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PubMed1992

High-performance liquid chromatographic determination of catecholamines and their precursor and metabolites in human urine and plasma by postcolumn derivatization involving chemical oxidation followed by fluorescence reaction.

A high-performance liquid chromatographic method for the determination of catecholamines and their precursor and metabolites [amino compounds (norepinephrine, epinephrine, dopamine, normetanephrine, metanephrine, 3-methoxytyramine, and L-DOPA), acidic compounds (3,4-dihydroxyphenylacetic acid, vanillyl-mandelic acid, and homovanillic acid), and alcoholic compound [4-hydroxy-3-methoxyphenyl)ethylene glycol)] in human urine and plasma. Urine and plasma samples deproteinized with perchloric acid in the presence of isoproterenol and 3,4-dihydroxyphenylpropanoic acid (internal standards) are fractionated by solid-phase extraction on a strong cation-exchange resin cartridge (Toyopak IC-SP S) into two fractions (amine fraction and acid-alcohol fraction). The compounds in each fraction are separated by an ion-pair reversed-phase chromatography on a TSK gel ODS-80TM with isocratic elution and on-line derivatized by periodate oxidation followed by a fluorescence reaction using meso-1,2-diphenylethylenediamine. The detection limits (S/N = 5) vary from 0.5 to 95 pmol/ml, depending on the compounds.

Adult↗
PubMed1995

Highly enantioselective capillary electrophoretic separations with dilute solutions of the macrocyclic antibiotic ristocetin A.

Ristocetin A is one of a series of structurally related amphoteric, glycopeptide, macrocyclic antibiotics. These compounds have several features that make them attractive as chiral selectors. These include spatially oriented functional groups that are known to provide the types of interactions that are conducive to enantio-recognition, a somewhat rigid "pocket" that can provide a site for hydrophobic interactions and polar, flexible arms (i.e., pendent sugar moieties) that can rotate to hydrogen bond and otherwise interact with a variety of chiral analytes. In addition, these compounds are sufficiently soluble in water, aqueous buffers and aqueous-organic solvents that are commonly used in capillary electrophoresis (CE). The use and optimization of ristocetin A as a chiral selector in CE is discussed. Over 120 racemates are resolved including a variety of N-blocked amino acids, non-steroidal anti-inflammatory compounds and a large number of biologically important compounds containing carboxylic acid groups (e.g., mandelic acid derivatives, lactic acid derivatives, folinic acid, tropic acid).

Carbohydrate Sequence↗
PubMed1995

Capillary zone electrophoresis of organic acids in serum of critically ill children.

Capillary zone electrophoresis with indirect UV detection was found to be suitable for the determination of organic acids in serum. Serum can be analysed directly without any deproteination in a capillary coated with linear polyacrylamide. With 10 mM epsilon-aminocaproic acid-10 mM mandelic acid (pH 3.8) as the operational electrolyte, anions such as pyruvate, phosphate, citrate, malate, acetoacetate and lactate can be determined in 12 min. In quantitative analysis, the calibration line for lactate is linear over the range 0-10 mM. The detection limit for citrate was 8 microM. The effect of the chloride concentration on the migration times of minor peaks is discussed. The potential of the method was demonstrated by analysing sera from several critically ill children.

Acids↗
PubMed2001

Effect of chronic protein restriction on motor co-ordination and brain neurotransmitters in albino rats.

In this study we evaluated the motor co-ordination in Wistar strain albino rats that were maintained on a protein-restricted diet for a period of 1 year immediately after the weaning period, by substituting 75% of the normal diet with a carbohydrate-rich diet deficient in protein, for a period of 1 year immediately after the weaning period. This type of chronic protein restriction caused disturbances in motor co-ordination. It also caused a significant reduction in the basal levels of dopamine, norepinephrine, epinephrine and serotonin along with their metabolites homovanillic acid (HVA), vanillyl mandelic acid (VMA) and 5-hydroxy indoleacetic acid (5HIAA) and precursor L-dopa in the corpus striatum and cerebellum. Changes in these neurotransmitters could have caused altered co-ordination in the protein-restricted animals.

Animals↗
PubMed1996

CSF substance P somatostatin and monoaminergic transmitter metabolites in patients with narcolepsy.

We have measured the concentrations of substance P, somatostatin, homovanillic acid (HVA), vanillyl mandelic acid (VMA) and 5-hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid (CSF) of six patients suffering from narcolepsy and 12 age- and gender-matched controls using high pressure liquid chromatography (HPLC) and radioimmunoassay (RIA). Substance P and somatostatin were significantly decreased in our patients compared to controls (36.9 +/- 9.1 fmol/ml versus 52.5 +/- 9.9 fmol/ml, P < 0.05 and 30.3 +/- 7.8 fmol/ml versus 43.9 +/- 9.8 fmol/ml, P < 0.05, respectively). 5-HIAA (P < 0.05) and VMA (P < 0.05) were also significantly decreased. HVA was significantly increased (P < 0.01). The CSF concentrations of substance P and somatostatin correlated with the clinical parameters duration of disease (r = -0.68, P < 0.05 and r = -0.72, P < 0.05, respectively) and severity of cataplectic symptoms (r = -0.71, P < 0.05 and r = -0.78, P < 0.01). In addition, substance P correlated with the intensity of sleepiness and the frequency of day-sleep attacks (r = -0.69, P < 0.05 and r = -0.68, P < 0.05, respectively). Substance P affects the amount of dopamine release in the nigra-striatal region, and decreased amounts could contribute to the pathogenesis of narcolepsy. Reduced levels of substance P, which affects serotonin release, may be responsible for diminished release of serotonin which in turn could affect sleep cycles. Because somatostatin affects motor behavior through dopaminergic mechanisms and since the levels of somatostatin correlate with the intensity of cataplectic symptoms, we speculate that an interaction between somatostatin and dopaminergic neurons plays a role in the pathogenesis of narcolepsy.

Adult↗
PubMed2004

Spirocyclic zwitterionic lambda5Si-silicates with two bidentate ligands derived from alpha-amino acids or alpha-hydroxycarboxylic acids: synthesis, structure, and stereodynamics.

A series of zwitterionic lambda(5)Si-silicates with a (2,2,6,6-tetramethylpiperidinio)methyl group and two identical bidentate ligands derived from glycine, (S)-alanine, (S)-phenylalanine, glycolic acid, (S)-lactic acid, (S)-3-phenyllactic acid, or (S)-mandelic acid were synthesized and structurally characterized (solution and solid-state NMR spectroscopy; single-crystal X-ray diffraction). The chiral lambda(5)Si-silicates with ligands derived from optically active alpha-amino acids or alpha-hydroxycarboxylic acids were isolated as enantiomerically and diastereomerically pure compounds that undergo a (Lambda)/(Delta)-epimerization in solution.

Amino Acids↗
PubMed1989

Structure of a novel epidithiodioxopiperazine, emethallicin A, a potent inhibitor of histamine release from Emericella heterothallica.

A new epidithiodioxopiperazine derivative, emethallicin A (1), was isolated along with ergosterol from the mycelial extract of the heterothallic fungus, Emericella heterothallica (mating type A). The structure of emethallicin A (1) was established on the basis of chemical and spectroscopic investigations and finally by chemical transformation to apoaranotin (11). Emethallicin A (1) has the same basic skeleton as apoaranotin (11), with C6-C2 carboxylic acid (mandelic and phenylacetic acids) diester moieties, and showed a potent inhibitory activity on histamine release from mast cells.

Ascomycota↗
PubMedDate not supplied

[Hormonal and metabolic reactions in the human body during prolonged starvation].

This paper discusses hormonal and metabolic reactions of healthy volunteers exposed to 14-day starvation. This exposure led to many-fold increase of plasma and urinary epinephrine (E); drastic increase of ACTH and beta-endorphin (BE), morning and integrated concentrations of cortisol and STH, aldosterone, T3, glucagon, cAMP, cGMP, cAMP-cGMP, acetyl choline (AC), free fatty acids (FFA), lactate, metanephrine (MN) excretion; decrease of plasma norepinephrine (NE) and unchanged NE excretion; decrease of plasma concentrations of TTH, T4, T3, prolactin (PL), insulin (morning and integrated concentrations), C-peptide, FSH, LH, testosterone, histamine, prostaglandins (PG) A + E, PG F2, glucose and pH, as well as decrease of excretion of homovanillic acid (HVA), vanillyl mandelic acid (VMA), normetanephrine (NMN) and MN-E, NMN:NE. On recovery day 14 concentrations of E, NE, BE, STH, AC, cAMP, cGMP, FFA as well as E and dopamine excretion remained elevated while concentrations of T3, PL, FT, LT, testosterone PG A + E, PG 2 and excretion of MN, HVA, VMA, MN:E remained decreased, while other parameters returned to the normal.

Adult↗
PubMedDate not supplied

Effect of Datura (seed) on rat brain and urinary metabolites.

The effect of Datura alba (seed) extract on the brain and urinary metabolites of rats was studied. Treatment with Datura brought about a decrease in the activity of brain lipid peroxidase and catalase while an increase in the activity of fructose diphosphate aldolase and glucose 6-phosphate dehydrogenase was observed. An increase in the DNA and RNA contents of brain was noted after the treatment with Datura. The study also showed a marked decrease in the excretion of 5-hydroxyindole acetic acid and vanillyl mandelic acid in the urine of rats given Datura extract.

Animals↗
PubMed1984

Effect of a mild dose of X-irradiation on rats under stress.

This investigation was apt at studying the effect of a mild dose of X-rays on the normal and shock administered rats. Administration of stress brought about a marked depression in the contents of DNA, RNA and protein in the brain. On the other hand, total body exposure to X-rays was found to increase the levels of DNA, RNA and protein in the brain. Thus, the use of a mild dose of X-rays in stressed animals seems to be stimulatory to the diminished levels of DNA, RNA and protein in the brain. There were rising levels of 5-hydroxy indol acetic acid and Vinyl mandelic acid in the urine of stress administered rats and the enhanced levels of these urinary metabolites appeared to be refractory to the application of X-rays.

Animals↗
PubMedDate not supplied

[Catecholamines, their precursors and metabolites in human fatigue after exertion].

Alterations in metabolism of catecholamines were studied in sportsmen after development of acute fatigue as a result of the test physical loading. Three types of the alterations were characterized on the basis of differences in excretion with urine of free and sulphate-bound adrenaline, noradrenaline, of their precursors DOPA and dopamine as well as acid metabolites (vanillyl mandelic acid). The first type of the alterations in catecholamines metabolism comprized the cases, when excretion of catecholamines, their precursors and metabolites did not increase; this appears to relate to the partial exhaustion of hormones and peripheric mediators of sympathoadrenal system. The second type was characterized by decreased excretion of the substances studied, by development of the "perversed" reactions due to modifications in the regulatory system, which led to the inhibition of the system instead of its stimulation. The third type was manifested as the hyperfunction of the system. The increased synthesis of catecholamines during the hyperfunction suggests that this process serves as a compensatory reaction to their preceding elevated secretion; the phenomenon appears to depend on the increased secretion of the newly formed catecholamines. Excretion of catecholamines and their precursors was decreased for a long time after development of chronic fatigue in the resting state and the increase in excretion of the substances studied was not observed after physical loading.

Adolescent↗
PubMed1985

No acute behavioural effects of exposure to styrene: a safe level of exposure?

To determine whether exposure to low levels of styrene (below 110 mg/m3) causes acute behavioural effects and symptoms that may be related to concentrations of styrene in air or urinary mandelic acid or both, 12 men occupationally exposed to styrene were studied and compared with a reference group of 10 unexposed men. Simple reaction time was measured before and after work and information about symptoms was obtained by questionnaire. Active and passive sampling of airborne styrene was carried out and urinary mandelic acid concentrations were measured. Although the size of the study groups is small, the results indicate that exposure to styrene below 110 mg/m3 does not cause any acute adverse effects on the central nervous system.

Adult↗
PubMed1981

Simultaneous determination of cyclandelate and its metabolite in human plasma by capillary column gas-liquid chromatography.

A method was developed for the simultaneous determination of cyclandelate and mandelic acid concentrations in plasma, involving extraction from plasma followed by trimethylsilylation and chromatography of the derivatives on a glass capillary column with hydrogen flame-ionization detection. Calibration graphs were linear down to at least 20 microgram/ml for each substance. The precision was excellent with a pooled relative standard deviation of 6.3% and 6.4% for cyclandelate and mandelic acid serum samples, respectively. Concentrations below 500 ng/ml of each substance could be detected in human plasma. The method was developed for use in bioavailability and metabolism studies.

Animals↗
PubMedDate not supplied

Enantioselective synthesis of phenylacetamides in the presence of high organic cosolvent concentrations catalyzed by stabilized penicillin G acylase. Effect of the acyl donor.

Immobilization of penicillin G acylase on glyoxyl agarose and its further hydrophilization by physicochemical modification with ionic polymers has made it possible to perform the direct condensation between (+/-)-2-hydroxy-2-phenylethylamine [(+/-)-1] and different acyl donors in the presence of high concentrations of organic cosolvent (up to 90%) in the reaction medium. Using 50 mM phenyl acetic acid and these drastic reaction conditions, too harsh for any other PGA preparation, we have achieved an almost quantitative transformation (more than 99%) of 10 mM (+/-)-1 into the corresponding amide. Remarkably, the enantioselectivity of the enzyme immobilized on the amine was strongly dependent on the acyl donor employed. Thus, using phenylacetic acid (2), the enantioselectivity was almost negligible (1.3 favoring the S isomer), whereas using S-mandelic acid [(S)-4], the E factor reached a value of 21 (also favoring the S isomer). By using R-mandelic acid [(R)-4], we observed a different enantioselectivity (E was 3.6 favoring the R). At 4 degrees C, the E value reached a value higher than 100 when (S)-4 was used as the acyl donor. The reaction performed under these conditions allowed us to produce (2S,2'S)-N-2'-hydroxy-2'-phenyl)-2-hydroxyphenylacetamide [(2S,2'S)-7] with a diasteromeric excess higher than 98%.

Acetamides↗
PubMed2002

Audiometric findings in workers exposed to low levels of styrene and noise.

Audiometry and exposure measurements were conducted on workers from fiberglass and metal products manufacturing plants and a mail distribution terminal (N = 313). Workers exposed to noise and styrene had significantly worse pure-tone thresholds at 2, 3, 4, and 6 kHz when compared with noise-exposed or nonexposed workers. Age, noise exposure, and urinary mandelic acid (a biologic marker for styrene) were the variables that met the significance level criterion in the multiple logistic regression. The odds ratios for hearing loss were 1.19 for each increment of 1 year of age (95% confidence interval [CI], 1.11-1.28), 1.18 for every decibel >85 dB(A) of noise exposure (95% CI, 1.01-1.34), and 2.44 for each millimole of mandelic acid per gram of creatinine in urine (95% CI, 1.01-5.89). Our findings suggest that exposure to styrene even below recommended values had a toxic effect on the auditory system.

Adult↗
PubMed2006

Enhancing the catalytic potential of nitrilase from Pseudomonas putida for stereoselective nitrile hydrolysis.

(R)-mandelic acid was produced from racemic mandelonitrile using free and immobilized cells of Pseudomonas putida MTCC 5110 harbouring a stereoselective nitrilase. In addition to the optimization of culture conditions and medium components, an inducer feeding approach is suggested to achieve enhanced enzyme production and therefore higher degree of conversion of mandelonitrile. The relationship between cell growth periodicity and enzyme accumulation was also studied, and the addition of the inducer was delayed by 6 h to achieve maximum nitrilase activity. The nitrilase expression was also authenticated by the sodium dodecyl phosphate-polyacrylamide gel electrophoresis analysis. P. putida MTCC 5110 cells were further immobilized in calcium alginate, and the immobilized biocatalyst preparation was used for the enantioselective hydrolysis of mandelonitrile. The immobilized system was characterized based on the Thiele modulus (phi). Efficient biocatalyst recycling was achieved as a result of immobilization with immobilized cells exhibiting 88% conversion even after 20 batch recycles. Finally, a fed batch reaction was set up on a preparative scale to produce 1.95 g of (R)-(-)-mandelic acid with an enantiomeric excess of 98.8%.

Acetonitriles↗
PubMed1981

Acute behavioral effects of styrene exposure: a further analysis.

Studies were carried out on two groups to styrene-based resin. Early morning urinary mandelic acid concentrations after two days without exposure correlated with reaction time measured on arrival at work. Men were found to differ considerably in their rate of clearance of mandelic acid-those with slow reaction times. After some months at reduced exposure, a small group of men with previously high mandelic acid concentrations has speeded up on the reaction time task.

Adult↗