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At least 307 records · Page 17Linked to original sources
PubMed2003

On-line preconcentration prior to on-column derivatization monolith octadecasiloxane capillary electrochromatography for the determination of biogenic amines.

To expand the applications of the on-line preconcentration technique with capillary electrochromatography (CEC) to biogenic amines that have no specific chromophore or fluorophore in their molecules, a method of on-line preconcentration prior to on-column derivatization CEC is presented. A monolithic ODS capillary column (20 cm effective length x 75 microm i.d.) for CEC was fabricated using a thermal sol-gel reaction of tetraethyl orthosilicate to capture ODS particles (5-microm particle diameter) in a capillary tube. A standard model biogenic amine solution consisting of histamine, methylhistamine, and serotonin was electrokinetically injected from the anodic site of the capillary column with 5 kV, and these amines were effectively concentrated at the inlet site of the capillary column by a field-amplified sample stacking, a gradient effect mode, or both. This preconcentration occurred whenever the several types of solvent for reconstitution of the amines, e.g., water (noneluting solvent or low-conductivity solvent), 0.9% sodium chloride (noneluting solvent or high-conductivity solvent), or 60% acetonitrile in 10 mM borate buffer (pH 10) (eluting solvent) were employed. After concentration, the amines were subsequently derivatized, separated, and detected during CEC with an optimum CEC run buffer solution containing 60% acetonitrile in 5 mM o-phthalaldehyde/2-mercaptoethanol-10 mM borate buffer (pH 10) when 5 kV was continuously applied. Using the present system, equipped with a fluorescence detector instead of a UV/visible detector, the detection sensitivity for amines reached a 0.1 microM level, which increased sensitivity by a factor of 10(3) times greater than that of normal on-column derivatization CEC.

Biogenic Amines↗
PubMed2006

Simultaneous determination of biogenic monoamines in rat brain dialysates using capillary high-performance liquid chromatography with photoluminescence following electron transfer.

Simultaneous determination of biogenic monoamines such as dopamine, serotonin, and 3-methoxytyramine in brain is important in understanding neurotransmitter activity. This study presents a sensitive determination of biogenic monoamines in rat brain striatum microdialysates using capillary high-performance liquid chromatography with the photoluminescence following electron-transfer detection technique. Separation conditions were optimized by changing the concentration of an ion-interaction agent and the percentage of an organic modifier. The high concentration of ion-interaction agent enabled the amines as a class to be separated from interfering acids, but also made the separation very long. To shorten the separation time, 10% (v/v) acetonitrile was used as the organic modifier. Eight chromatographic runs during a 3-h period were analyzed in terms of retention times, peak heights, and peak widths. Chromatograms are very reproducible, with less than 1% changes in peak height over 3 h. Typical concentration detection limits at the optimum separation conditions were less than 100 pM for metabolic acids and approximately 200 pM for monoamines. The injection volume of the sample was 500 nL. Thus, the mass detection limits were less than 50 amol for metabolic acids and approximately 100 amol for monoamines. Typical separation time was less than 10 min. To validate the technique, the separation method was applied to the observation of drug-induced changes of monoamine concentrations in rat brain microdialysis samples. Local perfusion of tetrodotoxin, a sodium channel blocker, into the striatum of an anesthetized rat decreased dopamine, 3-methoxytyramine, and serotonin concentrations in dialysates. Successive monitoring of striatal dialysates at a temporal resolution of 7.7 min showed that the injection of nomifensine transiently increased dopamine and 3-methoxytyramine concentrations in rat brain dialysate.

Animals↗
PubMed2006

Coated wire potentiometric detection for capillary electrophoresis studied using organic amines, drugs, and biogenic amines.

Capillary electrophoresis was coupled successfully and reliably to potentiometric sensors, which are based on an ionically conductive rubber phase coating, applied on a 250 microm diameter metal substrate. The membrane components included potassium tetrakis(p-chlorophenyl)borate (TCPB), bis(2-ethylhexyl)sebacate (DOS), and high molecular mass poly(vinyl chloride) (PVC). Potentiometry reveals a very sensitive CE detection mode, with sub-micromolar detection limits for amines and the randomly chosen drugs quinine, clozapine, cocaine, heroine, noscapine, papaverine, and ritodrine. The lowest detection limit, 1 x 10(-8) M injected concentration, was obtained for the quaternary ammonium compound tetrahexylammonium chloride. The more polar lower aliphatic amines and the biogenic amines dopamine, adrenaline, and cadaverine have much higher detection limits. The detection limits are log P dependent. Addition of a commercially available calixarene molecule or a synthetic macrocyclic amphiphilic receptor molecule to the electrode coatings enhanced the sensitivity respectively for the lower aliphatic amines and for the biogenic amines. A transpose of the Nikolskii-Eisenman-type function was suggested and used to convert the signal of the detector to a concentration-dependent signal.

Biogenic Amines↗
PubMed2002

Principal component analysis of biogenic amines and polyphenols in Hungarian wines.

Biogenic amines, polyphenols, and resveratrol were analyzed quantitatively in 25 different Hungarian wines from the same wine-making region, harvest of 1998. Polyphenols were determined according to a spectrophotometric method, whereas other substrates were analyzed using overpressured-layer chromatography (OPLC). Principal component analyses (PCA) were performed on data matrices consisting of substrates (columns) and different sorts of wines (rows) from the region of Pécs (southern Hungary). It was found that four (unrotated) principal components account for >80% of the total variance in the data. The plots of component loadings showed significant groupings for concentrations of biogenic amines (and polyphenols). Similarly, the component scores grouped according to the different sorts of wines. The loading plots reveal that there is no need to measure all of the variables to achieve the same characterization. It is enough to measure one variable per group. Naturally, this conclusion is valid only within the limits of the present study; wines from other regions may behave differently.

Biogenic Amines↗
PubMed2002

High-performance liquid chromatographic determination of biogenic amines in poultry carcasses.

Biogenic amines, produced by bacterial decarboxylation of amino acids, have been associated with toxicological symptoms in broilers fed various poultry byproducts. A reversed-phase high-performance liquid chromatographic method is described for the quantitation of eight biogenic amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) in chicken carcasses. Amines were extracted with perchloric acid, derivatized with dansyl chloride, separated using gradient elution (methanol and water), and detected by fluorescence. Benzylamine was used as the internal standard. Linearity, repeatability, and recovery of the method were evaluated. The method was linear for all of the amines studied at concentrations ranging from 0.05 to 25 microg/mL. Average recoveries ranged from 92.6% to 96.8% for all amines except for histamine, which was 74.6%.

Animals↗
PubMed2005

Rapid assay for analyzing biogenic amines in cheese: matrix solid-phase dispersion followed by liquid chromatography-electrospray-tandem mass spectrometry.

A new rapid and sensitive method based on matrix solid-phase dispersion (MSPD) followed by liquid chromatography-electrospray-tandem mass spectrometry was devised for the determination of biogenic amines at trace levels in cheese samples. The method required 0.25 g of sample, CN-bonded silica as a dispersant sorbent, and a formic acid aqueous solution/methanol mixture as an eluting solvent. Extraction recoveries from soft cheese products were calculated in the 98 +/- 4-110 +/- 6% range. A procedure based on solid-phase extraction was also evaluated for the extraction of these compounds in cheese. Chromatographic separation was performed using a C18 column with an aqueous ammonium acetate/methanol mixture as the mobile phase under gradient conditions. The method was validated in terms of detection limits (LOD), quantitation limits (LOQ), linearity, recovery, precision, and trueness. Results in the 0.05-0.25 mg kg(-1) range were obtained for the LOD of histamine, tyramine, and beta-phenylethylamine in soft cheese samples. Linearity was established over 2 orders of magnitude. Excellent precision in terms of intra-day repeatability was calculated (RSD% < 5). The applicability of the method to the determination of biogenic amines in cheese products was demonstrated.

Biogenic Amines↗
PubMed2005

Influence of the freshness grade of raw fish on the formation of volatile and biogenic amines during the manufacture and storage of vinegar-marinated anchovies.

Volatile and biogenic amines from three batches of anchovies, marinated in vinegar, were studied. The anchovies had been vacuum-packed and kept in refrigerated storage for 3 months. Trimethylamine and total volatile basic nitrogen levels were very low and constant throughout marinating and storage process: less than 1 and 10 mg/100 g, respectively. Certain amine levels, mainly those of tyramine and serotonin, increased slightly, particularly during storage. However, even the highest recorded levels were much lower than those considered to be hazardous for human consumption. To study the influence of raw material freshness in the amine profile, two laboratory trials using fresh and spoiled anchovies and simulating the industry standard marinating process were carried out. Levels for both volatile and biogenic amines were dependent on raw material quality, proving consistently higher in those deriving from nonfresh fish. Vinegar marinating leads to a decrease in the accumulation of amines in anchovy while their concentration in the vinegar solution increases due to the vinegar effect as solvent extractor.

Acetic Acid↗
PubMed2000

Biogenic amines occurrence in wine. Amino acid decarboxylase and proteolytic activities expression by Oenococcus oeni.

This work deals with the study of the proteolytic and amino acid decarboxylase activities of selected Oenococcus oeni isolates and the effect of yeast autolysis on biogenic amines production in wine. A total of 220 isolates of O. oeni were tested for decarboxylase and proteolytic activity. Only six isolates showed both activities, but only after a period of adaptation in a growth medium containing wine. The results reported on this paper show that proteolytic activity was dependent on medium composition and bacterial growth phase. It can be assumed that the ability of O. oeni to use wine peptides and to produce biogenic amines is not a constant characteristic of this species, and enzymatic system expression appears to be closely dependent on nutritional and energetical composition of the medium. It also seems to be strain dependent and not widespread among this bacterial community.

Aromatic-L-Amino-Acid Decarboxylases↗
PubMed1997

Mutagenesis reveals structure-activity parallels between human A2A adenosine receptors and biogenic amine G protein-coupled receptors.

Structure-affinity relationships for ligand binding at the human A2A adenosine receptor have been probed using site-directed mutagenesis in the transmembrane helical domains (TMs). The mutant receptors were expressed in COS-7 cells and characterized by binding of the radioligands [3H]CGS21680, [3H]NECA, and [3H]XAC. Three residues, at positions essential for ligand binding in other G protein-coupled receptors, were individually mutated. The residue V(3.32) in the A2A receptor that is homologous to the essential aspartate residue of TM3 in the biogenic amine receptors, i.e., V84(3.32), may be substituted with L (present in the A3 receptor) but not with D (in biogenic amine receptors) or A. H250(6.52), homologous to the critical N507 of rat m3 muscarinic acetylcholine receptors, may be substituted with other aromatic residues or with N but not with A (Kim et al. J. Biol. Chem. 1995, 270, 13987-13997). H278(7.43), homologous to the covalent ligand anchor site in rhodopsin, may not be substituted with either A, K, or N. Both V84L(3.32) and H250N(6.52) mutant receptors were highly variable in their effect on ligand competition depending on the structural class of the ligand. Adenosine-5'-uronamide derivatives were more potent at the H250N(6.52) mutant receptor than at wild type receptors. Xanthines tended to be close in potency (H250N(6.52)) or less potent (V84L(3.32)) than at wild type receptors. The affinity of CGS21680 increased as the pH was lowered to 5.5 in both the wild type and H250N(6.52) mutant receptors. Thus, protonation of H250(6.52) is not involved in this pH dependence. These data are consistent with a molecular model predicting the proximity of bound agonist ligands to TM3, TM5, TM6, and TM7.

Adenosine↗
PubMed1999

Comparison of the effects of antidepressants and their metabolites on reuptake of biogenic amines and on receptor binding.

1. The present survey compares the effects of antidepressants and their principal metabolites on reuptake of biogenic amines and on receptor binding. The following antide-pressants were included in the study: the tricyclic antidepressants amitriptyline, dothiepin, and lofepramine and the atypical antidepressant bupropion, which all have considerable market shares in the UK and/or US markets; the selective serotonin reuptake inhibitors (SSRIs) citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline; and the recently approved antidepressants venlafaxine and nefazodone. 2. Amitriptyline has similar in vitro reuptake inhibitory potencies for 5-HT and NA, whereas the metabolite nortriptyline is preferentially a NA reuptake inhibitor. Both amitriptyline and nortriptyline are also 5-HT2 receptor antagonists. 3. Dothiepin has equipotent 5-HT and NA reuptake inhibitory activity, whereas northiaden shows a slight selectivity for NA reuptake inhibition. Dothiepin and northiaden are also 5-HT2 receptor antagonists. The slow elimination rate of northiaden (36-46 hr) compared to dothiepin (14-24 hr) suggests that northiaden contributes significantly to the therapeutic effect of dothiepin. 4. Lofepramine is extensively metabolized to desipramine. Desipramine plays an important role in the antidepressant activity of lofepramine, as the plasma elimination half-life of lofepramine (4-6 hr) is much shorter than that of desipramine (24 hr). Both compounds are potent and selective inhibitors of NA reuptake. 5. The five approved SSRIs, citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline, are potent 5-HT reuptake inhibitors, and the demethyl metabolites, norfluoxetine, demethylsertraline, and demethylcitalopram, also show selectivity. Paroxetine and sertraline are the most potent inhibitors of 5-HT reuptake, whereas citalopram is the most selective. Fluoxetine is the least selective and the metabolite of fluoxetine, norfluoxetine, is a more selective and more potent 5-HT reuptake inhibitor than the parent compound and has an extremely long half-life (7-15 compared to 1-3 days). Thus the metabolite plays an important role for the therapeutic effect of fluoxetine. Fluoxetine is also a 5-HT2C receptor antagonist. Demethylsertraline is a weaker and less selective 5-HT reuptake inhibitor in vitro than sertraline, but demethylsertraline has a very long half-life (62-104 hr) compared to the parent compound (24 hr) and it might play a role in the therapeutic effects of sertraline. Demethylcitalopram has about a 10 times lower 5-HT reuptake inhibitory potency in vitro than citalopram, and the elimination half-lives are approximately 1.5 and 2 days, respectively. 6. Bupropion and hydroxybupropion are weak inhibitors of biogenic amine reuptake. The mechanisms of action responsible for the clinical effects of bupropion are not fully understood, but it has been suggested that both dopaminergic and noradrenergic components play a role and that the hydroxybupropion metabolite contributes significantly to the antidepressant activity. 7. Venlafaxine and O-demethylvenlafaxine are weak inhibitors of 5-HT and NA reuptake, and the selectivity ratios are close to one. O-Demethylvenlafaxine is eliminated more slowly than venlafaxine (plasma half-lives of 5 and 11 hr, respectively), and it is likely that it contributes to the overall therapeutic effect of venlafaxin. 8. Nefazodone and alpha-hydroxynefazodone are equipotent 5-HT and NA reuptake inhibitors. Both compounds are also 5-HT2 receptor antagonists. Both parent compound and metabolite have short elimination half-lives.

Animals↗
PubMed2000

A dual-probe microdialysis study in simultaneously monitoring extracellular pyruvate, lactate, and biogenic amines in gerbil striata during unilateral cerebral ischemia.

A dual-probe microdialysis technique coupled with liquid chromatographic assays was developed for the simultaneous monitoring of neurochemicals in gerbil striata during cerebral ischemia. Isocratic separation of lactate and pyruvate was achieved within 5 min whereas the separation of biogenic amines was completed within 30 min. An unilateral ligation was produced by occlusion of the right common carotid artery for 30 mins in anesthetized gerbils to perform a typical focal cerebral ischemia. Microdialysis probes were inserted in both sides of the striata to simultaneously monitor biogenic amines, lactate and pyruvate during cerebral ischemia. Dynamic and comparative changes of these analytes in ipsilateral and contralateral sides of the brain can be simultaneously measured by the assay. The present assay can be used as a research tool to explore neurochemical substances and their relationships during cerebral ischemia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2003

Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson's disease.

To study changes in amino acid metabolism and biogenic amines in Parkinson's disease, we set up a prospective study and measured biogenic amines, their main metabolites, and 22 different amino acids, in cerebrospinal fluid of Parkinson's disease patients (n = 24) and age-matched controls (n = 30). A trend toward higher dopamine levels in Parkinson's disease patients was interpreted as an effect of treatment with levodopa and/or selegiline. Significantly lower concentrations of the dopamine metabolite 3,4-dihydroxyphenylacetic acid in the Parkinson's disease group might reflect dopaminergic cell loss. Our results revealed decreased serotonin catabolism that was interpreted as an effect of treatment with selegiline. Whereas all amino acid levels were unchanged, taurine was significantly lower in Parkinson's disease patients. Studies showed that taurine exerts a trophic action on the central nervous system. In this view, decreased taurine in a neurodegenerative disorder as Parkinson's disease deserves attention.

Aged↗
PubMed2003

Effect of acute progestational hypoxia on the content of biogenic amines in the brain of albino rat pups: Peptide correction.

We studied the effect of exposure to acute hypobaric hypoxia in the progestational period on the content of biogenic amines in the brainstem and cerebral cortex in rat pups of different age. The possibility of correcting hypoxia-induced changes with regulatory peptides was evaluated. We found that early antenatal hypoxia disturbs maturation of catecholaminergic systems in the brain. It should be emphasized that the differences from the control varied depending on the age of rat pups. Single intranasal administration of Semax heptapeptides and beta-casomorphine-7 to pregnant females prevented changes in the content of biogenic amines in CNS of the offspring during postnatal ontogeny.

Aging↗
PubMed2003

Functional consequences of homo- but not hetero-oligomerization between transporters for the biogenic amine neurotransmitters.

Before this study, the human norepinephrine transporter (hNET) was the only member of the biogenic amine neurotransmitter transporter family that had not been demonstrated to be a functional homo-oligomer. Here, using two forms of the transporter, I155C and hNET-myc, with distinct antigenicity and inhibitor sensitivity, we demonstrated that hNET exists as a homo-oligomer. hNET I155C is a functional mutant and is sensitive to inactivation by the sulfhydryl reagent [2-(trimethylammonium)ethyl]methanethiosulfonate, while hNET-myc is resistant to inactivation by this reagent. Coimmunoprecipitation of these two forms demonstrated that a physical interaction exists between norepinephrine transporter monomers. Further characterization of this physical interaction has revealed that the activity of norepinephrine transporters depends on interactions between monomers. Because norepinephrine transporters and serotonin transporters are the only two members of the neurotransmitter transporter family endogenously expressed in the cell membrane of the same cells, placental syncytiotrophoblasts, we tested the ability of norepinephrine transporters and serotonin transporters to associate and function in a hetero-oligomeric form. Similarly, coexpression of hNET-myc with serotonin transporter-FLAG showed a physical interaction in coimmunoprecipitation assays. However, coexpression of serotonin and norepinephrine transporters did not sensitize norepinephrine transporter activity to inhibition by citalopram, a selective serotonin transport inhibitor. Thus, the norepinephrine transporter-serotonin transporter physical association did not produce functional consequences. Based on this, we propose that the transporters for biogenic amine neurotransmitters interact functionally in homo- but not hetero-oligomeric forms.

Amino Acid Sequence↗
PubMed1999

Placental biogenic amine transporters: in vivo function, regulation and pathobiological significance.

The biogenic amine transporters are part of a large family of plasma membrane transporters. These carriers mediate the re-uptake of neurotransmitters from the synaptic cleft and plasma compartments. Re-uptake process is inhibited by drugs like cocaine, fluoxetine and tricyclic antidepressants. There are specific transporters for norepinephrine, epinephrine, dopamine and serotonin. The placenta expresses the norepinephrine and serotonin transporters, which is unusual as they are otherwise expressed predominantly in neuronal tissue. Fetal catecholamine clearance rate is higher than under any other physiological conditions and is mediated in large measure by the placental transporters. The high intrauterine catecholamine secretion and clearance rates are part of the unique fetal neuroendocrine milieu. They condition the fetus to a high capacity for catecholamine secretion in the early postnatal period when elevated sympathoadrenal system activity is vital for postnatal survival. Because of the prominent catecholamine clearance rate, the fetus is vulnerable to the adverse effects of re-uptake inhibitors. Understanding the mechanisms of expression and regulation of placental biogenic amine transporters is important to the pathobiology of fetal conditions associated with elevated catecholamine levels or intrauterine exposure to uptake inhibitors like cocaine.

Biogenic Monoamines↗
PubMedDate not supplied

Localization of biogenic amines and neuropeptides in adrenal medullary cells of birds.

The present article reviews the immunohistochemical findings on the localization of biogenic amines and neuropeptides in adrenal medullary cells of birds. In the chicken, about 70% of medullary cells are adrenaline-containing cells and the rest of cells seem to be noradrenaline-containing cells. The ratio of adrenaline-cells to noradrenaline-cells extremely varies among avian species. Besides adrenaline and noradrenaline, medullary cells of birds contain many kinds of biogenic amines and neuropeptides: serotonin, galanin, cholecystokinin, somatostatin, enkephalin, neuropeptide tyrosine and atrial natriuretic peptide. The existence of these bioactive substances in medullary cells also exhibits interspecies heterogeneity. In the chicken, serotonin and galanin are contained in both adrenaline- and noradrenaline-cells of the adrenal gland. Cholecystokinin- and somatostatin-immunoreactivity is restricted to adrenaline-containing cells. Enkephalin-immunoreactivity is seen in both adrenaline- and noradrenaline-cells, but in about half of medullary cells. Neuropeptide tyrosine-immunoreactivity is found in the adrenal gland of the chick embryo and newly hatched chick, but not in the adult chicken. Serotonin and these neuropeptides may be selectively coreleased with adrenaline and/or noradrenaline from adrenal medullary cells of the chicken.

Adrenal Medulla↗
PubMed1985

Reduction of biogenic amine levels in the Rett syndrome.

The Rett syndrome is a progressive disorder in female patients that is characterized by autistic behavior, dementia, ataxia, loss of purposeful use of the hands, and seizures. The results of laboratory investigations are usually normal, with the exception of electroencephalography. In an attempt to understand the pathogenesis of this syndrome, we assayed biogenic amine metabolites in the cerebrospinal fluid of six patients, 2 to 15 years of age. 3-Methoxy-4-hydroxyphenylethylene glycol (MHPG, a metabolite of norepinephrine), homovanillic acid (a metabolite of dopamine), and 5-hydroxyindoleacetic acid (5-HIAA, a metabolite of serotonin) were quantitated by a method involving gas chromatography and mass spectrometry. Levels of MHPG and homovanillic acid were significantly reduced in all the patients as compared with those in controls of similar age (P = 0.01 and 0.008, respectively). The reduction in the level of 5-HIAA was not significantly different from that in the controls (P = 0.15). These findings suggest an underlying disorder of biogenic amines in the Rett syndrome and may provide new insight into its pathogenesis.

Adolescent↗
PubMed2002

Inhibition of hemostasis by a high affinity biogenic amine-binding protein from the saliva of a blood-feeding insect.

The saliva of the blood-feeding insect Rhodnius prolixus contains numerous pharmacologically active substances. Included among these are a number of lipocalin proteins that bind various ligands important in hemostasis and inflammation. One such protein is a biogenic amine-binding protein (ABP) that binds serotonin, epinephrine, and norepinephrine. Based on amino acid alignments, it is most similar to the nitrophorin group of lipocalins found in the same insect species. Physiologically, this protein appears to act as both a vasodilator and platelet aggregation inhibitor. This protein inhibits smooth muscle contraction of the rat uterus in response to serotonin and of the rabbit aorta in response to norepinephrine. Platelet aggregation induced by a combination of low concentrations of ADP and either serotonin or epinephrine is inhibited because of the binding of serotonin and epinephrine. Potentiation of aggregation induced by low concentrations of collagen along with serotonin or epinephrine is also inhibited. Dissociation constants for biogenic amines were measured using isothermal titration calorimetry and the Hummel-Dreyer method of equilibrium gel filtration. In this manner, K(d) values of 102, 24, and 345 nm were found for serotonin, norepinephrine, and epinephrine, respectively. Molecular modeling of ABP suggests that ligand binding is mediated by interaction with the side chains of aromatic amino acids and charged residues that line the binding pocket.

Amino Acid Sequence↗