Biomedical subjects

Thomas B Cooper

Publications and source records attributed to Thomas B Cooper.

At least 37 records · Page 2Linked to original sources

PubMed2004

Age effects on cortisol levels in depressed patients with and without comorbid post-traumatic stress disorder, and healthy volunteers.

BACKGROUND: Post-traumatic stress disorder (PTSD) and major depression are frequently comorbid. Age and major depression are associated with higher cortisol levels and dexamethasone resistance, whereas PTSD is associated with lower cortisol and dexamethasone supersensitivity. Therefore, we examined the effect of age on the hypothalamic-pituitary-adrenal (HPA) system in depressed patients with and without PTSD. METHODS: Thirty-one depressed patients without PTSD, 12 depressed patients with PTSD, and 23 healthy volunteers were studied on 2 days. Subjects received single-blind placebo on day 1 and fenfluramine on day 2. Cortisol levels were drawn before challenge and for 5 h thereafter. RESULTS: Cortisol levels increase with age in depressed patients without PTSD but not in depressed patients with PTSD or in healthy volunteers. Number of previous major depressive episodes was a predictor of the cortisol response to fenfluramine administration in depressed patients without PTSD. CONCLUSIONS: The results of our study highlight the importance of considering age in psychobiology. Further research is needed to fully delineate the role of age in abnormalities of the HPA axis found in major depression and PTSD.

Adult↗

PubMed2004

Cortisol response to diazepam: its relationship to age, dose, duration of treatment, and presence of generalized anxiety disorder.

OBJECTIVE: Acute diazepam administration has been shown to decrease plasma cortisol levels consistent with decreased activity of the hypothalamic-pituitary-adrenal axis, especially in individuals experiencing stress. However, the effects of chronic diazepam treatment on cortisol have been less studied, and the relationship to age, anxiety, duration of treatment, and dose are not well understood. METHOD: This double-blind placebo-controlled study examined acute and chronic effects of diazepam on plasma cortisol levels in young (19-35 years) and elderly (60-79 years) individuals with and without generalized anxiety disorder (GAD). Subjects received single oral challenges of placebo or diazepam (2.5 mg or 10 mg) in a placebo-controlled cross-over design, followed by 3 weeks of chronic daily treatment with 2.5 mg or 10 mg diazepam or placebo taken at 10 p.m., and then by a final acute challenge with a single oral dose of the same study medication received during chronic treatment. RESULTS: The elderly experienced significant reductions in plasma cortisol levels compared to placebo both in the initial challenge and during chronic treatment, but the young did not. However, cortisol response to drug was comparable in both groups. Final challenge did not produce any significant cortisol effects in either group and the cortisol response in the elderly was significantly reduced compared to the initial challenge. GAD status was not a factor in plasma cortisol responses to diazepam. CONCLUSIONS: Diazepam reduced cortisol both acutely and during chronic treatment, but not during final challenge, consistent with some tolerance development. This effect was most apparent in the elderly compared with the young adults and was not modulated by GAD status or dosage, and was not related to drug effects on performance and on self-ratings of sedation and tension.

Adult↗

PubMed2004

Sensitive and simple gas chromatographic-mass spectrometric determination for amphetamine in microdialysate and ultrafiltrate samples.

A gas chromatographic-mass spectrometric (GC-MS) method is described for the measurement of amphetamine (AMP) using negative chemical ionization (NCI) mode. Without prior extraction AMP was derivatized with 2,3,4,5,6-pentafluorobenzoyl chloride (PFBC) and simultaneously extracted into toluene. The toluene extract was injected directly into GC-MS equipped with a HP-1 capillary column. The method is simple and more sensitive than most of the previously published methods. The limit of quantification of amphetamine is 25pg (1.4pg on column) with a very limited sample volume (25microl). The within-day precision was from 1.7 to 5.1% and between-day precision was from 2.2 to 7.3%. The method has been used for the measurement of several thousand microdialysate and ultrafiltrate samples and proven reliable.

Amphetamine↗

PubMed2004

In vivo vulnerability to competition by endogenous dopamine: comparison of the D2 receptor agonist radiotracer (-)-N-[11C]propyl-norapomorphine ([11C]NPA) with the D2 receptor antagonist radiotracer [11C]-raclopride.

(-)-N-Propyl-norapomorphine (NPA) is a full dopamine (DA) D2 receptor agonist and [11C]NPA is a suitable radiotracer to image D2 receptors configured in a state of high affinity for agonists with positron emission tomography (PET). In this study the vulnerability of the in vivo binding of [11C]NPA to acute fluctuation in synaptic DA was assessed with PET in baboons and compared to that of the reference D2 receptor antagonist radiotracer [11C]raclopride. Three male baboons were studied with [11C]raclopride and [11C]NPA under baseline conditions and following administration of the potent DA releaser amphetamine (0.3, 0.5, and 1.0 mg kg(-1) i.v.). Kinetic modeling with an arterial input function was used to derive the striatal specific-to-nonspecific equilibrium partition coefficient (V3"). [11C]Raclopride V3" was reduced by 24 +/- 10%, 32 +/- 6%, and 44 +/- 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg(-1), respectively. [11C]NPA V3" was reduced by 32 +/- 2%, 45 +/- 3%, and 53 +/- 9% following amphetamine doses of 0.3, 0.5, and 1.0 mg kg(-1), respectively. Thus, endogenous DA was more effective at competing with [11C]NPA binding compared to [11C]raclopride binding, a finding consistent with the pharmacology of these tracers (agonist vs. antagonist). These results also suggest that 71% of D2 receptors are configured in a state of high affinity for agonists in vivo. In conclusion, [11C]NPA might provide a superior radiotracer to probe presynaptic DA function with PET in health and disease.

Algorithms↗

PubMed2004

Determination of plasma ziprasidone using liquid chromatography with fluorescence detection.

A liquid chromatographic procedure was developed for the determination of a new antipsychotic agent ziprasidone in plasma using fluorescence detection. A one-step liquid-liquid extraction from 1 ml of alkalinized plasma containing an internal standard alpha-ergocryptine using methyl-t-butyl ether afforded a greater than 84% recovery of ziprasidone. Chromatography was performed using a reversed-phase trimethylsilyl bonded silica column with a mobile phase of 72:28 phosphate buffer:acetonitrile at a flow rate of 1.5 ml/min. Detection of the eluted peaks was observed using excitation and emission wavelengths of 320 and 410 nm, respectively. Chromatographic run time did not exceed 14 min with no interference from endogenous material. The calibration curve was linear over the concentration range of 0.5 to 200 ng/ml and the inter- and intra-assay imprecision (CV) was less than 10%. The lower limit of quantitation was assessed at 0.5 ng/ml. Specificity of the method is demonstrated by the lack of interference from a large number of commonly used drugs and their metabolites in clinical use. The utility of the method is exemplified with the presentation of clinical data from patients receiving ziprasidone.

Antipsychotic Agents↗

PubMed2004

Baseline plasma GABA: its relationship to the adverse effects of acute lorazepam administration on cognition in the elderly.

The GABA system is an active target for drugs to treat a variety of disorders and the availability of an indirect measure of central GABA activity would not only enhance psychiatric research, but also permit assessment of the pharmacodynamic effects of drugs designed to act on this system. The relationships between plasma baseline pre-drug GABA concentrations and cognitive impairments induced by an acute oral dose of lorazepam (0.5 and 1.0 mg) were investigated in 22 healthy elderly individuals. Partial correlations controlling for plasma lorazepam concentrations revealed no significant relationship between baseline plasma GABA levels and lorazepam-induced impairments on tests of cognitive functioning. Plasma GABA concentration does not appear to be a useful marker of susceptibility to benzodiazepine-induced cognitive toxicity in the elderly. Other approaches to estimating central GABA activity should be pursued.

Affect↗

PubMed2004

Alcohol reduces GM1 ganglioside content in the serum of inbred mouse strains.

BACKGROUND: Endogenous and exogenous gangliosides in the plasma affect physiologic and pathologic processes such as angiogenesis and atherogenesis. However, the genetic and environmental factors that regulate the expression of plasma gangliosides are not well known. As shown in the liver and the brain, profiles of gangliosides in the plasma may be strain-specific and can be altered by intake of alcohol. Therefore, we analyzed serum gangliosides derived from inbred mouse strains with and without alcohol treatment. METHODS: C57BL/6ByJ (B6By) and BALB/cJ mice (60-70 days old) were injected with 20% alcohol (1-6 g/kg) or saline intraperitoneally, and the ganglioside content of the serum, liver, and cerebellum was measured 4 hr after the injection. Also, the effect of oral alcohol self-administration for 18 days with escalating (3-12%) concentrations of alcohol on the serum GM1 content was studied in B6By mice. The quantification of GM1 was performed with a thin-layer chromatography-staining procedure using a cholera toxin B subunit, and the content of other gangliosides was measured after staining with resorcinol reagent. RESULTS: We found that basal GM1 (containing N-glycolylneuraminic acid) content in the serum of BALB/cJ mice (4.8 +/- 0.26 ng/microl) was 25 times higher than that of B6By mice (0.19 +/- 0.01 ng/microl); the major ganglioside in both strains was GM2. The ganglioside profile in the liver was similar to that of the serum, and the GM1 content in BALB/cJ was nine times higher than that of B6By. Both injection and oral self-administration of alcohol lowered GM1 levels in the serum. CONCLUSIONS: Endogenous ganglioside profiles in the serum are under genetic control among inbred mouse strains, and they can be altered by acute and chronic alcohol administration. These genetic and alcohol-induced differences in the plasma gangliosides, which appear to reflect ganglioside metabolism in the liver, may affect alcohol-related behaviors and pathologic processes.

Animals↗

PubMed2004

Overt aggression and psychotic symptoms in patients with schizophrenia treated with clozapine, olanzapine, risperidone, or haloperidol.

The subjects were 157 treatment-resistant inpatients diagnosed with chronic schizophrenia or schizoaffective disorder. They were randomly assigned to treatment with clozapine, olanzapine, risperidone, or haloperidol in a 14-week, double-blind trial. Incidents of overt aggression were recorded and their severity was scored. The Positive and Negative Syndrome Scale was administered. Atypical antipsychotics showed an overall superiority over haloperidol, particularly after the first 24 days of the study when the dose escalation of clozapine was completed. Once an adequate therapeutic dose of clozapine was reached, it was superior to haloperidol in reducing the number and severity of aggressive incidents. Patients exhibiting persistent aggressive behavior showed less improvement of psychotic symptoms than the other patients. There was an interaction between aggressiveness, medication type, and antipsychotic response: risperidone and olanzapine showed better antipsychotic efficacy in patients exhibiting less aggressive behavior; the opposite was true for clozapine. Clozapine appears to have superior antiaggresive effects in treatment-resistant patients; this superiority develops after the patient has been exposed to an adequate dose regimen.

Aggression↗

PubMed2004

Haloperidol half-life after chronic dosing.

In normal subjects after a single oral dose, haloperidol half-life has been reported to range 14.5-36.7 hours (or up to 1.5 days). After chronic administration, half-lives of up to 21 days have been reported. The objective of this study was to evaluate specific factors that might account for differences in haloperidol half-life in patients taking haloperidol chronically, including gender, age, weight, race, CYP2D6 and CYP3A5 genotypes, comedication, and smoking.Thirty-one patients were administered haloperidol for 4 weeks followed by a 1-week washout before administration of clozapine. Haloperidol plasma levels were measured weekly for at least 2 months after discontinuation. The geometric mean for haloperidol half-life and detectable levels duration were 3.9 and 13.8 days, respectively. Within 31 subjects, 58% (18/31) had half-lives <3 days (1.2-2.3 days) and 42% (13/31) had half-lives > or =3 days. Two of 3 patients with half-lives longer than 30 days (720 hours) and levels detectable >2 months had received haloperidol decanoate. Five patients who received haloperidol decanoate in the prior year were excluded from a comparison between patients with long haloperidol half-lives (> or =3 days, n = 10) and patients with short half-lives (<3 days, n = 16). The only significant difference between the two groups was that African-Americans (n = 4) were all found to have a long haloperidol half-life (P = 0.014). CYP3A5 genotype did not appear to influence haloperidol half-life but the two CYP2D6 poor metabolizer had half-lives > or =3 days. This study suggests that haloperidol half-life following repeated drug administration is substantially more prolonged than what has been observed after acute haloperidol administration.

Adult↗

PubMed2004

The number of previous depressive episodes is positively associated with cortisol response to fenfluramine administration.

Multiple reports document hypothalamic-pituitary-axis (HPA) hyperactivity in depressed patients. Measurement of cortisol levels after ingestion of fenfluramine, a specific serotonin releaser/uptake inhibitor agent, provides an index of HPA activity. To our knowledge, this is the first study of the effect of a number of previous depressive episodes on cortisol responses to fenfluramine administration. Thirty-one unipolar depressed patients and 23 healthy volunteers entered the study. Demographic and clinical parameters were assessed and recorded. Response to fenfluramine administration was measured by the difference between maximum hourly plasma cortisol measurements after fenfluramine administration and baseline levels measured before fenfluramine administration. The number of previous major depressive episodes was a predictor of cortisol response to fenfluramine administration in depressed subjects. Higher cortisol responses were associated with more prior episodes of major depression. The relationship of cortisol to the number of previous depressive episodes remained significant after controlling for age. Our finding highlights the importance of possible cumulative effects of repeated episodes of major depression. Prevention and early recognition of depressive episodes may prevent these cumulative adverse effects.

Adult↗

PubMed2004

Prolactin levels in schizophrenia and schizoaffective disorder patients treated with clozapine, olanzapine, risperidone, or haloperidol.

BACKGROUND: Prolactin levels are elevated to varying degrees by antipsychotics. Prolactin elevations may result in sexual and other adverse effects, and they may be related to antipsychotic effects. We used the data collected in a trial of antipsychotics to study the differential effect of these drugs on prolactin level, to explore the relation between clinical effects and prolactin level, and to determine the relationship between plasma levels of antipsychotics and prolactin level. METHOD: Treatment-resistant patients (133 men, 24 women) diagnosed with DSM-IV schizophrenia or schizoaffective disorder participated in a double-blind, randomized, 14-week trial comparing clozapine (N = 40), olanzapine (N = 39), risperidone (N = 41), and haloperidol (N = 37). Plasma levels of prolactin and antipsychotics were determined at baseline and at weeks 5, 8, 10, 12, and 14 during the trial. Clinical effects were measured with the Positive and Negative Syndrome Scale and the Extrapyramidal Symptom Rating Scale. Statistical analyses were limited to the 75 men for whom repeated prolactin levels were available. Data were gathered from June 1996 to December 1999. RESULTS: Risperidone caused significant elevation of prolactin levels (p <.05) that appeared to be dose-dependent. Clozapine and olanzapine were associated with decreases of prolactin, whereas haloperidol led to a minor, nonsignificant increase. Plasma olanzapine and prolactin levels were correlated. Prolactin levels were not related to clinical improvement or extrapyramidal side effects. CONCLUSION: Antipsychotics show major differences in their effects on prolactin, and risperidone has clearly the most robust effect.

Adult↗

PubMed2004

Effects of atypical antipsychotics on the syndromal profile in treatment-resistant schizophrenia.

BACKGROUND: There has been considerable support for the observation that atypical antipsychotics have a broader range of therapeutic effects than traditional antipsychotics. We are exploring whether this expanded clinical efficacy can also be seen in patients with treatment-resistant schizophrenia. METHOD: The subjects were 157 treatment-resistant inpatients diagnosed with DSM-IV schizophrenia or schizoaffective disorder. They were randomly assigned to treatment with clozapine, olanzapine, risperidone, or haloperidol in a 14-week double-blind trial and rated with a standard measure of clinical antipsychotic efficacy (Positive and Negative Syndrome Scale [PANSS]). Factor analysis at baseline and endpoint together with changes in 5 PANSS-derived factors were examined. Data were gathered from June 1996 to December 1999. RESULTS: The underlying PANSS factor structure, as indicated by the factor loadings, was essentially identical at baseline and endpoint. At baseline, the excitement factor was followed by the positive, negative, cognitive, and depression/anxiety factors, explaining 49.4% of the total variance. At endpoint, the positive factor was followed by the negative, excitement, cognitive, and depression/anxiety factors, explaining 55.5% of the total variance. The endpoint data indicated statistically significant (p <.05) improvements over time on the positive factor for all 3 atypicals, but not for haloperidol. The negative factor showed significant improvement for clozapine and olanzapine, with significant worsening for haloperidol. Clozapine, olanzapine, and risperidone were superior to haloperidol on the negative factor, while clozapine was also superior to risperidone. The cognitive factor showed significant improvement for all atypicals, as did the depression/anxiety factor. Only clozapine showed improvement on the excitement factor and was superior to both haloperidol and risperidone. CONCLUSIONS: Treatment with atypical antipsychotics did not substantially change the underlying PANSS 5-factor structure. However, antipsychotic treatment with all 3 atypical medications was associated with significant improvements on 3 of 5 syndromal domains (positive, cognitive, and depression/anxiety) of schizophrenia. Clozapine and olanzapine also showed improvement on the negative factor. Only clozapine was associated with improvement on the excitement domain. This finding confirms that atypicals are associated with improvement of an expanded spectrum of symptoms in treatment-resistant patients.

Adult↗

PubMed2003

Chronic ethanol inhibits the anandamide transport and increases extracellular anandamide levels in cerebellar granule neurons.

Ethanol increases extracellular anandamide levels in neuronal cells. However, the molecular mechanisms by which this occurs are unknown. Chronic exposure of cerebellar granule neurons to ethanol increased the levels of anandamide accumulated in the cellular medium. Anandamide uptake was saturable and was inhibited (30% at 3 min) in response to chronic exposure to ethanol. Chronic ethanol treatment did not alter the K(m), but significantly decreased V(max) of anandamide transport (33%) (P<0.0001). Fatty acid amide hydrolase activity was not affected by chronic ethanol treatment. Anandamide transport processes are independent of cannabinoid CB1 receptor, as cannabinoid CB1 receptor knockout mice exhibited time-dependent anandamide transport and cannabinoid CB1 receptor antagonists did not alter the effects of chronic ethanol on anandamide transport. Furthermore, anandamide transport was inhibited by acute ethanol in a time- and dose-dependent manner. Interestingly, acute ethanol-induced inhibition of anandamide transport was abolished in neurons exposed to chronic ethanol, suggesting that the anandamide transport processes may play a role in the development of long-term cellular tolerance to ethanol.

Animals↗

PubMed2003

Positron emission tomography of regional brain metabolic responses to a serotonergic challenge and lethality of suicide attempts in major depression.

BACKGROUND: Lower serotonergic activity correlates with high-lethality suicide attempts in major depression. Postmortem studies of serotonin receptors in suicides localize changes to the ventral prefrontal cortex (PFC). We studied serotonergic response in ventral PFC in depressed patients surviving a high-lethality suicide attempt. METHODS: Depressed patients with a history of a high-lethality suicide attempt (n = 16) were compared with those with low-lethality attempts (n = 9) for level of depression, suicidal intent and ideation, impulsivity, aggression, and neuropsychological test performance. Subjects were scanned while medication free after a single-blind placebo and after fenfluramine hydrochloride administration on a second day. Brain responses were measured by positron emission tomography imaging of fludeoxyglucose F 18 and serial prolactin levels. Scans were compared by means of statistical parametric mapping. Correlations of changes in relative regional cerebral uptake (rCMRglu) with clinical and neuropsychological measures were assessed. RESULTS: Depressed high-lethality suicide attempters had lower rCMRglu in ventral, medial, and lateral PFC compared with low-lethality attempters. This difference was more pronounced after fenfluramine administration. Lower ventromedial PFC activity was associated with lower lifetime impulsivity, higher suicidal intent (planning), and higher-lethality suicide attempts. Higher verbal fluency was positively correlated with rCMRglu in the same regions. CONCLUSIONS: Prefrontal localized hypofunction and impaired serotonergic responsivity are proportional to the lethality of the suicide attempt and may mediate the effects of suicide intent and impulsivity on lethality. Positron emission tomographic neuroreceptor studies are needed to determine whether postmortem serotonin receptor findings are also present in vivo and contribute to the abnormal rCMRglu responses.

Adult↗

PubMed2003

Prolactin response to fenfluramine administration in patients with unipolar and bipolar depression and healthy controls.

The hormonal response to the serotonin releasing agent/uptake inhibitor fenfluramine has been used as an indicator of central serotonin system function. The serotonergic system plays an important role in the etiology and pathogenesis of mood disorders. We compared the prolactin response to fenfluramine administration in unipolar depressed patients (major depressive disorder), depressed patients with bipolar disorder, and healthy controls. We found a trend towards a blunted prolactin response in depressed patients compared to healthy controls, after controlling for sex, family history, family history-by-gender interaction, and baseline levels. There was no significant difference between unipolar and bipolar patients in the baseline prolactin levels or the response to the fenfluramine administration. We also found a negative correlation between aggression and impulsivity scores and prolactin responses in subgroup with unipolar but not bipolar depression. Female patients with unipolar depression who had first-degree relatives with unipolar depression and normal controls had significantly higher prolactin responses than female patients with unipolar depression who did not have first-degree relatives with unipolar depression. The lack of difference in the response to fenfluramine administration between unipolar and bipolar depressed patients may indicate that overall serotonergic function in unipolar and bipolar depressed patients is similarly impaired.

Adult↗

PubMed2003

How can we improve the assessment of safety in child and adolescent psychopharmacology?

OBJECTIVE: To identify approaches to improving methods for assessing tolerability and safety of psychotropic medications in children and adolescents. METHOD: Strengths and limitations of current methodology were reviewed and possible alternatives examined. RESULTS: Research on the validity of safety evaluation has been extremely limited. No evidence-based "gold standard" exists. Clinical trials remain the best design to establish causality, but sample size limitations prevent the detection of infrequent, though serious, adverse events. Other designs, such as cohort and case-control studies, and approaches, such as mining of large databases, must be considered. CONCLUSION: The current lack of methodological standardization across studies prevents generalizations and meta-analyses. Because the issues relevant to drug safety are diverse, a variety of methodological approaches and instruments are needed. It is, however, possible to adopt standard basic definitions of adverse events, degree of severity, ascertainment methods, and recording procedures, as a common "core," to which more specific assessment instruments can be added. Systematic empirical testing and validation of safety methodology is needed.

Adolescent↗

PubMed2003

Review of safety assessment methods used in pediatric psychopharmacology.

OBJECTIVE: Elicitation is an essential and critical step in ascertaining adverse events (AEs). This report reviews elicitation methods used in published clinical trials of psychopharmacological agents in children. METHOD: Pediatric psychopharmacology reports were reviewed for safety methods in the Medline database. Studies were included if they were published 1980 or later, provided data on AEs, and described the ascertainment methodology used for determining them. RESULTS: A review of 196 pediatric psychopharmacology articles depicting safety assessments in clinical studies over the past 22 years revealed that there was no common method used for eliciting or reporting AE data. CONCLUSION: The current inconsistency in safety data ascertainment is a major limitation that likely impairs the ability to promptly and accurately identify drug-induced AEs. Research on how best to standardize safety methods should be considered a priority in pediatric psychopharmacology.

Adolescent↗

PubMed2003

Developing methodologies for monitoring long-term safety of psychotropic medications in children: report on the NIMH conference, September 25, 2000.

OBJECTIVE: To improve the methods for long-term assessment of drug-associated side effects and advance knowledge of the safety profile of psychotropic medications in children and adolescents. METHOD: A multidisciplinary, interactive workshop was hosted by the National Institute of Mental Health (NIMH) and the Research Units on Pediatric Psychopharmacology network. Participants were experts in child and adolescent psychiatry, psychopharmacology, pharmacoepidemiology, and statistics from academia, the pharmaceutical industry, the Food and Drug Administration (FDA), and the NIMH. Evaluation of drug safety was examined from five perspectives: research design and methods, industry, regulatory requirements, bioethics, and practice settings. For each of these areas, special emphasis was placed on identifying barriers and generating solutions. RESULTS: A major obstacle is the lack of standardization of the methods used for collecting safety data. The limitations of both randomized clinical trials and passive postmarketing surveillance in assessing long-term safety were recognized. The need to consider alternative approaches, such as registries and trend analysis of population-based databases, was highlighted. Recommendations were proposed together with possible approaches to implementation. CONCLUSIONS: A concerted effort by academic researchers, industry, FDA, practitioners, and NIMH is needed to standardize methods and lay the foundations for systematic research on the long-term safety of psychotropic medications in children.

Adolescent↗