites were 1-phenylethanol, mandelic acid, and benzoic acid. The metabolic conversion proceeded mainly through oxidation of the side chain, whereas ring oxidation seemed to be of minor importance. At the exposure level of 600 ppm, only 6% of the amount absorbed was eliminated in the urine during exposure. During the period of 48 h from the onset of exposure, the total urinary elimination was 59%. The corresponding values at 300 ppm were 13 and 83%.

Aerosols↗
PubMed2002

Hydroxamates as substrates and inhibitors for FMN-dependent 2-hydroxy acid dehydrogenases.

Long-chain hydroxy acid oxydase (HAO) is a member of a flavoenzyme family with significant amino acid sequence similarity and strongly conserved three-dimensional structure; in particular, active-site amino acids involved in catalysis are invariant, with one exception, and numerous enzymatic studies suggest an identical chemical mechanism involving an intermediate carbanion for all family members. Known physiological substrates are a variety of L-2-hydroxy acids. Peroxisomal HAO differs from the other family members in that its actual physiological substrate is not known; it was first described as an L-amino acid oxidase, and recently was identified as an enzyme that converts creatol (hydroxycreatinine) to methylguanidine (a metabolite involved in a variety of uremic syndromes). Creatol (2-amino-5-hydroxy-1-methyl-4(5H)imidazolone) is not a 2-hydroxy acid. We show in this work that 2-hydroxyphenyl acetohydroxamate (HYPAH, the hydroxamate of mandelic acid), a compound that bears similarity both to mandelate (one of the best substrates known) and to creatol, is turned over by HAO, but between 10- and 100-fold less efficiently than mandelate itself. The compound also binds to the active site of homologous flavocytochrome b(2) (L-lactate dehydrogenase). Comparative pH-rate studies for mandelate and its hydroxamate suggest that HYPAH may bind in its ionized form. Both pH-rate profiles are bell-shaped curves, as are those determined for two other family members, flavocytochrome b(2) and mandelate dehydrogenase; while the group with an acid pK(a) between 5 and 6 is most likely the active-site histidine (the residue which abstracts the substrate C2 proton), the identity of the basic group is less clear. It has been proposed to be one of the active site arginines (Lehoux, I., and Mitra, B. (1999) Biochemistry38, 5836-5848); we suggest as an alternative that it could be the lysine residue that interacts with the flavin N1 and O2 positions and stabilizes the negative charge of reduced flavin. In addition to these studies, we have found that HAO is competitively inhibited by benzohydroxamate, which is one atom shorter than HYPAH; its affinity is nearly 100-fold lower than that of the substrate, in contrast to the strong inhibition it exerts on mandelate racemase (Maurice, St. M., and Bearne, S. L. (2000) Biochemistry39, 13324-13335). In the latter case, the 100-fold higher affinity compared to mandelate was proposed to arise from the fact that the hydroxamate can mimic the enolic intermediate which lies on the reaction pathway after C2 proton abstraction. Thus our results do not support the existence of a similar enolic intermediate for HAO (and probably its homologues), although they do not disprove it.

Alcohol Oxidoreductases↗
PubMed1984

Urinary excretion of mandelic and phenylglyoxylic acids after human exposure to styrene vapour.

The kinetics of the urinary excretion of mandelic and phenylglyoxylic acids were studied in volunteers exposed to the known concentrations of styrene vapour. The level and the time of exposure were suitably changed to simulate situations in the industrial environment. The aim was to find out the reasons for the contradictory reports in the literature and to verify parameters characterizing the course of excretion of both metabolites. It was found that the course of mandelic acid excretion might be influenced by the length of styrene exposure. If exposure was longer than 4 hours the maximum of excretion was at the end of the exposure time; after short-term exposures (4 h or less) it was somewhat delayed. Maximum excretion of phenylglyoxylic acid was delayed both after short-term and 8-hour exposures. Excretion of the metabolites was diphasic (biexponential). The effective half-lives were found to be independent of the level of exposure. The apparent half-lives (determined in the post-exposure time of 0-16 hours) tended to become prolonged at daily repeated exposures. The ratio of mandelic to phenylglyoxylic acid changed considerably with the level of exposure. In biological monitoring it is advisable to determine both metabolites.

Female↗
PubMed1967

The metabolism of phenethyl bromide, styrene and styrene oxide in the rabbit and rat.

1. The chief sulphur-containing metabolite of styrene and sytrene oxide in the rabbit and rat is chromatographically identical with N-acetyl-S-(beta-hydroxyphenethyl)-l-cysteine and this compound is also formed, together with N-acetyl-S-phenethyl-l-cysteine, as a metabolite of phenethyl bromide. 2. The amounts of the phenethylmercapturic acid and its hydroxy derivative excreted in the urine of animals dosed with phenethyl bromide, styrene, styrene oxide, phenyl glycol, S-phenylethylcysteine and phenethylmercapturic acid have been determined. 3. Liver slices convert phenethylcysteine and phenethylmercapturic acid into N-acetyl-S-(beta-hydroxyphenethyl)-l-cysteine. 4. Methods for the determination by gas-liquid chromatography of mandelic acid and hippuric acid, which are metabolites of some of the compounds studied, are described.

Animals↗
PubMed1988

Biological exposure limits estimated from relations between occupational styrene exposure during a workweek and excretion of mandelic and phenylglyoxylic acids in urine.

Styrene exposure of 18 workers in fiberglass reinforced plastic industries was measured for 30-min periods throughout each workday for a week. The styrene uptake was estimated using pulmonary ventilation measurements. All urine voidings were collected separately and the styrene metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined. The relationship between both exposure and uptake versus excretion of these metabolites was studied. Styrene metabolite concentrations and excretion rates (with 95% tolerance limits) were calculated to correspond to a constant 8-h exposure at the Swedish exposure limit level (25 ppm) or an uptake of an exposure limit related styrene dose (6.3 mmol). The tightest tolerance limits were obtained for excretion rate of MA + PGA per 24 h. The calculated biological exposure limit was 3.4 (+/- 0.7) mmol MA + PGA/24h for a dose of 6.3 mmol styrene.

Air Pollutants, Occupational↗
PubMed2005

Analysis of urinary biomarkers for exposure to alkyl benzenes by isotope dilution gas chromatography-mass spectrometry.

A validated GC-MS method for the analysis of urinary metabolites of alkyl benzenes is reported. Metabolites for exposure to toluene, xylene and ethylbenzene were analyzed simultaneously using stable isotope substituted internal standards. The method entailed acidic deconjugation of urine samples followed by extractive alkylation with pentafluorobenzyl bromide as alkylating agent. The resulting pentafluorobenzyl derivatives of ortho-, meta-, para-cresol, mandelic acid (MA), hippuric acid (HA) and ortho-, meta-, para-methylhippuric acid (MHA) were then quantified by SIM. Optimized reaction conditions for the extractive alkylation step are reported. The derivatives were found to be sufficiently stable for overnight batch analysis. The LODs were below 0.1 micromol/L for the cresols and below 1 micromol/L for MA and the HAs. Within-batch precision for o-MHA was 7%, for m-MHA 5%, for p-MHA 5.2% and below 5% for the rest of the analytes.

Alkylation↗
PubMed1969

Factors affecting the synthesis of ampicillin and hydroxypenicillins by the cell-bound penicillin acylase of Escherichia coli.

1. The effect of pH, temperature, reactant concentration and reaction time has been investigated for the synthesis of benzylpenicillin, dl-alpha-hydroxybenzylpenicillin and d-alpha-aminobenzylpenicillin from 6-aminopenicillanic acid by the penicillin acylase of Escherichia coli. 2. Synthesis of penicillins from carboxylic acids proceeds most rapidly at pH5; with amides the optimum pH is higher (6-7) but the reverse reaction rapidly sets in. This can be counteracted by lowering the pH or adding more amide. Optimum temperatures are 35-40 degrees . 3. Most rapid synthesis of penicillin was obtained with the N-acylglycine and methyl ester derivatives of carboxylic acids. Increasing the amide/6-APA ratio above 1:1 raised the rate of synthesis of penicillins. 4. Preferential synthesis of d-alpha-hydroxybenzylpenicillin takes place in a reaction mixture containing dl-mandelic acid. 5. From d- and l-mandelamide, d- and l-alpha-hydroxybenzylpenicillins were prepared, the former being more bioactive than the latter. p-Hydroxy- and 3,4-dihydroxybenzylpenicillins were also prepared, the latter being more active against some Gram-negative bacteria than benzylpenicillin.

Amides↗
PubMed1992

The effect of repeated instillations of antiseptics on catheter-associated urinary tract infections: a study in a physical model of the catheterized bladder.

The activity of three antiseptic bladder washout solutions was examined in a physical model of the catheterized bladder. Tests were performed against cultures of four common urinary tract pathogens that had established themselves in the model and colonized the surfaces with biofilm. Double instillations of chlorhexidine (0.02% w/v) at 6-h intervals failed to eliminate Pseudomonas aeruginosa, Proteus mirabilis, and Providencia stuartii from the bladder model. Escherichia coli, however, was susceptible to a second instillation provided that it was performed within 12 h. Supplementing chlorhexidine with EDTA and TRIS potentiated its activity against E. coli. Mandelic acid (1.0% w/v) was the most effective of the agents, double instillations eliminating all but Pr. mirabilis infections.

Administration, Intravesical↗
PubMed1990

Anticholinergic agents. 2. Absolute configurations of 2-methyl-1,1-diphenyl-3-(1-piperidyl)-1-propanol and 2-methyl-1,1-diphenyl-3-(1-pyrrolidyl)-1-propanol. Crystal structures of the corresponding mandelates.

Racemic 2-methyl-1,1-diphenyl-3-(1-piperidyl)-1-propanol (4) and 2-methyl-1,1-diphenyl-3-(1-pyrrolidyl)-1-propanol (5) have been synthesized and optically resolved employing (R)- and (S)-mandelic acid, respectively, as resolving agents. The absolute configurations of the enantiomers of 4 and 5 have been established as (-)-(R) and (+)-(S) by crystal structure analyses of (-)-(R)-2-methyl-1,1-diphenyl-3-(1-piperidinio)-1-propanol (+)-(S)-mandelate and (+)-(S)-2-methyl-1,1-diphenyl-3-(1-pyrrolidinio)-1-propanol (-)-(R)-mandelate. The corresponding methiodides have been prepared.

Crystallography↗
PubMed1978

Chromosome investigations on workers exposed to styrene/polystyrene.

Chromosomes investigations were undertaken on 12 employees with three to 34 years possible exposure to styrene in order to determine if there was a possibility of chromosome impairment. The data did not reveal any significant differences between persons exposed to styrene and members of the control group. The concentrations of styrene at the workplace were far below the MAC value and also the mandelic acid content of the urine was far below the norm.

Adult↗
PubMed1998

[Determination of enantiomeric purity by simultaneous dual circular dichroism and ultraviolet spectrophotometry].

A method is described for the determination of enantiomeric composition. The ellipticity and absorbances of the sample are measured simultaneously by CD and UV spectroscopies, and the resulting G value is determined. G is an intensive physico-chemical parameter, a close derivative of anisotropy factor. Its magnitude is identical with opposite sign for enantiomers. The experimental G value is concentration-independent, as long as both absorption and ellipticity are linear functions of concentration. The analytical procedure introduced here is simple, rapid, and inexpensive, even though it includes calibration with standards of established enantiomeric composition. Provided the sample contains some UV-active contaminant(s), the method can be used after achiral chromatographic purification. By virtue, the method lacks several sources of error, arising normally from concentration inaccuracies. Applicability of the principles is tested by the example of phenylglycine and mandelic acid. Advantages of the method allowed the determination of phenylglycine enantiomer purity with an accuracy of 0.1%.

Calibration↗
PubMed2002

Absolute configuration of tert-butyl-1-(2-methylnaphthyl)phosphine oxide.

The enantiomers of tert-butyl-1-(2-methylnaphthyl)phosphine oxide 1 have been separated using a homemade HPLC column and an analytical gradient system. Vibrational absorption and circular dichroism spectra for both enantiomers have been measured in CD2Cl2 and CH2Cl2 solutions in the 2000-900 cm(-1) region. The fully relaxed potential energy surface of (S)-tert-butyl-1-(2-methylnaphthyl)phosphine oxide, obtained using the B3LYP functional with a 6-31G basis set, indicated two stable conformers with their populations in a approximately 2:1 ratio. The vibrational absorption and VCD spectra are predicted for these two conformers using the B3LYP functional with a 6-31G basis set. The comparison of predicted and experimental spectra indicated that (+)-tert-butyl-1-(2-methylnaphthyl)phosphine oxide is in the (S)-configuration. This assignment is supported by the ab initio prediction of positive optical rotation for the most stable conformer with an (S)-configuration and the nonequivalence sense of the tert-butyl group chemical shift observed in the 1H NMR spectrum of this enantiomer measured in the presence of (+)-(S)-mandelic acid as a chiral solvating agent.

Chromatography, High Pressure Liquid↗
PubMed1978

Mutagenicity study of workers employed in the styrene and polystyrene processing and manufacturing industry.

Mutagenicity studies were undertaken on lymphocytes from the following groups of persons exposed to styrene or polystyrene: one group from a styrene manufacturing plant, one from a polystyrene plant, and three from plants processing unsaturated polyester resins with different manufacturing methods. For all the groups the concentration of styrene in the atmosphere of the workplace was measured at various points and the amount of urinary mandelic acid was determined. In each case 100 metaphases were analyzed for chromosomal aberrations. The results were compared with reference groups.

Adult↗