Phenylacetic acid production in dominant and non-dominant vervet monkeys

Free and conjugated plasma phenylacetic acid concentrations were significantly higher in dominant male vervet monkeys than in non-dominant males living in stable social groups. These findings may be connected with an earlier observation that plasma from aggressive human psychopaths contains higher concentrations of phenylacetic acid than non-aggressive controls; whether they reflect an increased production of phenylethylamine is still unknown.

Homovanillic acid in caudate and pre-frontal cortex following neuroleptics

Homovanillic acid (HVA) was measured in rat caudate and pre-frontal cortex 3 h following a single dose of a variety of neuroleptics. Thioridazine, haloperidol, fluphenazine, and metoclopramide increased HVA levels in caudate more than in pre-frontal cortex; whereas sulpiride and clozapine produced greater increases in HVA in pre-frontal cortex. These results are consistent with the proposal that rat pre-frontal cortex is relatively deficient in dopamine autoreceptors.

Characteristics of dopamine uptake and 3,4-dihydroxyphenylacetic acid (DOPAC) formation in the dopaminergic terminals of the neurointermediate lobe of the pituitary gland

The kinetics of dopamine (DA) uptake were studied in synaptosomal preparations of the neurointermediate lobe (NIL) of the pituitary gland, a region containing the terminals of the tuberoinfundibular dopaminergic neurons. Lineweaver-Burk plots of the initial velocity of DA uptake versus the concentration of DA yielded a single straight line in the NIL. The Km values in the NIL of the rat and the steer were 2.2+/-0.5 x 10(-6) M and 2.0+/-0.1 x 10(-6) M, respectively. The uptake was predominantly into dopaminergic terminals since preincubation with desipramine did not affect the Vmax or Km of DA uptake. Observed uptake was predominantly due to transport across the neuronal membrane and not into storage granules, since reserpine caused only a small decrease in uptake. The concentration of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the NIL was 3.6 ng/mg protein. The ratio of DA to DOPAC in the NIL (3.73) was similar to that obtained in the medial basal hypothalamus, another region innervated by the tuberoinfundibular dopaminergic neurons. The kinetics of DA uptake in the nerve terminals of the NIL are similar to those observed in the DA terminals in the median eminence. The affinity of uptake in the terminal fields of the tuberoinfundibular system is considerably lower than in terminals of the mesolimbic and nigrostriatal dopaminergic terminals.

Production of phenylacetic and hydroxyphenylacetic acids by clostridium botulinum type G

Phenylacetic and hydroxyphenylacetic acids were present as major acids in spent growth medium from Clostridium botulinum type G. These aromatic acids were identified by gas-liquid chromatography and mass spectrometry.

The metabolism of phenylacetic acid by Aspergillus fumigatus ATCC 28282: identification of 2,6-dihydroxyphenylacetic acid

Aspergillus fumigatus ATCC 28282 converted phenylacetic acid into a new dihydroxylated compound (2,6-dihydroxyphenylacetic acid) which was identified as 2,6-dimethoxyphenylacetic acid methyl ester. Two other new metabolites have been isolated also and identified as orthohydroxyphenylacetic acid and meta-hydroxyphenylacetic acid.

Microbial metabolism of phenolic amines: degradation of dl-synephrine by an unidentified arthrobacter

Microorganisms capable of degrading dl-synephrine were isolated from soil of Citrus gardens by enrichment culture, with dl-synephrine as the sole source of carbon and nitrogen. An organism which appears to be an arthrobacter, but which cannot be identified with any of the presently recognized species was predominant in these isolates. It was found to metabolize synephrine by a pathway involving p-hydroxyphenylacetaldehyde, p-hydroxyphenylacetic acid, and 3,4-dihydroxyphenylacetic acid as intermediates. Some of the enzymes of this pathway were demonstrated in cell-free extracts. An aromatic oxygenase, which could also be readily obtained in a cell-free system, was found to degrade 3,4-dihydroxyphenylacetic acid by meta cleavage.

Absorption, metabolism and distribution of (14C)-O-methyldopa and (14C)-L-dopa after oral administration to rats

1 The absorption, tissue distribution, and metabolism of [(14)C]-O-methyldopa were compared with those of [(14)C]-L-DOPA after oral administration to rats.2 Total radioactivity in the plasma and brain of rats treated with [(14)C]-O-methyldopa was significantly higher (2 fold and 30-50 fold, respectively) than that of rats treated with [(14)C]-L-DOPA.3 Total radioactivity in the gut washings and intestinal tissue 2 h after oral administration was significantly higher in rats treated with [(14)C]-L-DOPA than in rats treated with [(14)C]-O-methyldopa. The reverse was observed in the stomach tissues.4 Peripheral metabolism of [(14)C]-O-methyldopa was much lower than that of [(14)C]-L-DOPA; the major metabolite of [(14)C]-O-methyldopa in the plasma is L-DOPA, whereas L-DOPA is mainly metabolized to phenylcarboxylic acids.

The kinetics of intramolecular distribution of 15N in uric acid after administration of (15N) glycine. A reappraisal of the significance of preferential labeling of N-(3+9) of uric acid in primary gout

THE CONCEPT OF AN ABNORMALITY OF GLUTAMINE METABOLISM IN PRIMARY GOUT WAS FIRST PROPOSED ON THE BASIS OF ISOTOPE DATA: when [(15)N]glycine was administered to gouty subjects, there was disproportionately great enrichment of N-(3 + 9) of uric acid, which derive from the amide-N of glutamine. An unduly high concentration of (15)N in glutamine was postulated, and attributed to a hypothetical defect in catabolism of glutamine. Excess glutamine was proposed as the driving force of uric acid overproduction. WE HAVE REEXAMINED THIS PROPOSITION IN FOUR GOUTY SUBJECTS: one mild overproducer of uric acid with "idiopathic gout," one marked overproducer with high-grade but "partial" hypoxanthine-guanine phosphoribosyl-transferase deficiency, and two extraordinary overproducers with superactive phosphoribosylpyrophosphate synthetases. In the last three, the driving force of excessive purine biosynthesis is a known surplus of alpha-5-phosphoribosyl-1-pyrophosphate. Disproportionately high labeling of N-(3 + 9) was present in all four gouty subjects, most marked in the most flamboyant overproducers. The precursor glucine pool was sampled by periodic administration of benzoic acid and isolation of urinary hippuric acid. Similarly, the precursor glutamine pool was sampled by periodic administration of phenylacetic acid and isolation of the amide-N of urinary phenylacetylglutamine. The time course of (15)N enrichment of hippurate differed from that of the amide-N of glutamine. Whereas initial enrichment values of hippurate were very high, those of glutamine-amide-N were low, increasing to a maximum at about 3 h, and then declining less rapidly than those of hippurate. However, enrichment values of hippurate and of phenacetyl glutamine were normal in all of the gouty subjects studied. Thus, preferential enrichment of N-(3 + 9) in gouty overproducers given [(15)N]glycine does not necessarily reflect a specific abnormality of glutamine metabolism, but rather appears to be a kinetic phenomenon associated with accelerated purine biosynthesis per se.In addition, greater enrichment of N-9 than of N-3 on days 1 and 2 provided suggestive evidence for a second pathway for synthesis of the initial precursor of purine biosynthesis, phosphoribosylamine, perhaps utilizing ammonia rather than the amide-N of glutamine as nitrogen donor. In this limited study, the activity of this potential second pathway did not appear to be selectively increased in gout.

Differentiation between Pseudomonas testosteroni and P. acidovorans by gas chromatography

Pseudomonas acidovorans can be distinguished from P. testosteroni by gas chromatography on the basis of acids detected after 20 h growth on heart infusion agar plates. The data obtained support the findings of other workers that P. acidovorans and P. testosteroni are two different species and indicate that gas chromatography may be used effectively to distinguish other members of the genus.

Biosynthesis of cerebral phenolic amines. I. In vivo formation of p-tyramine, octopamine, and synephrine

Following the intraventricular injection of 14C-labelled dopamine, p-tyrosine, and p-tyramine to rats pretreated with a monoamine oxidase inhibitor, the labelled phenolic amines p-tyramine, octopamine, and synephrine were isolated and identified as their DNS derivatives. Differences in the amounts of the phenolicamines formed suggest that mechanisms other than just decarboxylation are involved.

Uptake and metabolism of beta-phenethylamine and tyramine in mouse brain and heart slices

Tritium labelled β-phenethylamine and tyramine were incubated with slices of mouse brain and heart. Cocaine (3 × 10−5M) caused a reduction of 30% in the uptake of tyramine as well as in the formation of its metabolite 4-hydroxyphenylacetic acid. Cocaine had no effect on either the uptake of phenethylamine nor its deamination to phenylacetic acid.

Metabolism of coumarin and 4-methylcoumarin by rat-liver microsomes

The metabolism of coumarin and 4-methylcoumarin by rat-liver microsomes has been studied. The major metabolites of coumarin in vitro, viz. 3- and 7-hydroxycoumarin, o-hydroxyphenyllactic acid, and o-hydroxyphenylacetic acid, were identified by thin-layer chromatography, and ultraviolet and fluorescence spectroscopy. Metabolites derived from 4-methylcoumarin in vitro have shown similar chromatographic and spectral characteristics as those of coumarin, suggesting that they are the methyl analogues of corresponding coumarin metabolites.

Identification of products produced by the anaerobic degradation of rutin and related flavonoids by Butyrivibrio sp. C3

Butyrivibrio sp. C3 degrades rutin anaerobically to yield phloroglucinol, carbon dioxide, 3,4-dihydroxy-benzaldehyde, and 3,4-dihydroxyphenylacetic acid. The sugars are first released by intracellular glycosidases and then the heterocyclic ring of the aglycone undergoes hydrolytic cleavage. The glycosides of quercetin added to the medium are readily metabolized, but the aglycone is not.

Release to the cerebral ventricles of substances with possible transmitter function in the caudate nucleus

1. One caudate nucleus of the anaesthetized cat was superfused by perfusing the anterior horn of one lateral cerebral ventricle. The perfusates were examined for their content in acetylcholine (ACh), dopamine, homovanillic acid (HVA) and 5-hydroxytryptamine (5-HT), at rest and after a variety of stimuli.2. When prostigmine was added to the perfusion fluid, ACh appeared in the effluent; its concentration tended to rise in the course of an experiment. Various afferent stimuli, all of which caused evoked responses recorded from the contra-lateral caudate nucleus, increased the ACh content of the effluent. Effective stimuli were noise and electrical stimulation of afferent nerves or of certain regions of the brain including the ipsi-lateral substantia nigra.3. The dopamine content of the effluent was extremely low (of the order of 50 pg/min) at rest, but, on occasion, rose sharply when the substantia nigra was stimulated electrically with trains of pulses repeated once every 3 sec. The results were inconsistent.4. Since dopamine in tissue is rapidly transformed enzymically into HVA, the appearance of this acid in the perfusate was examined.5. At rest, HVA was found to appear in the effluent at a rate of 2-8 ng/min. Its concentration was rapidly depressed by increasing the depth of anaesthesia.6. Stimulation of the substantia nigra for periods of 3 or 4 min caused an increment in the HVA content of the effluent lasting 1 hr or more. It was frequently seen when two points of the substantia nigra were stimulated simultaneously, less regularly with only one stimulating electrode, and rarely if this was placed in the most caudal part of the substantia nigra.7. These results strongly support the view that there is a dopaminergic nigro-striatal pathway. The following assumption would explain the erratic appearance of dopamine and the long duration of increments in HVA: many of the axons originating in the substantia nigra end either in the putamen or in parts of the caudate nucleus which are far away from the ventricular surface; any dopamine released from these axons will not reach the ventricular surface at all, and HVA will, at best, reach it very slowly.8. Small amounts of 5-HT appeared in the ventricular perfusate, and the quantity rose after the administration of monoamine oxidase inhibitors. It was not increased by the type of stimuli used in this work to elicit the release of ACh or HVA.

The effect of tropolone on the formation of 3,4-dihydroxyphenylacetic acid and 4-hydroxy-3-methoxyphenylacetic acid in the brain of the mouse

1. The development of a very sensitive and specific fluorimetric assay for 3,4-dihydroxyphenylacetic acid has made it possible to measure how inhibitors of the enzyme catechol-O-methyl transferase affect the relative concentrations of this acid and its O-methylated derivative 4-hydroxy-3-methoxyphenylacetic acid (homovanillic acid) in the brains of mice treated with L-3,4-dihydroxyphenylalanine or probenecid.2. It was found that tropolone and tropolone-4-acetamide reduce the concentration of homovanillic acid in the brains of the treated mice to an extent dependent on the dose.3. The concentration of 3,4-dihydroxyphenylacetic acid in the brain was increased by the administration of tropolone or tropolone-4-acetamide but the dose and response were not simply related to one another.4. The results suggest that, in vivo, the formation of 3,4-dihydroxyphenylacetic acid is not always a simple alternative to the formation of homovanillic acid when the enzyme catechol-O-methyl transferase is inhibited.