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Biomedical subjects

C A Tamminga

Publications and source records attributed to C A Tamminga.

At least 19 recordsLinked to original sources
PubMed1998

Antipsychotic properties of the partial dopamine agonist (-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine(preclamol) in schizophrenia.

BACKGROUND: In an ongoing effort to characterize the clinical pharmacologic profile of the partial dopamine agonist (-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [(-)-3PPP], we administered it to drug-free schizophrenic patients in two consecutive studies. METHODS: In a preliminary dose-finding study, 9 patients were treated using a 6-week placebo-controlled crossover design. Then, to properly demonstrate the antipsychotic effect, we carried out an early efficacy study; here 10 patients received (-)-3PPP, 300 mg B.I.D., in a 1-week placebo-controlled crossover study. RESULTS: Dose-Finding Study: (-)-3PPP showed apparent antipsychotic effect in repeated dosing, with 300 mg B.I.D. being the most effective dose for antipsychotic action; however, the apparent antipsychotic action was not sustained for longer than 1 week, presumably because of desensitization of the receptor by the agonist. Early Efficacy Study: Positive symptoms as measured by the Psychosis Change Scale decreased in 1 week by 30% with (-)-3PPP compared to placebo, and negative symptoms measured with the Brief Psychiatric Rating Scale Withdrawal subscale decreased by 28% with the drug. In both studies, (-)-3PPP lacked any evidence of motor side effects. CONCLUSIONS: These data show that psychotic symptoms decrease with (-)-3PPP and suggest that the treatment of schizophrenia with partial dopamine agonist is a promising strategy. Future attention will be directed toward testing techniques to diminish the tachyphylaxis to allow an ongoing therapeutic effect.

Adult↗
PubMed1998

Phencyclidine (PCP) and dizocilpine (MK801) exert time-dependent effects on the expression of immediate early genes in rat brain.

The mRNA expression pattern for four different immediate early genes was examined dynamically in rat brain after administration of phencyclidine (PCP; 0.86 or 8.6 mg/kg) or MK801 (0.1 or 1.0 mg/kg). Following each treatment, the expression of cfos, cjun, junB, and zif268 mRNA changed distinctively and dynamically between 1 and 48 hours. cfos mRNA was induced in cortical areas at early times after either dose of PCP or of MK801; the change was especially prominent in cingulate and auditory cortices. zif268 mRNA showed an early (1 hour) activation and a delayed (24-48 hour) suppression after PCP and MK801 in neocortical areas. PCP also caused cjun and junB mRNA induction in cortical areas at early times, with a distribution and time course similar to its effects on cfos mRNA. No alterations in cfos, cjun, or junB mRNA were found in neocortical or hippocampal areas at any delayed time (>6 hours) after PCP treatment, whereas suppression of zif268 expression was prominent even at 48 hours post-treatment. CPP, a competitive NMDA antagonist, showed a similar pattern of effects on cfos and zif268 mRNA expression. These functional consequences of a PCP- or MK801-induced reduction in NMDA-sensitive glutamate transmission may be relevant to an understanding of animal NMDA pharmacology and/or to clinical psychotomimetic side effects of antiglutamatergic treatments.

Animals↗
PubMed1998

Mixture in the distribution of haloperidol-induced oral dyskinesias in the rat supports an animal model of tardive dyskinesia.

Spontaneous adventitious oral movements which are produced in rats by very chronic (6-month) neuroleptic treatment have some phenomenologic and pharmacologic characteristics in common with tardive dyskinesia in humans. However, since not all of the features match, this putative model has been questioned and further support is warranted. Data from several laboratories support dichotomizing these neuroleptic-induced rat oral movements into "low" or "not TD-like" movements and "high" or "TD-like" movements, similar to the division of neuroleptic-induced involuntary movements in humans. Here, we have used mixture analysis to test this proposal statistically in 185 haloperidol-treated and 127 water-treated animals. Rats from several different studies were grouped together to form these two cohorts. The haloperidol dose, route of administration, rating technique, and balanced experimental groups were held constant across all experiments. Results show that two distinct groups of rat movements are induced by very chronic haloperidol treatment (1.5 mg/kg per day). The "low" vacuous chewing movement (VCM) group of rats had an average of 3.6 VCMs/5 min, and the "high" VCM group had an average of 16.1 VCMs/5 min; the control group, with a median VCM rate of 2.0 VCMs/5 min, demonstrated a single distribution. These data suggest that rats, like humans, dichotomize into two groups either expressing or not expressing "high" VCM dyskinesias with very chronic haloperidol treatment.

Animals↗
PubMed1998

Schizophrenia and glutamatergic transmission.

Schizophrenia is a human brain disease with well-defined symptoms and a lifelong disease course, but without a current biological explanation. Several observations implicate brain glutamatergic abnormalities in the pathophysiology of this illness. This evidence includes both human neurochemical and clinical pharmacologic data. Furthermore the psychotomimetic action of phencyclidine, the noncompetitive NMDA-sensitive glutamate receptor antagonist, suggests the association between human psychosis and NMDA receptor blockade. This paper reviews basic aspects of glutamatergic transmission in animal and human brain with particular attention to its putative role in schizophrenia. Consideration is given to other glutamate-related human brain diseases and their purported mechanisms. Evidence of glutamatergic abnormalities in schizophrenia is critically reviewed, including data using postmortem neurochemistry, in vivo human brain imaging, clinical pharmacology, and animal models. The current theoretical formulations based on these studies are articulated. We propose a "working" glutamate hypothesis of schizophrenia which postulates a diminished glutamatergic transmission in the hippocampal glutamate-mediated efferent pathways and cerebral dysfunction in the hippocampus and its target areas, especially the anterior cingulate cortex. Considerable work remains to be done in this area to formulate and test a comprehensive hypothesis.

Brain Chemistry↗
PubMed1997

Benzodiazepine receptors in the post-mortem brain of suicide victims and schizophrenic subjects.

To examine the role of benzodiazepine (BZ) receptors in suicide and schizophrenia, we determined BZ receptors in post-mortem brain (Brodmann's area 10) obtained from suicide victims, schizophrenic patients, and control subjects using [3H]RO15-1788 as the radioligand. The maximum number of binding sites (Bmax) of BZ receptors in the cortex of suicide victims was significantly higher compared with controls, but this increase was mainly due to those suicide victims who died by violent means and whose Bmax was significantly higher than of those who died by non-violent means or control subjects. In schizophrenic patients, Bmax was not significantly different from that of control subjects. When the schizophrenic subjects were separated into two groups, those on neuroleptics and those off neuroleptics for at least 12 months, however, the mean Bmax of BZ receptors in the prefrontal cortex in post-mortem brain obtained from schizophrenic patients on neuroleptics was significantly lower than Bmax in drug-free schizophrenic patients or normal controls. There were no significant differences among groups in values of the apparent dissociation constant (KD) of [3H]RO15-1788 binding. These results suggest that BZ receptors are up-regulated in the cortex of suicide victims, specifically those who used violent means, and that neuroleptic treatment may result in decreased central BZ receptor binding in the cortex of schizophrenic patients. Thus, the method of suicide and previous exposure to neuroleptics should be considered in the interpretation of data on BZ receptors.

Adult↗
PubMed1997

Protein kinase C in the postmortem brain of teenage suicide victims.

Increased serotonin2A (5-HT2A) receptors have been reported in the postmortem brain of suicide victims. To examine if this increase is associated with the dysregulation of postreceptor sites in the signaling cascade, we determined [3H]phorbol dibutyrate (PDBU) binding to protein kinase C (PKC) in postmortem brain samples (Brodmann's areas 8 and 9) obtained from teenage suicide victims and control subjects. [3H]PDBU binding to PKC was determined in membranal and cytosolic fractions. We observed that Bmax of [3H]PDBU binding sites was significantly decreased in both membranal and cytosolic fractions in brain samples from Brodmann's areas 8-9 compared to matched controls. These results thus suggest that PKC may play a role in the pathophysiology of suicidal behavior.

Adolescent↗
PubMed1997

The Maryland Psychiatric Research Center scale and the characterization of involuntary movements.

The Maryland Psychiatric Research Center involuntary movement scale (MPRC scale) has been used in the evaluation of 1107 patients referred for drug-induced movement disorders. The scale has increased discrimination of body area and severity compared to other scales. Validity was examined using principal component analyses, pharmacologic response studies and associations with AIMS, global judgement and motor diagnosis. Reliability was examined using Cronbach's alpha, intraclass correlation coefficient (ICC) between raters and test-retest measurements. The prevalence of dyskinetic and parkinsonian signs at several levels of severity are reported. Total dyskinesia was strongly correlated with AIMS score, r = 0.97. Inter-rater reliability was 0.81-0.90 for total dyskinesia score. Receiver Operating Characteristic (ROC) analysis shows a total dyskinesia score of 4 or above to predict tardive dyskinesia, consistent with RDC-TD criteria. Hand dyskinesia showed a high prevalence comparable to that of oral dyskinesias. The MPRC scale is a valid, sensitive and reliable instrument for the rating of neuroleptic-induced dyskinetic and parkinsonian syndromes and may offer advantages over other scales in neurophysiologic research and brain imaging with its ease of use, uniform structure and greater discrimination of anatomic place and severity in the rating of involuntary movements.

Dyskinesia, Drug-Induced↗
PubMed1997

The effect of chronic haloperidol treatment on dendritic spines in the rat striatum.

Previous studies have shown that schizophrenics, in comparison to controls, have reduced cortical spine density and smaller striatal spines. The current study in the rat was conducted to determine whether such differences could result from chronic neuroleptic treatment and whether they are correlated with neuroleptic-induced oral dyskinesias. Rats administered 1.5 mg/kg/day of haloperidol (HA) (n = 28) or water (n = 10) were tested for vacuous chewing movements (VCMs). After 6 months, rats were divided into low and high VCM groups; all but seven high VCM rats were sacrificed. These rats (withdrawn group) were withdrawn from HA for 4 weeks. Random electron micrographs of the striatum were analyzed for spine changes. Spine size was not significantly affected by HA (0.193 vs 0.174 microm2, HA and control, respectively) nor correlated with oral dyskinesias (0.191 vs 0.196 microm2, low and high VCM groups, respectively). These results suggest that smaller spines in schizophrenic striatum may be correlated with the disease rather than caused by neuroleptic treatment. Spine density decreased in the HA-treated group (32.7 +/- 9.5) in comparison to controls (53.7 +/- 7.3, P < 0.001) and remained low in the withdrawn group (35.0 +/- 4.2, P < 0.01). Spine density also decreased in both the low (37.3 +/- 9.9, P < 0.01) and the high (28.0 +/- 7.0, P < 0.000) VCM groups in comparison to controls. However, there was no significant difference between high and low VCM groups, suggesting that decreased spine density is independent of oral dyskinesias. These results suggest that the decreased spine density observed in schizophrenic cortex may be a result of neuroleptic treatment.

Animals↗
PubMed1997

The dose-response characteristics of rat oral dyskinesias with chronic haloperidol or clozapine administration.

Whether the pathophysiology and treatment of neuroleptic-induced oral dyskinesias in rats parallel that for tardive dyskinesia in humans remains a question. To address the issue further, Sprague Dawley rats were treated for 6 months with multiple oral doses of haloperidol (1.5 and 3.0 mg/ kg/day) or clozapine (10, 20, and 30 mg/kg/day) and compared with water treated animals. The rate of oral dyskinesias was monitored at study start and monthly by trained raters who were blind to treatment group. All haloperidol-treated rats developed oral dyskinesias at a significantly higher rate than rats treated with water (p = 0.0007) or those treated with clozapine (p = 0.0017). Each dose of haloperidol produced significantly higher rates of oral dyskinesias than did any dose of clozapine and did so in an apparent dose-sensitive manner. Clozapine lacked a dose-sensitive relationship with the oral dyskinesias, and failed to show a significant difference in rate from control rats at any dose. Plasma levels of haloperidol with these doses were in the human therapeutic range; with clozapine only the highest dose produced plasma levels in the human therapeutic range. These data show little association between rat oral dyskinesias and clozapine treatment, whereas a strong association is present with haloperidol. The data are, thereby, consistent with the clinical association of tardive dyskinesia with typical neuroleptics like haloperidol but not with the atypical neuroleptic clozapine.

Administration, Oral↗
PubMed1997

Neurochemical and metabolic consequences of elevated cerebrospinal fluid quinolinic acid concentrations in rat brain.

Quinolinic acid (QUIN) is an endogenous excitatory amino acid, which is elevated in brain tissues or cerebrospinal fluid (CSF) in several acute and chronic inflammatory central nervous system (CNS) diseases. The functional significance of this elevation is unknown but speculations of excitotoxicity have been raised. We have begun to address the pathologic consequences of elevated CSF QUIN by studying the effects of intracerebroventricular (i.cv) administration of QUIN on regional choline acetyltransferase (ChAT) activity, somatostatin content and glucose metabolism in the rat brain. QUIN (12 and 60 nmol) i.cv administration once a day for 7 days (total dose; 84 and 420 nmol, respectively) had minimal effect on somatostatin content and no effect on ChAT activity. In contrast, following continuous i.cv infusion of QUIN for 14 days using an osmotic minipump (480 nmol), ChAT activity dropped in the hippocampus and the striatum and somatostatin content was reduced in the frontal cortex, hippocampus, striatum and amygdala. Moreover, following the QUIN infusion, glucose utilization decreased in the basal nucleus of Meynert, frontal cortex, and portions of the basal ganglia and the limbic system. These results indicate that subchronic i.cv infusion of QUIN to rats results in selective regional neurochemical and metabolic changes distributed throughout the CNS. These results suggest target brain areas and transmitter systems which may be associated with neurologic syndromes characterized by elevated CSF QUIN levels.

Animals↗
PubMed1997

Sertindole in the treatment of psychosis in schizophrenia: efficacy and safety.

Evidence from clinical trials supports the claim that sertindole is a potent antipsychotic drug at a dose of 12-24 mg/day. Its action against positive symptoms is as potent as that of the traditional antipsychotic haloperidol. Its action against negative symptoms is significantly different from that of placebo and quantitatively larger than that of haloperidol. Its most distinctive characteristic is a reduction in motor side effects over a whole range of comparable drug and comparator doses. More work is needed to determine whether sertindole's actions against negative symptoms influence the primary or the secondary negative system. There are insufficient data at present to compare sertindole with the highly efficacious drug clozapine or the other new antipsychotic olanzapine.

Antipsychotic Agents↗
PubMed1997

Controlled, dose-response study of sertindole and haloperidol in the treatment of schizophrenia. Sertindole Study Group.

OBJECTIVE: This multicenter, double-blind, placebo-controlled study evaluated the efficacy and safety of three doses of sertindole (12, 20, and 24 mg/day) and haloperidol (4, 8, and 16 mg/day) in the treatment of psychotic symptoms for 497 hospitalized patients with schizophrenia. METHOD: The patients were randomly assigned to one of the medication groups and received treatment for 8 weeks. Changes in Positive and Negative Syndrome Scale, Scale for the Assessment of Negative Symptoms, Brief Psychiatric Rating Scale, and Clinical Global Impression scores were used as evaluations of treatment efficacy. Three rating scales were used to assess extrapyramidal symptoms as well as the occurrence of adverse events and the use of medications related to extrapyramidal symptoms. RESULTS: Both sertindole and haloperidol were comparably effective in the treatment of psychosis, and all dose levels were significantly more effective than placebo. For the treatment of negative symptoms, only sertindole, 20 mg/day, was significantly more effective than placebo. For all extrapyramidal symptom measures, sertindole was clinically and statistically indistinguishable from placebo, and rates of extrapyramidal symptoms were not dose related. All dose levels of haloperidol produced significantly more extrapyramidal symptoms than placebo or sertindole. Adverse events associated with sertindole treatment were mild in severity. CONCLUSIONS: Sertindole is a new antipsychotic agent effective for the treatment of both the positive and negative symptoms of schizophrenia, with motor side effects that are indistinguishable from those associated with placebo.

Adolescent↗
PubMed1997

Time to clozapine response in a standardized trial.

OBJECTIVE: The authors sought to determine the time to clozapine response in treatment-refractory patients with schizophrenia. METHOD: Antipsychotic response to a clozapine trial was examined in 50 treatment-refractory schizophrenic inpatients. Subjects were treated with clozapine for at least 12 months, regardless of response status, according to a standardized, increasing dose protocol. Behavioral changes were measured through monthly assessments with the Brief Psychiatric Rating Scale. RESULTS: Thirty-four subjects (68%) met clinical response criteria by the end of the trial. Response was achieved at a mean dose of 468 mg/day (SD = 168). The dose of 30 (88%) of the responding patients was 600 mg/day or less. The mean time to response was 82 days (SD = 100, range = 10-401). It took an average of 60 days (SD = 87) for subjects to reach the dose at which clozapine response was achieved. Once this dose was reached, the average response time was 17 days (SD = 14, range = 2-56). All 34 subjects who responded met criteria within 8 weeks of a clozapine dose escalation. No late response was found in the remaining 16 subjects despite a mean follow-up period of 75 weeks (SD = 50). CONCLUSIONS: In this study, all patients who responded to clozapine did so within 8 weeks of a change in dose. Thus, there appears to be little clinical gain in prolonging exposure to clozapine beyond 8 weeks at any particular dose if no response is seen.

Adult↗
PubMed1997

The promise of new drugs for schizophrenia treatment.

OBJECTIVE: To present aspects of preclinical and clinical pharmacology of new antipsychotic drugs and to emphasize those preclinical drug characteristics which might predict desirable clinical actions. METHOD: Review of the relevant literature and publicly presented data. RESULTS: Traditional neuroleptics have considerable effectiveness in treating positive symptoms of psychosis but can cause serious motor side effects. Clozapine produces no motor side effects and delivers a unique antipsychotic action. Risperidone also produces low motor side effects, but only at relatively low doses. Olanzapine and sertindole are newly introduced. Both have potent antipsychotic actions, with greatly reduced motor side effects. Both drugs also have possible advantages in negative symptoms. CONCLUSIONS: These data support the conclusion that several new antipsychotics are becoming available for general use which are safe and effective in the treatment of psychosis and have several advantages over traditional neuroleptics.

Antipsychotic Agents↗
PubMed1997

The application of neuroimaging techniques to drug development.

Neuroimaging is a powerful and innovative tool for studying the pathology of psychiatric diseases and, more recently, for studying the drugs used in their treatment. Technological advances in imaging have made it possible to noninvasively extract information from the human brain regarding a drug's mechanism and site of action. Until now, our understanding of human brain pharmacology has depended primarily on indirect assessments or models derived from animal studies. However, the advent of multiple techniques for human brain imaging allows researchers to focus directly on human pharmacology and brain function. This review outlines available neuroimaging techniques and examines how these various methods have already been applied to the drug development process, as well as how they might be applied in the future.

Antipsychotic Agents↗
PubMed1997

Gender and schizophrenia.

Schizophrenia is a chronic psychotic illness that characteristically manifests itself from the early adult years throughout the entirety of life. Its symptoms are well known, its phenomenology has been exhaustively studied, and palliative treatments exist, although they rarely produce complete response. The pathophysiology and the etiology of the illness remain unknown. Clues to the basic understanding of schizophrenia are rare, but they do appear. Gender differences in schizophrenia have always been implicated in the challenge to clearly understand the disorder. Male and female schizophrenics display identical symptomatic features during acute illness, seemingly minimizing the relevance of gender issues. Within the last decade, however, more careful screening has revealed significant gender differences in schizophrenia: in age at onset, premorbid personality, subtype of schizophrenia, psychosocial function, and treatment response. Attention to these differences could be important to answer theoretical and therapeutic questions regarding the disorder.

Adaptation, Psychological↗