Spontaneous onset of type I atrial flutter in patients

OBJECTIVES

This study sought to characterize the spontaneous onset of atrial flutter in patients.

BACKGROUND

Temporary epicardial electrodes are routinely placed on the atria of patients at the time of open heart surgery and brought out through the anterior chest wall for potential diagnostic and therapeutic use in the postoperative period. We utilized these electrodes to study the spontaneous onset of type 1 atrial flutter in 16 patients in the postoperative period after open heart surgery.

METHODS

Twenty-seven episodes of the spontaneous onset of type I atrial flutter from sinus rhythm were studied in these 16 patients by recording bipolar atrial electrograms simultaneously with at least one electrocardiographic lead during each episode.

RESULTS

In all 27 episodes, the onset of type I atrial flutter was through a transitional rhythm of variable duration (mean 9.3 s) precipitated by a premature atrial beat. In 21 episodes, the transitional rhythm was atrial fibrillation; in 3 episodes it was type II atrial flutter that appeared to generate atrial fibrillation; and in 3 episodes it was a brief (3 to 6 beats), rapid, irregular arrhythmia.

CONCLUSIONS

Type I atrial flutter does not start immediately after a premature atrial beat. Rather, it starts after a transitional rhythm that is usually atrial fibrillation. Extrapolating from mapping studies of the onset of atrial flutter in the canine pericarditis model, we suggest that a transitional rhythm is required for the initiation of type I atrial flutter because during that rhythm, the requisites for development of the atrial flutter reentry circuit evolve.

5-HT3 receptor antagonism by ondansetron does not attenuate prolactin response to d-fenfluramine challenge in healthy human subjects

Prolactin responses to d-fenfluramine (d-FEN) challenge (0.5 mg/kg PO) were examined after pre-treatment with and without the 5-HT3 receptor antagonist ondansetron (16 mg PO) in 11 physically healthy male volunteers. Compared to pretreatment with placebo, pre-treatment with ondansetron did not significantly attenuate the PRL response to d-FEN challenge. These data are consistent with other data suggesting little role for 5-HT3 receptors in the PRL response to 5-HT agonist challenge in human subjects.

Hostility is associated with a low prolactin response to meta-chlorophenylpiperazine in abstinent alcoholics

The prolactin response to the administration of serotonin agonists is an index of central nervous system serotonin (5HT) activity. This index is blunted in association with hostile aggression in personality-disordered individuals without substance abuse. We tested whether prolactin response to the partial 5HT agonist meta-chlorophenylpiperazine (MCPP) (0.35 mg/kg po) was associated with measures of trait hostility in alcoholics who were completing a 3-week rehabilitation program after medical detoxification. We also tested whether the same 5HT index differed in the group of alcoholics compared with the healthy volunteers. The prolactin response to MCPP was inversely associated with the main index of trait hostility and was similarly inversely associated with an index of depression. There was, however, no difference in neuroendocrine or temperature responses to MCPP between the alcohol-dependent group and the healthy volunteers.

Lithium distribution in experimental inflammation of brain and spinal cord

1. Autoimmune inflammation of the nervous system caused extensive changes in the distribution of lithium injected into rats. 2. Serum lithium levels were greatly increased because of failure of renal excretion caused by pre-renal azotemia, urinary retention and lack of dietary sodium. Brain, spinal cord, pituitary and adrenal levels of lithium were also elevated, reflecting the high serum levels. 3. However, the location and degree of this elevation corresponded to the predominant location of the inflammation. As a result, lithium levels in spinal cord approached and even exceeded the lithium content of brain.

5-HT2a/2c receptor blockade by amesergide fully attenuates prolactin response to d-fenfluramine challenge in physically healthy human subjects

Prolactin responses to d-fenfluramine (d-FEN) challenge (0.5 mg/kg PO) were examined after pre-treatment with and without the 5-HT2a/2c receptor antagonist amesergide in eight physically healthy male volunteers. Compared to pretreatment with placebo, pre-treatment with amesergide completely blocked the prolactin (PRL) response to d-FEN challenge in all subjects. These data are consistent with data demonstrating a complete blockade of the PRL response to d-FEN with the 5-HT2a/2c receptor antagonist ritanserin, and suggest that the PRL response to d-FEN challenge in humans may largely be due to activation of the 5-HT2a/2c receptor.

Pregnancy enhances cocaine-induced stimulation of uterine contractions in the chronically instrumented rat

OBJECTIVE

Our purpose was to test whether cocaine stimulates uterine activity in nonpregnant and pregnant rats.

STUDY DESIGN

The carotid artery and jugular vein were chronically catheterized, and a microballoon probe was inserted into the uterine cavity of 15 pregnant and 14 nonpregnant female rats. Conscious animals received a bolus dose of either cocaine or saline solution intravenously. Cardiovascular and uterine contractile responses were studied.

RESULTS

Cocaine (2.5 mg/kg) induced a marked increase in uterine activity and arterial blood pressure in both pregnant and nonpregnant animals without producing systemic toxicity. The maximum change in uterine contractions was greater in the pregnant group than in the nonpregnant group, and blood pressure responses were transient in both.

CONCLUSION

This study is the first demonstration that cocaine stimulates the rat uterus in vivo, with a greater increase in contractions in pregnant compared with nonpregnant animals. These differences are not related to the hemodynamic response or pharmacokinetic profile of cocaine.

Hormonal responses to meta-chlorophenylpiperazine (m-CPP) are undiminished by acute m-CPP pretreatment

Two challenges with meta-chlorophenylpiperazine (m-CPP, 0.5 mg/kg, p.o.) were performed in healthy volunteers to test the short-term stability of hormonal responses. Challenges were performed in an identical fashion and were conducted on sequential days. Circulating m-CPP plasma levels, as well as prolactin and cortisol responses to m-CPP, were correspondingly similar in magnitude on the 2 days. These data suggest that both prolactin and cortisol responses to single oral administrations of m-CPP are stable over at least a 24-h period.

Blunted change in cerebral glucose utilization after haloperidol treatment in schizophrenic patients with prominent negative symptoms

OBJECTIVE

The purpose of this report was to determine 1) the effects of chronic haloperidol treatment on cerebral metabolism in schizophrenic patients, 2) the relation between negative symptoms and haloperidol-induced regional changes in cerebral glucose utilization, and 3) the relation between metabolic change and clinical antipsychotic effect.

METHOD

Cerebral glucose utilization, as determined by position emission tomography (PET), was studied in 18 male schizophrenic subjects before and after chronic treatment with haloperidol at a standardized plasma level.

RESULTS

Overall, haloperidol caused a widespread decrease in absolute cerebral glucose metabolism. The cerebral metabolic response to haloperidol was blunted in patients with high pretreatment negative symptom scores.

CONCLUSIONS

Taken together with the results from a previously reported PET study of the effects of an acute amphetamine challenge (in which 14 of the current subjects participated), these data suggest that the negative symptom complex is associated with diminished cerebral response to change in dopaminergic activity. This deficit cannot be solely accounted for by structural differences.

Determination of 3,4-dihydroxyphenyl glycol in plasma by gas chromatography-mass spectrometry and high-performance liquid chromatography methods

Several modifications of GC-MS and HPLC methods for plasma level DHPG have been described. The effects of storage temperature and stabilizing agents on DHPG stability have been studied. The stabilizing agent has been found to play a more important role than low-temperature storage in preventing DHPG from decomposition during sample storage. A specific and sensitive GC-MS method (electron impact) has been established using stable isotope-labeled DHPG as an internal standard. HPLC has been improved by modifying the conditions, resulting in a good separation of DHPG and internal standard from solvent front other early eluting compounds. Comparison of the GC-MS and HPLC procedures demonstrates a strong correlation between these two methods.

Demonstration in vivo of reduced serotonin responsivity in the brain of untreated depressed patients

OBJECTIVE

For over 25 years, it has been hypothesized that major depression is due to a deficiency of available serotonin or subsensitivity of key serotonin receptors in relevant brain regions. Direct evidence supporting this hypothesis has been lacking because of the difficulty in studying regional brain serotonergic function. The authors have developed a method for visualizing in vivo regional brain responses to serotonin release by comparing regional brain glucose metabolism after administration of the serotonin-releasing drug dl-fenfluramine, relative to placebo.

METHOD

Results with healthy subjects (N = 6) were compared to those obtained with drug-free inpatients with moderately severe major depression (N = 6).

RESULTS

Healthy subjects had several areas of statistically significant increases in metabolism, mostly in the left prefrontal and temporoparietal cortex, and areas of decreased metabolism, such as in the right prefrontal cortex. In contrast, the depressed patients had no areas of increase or decrease in metabolism, differing significantly from healthy subjects. Results with patients resembled those with healthy subjects (N = 10) who were scanned twice without active drug on either occasion.

CONCLUSIONS

This study provides the first direct visualization of blunted regional brain responses to serotonin release in the brain of patients with major depression, a finding that supports the hypothesis of impaired serotonergic transmission in depression.

Amphetamine and negative symptoms of schizophrenia

The purpose of this study was to assess further the effect of amphetamine on negative symptoms of schizophrenia. Thirty-seven schizophrenic males meeting DSM-III criteria were rated with the Brief Psychiatric Rating Scale, the Abrams and Taylor Scale, and the Abnormal Involuntary Movements Scale before and after double-blind administration of either amphetamine (n = 26) or placebo (n = 11). Our results indicated that amphetamine administration generally did not improve negative symptoms, even when accounting for changes in positive symptoms. However, greater baseline negative symptoms were associated with a modest diminution after amphetamine treatment. Therefore, amphetamine may modestly improve negative symptoms in those schizophrenics in whom this symptomatology is more severe.

Placebo washout in trials of antipsychotic drugs

For antipsychotic phase 3 clinical trials, we compare the relative merits of a placebo washout period with an alternate design strategy using a low-dose antipsychotic treatment. Evaluations are made with respect to the achievement of specific clinical trial design goals including the effect on power for detecting between-treatment and within-treatment pre-post differences. The relative merits of these two designs are discussed separately for those patients who enter the initial leadin period after withdrawal from previous antipsychotic medication and for those not on medication immediately before that period.

Clozapine plasma level monitoring: current status

Plasma level monitoring of clozapine and metabolites may prove beneficial in treating patients who show unusual drug metabolic activity. A threshold plasma level for patients who will respond to this medication is suggested. The interaction of gender, age, smoking, other medication and side effects with plasma clozapine and metabolites are discussed. Plasma level monitoring of clozapine and/or metabolites is recommended in patients who do not respond at usual therapeutic dose, who show untoward side effects at low dose or who are treated with other medications. Finally monitoring of patients who require more than 600 mg/day should be implemented because there is evidence that the incidence of seizures increases significantly above this dosage level. There is some evidence that high plasma clozapine levels are associated with seizures.

Serotonin in violent patients with schizophrenia

CSF levels of 5-hydroxyindolacetic acid (5-HIAA), the serotonin metabolite, were assayed in 10 violent and 10 matched nonviolent patients with schizophrenia. Mean group levels of 5-HIAA in cerebrospinal fluid were found to be nearly identical. Possible explanations, including effects of medications, are discussed.

Plasma haloperidol levels and clinical effects in schizophrenia and schizoaffective disorder

BACKGROUND

Plasma haloperidol levels between 5 and 11 ng/mL may be clinically optimal for acutely exacerbated schizophrenia, but the evidence for this therapeutic window has been inconsistent.

METHODS

Haloperidol was administered in a double-blind manner during two consecutive 3-week experimental periods to 65 patients with acutely exacerbated schizophrenia or schizoaffective disorder. Two plasma levels were targeted: "low" (2 ng/mL) and "moderate" (10 ng/mL). The subjects were randomly assigned to four treatment sequences (low-low, low-moderate, moderate-moderate, or moderate-low).

RESULTS

In the first 3 weeks, the antipsychotic efficacy of haloperidol increased with plasma levels up to approximately 12 ng/mL. In the second 3 weeks, decrease of plasma levels reduced negative symptoms.

CONCLUSION

For most patients, plasma levels not exceeding 12 ng/mL yield the best results in the first 3 weeks of treatment. Subsequent lowering of the plasma levels may improve negative symptoms.

Decline of DNA damage and other biomarkers in peripheral blood following smoking cessation

Serial samples from 40 heavy smokers ( > or = pack/day for > or = 1 year) enrolled in a smoking cessation program were assayed for cotinine, polycyclic aromatic hydrocarbon (PAH)-DNA, 4-aminobiphenyl-hemoglobin (4-ABP-Hb) adducts, and glycophorin A (GPA) mutations. Blood samples were taken while subjects were smoking, and 10 weeks and 8 and 14 months after quitting. Cotinine was used to assess compliance with the cessation protocol. A significant reduction in mean PAH-DNA and 4-ABP-Hb adducts was observed after cessation in all persons who were cotinine-verified quitters ( < or = 25 ng/ml) for > or = 8 months (P < 0.05). Neither the GPA N/phi nor the GPA N/N mutation Vf was significantly reduced after smoking cessation, but results are limited by the small number (n = 18) of heterozygous individuals studied. The substantial reduction (50-75%) in PAH-DNA and 4-ABP-Hb adduct levels after quitting indicates these carcinogen adducts are reflective of smoking. Passive exposure to smoke at home was significantly associated with PAH-DNA adducts in active smokers and in ex-smokers 10 weeks after quitting (P < 0.01). The estimated half-life of the PAH-DNA adducts in leukocytes is 9-13 weeks by inspection of the mean biomarker levels from baseline and 10 weeks sample and 23 (95% confidence interval, 10-36 weeks) using a linear regression model that adjusted for background.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of 8-hydroxydeoxyguanosine by an immunoaffinity chromatography-monoclonal antibody-based ELISA

The postulated importance of oxidative damage to DNA in aging and age-related degenerative pathologies such as cancer has prompted efforts to develop sensitive quantitation methods. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is a widely used marker for oxidative damage to DNA. To develop an immunoassay for quantitation of 8-OHdG, two monoclonal antibodies have been developed and characterized by competitive enzyme-linked immunosorbent assay (ELISA). Antibody 1F7 has 50% inhibition at 5 pmol 8-OHdG and 1 x 10(5) pmol dG, while antibody 1F11 has 50% inhibition at 2.5 pmol 8-OHdG and 2000 pmol dG. Both antisera crossreact with guanosine and several structurally related derivatives, including 6- and 8-mercaptoguanosine, 8-bromoguanosine, 8-methylguanine, and 7-methylguanosine. Immunoaffinity columns were prepared with antibody 1F7, which exhibits higher selectivity than 1F11, to isolate 8-OHdG from DNA hydrolyzates followed by ELISA quantitation with antibody 1F11. This method allows the analysis of approximately one 8-OHdG/10(5) dG using 100 micrograms DNA. To validate the assay, DNA extracted from human placental tissues were assayed by both ELISA and HPLC with electrochemical detection. Values by both methods correlated well (r = 0.87, p < 0.001), but the levels determined by ELISA were approximately sixfold higher than those determined by HPLC. This may be due to oligonucleotides detected by the ELISA but not the HPLC method or crossreactivity with other damaged bases present in the immunoaffinity purified material. Placental samples from current smokers had significantly higher 8-OHdG by ELISA than those from nonsmokers (p < 0.05). The method of immunoaffinity purification combined with ELISA quantitation has sufficient sensitivity for detecting 8-OHdG in human DNA samples. Although absolute values are higher than those determined by HPLC, the method provides a good alternative to the HPLC-EC method for monitoring relative oxidative damage in molecular epidemiological studies.

Fluphenazine plasma levels, dosage, efficacy, and side effects

OBJECTIVE

The authors sought to determine whether fluphenazine dose or plasma level predicts clinical improvement or side effects during acute treatment.

METHOD

Oral fluphenazine was given in fixed, randomized, double-blind doses (10, 20, or 30 mg/day) for 4 weeks to 72 inpatients with acute schizophrenic exacerbations. Outcome measures included percentage improvement in ratings of positive symptoms (hallucinations, delusions, and thought disorder), percentage improvement in negative symptoms, and maximum score for extrapyramidal symptoms. Response was defined as an improvement in positive symptoms of 40% or more.

RESULTS

The 42 responders had a shorter duration of illness, less chronic course, and lower rate of akathisia. Plasma level and dose did not differentiate responders and nonresponders, but they did predict percentage improvement in positive symptoms within the responder subgroup. Akathisia was more common and extrapyramidal symptoms were more severe at higher plasma levels.

CONCLUSIONS

Responders showed the greatest improvement at fluphenazine plasma levels above 1.0 ng/ml and doses above 0.20-0.25 mg/kg per day. Since the literature suggests that optimal plasma levels are similar during acute and maintenance treatment, monitoring of plasma levels may thus be useful. Conditions for applying the "responder-only" analytic strategy in future studies are discussed.

CYP1A1 messenger RNA levels in placental tissue as a biomarker of environmental exposure

The human CYP1A1 gene codes for an inducible enzyme system involved in biotransformation of certain xenobiotics, including polycyclic aromatic hydrocarbons; some of the metabolites are carcinogenic and mutagenic. Effects of environmental exposures (smoking, air pollution, and diet) on CYP1A1 gene induction in placental tissue and the modulation of induction by the CYP1A1 MspI RFLP were evaluated in two groups from Poland: 70 mother-child pairs from Krakow, a city with elevated air pollution; and 90 pairs from Limanowa, a less polluted area. Compared to placentas from nonsmoking women, CYP1A1 mRNA levels were significantly increased in placentas from current smokers (P < 0.001). Ex-smokers also had significantly higher placental mRNA levels, including women who quit smoking prior to pregnancy (P < 0.01). A marginal increase in CYP1A1 mRNA with environmental tobacco smoke exposure was evident. Within Krakow, there was an increase in CYP1A1 mRNA with ambient pollution at the place of residence for each woman, which was significant among women who were not employed away from the home (P < 0.05 controlling for smoking status, diet, and use of coal for heating). Significant increases in mRNA were associated with dietary consumption of smoked meat, cheese, and fish (P < 0.01). The CYP1A1 MspI RFLP was not a significant determinant of CYP1A1 mRNA levels after controlling for smoking and other variables. Human placenta provides a readily available and responsive system that can serve as a model for evaluating environmental and genetic determinants of CYP1A1 induction.

Biomarkers of environmental tobacco smoke in preschool children and their mothers

BACKGROUND

Adverse health effects attributable to environmental tobacco smoke (ETS) include respiratory illness and lung cancer in nonsmokers. There is accumulating evidence that children may be at heightened risk of cancer later in life as a result of exposure to carcinogens during their early development. It is of concern that as many as 9 million American children under the age of 5 years may be exposed to ETS.

PURPOSE

Our goal was to assess whether levels of cotinine and polycyclic aromatic hydrocarbon-albumin (PAH-albumin) are associated with ETS exposure in children and in women of reproductive age, after accounting for background exposures to PAHs in the diet, workplace, and the home environment.

METHODS

The study cohort was composed of 87 Hispanic and African-American mothers and 87 of their preschool children (2-5 years of age). Plasma cotinine was analyzed by gas chromatography; PAH-albumin adducts in peripheral blood were analyzed by enzyme-linked immunosorbent assay. Exposure data were obtained by interview-administered questionnaires.

RESULTS

Both cotinine and PAH-albumin were significantly higher in the children whose mothers smoked than in the children of nonsmoking mothers (P < .001 and P < .05, respectively). Among the children of nonsmoking mothers, cotinine levels were also significantly higher in those who had ETS exposure from others in the household compared with the unexposed children. By regression analysis, after adjustment for ethnicity, there was a significant dose-response relationship between cotinine and the number of cigarettes smoked per day by the mother, both in the children (partial r2 = .23; P = .01) and in the mothers (partial r2 = .22; P = .01). Among the nonsmoking mothers, regression of biomarkers against total passive smoking exposure also showed a significant association with cotinine (r2 = .25; P = .04). PAH-albumin did not show the same dose-related response with the smoking variables. Mothers' cotinine levels were significantly correlated with those of their children (r = .76; P < .001) as were PAH-albumin adducts (r = .27; P = .014).

CONCLUSION

ETS exposure of young children via their mothers' smoking is associated with increases not only in the internal dose of ETS (cotinine), which has been previously reported, but also in the biologically effective dose of the carcinogenic (PAH) components of ETS (PAH-albumin adducts). This observation underscores the carcinogenic and public health hazard of ETS.

IMPLICATIONS

Given the relatively low level of ETS exposure in this study, these results reinforce the need for effective programs aimed at smoking prevention and cessation among women, particularly women of reproductive age and minorities.

Acute d-amphetamine challenge in schizophrenia: effects on cerebral glucose utilization and clinical symptomatology

The effects of d-amphetamine (0.5 mg/kg orally) on regional cerebral glucose utilization were measured with positron emission tomography (PET) in 17 schizophrenics (along with a placebo-control group of an additional six schizophrenic patients). The acute d-amphetamine challenge tended to decrease glucose utilization throughout much of the brain, with a regional effect that was statistically significant in the left temporal cortex. There was no apparent relationship between the effects of amphetamine-induced changes in regional cerebral metabolism and psychotic symptom exacerbation. An exploratory analysis suggested that features characteristic of Crow's type II syndrome were significant predictors of cerebral hyporesponsivity to stimulant challenge, however.

Effects of haloperidol and reduced haloperidol on binding to sigma sites

The s.c. administration of a single dose of 0.1 mg/kg of reduced haloperidol to guinea pigs produced a marked inhibition of the binding of [3H]dextromethorphan and [3H]3-(3-hydroxyphenyl)-N-(n-propyl)piperidine ([3H](+)-3-PPP) to brain. The inhibition was still evident 10 days later, and it was accompanied by residual brain levels of reduced haloperidol, and much lower levels of haloperidol. Scatchard and computer-assisted analysis demonstrated that the inhibition was due to a reduction in the number of binding sites without changes in the affinity. In the rat, haloperidol and reduced haloperidol also produced a rapid inhibition of binding to sigma sites. Interestingly, the brain of the reduced haloperidol-treated rats contained both haloperidol and reduced haloperidol, but the levels of reduced haloperidol in the haloperidol-treated rats were undetectable. However, the inhibition observed was of comparable magnitude, indicating that the haloperidol remaining in the brain is also inhibitory. In vitro experiments showed that the inhibition produced by haloperidol and reduced haloperidol was apparently competitive, but when brain membranes were preincubated with either drug, the inhibition was noncompetitive. By contrast, the inhibition produced by dextromethorphan was always competitive. Moreover, the inhibition produced by haloperidol and reduced haloperidol could not be reversed by washing. This investigation strongly suggests that the inhibition observed after the administration of haloperidol or reduced haloperidol is not a classic agonist-induced receptor down-regulation. The results indicated that the inhibition produced is a complex phenomenon, and suggest the formation of a slowly reversible or irreversible complex with reduced haloperidol or haloperidol.

Persistent psychosis after reduction in pre- and post-synaptic dopaminergic function

The purpose of this study was to evaluate the hypothesis that neuroleptic non-response in the face of "adequate" DA post-synaptic receptor blockade reflects failure of regulatory mechanisms to decrease DA pre-synaptic activity. Eight chronic schizophrenics, meeting rigorous criteria for neuroleptic non-response, were treated for four weeks with alpha-methylparatyrosine as an adjunct to their previously stable neuroleptic dose. Treatment with AMPT produced a prompt decrease in plasma HVA that was, on average, 72% lower at the end of the study. While there was also strong clinical evidence of reduction in central dopaminergic activity (both a significant reduction in dyskinetic movements and increase in extrapyramidal symptoms), there was virtually no change in severity of psychotic symptoms. Thus, in this group of non-responders, psychotic symptoms persisted despite both extensive dopamine post-synaptic receptor blockade and marked reduction of presynaptic activity. These symptoms may not be directly DA dependent.

Abnormal behavioral responses to fenfluramine in patients with affective and personality disorders. Correlation with increased serotonergic responsivity

Serotonergic responsivity was assessed in 20 psychiatric patients by the prolactin response to a fenfluramine challenge test. During the fenfluramine challenge 6 of 20 patients (30%) spontaneously reported psychopathologic reactions that included: increased anxiety/agitation, psychotic symptoms, illusions, mood elevation, and anergia. The time of peak behavioral symptoms (2.5 +/- 0.8 hrs) corresponded closely to the time of peak increase in prolactin levels (3.0 +/- 1.1 hr). Abnormal behavioral responders had statistically significant greater increases in prolactin 1 to 4 hr after fenfluramine when compared to normal responders. Patients who developed an abnormal psychopathologic response to fenfluramine were characterized by higher levels of anxiety and agitation at the time of admission to the hospital but otherwise were not distinguishable on the basis of severity of other psychiatric symptoms. This study suggests that increased serotonergic transmission may trigger anxiety, psychosis, and mood elevation in specific vulnerable individuals, whereas other patients with similar psychiatric illnesses are not affected.

Pregnancy decreases the threshold for cocaine-induced convulsions in the rat

The objective of this study was to test our hypothesis that pregnancy modifies the central nervous and cardiovascular toxicity of cocaine. Ten chronically catheterized term pregnant rats and 13 chronically catheterized nonpregnant female rats were infused with cocaine (2 mg/kg/min) intravenously to observe the sequential toxic manifestation of cocaine from mild central nervous stimulation (hyper-locomotor activities) to fatal cardiovascular collapse. Arterial blood samples were withdrawn at the onset of major toxic signs or symptoms--namely convulsion, hypotension, and circulatory collapse--for determination of cocaine concentrations and plasma cholinesterase activity. The dosage and plasma concentrations of cocaine associated with the onset of convulsions and cardiovascular depression were significantly lower in pregnant rats when compared with the nonpregnant animals. The mean time required to develop convulsions in the pregnant rat was significantly shorter (21 minutes) than that in the nonpregnant animal (33 minutes). However, once convulsive activity had developed, the time interval to achieve circulatory collapse was similar in both groups. Although the baseline plasma cholinesterase activity was higher in the pregnant rats than in the nonpregnant ones, the values in the samples obtained from the pregnant group at the onset of circulatory collapse were similar to the baseline values for the nonpregnant group. These findings suggest that a higher enzyme activity does not protect the development of toxic manifestations in the pregnant rat as compared to the nonpregnant animal when cocaine was administered at the same infusion rate.

The effects of fenfluramine on sleep and prolactin in depressed inpatients: a comparison of potential indices of brain serotonergic responsivity

The effects of fenfluramine, an indirect serotonergic agonist, on electroencephalographic sleep and prolactin secretion were assessed in 12 unmedicated inpatients with a primary diagnosis of major depressive episode. Compared to prefenfluramine profiles, sleep studies performed following fenfluramine administration showed a statistically significant reduction of slow-wave sleep (SWS) (p < 0.001) and a corresponding increase in percentage of stage-2 sleep (p < 0.007). Automated delta wave counts per min decreased significantly during the first nonrapid eye movement (NREM) period (p = 0.04), and automated rapid-eye movement (REM) counts were also decreased in the second REM period (p = 0.02). These effects on sleep electroencephalogram (EEG) did not correlate significantly with another measure of serotonergic responsivity, namely peak prolactin level following fenfluramine, nor with the severity of depression. The reductions in SWS and REM counts are proposed to be the result of time-dependent changes in serotonergic neurotransmission following the administration of fenfluramine. These findings are consistent with earlier work suggesting a role for serotonin in initiation and regulation of SWS and REM sleep.

Smoking cessation, clonidine, and vulnerability to nicotine among dependent smokers

OBJECTIVE

This study examines the efficacy of clonidine in smoking cessation and the influence of gender, history of major depression, and measures of nicotine dependence.

METHODS

The study was designed as a 10-week double-blind randomized comparison stratified for gender and major depression. Three hundred subjects who smoked cigarettes heavily were enrolled in the study. Abstinence from smoking was evaluated by self-report and verified by serum cotinine levels.

RESULTS

Gender, major depression recurrent type, and measures of nicotine addiction were risk factors for treatment failure. There was no clonidine effect in men, but there was a modest effect in women (odds ratio, 2.01; 95% confidence interval, 1.00 to 4.10) that was most pronounced (odds ratio, 8.5; 95% confidence interval, 1.67 to 43.62) among women with the highest risks.

CONCLUSION

Measures of addiction and major depression predict treatment failure. Together they are stronger predictors of outcome than drug. Clonidine is a limited aid in cessation, and drug effects come primarily from women at high risk for treatment failure. An increased risk for psychiatric complications after smoking cessation was apparent among smokers with histories of major depression, particularly bipolar disease.

Plasma homovanillic acid in neuroleptic responsive and nonresponsive schizophrenics

Changes in plasma homovanillic acid (HVA) were investigated in neuroleptic responsive and nonresponsive schizophrenics in order to delineate parameters of dopamine regulation, which may underlie differences in neuroleptic responsivity. Nineteen schizophrenics were treated with haloperidol for 6 weeks. HVA was sampled at baseline, 24 hr after initial neuroleptic dose, and after 6 weeks of treatment. Subjects were pretreated with debrisoquin in order to reduce the peripheral production of HVA. The responders had an initial rise in HVA at 24 hr after first neuroleptic dose, followed by a decline back to baseline over the 6 weeks of treatment. The nonresponders' HVA failed to rise at 24 hr after first neuroleptic dose. At 6 weeks of treatment their HVA had fallen to significantly below baseline. Thus, a rise in HVA 24 hr after the first dose of neuroleptic predicted treatment response; a fall in HVA at 6 weeks to below pretreatment values was associated with neuroleptic nonresponse.

Timing of neuroendocrine responses and effect of m-CPP and fenfluramine plasma levels in OCD

The present study assesses the timing of and relationship between neuroendocrine response and metabolite blood levels following the partial serotonin (5-HT) agonist m-CPP and the 5-HT releaser/reuptake blocker fenfluramine. Cortisol levels peaked significantly earlier than did prolactin, m-CPP, fenfluramine, or norfenfluramine blood levels by time-to-peak analysis. This earlier cortisol response to both 5-HT agents raises the possibility that peripheral mechanisms may play a role in cortisol release. Since peak m-CPP level correlated even more closely to peak prolactin rise than did peak fenfluramine, this suggests that prolactin response to oral m-CPP challenge is useful in assessing 5-HT function.

Post-dexamethasone cortisol levels and computerized tomographic findings in manic patients

The relations of post-dexamethasone cortisol levels to computerized tomography (CT) scan findings of lateral and third ventricle size and cortical sulcal prominence rated separately for frontal and parieto-occipital distributions were examined in 15 manic patients. Failure to suppress endogenous cortisol after a dexamethasone challenge was associated with larger third ventricles, but not to any of the other CT scan measures.

Gender-related differences in cocaine toxicity in the rat

To test our hypotheses that gender-related differences in cocaine toxicity exist in the rat, cocaine (2 mg/kg/min) was infused intravenously in chronically catheterized male and ovariectomized or intact female rats until the onset of circulatory collapse. Sequential manifestations of cocaine toxicity from mild central nervous stimulation to fatal cardiovascular collapse were observed. Arterial blood was withdrawn at the onset of the toxic signs or symptoms for determination of cocaine concentrations. Dosages and plasma concentrations of cocaine required to produce cardiovascular toxic manifestations were significantly lower in male and ovariectomized rats than in intact females. Plasma cholinesterase activity was lowest in the male animals and highest in intact females. These data suggest that systemic toxicity of cocaine is enhanced in male rats, because lower doses and plasma concentrations are required to induce toxic signs and symptoms.

Human brain fluoxetine concentrations

Data on 22 subjects treated with fluoxetine suggest that magnetic resonance spectroscopy (MRS) of fluorine-19 can measure brain concentrations of fluoxetine/norfluoxetine in vivo. Fluoxetine accumulates in the human brain relative to plasma, with brain concentrations of fluoxetine/norfluoxetine ranging up to 10.7 micrograms/ml. Brain concentrations may reach a plateau between 6 and 8 months of treatment. The apparent concentration in brain relative to plasma is 20:1, roughly parallel to brain antidepressant concentration ratios in animal studies.

Placental transfer of (3H)-GM1 and its distribution to maternal and fetal tissues of the rat

The demonstration that ganglioside GM1 pretreatment reduced the ethanol induced neurobehavioral effects in adult pups exposed to ethanol in utero, prompted study to examine whether GM1 crosses the placenta and penetrates fetal tissues. The present results indicate that 3H-galactose labeled GM1 not only passes the placenta but also served as a substrate for the synthesis of polysialogangliosides, and remained in various tissues up to 48 h after maternal (3H)-GM1 administration.

Vitamin E attenuates the toxic effects of 6-hydroxydopamine on free radical scavenging systems in rat brain

Rats were divided into the following four groups namely (a) sham-operated control, (b) 6-OHDA-treated, (c) sham-operated vitamin E-fed and (d) Vitamin E-fed treated with 6-OHDA. Total glutathione (GSH) and superoxide dismutase (SOD) were measured in brainstem (BS), striatum (ST), hippocampus, frontal cortex, and nucleus accumbens (N. Acc.). GSH and SOD levels were significantly decreased in all regions of 6-OHDA-treated rats compared to controls. Feeding of vitamin E resulted in a significant reduction of GSH in ST and N. Acc. but caused increases in SOD in BS, ST, and N. Acc. Pretreatment of rats with vitamin E caused significant attenuation of the effects of 6-OHDA on GSH and SOD in most of the brain regions. These results show that vitamin E can spare the scavenging systems from the injurious effects of 6-OHDA.

Sensitive and selective liquid-chromatographic assay of fluoxetine and norfluoxetine in plasma with fluorescence detection after precolumn derivatization

We determined fluoxetine (Prozac) and its major metabolite norfluoxetine in plasma by liquid chromatography with fluorescence detection. After liquid-liquid extraction from 1 mL of plasma, the extract was derivatized at room temperature with dansyl chloride, and the highly fluorescent derivatives were chromatographed with a reversed-phase C18 column and a mobile phase of phosphate buffer and acetonitrile. Dansylated fluoxetine, norfluoxetine, and the internal standard were eluted in less than 14 min with no interference from endogenous material. The calibration curve was linear over the concentration range 25-800 micrograms/L with inter- and intra-assay imprecision (CV) of less than 10%. Validity of the assay was checked by comparing results for 110 patients' samples with those by a liquid-chromatographic method with ultraviolet detection (r = 0.993 for fluoxetine, 0.957 for norfluoxetine). The identity of the dansylated derivatives was verified by positive chemical ionization mass spectroscopy. The lower limit of detection was approximately 3 micrograms/L. Because no major antidepressant, neuroleptic, or respective drug metabolites interfere with the quantification of fluoxetine and norfluoxetine, this is a useful procedure for pharmacokinetic studies and in clinical settings.

Neuroendocrine responses to challenge with dl-fenfluramine and aggression in disruptive behavior disorders of children and adolescents

Prolactin (PRL) and cortisol (CORT) responses to a single oral administration (1.0 mg/kg) of the indirect serotonin agonist dl-fenfluramine were assessed in unmedicated prepubertal and adolescent males with disruptive behavior disorders (DBD). Neuroendocrine responses were correlated with scores on aggression rating scales in prepubertal and adolescent DBD patients and compared with those of matched adolescent normal control subjects. Net dl-fenfluramine-induced PRL and CORT release was not correlated with aggression rating scores in prepubertal and adolescent DBD patients and did not differ significantly between adolescent DBD patients and normal control subjects. Although the present study does not demonstrate a serotonergic abnormality in aggression or DBD, this may be more a reflection of limitations of the neuroendocrine challenge test procedures or the methods used than evidence that serotonergic function in the central nervous system is normal in aggression.

Hormone responses to fenfluramine and placebo challenge in endogenous depression

Plasma prolactin and cortisol levels after oral administration of d-l fenfluramine hydrochloride (60 mg) and placebo were examined in 24 endogenously depressed patients and 21 age- and sex-matched normal control subjects in a randomized, double-blind study. Prolactin levels were significantly increased by fenfluramine in both groups, but the response was significantly blunted in the depressed patients compared with the controls. This effect was partially dependent upon elevated baseline cortisol levels in the depressed group and was also influenced by a history of weight loss. Plasma cortisol levels were not increased by fenfluramine in either group. These findings confirm previous reports and suggest that patients with endogenous major depression are characterized by central serotonergic hyporesponsivity. The need to account for baseline effects on hormonal responses to putative serotonergic agents is supported by the findings; however, these effects appear to be less striking when endogenicity is a prominent clinical feature of the depressive syndrome. The apparently complex influence of weight loss on prolactin response to serotonergic challenge remains to be clarified as well as the role played by the bioavailability of the challenge drug and its metabolite.

Baseline and 2- to 3-year follow-up characteristics of placebo-washout responders from the nortriptyline study of depressed 6- to 12-year-olds

Data are presented on the baseline characteristics and 2- to 3-year follow-up assessments of placebo-washout responders (PWRs) from a previously reported pharmacokinetically designed double-blind placebo-controlled trial of nortriptyline for major depressive disorder in 6- to 12-year-olds. Eleven of the 12 PWRs consented to participate in the follow-up study. At baseline, the only significant difference between the PWRs and the non-PWR subjects was that more females were PWRs. Notably, there were no significant differences with respect to severity, chronicity, age of onset, or comorbid psychopathology. The follow-up assessments showed that the rate of relapse to major depressive disorder and the rate of development of bipolarity were not significantly different for PWRs compared with non-PWRs. The authors discuss these findings vis-à-vis the adult literature and provide recommendations for the use of placebo-washout phases in future double-blind, placebo-controlled psychopharmacology trials in children.

Early findings from a pharmacokinetically designed double-blind and placebo-controlled study of lithium for adolescents comorbid with bipolar and substance dependency disorders

1. This manuscript reports the early findings from a National Institute on Drug Abuse funded study of lithium for adolescents dually diagnosed with bipolar and substance dependency disorders. The authors elected to publish early findings in the hope that it would accomplish a twofold mission. 2. The first part would be to encourage other investigators to participate in research in this area and the second would be to heighten the awareness of clinicians that adolescents presenting with either one of these disorders might also have the other. 3. The early findings demonstrated the feasibility of recruiting, retaining and monitoring this complex population on an outpatient basis. 4. Steady-state serum lithium levels were pharmacokinetically placed in the study range, 0.9-1.3 mEq/L. Preliminary results are encouraging in finding lithium more effective than placebo for alleviating both the substance dependency and the mood disordered symptomatology. 5. The characteristics of the study population to date have been chronicity of both disorders, impairment in the severe range in multiple areas of functioning, and strong family histories for both affective and substance use disorders. The substance dependency was to both alcohol and marijuana; but all subjects also had marked polydrug abuse. 6. In order to best monitor lithium compliance and drug/alcohol use during protocol, randomly timed weekly serum and urine assays were obtained. 7. The implications of these early findings for the outcome of this acute phase study and for the development of longitudinal treatment strategies are discussed.

Serum prolactin levels in homosexual and bisexual men with HIV infection

OBJECTIVE

Prolactin is a neurohormone that may be secreted in response to stress and also has regulatory effects on the immune system. Some, but not all, studies suggest that prolactin levels are higher than normal in persons with HIV infection. The authors measured prolactin levels in HIV-positive and HIV-negative homosexual and bisexual men to assess possible differences in levels and then examined relationships between prolactin level and measures of medical status, anxiety, depression, stress, and neuropsychological test performance.

METHOD

Blood for prolactin level determination was obtained from 121 HIV-seropositive and 79 HIV-seronegative homosexual and bisexual men enrolled in a longitudinal study. The men also underwent a daylong assessment that included medical, immunological, psychiatric, psychosocial, psychosexual, and neuropsychological evaluations.

RESULTS

There was no statistically significant difference in serum prolactin level among the seronegative men, the seropositive men with no or minimal physical symptoms, and the seropositive men with significant physical symptoms of HIV infection. Furthermore, within the HIV-seropositive group, the correlations between serum prolactin level and measures of depression, anxiety, stress, and neuropsychological test performance were all nonsignificant.

CONCLUSIONS

Serum prolactin level does not seem to respond to HIV infection or to be related to stress or psychiatric symptoms in HIV-infected men. As none of the subjects had AIDS, the possibility cannot be ruled out that prolactin level increases in very late stages of HIV infection.

Effects of fenfluramine on plasma homovanillic acid in healthy subjects

The specificity of fenfluramine as a pharmacological probe of the serotonin system has been questioned, since animal studies with high dose l-fenfluramine show increases in striatal levels of the dopamine metabolite homovanillic acid. To test the specificity of fenfluramine in humans with clinical doses, we compared plasma homovanillic acid (pHVA) concentration in healthy volunteers after administration of fenfluramine (60 mg) and placebo. There were no significant effects on pHVA, which supports previous findings that at doses used in pharmacological challenge paradigms, the effect of fenfluramine on the dopamine system is insufficient to alter measures of its change.

Pregnancy alters the hemodynamic responses to cocaine in the rat

To test our hypotheses that the hemodynamic response to cocaine may be altered during pregnancy, cocaine (0.33 mg/kg/min) was infused intravenously to chronically catheterized pregnant and nonpregnant female rats. Cardiac output and regional blood flow were measured, and cocaine concentrations in plasma and tissues, as well as plasma cholinesterase activity were determined. Results were compared between pregnant and nonpregnant groups. Cocaine produced a significant decrease in heart rate, accompanied by a fall in cardiac output, and decreased cerebral, myocardial, and placental blood flow in pregnant rats. The plasma cocaine concentration in pregnant animals was lower than that of nonpregnant ones, but tissue concentrations were similar in both groups. These results indicate that pregnancy enhances cardiovascular responses to subtoxic doses of cocaine. There was little placental transfer of cocaine with a fetal to maternal plasma concentration ratio of 0.28.