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PubMed1994

Purification and Characterization of an l-Amino Amidase from Mycobacterium neoaurum ATCC 25795.

An l-amino amidase from Mycobacterium neoaurum ATCC 25795 responsible for the enantioselective resolution of dl-alpha-methyl valine amide was purified and characterized. The purification procedure included ammonium sulfate fractionation, gel filtration, and anion-exchange chromatography, which resulted in a homogeneous preparation of the enzyme with a native molecular mass of 136 kDa and a subunit molecular mass of 40 kDa. The purified enzyme displayed the highest activity at 50 degrees C and at pH 8.0 and 9.5. The enzyme was strongly inhibited by the metal-chelating agent 1,10-phenanthroline, the disulfide-reducing agent dithiothreitol, and the cysteine proteinase inhibitor iodoacetamide. The purified amino amidase showed a unique l-enantioselective activity towards a broad range of both alpha-H- and alpha-alkyl-substituted amino acid amides, with the highest activity towards the cyclic amino acid amide dl-proline amide. No activity was measured with dl-mandelic acid amide nor with the dipeptide l-phenylalanine-l-leucine. The highest catalytic efficiency (k(cat)/K(m) ratio) was measured with dl-alpha-allyl alanine amide, dl-alpha-methyl phenylalanine amide, and dl-alpha-methyl leucine amide.

Journal Article↗
PubMed1993

Somatosensory evoked potentials in workers exposed to toluene and styrene.

Somatosensory evoked potentials (SEPs) were used to evaluate possible subclinical impairment of the nervous system due to occupational exposure to toluene and styrene. A group of 36 rotogravure printers with severe exposure to toluene, 20 workers with severe exposure to styrene in a glass laminate manufacturing plant, and a comparison group of healthy subjects were studied. The severity of exposure was documented by measurements of toluene and styrene concentrations in breathing zone air, by hippuric acid concentration in urine in the group exposed to toluene, and by urinary mandelic acid concentration in the group exposed to styrene. Somatosensory evoked potentials were measured by stimulation of the median nerve at the wrist and the tibial nerve at the ankle. Peripheral conduction velocities (CVs) in both extremities and central conduction time (CCT) after tibial nerve stimulation were significantly decreased in both exposed groups. Significantly prolonged latencies of peripheral and cortical SEPs to median nerve stimulation as well as cortical SEPs to tibial nerve stimulation were found in workers exposed to styrene. Some abnormalities in SEPs at peripheral or spinal and cortical levels were found in eight workers exposed to toluene and six workers exposed to styrene. Of these, in three workers exposed to toluene and two to styrene increased CCT and delayed latencies of cortical responses at normal conduction values in the periphery were found. A trend for increased frequency of abnormal SEPs with duration of exposure to toluene and styrene and alcohol abuse was found. Abnormalities in SEPs in the exposed groups are most probably of multifactorial origin. Central SEP abnormalities in both exposed groups could indicate early signs of subclinical dysfunction at spinal and cortical levels and could be due to toluene or styrene exposure probably potentiated by alcohol consumption in the group exposed to toluene.

Adult↗
PubMed1989

Clinical and biochemical responses to therapy in Alzheimer's disease and multi-infarct dementia.

Memory performance, central monoaminergic function and sympathetic nerve activity were studied in patients with dementia of the Alzheimer type (DAT) or with multi-infarct dementia before and after 4 weeks with single or combined drug therapy (choline-piracetam). Analysis of the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG), 3-methoxy-4-hydroxyphenylacetic acid (HVA) and 5-hydroxyindolacetic acid in the cerebrospinal fluid (CSF) and also in urine (plus 3-methoxy-4-hydroxy mandelic acid) showed that the basal values of HVA in the CSF and urine were lower in the more severely demented compared with the mildly demented subjects in both groups. The combined drug treatment resulted in a statistically significant increase in the MHPG level in the CSF of mildly demented subjects of the DAT group, while it seemed not to influence the other monoamine metabolites. The sympathetic nerve activity was similar in both patient groups and was unchanged after therapy. These findings suggest a dopaminergic deficit in advanced stages of the disease and a possible enhancement of the central noradrenergic output with therapy. No effects of therapy on memory performance or correlations between monoamine levels and memory test scores were noted.

Aged↗
PubMed2005

RISUG (reversible inhibition of sperm under guidance)--an antimicrobial as male vas deferens implant for HIV free semen.

HIV transmission from the male to the female is a major health problem. A hypothesis proposing an intra vas deferens implant of an antimicrobial compound to prevent the infection spread is presented. Mechanisms of action for the inhibition could include inactivating HIV in sperms passing through the vas deferens; drug release from the implant to destroy HIV entering into semen from genital structures distal to the vas deferens; and sperm acrosome released hyaluronidase mediated reabsorption of HIV. A subcomponent of the implant flowing along sperm pathway may have a role in reducing the entry of HIV from a positive female into penile tissue. A new drug RISUG (reversible inhibition of sperm under guidance) presently undergoing clinical trials for its contraceptive effect in the male (because it disrupts the sperm acrosome by an electrical charge and pH lowering effects) has also antimicrobial action. The drug being a combination of styrene maleic anhydride (SMA) and dimethyl sulfoxide (DMSO) on being injected into the lumen of the vas deferens produces styrene maleic acid thereby lowering pH; induces electrochemical action leading to a stable electrical charge generation; releases mandelic acid; and induces acrosome reaction in sperms with consequent release of hyaluronidase and sperm inactivation. Moreover, one time administration into the lumen of the vas gives long term action. All these phenomena very well match with the needs for HIV clearance of semen and hence RISUG is here proposed as a possible candidate material for the HIV inhibiting vas deferens implant when delivered in below contraceptive threshold dosage. For experimental validation, after obtaining data on the semen HIV load under control conditions in the HIV positive males inducted into the study, 30 mg of SMA in 120 microl of DMSO (contraceptive dose being 60 mg SMA+120 microl DMSO) is to be injected into vasa deferens bilaterally. Thereafter at intervals of one month the viral load needs to be determined in semen obtained either by masturbation or in lubricant free condom at intercourse - the method of collection remaining the same throughout for a particular subject. A significant reduction in the semen viral load following RISUG administration will validate the hypothesis. Speculated reduced female to male HIV transmission is more difficult to test. Nonspecific indications will come from a population study of the incidence of RISUG treated men becoming HIV positive as compared to that in the general population.

Anti-HIV Agents↗
PubMed1980

Determination of urinary mandelic and phenylglyoxylic acids in styrene exposed workers and a control population.

Styrene is rapidly metabolized in humans to mandelic () and phenylglyoxylic acids (P) which are excreted in urine. The present study investigates a gas chromatographic technique for measuring urinary concentrations of MA and PGA of workers exposed to styrene, compares the urinary concentrations of metabolites with time-weighted average air exposures to styrene and determines the levels of these metabolites in a population of workers not exposed to styrene. Post-shift urine specimens were obtained from a group of workers exposed to styrene in the reinforced plastic industry and from a control group. High positive correlation was found between post-shift urinary concentrations of metabolites and 8-hour TWA styrene exposure. Both MA and total metabolites (MA + PGA) gave correlation coefficient values of 0.96, p less than 0.0001. The mean MA excretion for the control groups was 6 mg/L. Determination of the concentration of these metabolites in a post-shift urine provides an effective means of estimating and monitoring human exposure to styrene.

Air Pollutants, Occupational↗
PubMed1979

New fluorometric analysis for mandelic and phenylglyoxylic acids in urine as an index to styrene exposure.

I describe a new fluorometric method for determination of mandelic and phenylglyoxylic acids in urine, the fluorometry being preceded by extraction into ether and thin-layer chromatography. The chromatographically separated acids were quantitated after conversion to stable highly fluorescent derivatives by treatment with concentrated sulfuric acid. This method proves to be more precise, accurate, and reproducible than the existing colorimetric method. The limit of detection is 2 microgram of either acid per milliliter of urine with a CV of less than 15%. The standard curve for either acid is essentially linear from 2 to 100 microgram/mL of urine, with a correlation coefficient (r) of 0.97. No satisfactory correlation was obtained between the concentrations of either acid metabolite as measured in rat urine by fluorometry and colorimetry. The present method is considered suitable for routine biological monitoring of persons exposed to both high and low concentrations of styrene.

Animals↗
PubMed1983

Monoamine metabolism during chronic benzodiazepine treatment and withdrawal.

Long-term normal-dose benzodiazepine treatment in seven patients was associated with reduced urinary excretion of MOPEG (4-hydroxy-3-methoxy-phenylglycol). Following the discontinuation of the drugs a characteristic withdrawal reaction occurred, with an increase towards normal values of the MOPEG excretion levels and changes in the excretion of 5-HIAA (5-hydroxyindoleacetic acid). No significant changes in the 24-hr urinary excretion of free cortisol or HMMA (3-methoxy-hydroxy-mandelic acid) were detected.

Adult↗
PubMed1981

Synthesis and relative stereochemistry of the four mercapturic acids derived from styrene oxide and N-acetylcysteine.

The chemical reaction between (+/-)-styrene oxide and N-acetylcysteine produces both positional isomers (1 and 2) as a mixture of diastereoisomers with a preference for the benzylic thioether isomer 1 (2 : 1). Synthesis of the mercapturic acid conjugates from either (+)- or (-)-styrene oxide produces only two of the four possible stereoisomers. The single diastereoisomers of 1 and 2 were separated by high pressure liquid chromatography (HPLC) and identified by 1H- and 13C-nuclear magnetic resonance (NMR). The relative stereochemistry at the benzylic carbon center of the mercapturic acid conjugates was assigned on the basis of the established chemical correlation between optically pure styrene oxide and its precursor mandelic acid, and considerations on the mechanism of ring opening of epoxides by sulfur nucleophiles. The stereochemical definition of the isomers 3-6 should prove useful in investigations of the biotransformation of the glutathione (GSH) conjugates of styrene oxide.

Acetylcysteine↗
PubMedDate not supplied

Effect of subchronic ethanol ingestion on styrene-induced damage to the tracheal and pulmonary epithelium of the rat.

Previous studies have indicated that ethanol may affect styrene metabolism and toxicity in target tissues (e.g. brain). Morphological and biochemical changes have been reported in the respiratory tract of laboratory animals exposed to styrene either by inhalation or i.p. injection. The aim of the present study was, therefore, to investigate the influence of subchronic ethanol administration (5% in a Lieber-DeCarli liquid diet) on the morphological alterations of the respiratory tract induced by styrene inhalation (300 ppm, 6 h day(-1), 5 days a week for 2 weeks) in rats. Levels of reduced glutathione (GSH) in lung and liver tissues as well as in erythrocytes and whole blood were studied as indicators of overall GSH status, and urinary levels of the styrene metabolites-mandelic acid and phenylglyoxylic acid-were also measured as indicators of styrene-absorbed dose. Rats exposed to 300 ppm styrene presented morphological alterations throughout the respiratory tract. Electron microscopy analysis showed diffuse cell damage involving the tracheal, bronchiolar and alveolar epithelium. These abnormalities were accompanied by 40% depletion of GSH in the lung tissue and also 35% depletion in hepatic GSH in the absence of alteration of the GSH content in blood. Styrene metabolism was apparently induced by subchronic ethanol treatment, as indicated by an increased excretion of urinary mandelic (+140%, P < 0.05) and phenylglyoxylic (+50%) acids. However, repeated ethanol administration did not exacerbate the lung GSH depletion nor the damaging effect to the respiratory tract induced by the 2-week exposure to styrene alone. The lack of effects of ethanol on styrene pulmonary toxicity after combined exposure may be due to the different tissue distribution of the cytochrome P-450 isoforms involved in the styrene biotransformation to styrene-7,8-oxide, and their different induction by ethanol.

Administration, Oral↗
PubMed1990

Effect of ethanol on the urinary excretion of mandelic and phenylglyoxylic acids after human exposure to styrene.

Administration of ethanol in several doses during human exposure to styrene can inhibit the urinary mandelic and phenylglyoxylic acid excretion in a way similar to that reported when ethanol was administered as a single dose. Sensitivity to this inhibitory effect has been found to differ with individual subjects. Differences in long-term consumption of ethanol resulting in different induction of the oxidizing enzymes are suggested to account for this finding. Intra-individual variation in the influence of acute ethanol ingestion on the excretion rate of the mentioned acids can also occur. The habit of drinking ethanol might be important, even for partial redirection of the styrene metabolism from styrene glycol oxidation to styrene glycol conjugation with beta-glucuronic acid and/or sulfate. The consequences of these observations for the occupational hygiene practice are briefly outlined.

Adult↗
PubMed1976

Effect of horn flies on vanilmandelic acid excretion of dairy cattle.

This study measured a physiological effect of known horn fly (Haematoba irritans L.) population densities on dairy cattle. Urinary excretion of the catecholamine metabolite, 3-methoxy-4-hydroxy mandelic acid, was an indicator of physiological response to the parasites. Six lactating Holstein cows were acclimated to the test room prior to a 3-wk control at 21 C. Animals were then exposed to approximately 500 horn flies per cow per day for 4 wk. On days 1 and 21 of exposure, two urine samples were obtained from each cow. Mean urinary values for cows were 13.3 +/- 3.1 mug/100 ml in the control period and 18.9 +/- 3.4 mug/100 ml during fly exposure. We believe that increased vanilmandelic acid reflects an increase in standing time and nervous activity associated with the physical disturbance due to the biting of the flies.

Animals↗
PubMed2003

Olfactory sensitivity to catecholamines and their metabolites in the goldfish.

The current study assessed the olfactory sensitivity of the goldfish (Carassius auratus L.) to the catecholamines, their immediate precursors and metabolites by use of the electro-olfactogram (EOG). The olfactory system of the goldfish was found to be sensitive to both adrenaline and dopamine with thresholds of detection of 10(-7.8) and 10(-7.9) M respectively, but less so to noradrenaline (threshold of detection 10(-6.3) M). The 3-O-methoxy metabolites (metadrenaline, normetadrenaline and 3-O-methoxytyramine) evoked larger amplitude EOGs than the non-metabolized form with lower thresholds of detection. However, the olfactory system was less sensitive to the amino acid precursors L-tyrosine and L-DOPA, and markedly less so to the alpha-deaminated metabolites (3,4-dihydroxyphenyl glycol, 3,4-dihydroxy mandelic acid and dihydroxyphenyacetic acid). Sensitivity to metabolites, both alpha-deaminated and 3-O-methoxylated, was similar to the alpha-deaminated forms. Cross-adaptation studies suggested that, while there is some degree of commonality of the receptor mechanisms with L-tyrosine and L-serine, a proportion of the response to the catecholamines is due to distinct receptor subtypes. Similarly, the 3-O-methoxy metabolites also had (a) separate receptor mechanism(s), although, again, there was overlap with the adrenaline/dopamine receptor site(s). Presence of the alpha-adrenoreceptor antagonist prazosin or the peripheral DA(2) dopamine receptor antagonist domperidone caused partial attenuation of the EOG responses to adrenaline and dopamine, but had much less effect on the responses to their 3-O-methoxy metabolites. The beta-adrenoreceptor antagonist sotalol had no such effect. This suggests that the olfactory catecholamine receptors are structurally and functionally distinct from systemic adreno- and dopamine receptors. The current study raises the possibility that release of catecholamines or their 3-O-methoxy metabolites to the water may play a role in chemical communication.

Action Potentials↗
PubMed2007

New macrocyclic compound as chiral shift reagent for carboxylic acids.

[structure: see text] We have prepared a novel chiral macrocyclic compound 3 from a C2-symmetric aminonaphthol in a high yield. Enantiomeric acids have large nonequivalent chemical shifts (up to 0.80 ppm) in the presence of 3 in 1H NMR (500 MHz) spectra. Quantitative analyses of a series of mandelic acids with different enantiomeric purities show that host 3 is an excellent chemical shift reagent for chiral carboxylic acids.

Carboxylic Acids↗
PubMed1996

Plasma levels of chromogranin A are directly proportional to tumour burden in neuroblastoma.

A novel animal experimental model involving the human, poorly differentiated, and adrenergic neuroblastoma cell line SH-SY5Y xenotransplanted to subcutaneous tissue of 13 nude rats (WAG rnu/rnu) was used to investigate the usefulness of six proposed neuroblastoma markers. It was shown that the plasma concentrations of human chromogranin A (CgA) as measured by RIA were directly proportional to tumour volume (r = 0.83, P < 0.001). To rule out possible liberation of CgA by tumour cell lysis, the CgA degradation product pancreastatin was also measured in plasma by a specific RIA, but was not detectable. Plasma neurone-specific enolase (NSE) was elevated in tumour-bearing animals (P < 0.01), but did not correlate with tumour volume (r = 0.49, P > 0.05). Urine homovanillic acid (HVA), detected by HPLC, was elevated in tumour-bearing animals (P < 0.01), but did not correlate with tumour volume (r = -0.32, P > 0.05). Urine vanillyl mandelic acid was not detectable. Urine dopamine was found in low concentrations that did not correlate with tumour volume. In summary, although plasma NSE and urinary HVA were elevated in tumour-bearing animals only plasma CgA correlated with tumour burden. This makes CgA a promising biochemical marker for neuroblastomas.

Adrenal Gland Neoplasms↗
PubMed2003

A rapid HPLC method for the determination of carboxylic acids in human urine using a monolithic column.

A rapid HPLC method for the determination of carboxylic acids in urine samples using a Chromolith Performance RP/18e 100/4.6 with Chromolith Guard Cartridge RP/18e 10/4.6 (Merck KgaA, Darmstadt, Germany) was developed. The method facilitates the simultaneous determination of aromatic hydrocarbon metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA) from styrene and ethylbenzene, hippuric acid (HA) from toluene and 2-, 3-, 4-methylhippuric acids (MHA) from xylene. 3-hydroxybenzoic acid (3-HBA) was used as internal standard. A chromatographic run is completed within less than 5 min for styrene, ethylbenzene and toluene metabolites, and within 10 min for xylene metabolites. The detection limits are 9 mg L(-1) urine for MA, 1.25 mg L(-1) urine for PGA, 4.9 mg L(-1) urine for HA, 22 mg L(-1) urine for 2-MHA, and 18.5 mg L(-1) urine for 3-MHA. No significant differences of the MA, PGA and HA concentrations in human urine samples obtained by HPLC chromatography on LiChrosorb RP 18 and on Chromolith RP/18e columns were found. The results were evaluated by using ANOVA.

Calibration↗
PubMed2001

Polymorphism of xenobiotic-metabolizing enzymes and excretion of styrene-specific mercapturic acids.

The role of polymorphic xenobiotic-metabolizing enzymes in the interindividual variability of phenylhydroxyethyl mercapturic acids (PHEMAs) was investigated in 56 styrene-exposed workers. Ambient monitoring was carried out using passive personal samplers (geometric mean, 157 mg/m3 8-h time-weighted average; geometric standard deviation, 2.90). Biomonitoring was based on mandelic acid and phenylglyoxylic acid in urine spot samples collected at the end of the work shift ("end-of-shift") and prior to the subsequent shift ("next morning"). Four PHEMA diastereoisomers, namely (R,R)-M1, (S,R)-M1, (S,R)-M2, and (R,R)-M2, were determined by HPLC/tandem mass spectrometry. The genotypes of glutathione S-transferases M1-1 (GSTM1), T1-1 (GSTT1) and P1-1 (GSTP1), and microsomal epoxide hydrolase (EPHX) were characterized by PCR-based methods. Workers bearing the GSTM1pos genotype showed PHEMA concentrations five and six times higher (in end-of-shift and next-morning samples, respectively) as compared to GSTM1null people. In GSTM1pos subjects, (R,R)-M1 was the main mercapturate affected by the GSTM1 status, accounting for 54 and 68% of total PHEMAs in end-of-shift and next-morning samples, respectively. Compared to GSTM1null, GSTM1pos subjects excreted more -M1 than -M2 and more (R,R)-M1 and (S,R)-M2 than (S,R)-M1 and (R,R)-M2 diastereoisomers. Thus, GSTM1-1 is the main isoenzyme catalyzing GSH-conjugation of styrene-7,8-oxide in humans and it seems to act in a regio- and stereoselective way. PHEMAs cannot be recommended as biomarkers of exposure to styrene, unless the GSTM1 genotype is considered in data interpretation. Their role as biomarkers of susceptibility deserves further studies.

Acetylcysteine↗
PubMed2006

Diastereoselective synthesis of some novel benzopyranopyridine derivatives.

BACKGROUND: The formation of novel N-substituted-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c]pyridines were observed unexpectedly during the acid-mediated ketal removal of ethylenedioxy ketal protected 4-piperidones. The literature revealed that benzopyranopyridine derivatives are of scientific interest and some exhibit interesting biological activities. Diastereomeric resolution was utilized to isolate optically pure chiral molecules. RESULTS: The acid catalyzed deprotection of N-substituted-4,4-ethylenedioxy-3- [(1,3-benzodioxol-5-yloxy)methyl]piperidines, prepared by condensation of the corresponding phenols and mesylate derivatives, unexpectedly resulted in cyclodehydration leading to new benzopyrano derivatives, N-substituted-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c]pyridines. The process involves the deprotection of the carbonyl protecting group, and then the cyclization reaction occurs followed by dehydration to give the final product.These N-substituted-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c] pyridines were dealkylated giving the corresponding N-unsubstituted derivatives. The cis-1,3,4,4a,5,10b-hexahydro-[6,7]-2H-[1]benzopyrano [3,4-c]pyridine derivative was also obtained from the N-benzylated-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c]pyridine via catalytic hydrogenation. The resolution of the enantiomers was carried out using D-(-)-mandelic acid as chiral reagent. The absolute configuration of the S,S-mandelate salt derivative was determined by X-ray crystallographic analysis. CONCLUSION: The approach led to the construction of N-substituted-1,2,3,4-tetrahydro[1,3]-dioxolo-[6,7]-5H-[1]benzopyrano [3,4-c] pyridines ring systems involving the one-pot deprotection, cyclization and dehydration of N-substituted-4,4-ethylenedioxy-3- [(1,3-benzodioxol-5-yloxy)methyl]piperidines. The hydrogenation of the N-benzylated benzopyrano [3,4-c]pyridine derivative followed by resolution led to the formation of a new compound.

Journal Article↗