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Michael Davidson - One of the best experts on this subject based on the ideXlab platform.

  • Effect of m-chlorophenylpiperazine on plasma Homovanillic Acid concentrations in healthy subjects.
    Biological psychiatry, 1992
    Co-Authors: René S. Kahn, P. Knott, Steven M. Gabriel, K. Dumont, Lisa Mastroianni, Michael Davidson
    Abstract:

    In view of the abundant anatomical and functional interactions between serotonin and dopamine systems, this study examined the effect of the serotonin agonist, m-chlorophenylpiperazine (mCPP) on plasma concentrations of the dopamine metabolite, Homovanillic Acid. Plasma prolactin levels, body temperature, and mCPP blood level were also measured. mCPP (0.35 mg/kg) and placebo were administered orally to 10 healthy men in a randomized double-blind design. Variables were measured for 210 min after administration of capsules. mCPP raised prolactin and temperature as compared to placebo, but did not affect plasma Homovanillic Acid concentrations. Results suggest that mCPP does not alter dopamine function.

  • Effects of neuroleptic treatment on symptoms of schizophrenia and plasma Homovanillic Acid concentrations.
    Archives of General Psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Seth Apter, P. Knott, Ramy Kaminsky, Mark E. Cooper, Kimberly Dumont, Kenneth L Davis
    Abstract:

    • Measurement of plasma concentrations of the dopamine metabolite, Homovanillic Acid, is an indirect tool to assess changes in dopamine turnover in schizophrenic patients. Plasma Homovanillic Acid concentrations have been reported to decrease during neuroleptic treatment, with the decrement correlating with symptomatic improvement in symptoms of schizophrenia. The present study tested the hypothesis that neuroleptic drugs decrease plasma Homovanillic Acid concentrations in those schizophrenic patients who improve with administration of neuroleptic drugs but not in patients who fail to display a treatment response. Twenty schizophrenic men who remained drug free for at least 2 weeks were treated with 20 mg/d of haloperidol for 5 weeks. Symptoms and plasma Homovanillic Acid concentrations were assessed on the last drug-free day and weekly for 5 weeks. Mean plasma Homovanillic Acid concentrations decreased in the group of patients who responded to neuroleptic treatment and did not change in the group of patients who did not improve. These findings suggest that there may be a qualitative distinction between responders and nonresponders to dopamine antagonists.

  • Changes in Plasma Homovanillic Acid Concentrations in Schizophrenic Patients Following Neuroleptic Discontinuation
    Archives of general psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Peter Powchik, Patricia A. Warne, Miklos F. Losonczy, Rami Kaminsky, Seth Apter, Stacey Jaff, Kenneth L Davis
    Abstract:

    • Changes in plasma levels of the dopamine metabolite Homovanillic Acid have been reported to correlate with changes in the severity of schizophrenic symptoms during neuroleptic administration and after neuroleptic discontinuation. This study examined the effects of discontinuation of neuroleptic treatment on plasma Homovanillic Acid levels in 23 patients with chronic schizophrenia. It was hypothesized that clinical decompensation would be associated with increased plasma Homovanillic Acid levels. Plasma Homovanillic Acid was measured during administration of neuroleptic medication and during a subsequent 6-week drug-free period. Nine patients decompensated during the drug-free period and 14 patients did not. Following drug discontinuation, plasma Homovanillic Acid concentrations were higher in schizophrenic patients who decompensated than in those who did not. Furthermore, peak plasma Homovanillic Acid elevation after discontinuation of neuroleptic medication was significantly correlated with peak Brief Psychiatric Rating Scale increase. The data suggest that, in some schizophrenic patients, symptomatic decompensation after discontinuation of neuroleptic treatment is associated with increases in dopamine turnover.

  • Acute administration of alprazolam has no effect on plasma Homovanillic Acid concentration in normal subjects.
    Schizophrenia research, 1991
    Co-Authors: Zvi Zemishlany, Michael Davidson, Stacey Jaff, Robert T. Mcqueeney
    Abstract:

    Alprazolam has been suggested as an adjuvant to neuroleptic drugs in the treatment of schizophrenic patients. In an attempt to investigate whether alprazolam has an effect on dopaminergic neurotransmission, plasma Homovanillic Acid concentrations were measured for 24 h following a challenge with 3 mg of alprazolam or placebo in eight healthy subjects. Alprazolam had no effect on plasma Homovanillic Acid which may suggest that this agent is devoid of activity at the dopaminergic system in normal subjects.

Kenneth L Davis - One of the best experts on this subject based on the ideXlab platform.

  • Effects of neuroleptic treatment on symptoms of schizophrenia and plasma Homovanillic Acid concentrations.
    Archives of General Psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Seth Apter, P. Knott, Ramy Kaminsky, Mark E. Cooper, Kimberly Dumont, Kenneth L Davis
    Abstract:

    • Measurement of plasma concentrations of the dopamine metabolite, Homovanillic Acid, is an indirect tool to assess changes in dopamine turnover in schizophrenic patients. Plasma Homovanillic Acid concentrations have been reported to decrease during neuroleptic treatment, with the decrement correlating with symptomatic improvement in symptoms of schizophrenia. The present study tested the hypothesis that neuroleptic drugs decrease plasma Homovanillic Acid concentrations in those schizophrenic patients who improve with administration of neuroleptic drugs but not in patients who fail to display a treatment response. Twenty schizophrenic men who remained drug free for at least 2 weeks were treated with 20 mg/d of haloperidol for 5 weeks. Symptoms and plasma Homovanillic Acid concentrations were assessed on the last drug-free day and weekly for 5 weeks. Mean plasma Homovanillic Acid concentrations decreased in the group of patients who responded to neuroleptic treatment and did not change in the group of patients who did not improve. These findings suggest that there may be a qualitative distinction between responders and nonresponders to dopamine antagonists.

  • Changes in Plasma Homovanillic Acid Concentrations in Schizophrenic Patients Following Neuroleptic Discontinuation
    Archives of general psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Peter Powchik, Patricia A. Warne, Miklos F. Losonczy, Rami Kaminsky, Seth Apter, Stacey Jaff, Kenneth L Davis
    Abstract:

    • Changes in plasma levels of the dopamine metabolite Homovanillic Acid have been reported to correlate with changes in the severity of schizophrenic symptoms during neuroleptic administration and after neuroleptic discontinuation. This study examined the effects of discontinuation of neuroleptic treatment on plasma Homovanillic Acid levels in 23 patients with chronic schizophrenia. It was hypothesized that clinical decompensation would be associated with increased plasma Homovanillic Acid levels. Plasma Homovanillic Acid was measured during administration of neuroleptic medication and during a subsequent 6-week drug-free period. Nine patients decompensated during the drug-free period and 14 patients did not. Following drug discontinuation, plasma Homovanillic Acid concentrations were higher in schizophrenic patients who decompensated than in those who did not. Furthermore, peak plasma Homovanillic Acid elevation after discontinuation of neuroleptic medication was significantly correlated with peak Brief Psychiatric Rating Scale increase. The data suggest that, in some schizophrenic patients, symptomatic decompensation after discontinuation of neuroleptic treatment is associated with increases in dopamine turnover.

Ricardo Dávila - One of the best experts on this subject based on the ideXlab platform.

  • Schizophrenia: Gender, family risk, and plasma Homovanillic Acid
    American journal of medical genetics, 1995
    Co-Authors: Ricardo Dávila, Mercedes Zumárraga, Isabel Andia, Miguel Angel Gonzalez-torres, María I. Zamalloa, Edurne Basterreche, José Guimón, Arnold J. Friedhoff
    Abstract:

    Plasma Homovanillic Acid concentration was assessed in 60 young schizophrenic patients, with and without first-degree relatives with schizophrenia, before treatment, and 3 days after starting haloperidol treatment. The baseline concentration of Homovanillic Acid in plasma was no different in the two groups before treatment; it was, however, significantly higher in the patients with relatives than in those without relatives diagnosed of schizophrenia after 3 days of haloperidol treatment. © 1995 Wiley-Liss, Inc.

  • Morning variations of plasma Homovanillic Acid in untreated schizophrenic patients
    Journal of psychiatric research, 1993
    Co-Authors: Mercedes Zumárraga, Isabel Andia, Begoña Bárcena, Miguel Angel Gonzalez-torres, Ricardo Dávila
    Abstract:

    Plasma concentrations of Homovanillic Acid were determined in samples obtained at 8.30 a.m. and 12.30 p.m. from 29 untreated schizophrenic patients, 14 males and 15 females. When the earlier samples were compared with the later, a significant decrease in mean plasma Homovanillic Acid level was observed, but only in the male patients. The morning fall was observed in 10 of 14 male patients and 6 of the 15 female patients. This morning rhythm in plasma Homovanillic Acid concentration may mask the putative rises in plasma Homovanillic Acid provoked by neuroleptic administration and may explain some of the observed differences between findings in studies involving the assessment of this metabolite.

René S. Kahn - One of the best experts on this subject based on the ideXlab platform.

  • Effect of m-chlorophenylpiperazine on plasma Homovanillic Acid concentrations in healthy subjects.
    Biological psychiatry, 1992
    Co-Authors: René S. Kahn, P. Knott, Steven M. Gabriel, K. Dumont, Lisa Mastroianni, Michael Davidson
    Abstract:

    In view of the abundant anatomical and functional interactions between serotonin and dopamine systems, this study examined the effect of the serotonin agonist, m-chlorophenylpiperazine (mCPP) on plasma concentrations of the dopamine metabolite, Homovanillic Acid. Plasma prolactin levels, body temperature, and mCPP blood level were also measured. mCPP (0.35 mg/kg) and placebo were administered orally to 10 healthy men in a randomized double-blind design. Variables were measured for 210 min after administration of capsules. mCPP raised prolactin and temperature as compared to placebo, but did not affect plasma Homovanillic Acid concentrations. Results suggest that mCPP does not alter dopamine function.

  • Effects of neuroleptic treatment on symptoms of schizophrenia and plasma Homovanillic Acid concentrations.
    Archives of General Psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Seth Apter, P. Knott, Ramy Kaminsky, Mark E. Cooper, Kimberly Dumont, Kenneth L Davis
    Abstract:

    • Measurement of plasma concentrations of the dopamine metabolite, Homovanillic Acid, is an indirect tool to assess changes in dopamine turnover in schizophrenic patients. Plasma Homovanillic Acid concentrations have been reported to decrease during neuroleptic treatment, with the decrement correlating with symptomatic improvement in symptoms of schizophrenia. The present study tested the hypothesis that neuroleptic drugs decrease plasma Homovanillic Acid concentrations in those schizophrenic patients who improve with administration of neuroleptic drugs but not in patients who fail to display a treatment response. Twenty schizophrenic men who remained drug free for at least 2 weeks were treated with 20 mg/d of haloperidol for 5 weeks. Symptoms and plasma Homovanillic Acid concentrations were assessed on the last drug-free day and weekly for 5 weeks. Mean plasma Homovanillic Acid concentrations decreased in the group of patients who responded to neuroleptic treatment and did not change in the group of patients who did not improve. These findings suggest that there may be a qualitative distinction between responders and nonresponders to dopamine antagonists.

  • Changes in Plasma Homovanillic Acid Concentrations in Schizophrenic Patients Following Neuroleptic Discontinuation
    Archives of general psychiatry, 1991
    Co-Authors: Michael Davidson, René S. Kahn, Peter Powchik, Patricia A. Warne, Miklos F. Losonczy, Rami Kaminsky, Seth Apter, Stacey Jaff, Kenneth L Davis
    Abstract:

    • Changes in plasma levels of the dopamine metabolite Homovanillic Acid have been reported to correlate with changes in the severity of schizophrenic symptoms during neuroleptic administration and after neuroleptic discontinuation. This study examined the effects of discontinuation of neuroleptic treatment on plasma Homovanillic Acid levels in 23 patients with chronic schizophrenia. It was hypothesized that clinical decompensation would be associated with increased plasma Homovanillic Acid levels. Plasma Homovanillic Acid was measured during administration of neuroleptic medication and during a subsequent 6-week drug-free period. Nine patients decompensated during the drug-free period and 14 patients did not. Following drug discontinuation, plasma Homovanillic Acid concentrations were higher in schizophrenic patients who decompensated than in those who did not. Furthermore, peak plasma Homovanillic Acid elevation after discontinuation of neuroleptic medication was significantly correlated with peak Brief Psychiatric Rating Scale increase. The data suggest that, in some schizophrenic patients, symptomatic decompensation after discontinuation of neuroleptic treatment is associated with increases in dopamine turnover.

Serge Przedborski - One of the best experts on this subject based on the ideXlab platform.

  • Variations of Homovanillic Acid levels in ventricular cerebrospinal fluid
    Acta Neurologica Scandinavica, 2009
    Co-Authors: Jerzy Hildebrand, Zouheir Moussa, Christian Raftopoulos, J. Vanhouche, Marie-aline Laute, Serge Przedborski
    Abstract:

    We studied the nycterohemeral variations of Homovanillic Acid (HVA) in ventricular cerebrospinal fluid (CSF) in 24 patients undergoing monitoring of intracranial pressure as part of the normotensive hydrocephalus (NTH) work-up. CSF samples were obtained every 4 h in each patient. The mean individual values of HVA in the ventricular CSF ranged from 133 to 421 ng/ml, and they could not be correlated to any clinical feature. The intraindividual levels of HVA were stable throughout 24 hours, with a variation coefficient inferior to 10% in 63% of cases, and inferior to 20% in all the patients.