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Biomedical subjects

J Potokar

Publications and source records attributed to J Potokar.

7 recordsLinked to original sources
PubMed2004

Using sleep to evaluate comparative serotonergic effects of paroxetine and citalopram.

BACKGROUND: SSRIs suppress rapid eye movement (REM) sleep, probably by increasing serotonin in the brainstem, and also increase sleep fragmentation. Although in the UK, paroxetine (PAR) and citalopram (CIT) have recommended doses of 20 mg/day for the treatment of depression, the recommended dose of CIT in USA is higher (40 mg). If similar doses of PAR and CIT have similar effects on central serotonin then they should have similar effects on sleep measures in volunteers. METHOD: This was a randomised, double blind placebo controlled crossover study in 12 healthy volunteers. Subjects took PAR 20 mg mane, CIT 20 mg mane or placebo mane for 3 days and sleep was recorded overnight at home on the third night. Standard measures of sleep were derived. RESULTS: REM sleep was significantly suppressed and sleep fragmentation increased by both drugs. Measures of REM sleep and sleep continuity previously found to be altered by SSRIs were considered together and compared with placebo as a 'serotonin response'; this was significantly greater in the PAR group. CONCLUSIONS: Sleep effects typical of SSRIs were greater with PAR 20 mg/day than CIT 20 mg/day, suggesting greater effects on 5HT uptake blockade.

Adult↗
PubMed2004

Evaluation of actigraphy and automated telephoned questionnaires to assess hypnotic effects in insomnia.

This study aimed to explore new methodologies in insomnia research, namely whether actigraphy was suitable to show hypnotic effects over weeks in insomnia, and to compare an automated method of questionnaire data collection with traditional methods. Thirty-eight insomniacs took part in a 5-week, double-blind, placebo-controlled study of the effects of 2 weeks of administration of temazepam 20 mg on sleep. Outcome measures were actigraphy and daily St Mary's Hospital Sleep Questionnaires (SMHSQ). Actigraphy was performed using Actiwatch (CNT) and analysed using both the automated Actiwatch sleep analysis software and non-parametric analysis of rest-activity rhythms. The questionnaires were administered as straightforward pencil-and-paper for half of the time and an automated telephoned system for the other half. The experimental paradigm allowed within-subject comparison of traditional and automated data collection, both on and off drug. Actigraphy showed a high degree of inter-subject variability but, nevertheless, some sleep variables (Fragmentation Index, Actual Sleep Time %) showed significant improvement during drug treatment, and Sleep Efficiency and Actual Sleep Time were significantly worsened during the first post-drug week. Nonparametric circadian rhythm analysis showed no significant effect. Subjective data from the SMHSQ showed significant drug effects and there was no significant difference in scores between the automated and pencil-and-paper methods; automated data collection was slightly more acceptable to patients and minimized data entry and management. Effect sizes using within-subject and between-subject comparisons were calculated for the subjective and objective measures to inform future studies

Adolescent↗
PubMed1999

Assessment of GABA(A)benzodiazepine receptor (GBzR) sensitivity in patients on benzodiazepines.

OBJECTIVES: To measure GABA(A) benzodiazepine receptor sensitivity in patients taking benzodiazepines and compare with matched controls. METHODS: Seven patients who were on prescribed benzodiazepines for an anxiety disorder or insomnia were recruited from general practice and an adult mental health service outpatient clinic. They were matched with seven volunteers. All subjects received an intravenous injection of midazolam 50 microgram/kg in 10 ml normal saline over 10 min. Objective responses to midazolam were assessed using saccadic eye movement velocity slowing and subjective assessments using visual analogue scales. Measurements were recorded for 120 min and plasma midazolam concentrations obtained at 15-min intervals post-infusion to 120 min. Ratios of pharmacodynamic/pharmacokinetic effects were obtained for each individual to estimate GABA(A) benzodiazepine receptor sensitivity. RESULTS: Patients had an attenuated response to midazolam on both subjective and objective measures. GABA(A) benzodiazepine receptor sensitivity was significantly reduced in the patient group. CONCLUSIONS: Chronic treatment with benzodiazepines was associated with reduced effects of midazolam. Saccadic eye movement velocity was especially sensitive as a measure of attenuated response.

Adult↗
PubMed1996

Cognitive processing in post-traumatic stress disorder.

Recent research has suggested an abnormal attentional bias to threat in anxiety disorders. We have assessed the processing of thoughts of trauma, panic attacks, general fear and positive affect in a cohort of 15 war veterans with post-traumatic stress disorder (PTSD) and an age- and sex-matched normal control group. Subjects with PTSD showed delayed processing of self-referential sentences when the themes of the sentences were traumatic experiences or positive affect, compared with controls. However, they were more efficient than control subjects in the processing of sentences describing situations of panic attacks and general fear. It would therefore appear that in patients with PTSD, cognitive processing is hindered by personally relevant themes of past traumatic experiences, whereas it may be facilitated by information related to general threat or internal body sensations of panic.

Adult↗
PubMedDate not supplied

Flumazenil in alcohol withdrawal: a double-blind placebo-controlled study.

The purpose of the present study was to study gamma-aminobutyric acid (GABA)-A receptor function in alcohol-dependent subjects during withdrawal, using the benzodiazepine antagonist flumazenil. In particular, we wanted to examine the hypotheses that an endogenous inverse agonist ligand at the GABA-A benzodiazepine receptor (GBzR) is active during withdrawal (in which case flumazenil should be anxiolytic), or whether chronic alcohol intake results in a shift in sensitivity of the receptor in the inverse agonist direction (in which case flumazenil should be anxiogenic). Results from 15 alcohol-dependent subjects in a double-blind placebo-controlled cross-over study showed that flumazenil was neither anxiolytic nor anxiogenic, although withdrawal scores were reduced during the course of the study. The fact that flumazenil was not anxiogenic, as it is in panic disorder, suggests that the GBzR is functioning differently in these two clinically similar conditions.

Adult↗