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Results for “Homovanillic Acid”

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At least 109 records · Page 6Linked to original sources
PubMed1992

[Bacterial contamination of infant urine samples obtained from filter papers used in neuroblastoma-screening tests. (6) Protective effects of preaddition of chlorhexidine digluconate in filter papers or containers for urine on bacterial break-down of creatinine, vanillylmandelic acid and homovanillic acid].

The effects of chlorhexidine digluconate preadded to urine samples for a neuroblastoma-screening test in preventing the break-down of creatinine (Cre), vanillylmandelic acid (VMA), and homovanillic acid (HVA) by creatinine-cleaving bacteria and the influence of the added disinfectant on the HPLC determination of urinary Cre, VMA, vanillillactic acid (VLA) and HVA. Laboratory or field experiments showed that preadded disinfectant (0.02% volume) nearly completely inhibited the growth of the bacteria and satisfactorily protected urinary Cre, VMA, and HVA from bacterial decomposition. Chlorhexidine digluconate was comparable to benzalkonium chloride in its inhibitory effects on the growth and activities of creatinine-cleaving bacteria. Unlike benzalkonium chloride, chlorhexidine digluconate added to urine samples gave no troubles in subsequent analytical processes. Addition of the disinfectant (0.02% volume) to standard Cre, VMA, VLA, and HVA solution did not affect retention times and sensitivities in HPLC analyses. To estimate influences of the added disinfectant on the serial HPLC determinations of VMA, VLA, and HVA on a large number of urine samples (40, 80, 120, 160, 200, or 5, 500), HPLC analyses were performed on standard VMA, VLA, and HVA solution with repeated injection of the disinfectant in great amounts into a column. The results showed no appreciable changes in the retention times and sensitivities of VMA, VLA, and HVA, and almost complete elution of the disinfectant retained on the column were possible with water-methanol (1:1, 2:8) or methanol washing.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Infections↗
PubMed1978

5-Hydroxyindoleacetic acid and homovanillic acid in human cerebrospinal fluid below partial and complete spinal subarachnoid block.

Concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were investigated by lumbar cerebrospinal fluid (CSF) of 21 patients with partial and total spinal subarachnoid block. HVA levels in CSF below a complete block were significantly lower and 5-HIAA levels were signigicantly higher than controls. Below a partial block, HVA levels were normal; 5-HIAA levels were higher than in patients with complete block. Possible explanations for these findings are discussed.

Adolescent↗
PubMed1992

Effects of chronic treatment with ethanol and withdrawal of ethanol on levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the striatum of the rat. Influence of benzodiazepines, barbiturate and somatostatin.

Administration of ethanol for 40 days, at 10.53 +/- 0.25 g/kg/day did not modify levels of dopamine (DA) or 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum of the rat; however, the concentration of homovanillic acid (HVA) and the ratio of turnover were increased in a statistically significant way (P < 0.05). Twenty-four hours after withdrawal of ethanol appears as the central time of the ethanol-induced abstinence syndrome, showing noticeable decreases in levels of DA (P < 0.05) and DOPAC (P < 0.05), with respect to control and chronically ethanol-treated groups. The concentrations of DA, DOPAC and HVA and ratio of turnover values showed a tendency to return to control normal levels of 48 hr after ethanol withdrawal, although the differences still showed statistical significance (P < 0.05). The intraperitoneal injection of saline, the water soluble benzodiazepine midazolam, the barbiturate thiopental and somatostatin, in single doses, resulted in a noticeable increase in levels of DA, DOPAC and HVA and ratio of turnover values. The intraperitoneal injection of midazolam produced statistically significant decreases in levels of DOPAC and ratio of turnover values (P < 0.01) in rats 48 hr after withdrawal of ethanol, with respect to control and chronically ethanol-treated animals, in contrast to the absence of changes produced when injecting thiopental or somatostatin.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1984

Measurement of urinary vanilmandelic acid and homovanillic acid by high-performance liquid chromatography with electrochemical detection following extraction by ion-exchange and ion-moderated partition.

An improved protocol has been developed to isolate homovanillic acid (HVA) and vanilmandelic acid (VMA) from urine with strong anion-exchange resin. The sample is diluted with acetate buffer and passed through a disposable column. HVA, uric acid, and many hydrophobic organic acids are removed with 1.0 M acetic acid--ethanol. Then VMA is eluted with 0.5 M phosphoric acid. Two isocratic mobile phases allow rapid high-performance liquid chromatographic measurement of VMA (5 min) and HVA (8 mins) on a 5-micron ODS column. Selective conditions were developed with dual-electrode coulometric detection to permit specific measurement of VMA, HVA, and internal standards, with less than 5% between-run variation.

Chromatography, High Pressure Liquid↗
PubMed1976

Probenecid-induced accumulation of cyclic nucleotides, 5-hydroxyindoleacetic acid, and homovanillic acid in cisternal spinal fluid of genetically nervous dogs.

These studies have been conducted on 40 dogs, twenty each of a genetically nervous strain and of a normal strain of short-haired pointers. The nervous strain after about age 3 months displays extreme hypervigilance, timidity, human avoidance, and often shows catatonic-like muscle rigidity when in the presence of humans or novel stimuli. Measurements of probenecid-induced accumulation of acid metabolites in cisternal cerebrospinal fluid (CSF) have been carried out. Among the compounds measured at from 1.5 hr to 6.0 hr after probenecid treatment, homovanillic acid (HVA) was similar for the two strains, 5-hydroxy-indoleacetic acid (5-HIAA) was lower, but cyclic adenosine-3',5'-monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) were higher for the nervous strain when compared with age- and sex-matched behaviorally normal dogs. Probenecid levels in CSF were similar at all points in time from 1.5 to 6.0 hr after its intravenous administration in a dose of 50 mg/kg body weight. These findings coupled with previously observed differences in the two strains suggest that hyperresponsiveness of the central nervous system (CNS) noradrenergic and cholinergic systems and a hyporesponsiveness of the serotoninergic system are related to the genetically expressed aberrant behavior.

Animals↗
PubMed1984

Effects of African trypanosomiasis on brain levels of dopamine, serotonin, 5-hydroxyindoleacetic acid, and homovanillic acid in the rabbit.

Serotonin (5-HT) levels fell by 21% in the mid-brain-thalamus-hypothalamus (MTH) region of the rabbit brain after chronic infection with the protozoan Trypanosoma brucei gambiense. 5-HT did not decrease significantly in the caudate/putamen (CP) or the pons/medulla (PM) region. 5-Hydroxyindoleacetic acid (5-HIAA) levels were unchanged in the MTH and caudate/putamen (CP) but increased by 17% in the pons/medulla (PM) after infection. Dopamine (DA) levels rose by 19% and homovanillic acid (HVA) by 33% in the PM during infection. DA and HVA tended to be lower in the CP of infected rabbits, but the apparent decreases were not statistically significant. DA and HVA levels in the MTH were also unchanged by infection. These neurochemical changes may be involved in the behavioral symptoms that frequently accompany this disease in man and cattle.

Animals↗
PubMed1977

[Determination of the urinary metabolites hydroxyindole-acetic acid, vanillyl mandelic acid and homovanillic acid by means of lipophilic gel chromatography and gas chromatography (author's transl)].

A specific and practicable method is described for the quantitative determination of urinary phenol- and indole-carboxylic acids. High specificity is achieved by a preliminary separation of the free acids (extracted from the urine sample) with the aid of organophilic gel chromatography on Sephadex LH 20, followed by gas chromatographic analysis of the silyl derivatives of the acids. The organophilic gel chromatography of the free acids shows a high recovery rate in the micro- and submicrogram range. The difficulties encountered in other techniques in the derivatisation and gas chromatographic separation of the individual components are avoided by using the preliminary separation, and by using N-methyl-N-trimethylsilyl-trifluoroacetamide for the derivatisation. Use of this preparation technique with a direct read-out gas chromatograph with automatic sample introduction, gives high accuracy and precision, and a facility for the determination of a wide range of aromatic acids in urine.

Chromatography, Gas↗