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PubMed1983

The effect of modified fasting on blood pressure and sympathetic activity: a correlation?

The effect of a low calorie diet (200 kcal/0.8 MJ) composed of 50 per cent glucose and 50 per cent protein was studied on blood pressure and sympathetic activity in eight normotensive obese subjects. The study lasted 21 days; during the first seven days (period I) a weight maintaining diet was given; this was followed by 14 d (period II) of modified fasting (200 kcal/0.8 MJ). Sodium and potassium intakes of 20 and 80 mmol per d respectively were maintained constant throughout the study. In period I blood pressure decreased slightly until day 5; this occurred concomitantly with a marked natriuresis. Thereafter blood pressure and sodium excretion remained stable. No significant change was observed in the urinary excretion of total catecholamines, noradrenaline and 4-hydroxy-3-methoxy mandelic acid. From the start of period II blood pressure decreased markedly, together with a significant decrease in the urinary excretion of the catecholamines and 4-hydroxy-3-methoxy mandelic acid. Both blood pressure and urinary excretion of catecholamines and 4-hydroxy-3-methoxy mandelic acid stabilized after day 7 of period II. These changes preceded the maximal sodium diuresis of severe calorie restriction. The results suggest a primary role for the sympathetic system in the hypotensive effect of short term calorie deprivation although some influence of natriuresis cannot be excluded.

Adolescent↗
PubMed2001

Oxidation-active flavin models: oxidation of alpha-hydroxy acids by benzo-dipteridine bearing metal-binding site in the presence of divalent metal ion and base in organic solvents.

The oxidizing ability of benzo-dipteridine bearing a bipyridin-6-ylmethyl moiety (4) was found to be increased with Zn(2+) by approximately 10(3)-fold for sulfite addition in MeOH and approximately 10(2)-fold for oxidation of an NADH model in MeCN. It was found for the first time that 4 is able to oxidize alpha-hydroxy acids to alpha-keto acids in the presence of a divalent metal ion such as Zn(2+), Co(2+), and Ni(2+) and an amine base in MeCN or t-BuOH, whereas benzo-dipteridine having a bipyridin-5-ylmethyl moiety (3) is unable to oxidize them under the same conditions. The oxidation reaction was kinetically investigated including the kinetic isotope effect for deuterated mandelic acids (k(H)/k(D) = 2.1-3.7) and the Hammett plots for substituted mandelic acids (V-shaped plots). In the reaction of alpha-substituted alpha-hydroxy acids such as alpha-methyl mandelic and benzylic acids with 4, novel oxidative decarboxylation was found to take place, giving acetophenone and benzophenone, respectively. The oxidation mechanism for mandelic acid was proposed to proceed via a ternary complex of 4.Zn(2+).PhCH(OH)CO(2)(-), in which alpha-oxyanion of mandelate attacks C(4a)-position of 4 to form an adduct followed by 1,2-elimination to afford benzoyl formate and 2e-reduced 4. The roles of the metal ion were proposed as follows; (i) activation of 4, (ii) substrate-binding site, and (iii) activation of the bound alpha-hydroxy acid by lowering pK(a)'s of alpha-OH and alpha-CH. This is a first example that a flavin model oxidizes alpha-hydroxy acids in the presence of a metal ion.

Journal Article↗
PubMed1962

Neuromuscular blocking properties of some bistropinium esters.

The neuromuscular blocking, anti-acetylcholine and ganglion blocking properties of two series of bistropinium esters were examined. The neuromuscular blocking activities of the mandelic acid esters of NN'-polymethylenebis(tropinium halides) were found to depend upon the number of carbon atoms (n) in the linking chain. Potency was enhanced more than 50 times as n was increased from 2 to 7. Compounds in which n equalled 7, 8, 9, 10 and 12 differed little in activity, but were generally more potent than tubocurarine in cats and rabbits. A peak of ganglion blocking action was obtained at the pentamethylene member. Esterification enhanced the feeble neuromuscular blocking properties of NN'-decamethylenebis(tropinium halide), the mandelic acid ester being more effective than the tropic, benzoic or phenylacetic acid esters in cats and rabbits. When two benzoic or mandelic acid esters of tropine were linked through their nitrogen atoms by a phenylenedimethyl grouping (-CH(2).C(6)H(4).CH(2)-), meta substitution was more effective than was ortho or para in producing neuromuscular block. The effectiveness of esterifying acids in m-phenylenedimethyl derivatives decreased in the following order, phenylacetic> tropic or mandelic>benzoic>acetic and diphenylacetic.

Ammonium Compounds↗
PubMed1994

Cytogenetic analysis of lymphocytes from fiberglass-reinforced plastics workers occupationally exposed to styrene.

In this study a group of 52 workers employed in a plant manufacturing fiberglass-reinforced plastic (FRP) pipes and cisterns, and therefore daily exposed to styrene, were monitored. As a control group 24 non-exposed workers from another factory producing and repairing pallets volunteered to participate. The airborne styrene during the monitoring ranged from 2.2 to 110.1 mg/m3. As a metabolic marker for styrene exposure mandelic acid was measured in the urine and ranged from 11 to 649 mg/g creatinine. From 43 exposed and 15 control workers sister-chromatid exchanges (SCE) and high frequency cell (HFC) data and from 49 exposed and 23 control workers micronucleus (MN) data from peripheral lymphocytes are reported. Although the two groups of workers could clearly be distinguished on the basis of the airborne styrene concentrations and urinary mandelic acid concentrations no differences in any of the cytogenetic markers were found. Correlations between the cytogenetic data and the level of airborne styrene concentrations or urinary mandelic acid levels could also not be demonstrated. Otherwise, smoking increased the SCE frequency. Grouping the workers according to smoking habits showed a statistically significant difference in SCE. Moreover, levels of urinary thiocyanate (SCN), which can be used as a metabolic marker for smoking, showed a significant positive correlation with the number of SCE. This indicates that SCE is a sensitive biomarker and might still be useful in biomonitoring. However, only chronic exposures over a long period would probably be detectable. In this study, where exposure was rather low and the number of working years was small (mean of 2.9 years), cytogenetic effects are probably too low or rare to be detectable with any assay.

Adult↗
PubMed2001

Intervention study on acquired color vision deficiencies in styrene-exposed workers.

The main aim of the study was to examine the possible effects of occupational exposure to styrene on color vision function and the course after reduction of exposure. Color vision function was examined in 22 styrene-exposed laminators and 11 control subjects at a boat manufacturing plant. The Lanthony D-15 desaturated panel was used to test acquired dyschromatopsia. In all, six examinations were performed: Monday morning and Thursday afternoon of the same week, before and immediately after a vacation of 4 weeks (altogether, phase 1), and approximately 10 months later (phase 2), after the exposure level of styrene had been reduced. Styrene uptake was objectified by biological monitoring measuring the metabolites mandelic acid and phenylglyoxcylic acid in urine samples taken on Thursday afternoon. In both Thursday examinations, styrene-exposed workers had higher color confusion index (CCI) values compared with controls, which indicated quantitative color vision loss. After an exposure-free period of 4 weeks, a significant decrease of CCI values to normal range was found in laminators. Reexamination 10 months later showed also lower CCI values in exposed workers, indicating a dose-effect relationship. Abnormal CCI values occurred primarily in subjects with an excretion of approximately 500 to 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine or more. We concluded that styrene-induced color vision dysfunction is reversible after an exposure-free interval of 4 weeks. The current Biological Tolerance Value of 600 mg mandelic acid plus phenylglyoxcylic acid per gram creatinine, as used in Germany, protects styrene-exposed workers from this subclinical effect.

Adult↗
PubMed1995

Effect of Sahaja yoga practice on stress management in patients of epilepsy.

An attempt was made to evaluate the effect of Sahaja yoga meditation in stress management in patients of epilepsy. The study was carried out on 32 patients of epilepsy who were rendomly divided into 3 groups: group I subjects practised Sahaja yoga meditation for 6 months, group II subjects practised postural exercises mimicking Sahaja yoga and group III served as the epileptic control group. Galvanic skin resistance (GSR), blood lactate and urinary vinyl mandelic acid (U-VMA) were recorded at 0, 3 and 6 months. There were significant changes at 3 & 6 months as compared to 0 month values in GSR, blood lactate and U-VMA levels in group I subjects, but not in group II and group III subjects. The results indicate that reduction in stress following Sahaja yoga practice may be responsible for clinical improvement which had been earlier reported in patients who practised Sahaja yoga.

Adolescent↗
PubMed1978

Morbidity among persons employed in styrene production, polymerization and processing plants.

BASF has been producing styrene and polystyrene since 1931. An investigation of morbidity was undertaken for 84 workers employed in the styrene plant and exposed for 1--36 years and 93 workers employed in the polystyrene plant and exposed for 1--38 years. In all groups the concentration of styrene in the atmosphere was measured at various points of the workplace. All workers underwent a thorough physical examination and also extensive laboratory tests, including the determination of urinary mandelic acid. The absenteeism and accident rates were also taken into consideration in both plants. Blood samples were also taken and mandelic acid tests made on a small group of 16 persons employed in polyester processing plants not attached to the BASF.

Absenteeism↗
PubMed1977

[A simple method for the simultaneous analysis of urinary homovanillic acid, vanilmandelic acid and 3, 4-dihydroxy mandeli acid by mass fragmentography (author's transl)].

Gas chromatography-mass spectrometry makes possible the simultaneous measurement of homovanillic acid (HVA), vanilmandelic acid (VMA) and 3, 4-dihydroxy mandelic acid (DOMA) in 2ml urine samples. The equipment used was the Shimadzu LKB 9000 GC-MS (MID-PM). The TMSi derivatives of the compounds were analysed by the GC-MS system equipped with a 3ft. X 3mm column packed with 1.5% OV-1 and the temperature was programed from 130 degrees to 260 degrees C at 10 degrees C/min increments. The mass spectrum showed molecular ions at m/e 326, 414, and 472 which correspond to the TMSi derivatives of HVA, VMA AND DOMA respectively. The peaks at m/e 326 (HVA), 297 (VMA) and 355 (DOMA) were applied to avail themselves of simultaneous multiple ion analyses by GC-MS. As little as 1pg of the compounds injected into the column could be measured reproducibly. The sensitivity is of the order of pg or ng, and the linearity of the response is maintained up to at least 200ng. The procedure was simpler and less time consuming than previous methods. It consists of extraction of the free acid into ether followed by complete silylation of the phenolic, alcoholic and carboxylic acid group with bis (trimethylsilyl) acetamide. Recoveried of HVA, VMA, DOMA added to urine were 93.8%, 71.2% and 23.6% respectively. The specificity of this method surpasses and cannot be compared to any other existing quantitative methods.

Gas Chromatography-Mass Spectrometry↗
PubMed1997

Metabolism of phenylethanolamines and 2-oxo-2-phenylethylamines in the rat.

1. The metabolism of a series of phenylethanolamines and 2-oxo-2-phenylethylamines was examined in vivo in the rat. 2. The urinary excretion of the corresponding mandelic acids was, in general, considerably greater for 2-oxo-2-phenylethylamines than for the corresponding phenylethanolamines. Of the putative metabolites of the former class of compounds only phenylglyoxals yielded mandelic acids.

Animals↗
PubMed1991

Effect of food on the bioavailability of cyclandelate from commercial capsules.

The bioavailability of five capsules of cyclandelate that are commercially available in Japan was determined in ten healthy volunteers by measuring mandelic acid (a main metabolite of cyclandelate) excreted in the urine. Bioinequivalence among the five capsules was demonstrated. The relative cumulative excretion of mandelic acid of the most poorly bioavailable capsule was 38% of the most highly bioavailable capsule. The effect of food on the bioavailability of these two capsules was investigated by use of two different kinds of food, one containing fat and one containing high carbohydrates but very low fat. The bioavailability of the two capsules was increased when subjects consumed both types of food before drug administration, although there was a greater effect on bioavailability with food containing fat. This suggests that the absorption of cyclandelate was incomplete in fasting subjects, even from the capsule with the highest bioavailability. Bioinequivalence between the two capsules remained after postprandial drug administration.

Administration, Oral↗
PubMed2006

Resolution of racemic 2-aminocyclohexanol derivatives and their application as ligands in asymmetric catalysis.

A preparatively easy and efficient protocol for the resolution of racemic 2-aminocyclohexanol derivatives is described, delivering both enantiomers with >99% enantiomeric excess (ee) by sequential use of (R)- and (S)-mandelic acid. A simple aqueous workup procedure permits the isolation of the amino alcohols in analytically pure form and the almost quantitative recovery of mandelic acid. Debenzylation of enantiopure trans-2-(N-benzyl)amino-1-cyclohexanol by hydrogenation and subsequent derivatization give access to a broad variety of diversely substituted derivatives. Furthermore, the corresponding cis isomers are readily available. Applications of these optically active aminocyclohexanols in catalyzed asymmetric phenyl transfer reactions to benzaldehydes and transfer hydrogenations of aryl ketones lead to products with up to 96% ee.

Alcohols↗
PubMed2006

[Preparation and evaluation of molecularly imprinted stationary phase used for thin-layer chromatography].

Thin-layer chromatography (TLC) using molecularly imprinted polymers (MIPs) as chiral stationary phases (CSPs) was applied to the determination of enantiomers of mandelic acid and its derivatives. In preparation of MIPs, L-mandelic acid, L-2-chloromandelic acid and L-4-chloromandelic acid were employed as templates; acrylamide (AM) and ethylene glycol dimethacrylate (EGDMA) were used as functional monomer and cross-linker respectively. With the development system of acetonitrile-5% acetic acid, the racemates of templates were completely separated on the CSPs, the chiral separation factor a were 1.45, 1.62 and 1.56, respectively. Furthermore, the CSPs were able to resolve the racemates of template's derivatives. The relationship between the chemical structure of the analytes and chiral recognition of the CSPs was also investigated. This method provides a rapid, sensitive and convenient way of analyzing and determining the enantiomers of chiral compounds.

Acetonitriles↗
PubMed1995

Chromosomal aberrations and micronuclei in reinforced plastics workers exposed to styrene.

The aim of this study was to investigate the cytogenetic changes induced in humans exposed to styrene in a reinforced plastics plant. Blood and urine samples were collected from 18 styrene exposed workers and 18 age and sex matched control subjects from the administrative department of the same factory. Chromosome aberrations (CAs) and micronuclei (MN) (cytokinesis block method) were analyzed in blood lymphocytes. All of the subjects included in the study were male non-smokers. The duration of employment ranged from 10 to 22 years (14.3 +/- 4.4). In order to monitor exposure to styrene, urinary mandelic acid (MA) levels were measured using a standard colorimetric method. The level of thioethers in the urine was also determined colorimetrically. The mean level of mandelic acid was significantly higher in the exposed workers (328.44 +/- 266.21 mg/g creatinine) compared with that of the controls (50.09 +/- 16.84 mg/g creatinine) (p < 0.05). The level of urinary thioethers was found to be higher among the exposed workers. The number of cells with chromosomal aberrations was significantly higher in the workers (6.06 +/- 4.41) compared with the controls (3.44 +/- 2.28) (p < 0.05). There was no significant increase in the frequency of micronuclei in the exposed workers compared to controls. Our results support earlier findings on increased rates of chromosomal aberrations in reinforced plastics workers.

Adult↗
PubMed1975

[Excretion of some metabolites of catecholamine, serotonin and steroid hormones following neurosensory loading].

The values of 17-ketosteroids (according toe Drekter, Pearson, Bartezak, modification of Kukuskina and Gurjeva), 5-hydroxyindole acetic acid (according to Sjoerdsma, Weisbach and Udenfriend) and 3-methoxy, 4-hydroxyvanillyl mandelic acid (according to Pisano et al, modification of Georges) were followed up in the 24-hour urine of 37 female-weavers (subdivided into two groups--healthy and neurotics) and 15 males--operators of control boards from the Chemical Combinate--Vratza. The urine was tested also according to the method of Wisser and Stamm, 1970, in mgr/2 hours. The comparison of the metabolite values before and after work revealed an increase of 17-ketosteroids and vanillyl-mandelic acid after neuro-sensory loading, especially in neurotics. Lower values, at the end of the working shift, were found for the 5-hydroyindole acetic acid, with the exception of those of the neurotics, that were elevated--an increased utilization of serotonin is relied on.

17-Ketosteroids↗
PubMed1978

Some hygienic and clinical observations on styrene exposure.

Styrene exposure levels in the range of 100--300 ppm as an 8-h time-weighted average have been measured in small shops manufacturing glass fiber reinforced plastic products such as boats, steeping baths, etc. Exposure control through determinations of mandelic acid in the urine at the end of the workday has been found suitable and convenient. Over the years during the 1970s, there seems to have been amendments in the exposure situation in Sweden if judged from mandelic acid monitoring. More or less severe central nervous disturbances have been observed among the workers. Elevated levels of amino-transferases have been recorded but are of unclear long-term importance to liver function.

Adult↗
PubMed2001

Histidine-functionalized silica and its copper complex as stationary phases for capillary electrochromatography.

A histidine-functionalized silica was prepared by covalent bonding of the functional groups to silane-treated silica gel. Conversion of functional groups was confirmed by infrared (IR) spectra, elemental analysis, and potentiometry. The functionality of the silica gel is 0.293 mmol g(-1). The coordination behavior of the histidine-functionalized silica was investigated by metal capacity and electron paramagnetic resonance (EPR). EPR measurements at different copper loadings were made. The results showed that the copper histidine complex might be distorted tetragonal. Both histidine-functionalized silica and its copper complex were employed as stationary phases for packed capillary electrochromatography (CEC). Electrical current was found helpful for evaluating the properties of frit construction and the stationary phase packing. Test samples include neutral compounds, inorganic anions and organic anions. Factors influencing the separation behavior have been studied. With copper-histidine functionalized silica under the condition of citrate buffer (10 mM, pH 4.0) and applied voltage of -20 kV, the separation of benzoic acid, D- and L-mandelic acid, phthalic acid and salicylic acid could be achieved within 12 min. The column efficiency for these acids was more than 1.2 x 10(5) plates m(-1), except salicylic acid.

Benzoic Acid↗
PubMed1975

Utilization of model compounds to evaluate effects of slight chemical modifications on their distribution. Pharmacokinetic parameters in rats and mechanisms inferred for their transmembrane transport.

The pharmacokinetics of each of the model compounds benzoylformic acid (I), p-methylbenzoylformic acid (II), p-ethylbenzoylformic acid (III), D-(-)-mandelic acid (IV), D-(-)-p-methylmandelic acid (V), D-(-)-p-ethylmandelic acid (VI), and D-(-)-p-isopropylmandelic acid (VII) were studied in rats to determine the influence of slight chemical modifications of the compounds on their distribution pharmacokinetic parameters in rats. The effects of the specific chemical modifications considered were those of the less than CHOH group of IV against the less than C=0 group of I, the para-alkylation of I and IV, and the branched alkyl group (isopropyl) against the straight chain alkyl groups of the homologs of IV. While the disappearance of I from the blood was describable by the three-compartment open model, that of IV was describable by the two-compartment open model. The apparent volume of distribution of the central compartment (V1) for IV was smaller than that for I, but the volume of the peripheral compartment (V2) for IV was greater than that (V2 + V3) for I. The disappearance of V, VI, and VII from the blood was also describable by the two-compartment open model, but the apparent V1 and V2 for these compounds were lower than those for the parent compound, IV. However, the disappearance of II and II from the blood was describable by a one-compartment open model. Evaluation of the appropriate distribution pharmacokinetic parameters suggested that the peripheral compartment for the anions of these compounds consisted of moderately perfused tissues and that the transmembrane transport of these organic anions between the central and peripheral compartments occurs by diffusion mainly through the aqueous membrane pores, which are lined with polar portions of membrane proteins and/or phospholipids. The possible increased hydrophobic bonding between the alkyl groups of these compounds and the hydrophobic groups of the proteins and/or phospholipids of the membrane pores is implicated to decrease the distribution of the para-alkylated homologs into the peripheral compartments and, consequently, diminish the volumes of their peripheral compartments. The heteroporosity of the membranes of the tissues of the central compartment is proposed as the reason for the diminished volume of the central compartment for V and VI as compared to that of IV or VII.

Animals↗
PubMed1987

Quantitation of urinary metabolites of toluene, xylene, styrene, ethylbenzene, benzene and phenol by automated high performance liquid chromatography.

An automated high performance liquid chromatographic method (HPLC) for the direct determination of urinary concentrations of hippuric acid (HA), and o-, m- and p-methyl hippuric acids (MHAs), metabolites of toluene and o-, m-, and p-xylenes, and of urinary phenyl glyoxylic acid (PGA) and mandelic acid (MA), metabolites of styrene or ethylbenzene, is described. Methanol was added to urine, the mixture was centrifuged and the supernatant was injected into HPLC. A stainless-steel column packed with octadecyl silanized silicate was used and the mobile phase was a mixed solution of 5 mM potassium phosphate monobasic/acetonitrile (90/10). The method is simple and specific. Urine can be analyzed without solvent extraction. Analysis can be performed satisfactorily within 45 min for samples containing HA, MHAs, PGA and MA, and within 15 min for those containing HA, PGA and MA. Another automated HPLC method for the determination of urinary concentrations of phenylsulfate (PhS) and phenylglucuronide (PhG), metabolites of benzene and phenol, is also described. Urine was centrifuged and the supernatant was injected into HPLC. A column packed with octadecyl silicate and a mobile phase of 50 mM of potassium phosphate monobasic/acetonitrile (85/15) were used. The whole analyses and quantitative determination can be performed within 15 min for samples containing PhS and PhG in the worker's urine with a simple mobile phase. The accuracy and precision in the present methods by the use of automated HPLC were satisfactory.

Autoanalysis↗