Biomedical subjects

T B Cooper

Publications and source records attributed to T B Cooper.

At least 37 records · Page 2Linked to original sources

PubMed2000

Disposition of bupivacaine and its metabolites in the maternal, placental, and fetal compartments in rats.

BACKGROUND: This study was designed to determine the disposition of bupivacaine and its metabolites in the maternal, placental, and fetal compartments, using multiple sampling time points in chronically prepared awake pregnant rats. METHODS: All animals received an intravenous infusion of bupivacaine at a rate of 0.33 mg. kg-1. min-1 over a period of 15 min. The fetuses were delivered either at the end of infusion or at 2 or 4 h after dosing. Maternal and fetal blood and tissue samples were obtained for the assays of bupivacaine and its metabolites using capillary gas chromatography-mass spectrometry. RESULTS: The elimination half-life of bupivacaine was 37.7 min. The major metabolite was 3'-hydroxybupivacaine. Bupivacaine and 3'-hydroxybupivacaine were present in all samples at the end of administration. The fetal to maternal concentration ratio of bupivacaine in plasma was 0.29, and in the placenta was 0.63. The amnion contained the highest bupivacaine concentration: threefold higher in the maternal and 11-fold higher than in the fetal plasma. At 4 h after dosing, bupivacaine was no longer detectable in any maternal and fetal samples, whereas 3'-hydroxybupivacaine was still present in all tissues except the fetal plasma and heart. CONCLUSIONS: These data indicate that a considerable amount of bupivacaine is taken up by both sides of the placenta, as well as the amnion and myometrium. 3'-Hydroxybupivacaine was present in all tissues except the fetal plasma and heart samples, even after the parent compound became no longer detectable. Whether this slow elimination of 3'-hydroxybupivacaine causes any adverse effects on the fetus-newborn needs to be explored.

Amnion↗

PubMed2000

High-dose treatment with haloperidol: the effect of dose reduction.

High doses of antipsychotic medications are sometimes prescribed in clinical practice, although the efficacy and safety of such treatment have not been established. The purpose of this study was to determine whether high-dose, long-term antipsychotic treatment prescribed on the basis of clinical judgment can be justified. Patients who were receiving high doses of haloperidol were screened, and those patients whose plasma levels were at least 15 ng/mL were randomly assigned to an experimental group (N = 11) or to a control group (N = 12). The experimental group underwent a dose reduction to achieve the target plasma level of 10 ng/mL. The reduction was gradual over a period of 12 weeks. The control group treatment was maintained at the original level. Both groups were then followed up for another 16 weeks, during which the plasma levels of haloperidol were kept constant. The study used double-blind procedures. Both groups showed an average slight symptom reduction. There was no significant difference in the severity of symptoms between the two groups at any time point. The dose reduction had no apparent adverse effects. Thus, the results of this study did not provide justification for high-dose, long-term antipsychotic treatment. However, these results must be interpreted with caution because the sample studied here was small and biased.

Adult↗

PubMed2000

Drug treatment of depression in frail elderly nursing home residents.

The authors conducted a randomized, double-blind, 10-week clinical trial of two doses of nortriptyline in eight nursing homes. Sixty-nine patients, average age 79.5 years, were randomized to receive regular doses (60 mg-80 mg/day) vs. low doses (10 mg-13 mg/day) of nortriptyline. Among the more cognitively intact patients, there was a significant quadratic relationship defining a "therapeutic window" for nortriptyline plasma levels and clinical improvement. There were also significant differences in plasma level-response relationships between depressed patients who were cognitively impaired and those who were more cognitively intact. Depression remains a syndrome that responds to specific treatment, even in frail nursing home patients, and those depressions that occur in patients with significant dementia may represent a treatment-relevant condition with a different plasma level-response relationship than in depression alone.

Aged↗

PubMed1999

Sensitive and selective liquid chromatographic assay of memantine in plasma with fluorescence detection after pre-column derivatization.

A procedure was developed for the determination of memantine in plasma using liquid chromatography with fluorescence detection. Following a liquid-liquid extraction from 1 ml of plasma containing the internal standard amantadine, 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 memantine and amantadine were eluted in less than 13 min with no interference from endogenous material. The calibration curve was linear over the concentration range of 3-400 ng/ml with inter- and intra-assay imprecision (C.V.) of less than 10%. The limit of quantitation was 3 ng/ml, and no major antidepressant, neuroleptic or their respective metabolites interfered with the quantitation of memantine. This method could also be applied to the quantitation of amantadine.

Excitatory Amino Acid Antagonists↗

PubMed1999

The effect of cotinine on nicotine- and cocaine-induced dopamine release in the nucleus accumbens.

Cotinine is the major metabolite of nicotine. Nicotine is rapidly metabolized and has a short half-life, but cotinine is metabolized and eliminated at a much lower rate. Because of the resulting increase with time in the cotinine to nicotine ratio in the body, including in the brain, it is of interest to examine the effect of cotinine on nicotine-induced changes. In studies on conscious, freely-moving rats, intravenous administration of either nicotine or cocaine induced the release of dopamine in the nucleus accumbens, as assayed by microdialysis. Prior intravenous administration of a high dose of cotinine (500 microg/kg) inhibited this nicotine- or cocaine-induced dopamine release. The action of cotinine does not seem to occur through its effect on the metabolism of nicotine or on its binding at the receptor site, because cotinine, unlike nicotine, does not affect the binding of the nicotinic ligand cytisine. The findings suggest that cotinine affects a putative component of the reward mechanism, and as such could have therapeutic value.

Alkaloids↗

PubMed1999

The disposition of cocaethylene in rat maternal, placental, and fetal compartments.

OBJECTIVE: The aim of this project was to examine the disposition of maternally administered cocaethylene in the fetus. STUDY DESIGN: Pregnant rats with long-term catheter placement received an intravenous infusion of cocaethylene during a period of 30 minutes. At either the completion of the infusion or 6 hours after the infusion the fetuses were delivered by hysterotomy. Maternal and fetal blood and major tissue samples were obtained for assays of cocaethylene and its metabolites. RESULTS: Cocaethylene was present in all samples obtained at the end of the infusion, but after 6 hours it was no longer detectable in the maternal and fetal systemic circulations. However, a substantial amount of cocaethylene was still present in the placenta on both the maternal and fetal sides, with the concentration on the maternal side being higher, indicating that the placenta stores cocaethylene. At the end of the infusion benzoylecgonine was found in all samples and the maternal concentrations were higher than the corresponding fetal concentrations. This order was reversed 6 hours after infusion. Extremely high concentrations of cocaethylene and benzoylecgonine were found in the amnion. CONCLUSIONS: These results suggest that the placenta limits the transfer of cocaethylene to the fetus. The high affinity of this compound for extraplacental sites cannot be ignored.

Amnion↗

PubMed1999

Role of gender in the toxicity of norcocaine.

Gender differences may significantly influence the toxicity of cocaine in mammals. In this study, the influence of gender on the toxicity of norcocaine, a pharmacologically active metabolite of cocaine, was compared with its parent compound in adult male and female rats. In addition, the plasma and tissue norcocaine concentrations were evaluated after the administration of norcocaine and cocaine. Norcocaine or cocaine was administered intravenously at a rate of 2 mg/kg/min until circulatory collapse. Arterial blood samples as well as heart, liver, and brain tissues were obtained at circulatory collapse for the measurement of concentrations of norcocaine as well as cocaine and its major metabolites. There were no gender-related differences in the doses of norcocaine required to produce circulatory collapse; however, there were significant gender-related differences in the norcocaine tissue-to-plasma concentration ratios (T:P ratios). After the administration of norcocaine, T:P ratios for heart, liver, and brain tissue were significantly greater in males. Furthermore, after cocaine administration, the hepatic norcocaine T:P ratio was approximately 3-fold greater in the male rats than in the female rats. In contrast, female rats had a greater percentage of norcocaine in the plasma at circulatory collapse after acute cocaine administration. Although no gender differences in the lethality of norcocaine were observed, it remains to be seen whether the gender differences in the distribution and uptake of norcocaine play a role in the hepatotoxicity of the drug, particularly after chronic exposure.

Animals↗

PubMed1999

The comparative toxicity of cocaine and its metabolites in conscious rats.

BACKGROUND: The metabolites of cocaine, benzoylecgonine and ecgonine methyl ester, have been considered pharmacologically inactive when administered systemically. However, recent in vitro studies suggest that this may not be true. The current study was designed to evaluate the systemic toxicity of cocaine and its metabolites when administered systemically to awake rats fitted with catheters for long-term monitoring. METHODS: Cocaine, norcocaine, cocaethylene, benzoylecgonine, and ecgonine methyl ester were infused intravenously to produce sequential behavioral alterations and central nervous system and cardiovascular toxic effects. Arterial blood pressure and heart rate were monitored continuously. Plasma and tissue samples were analyzed for all compounds by capillary gas chromatography-mass spectrometry. RESULTS: The dose of norcocaine necessary to produce toxic effects was smaller than that of cocaine and cocaethylene. Benzoylecgonine and ecgonine methyl ester did not produce toxic manifestations at infusion rates that produced toxicity in the cocaine, norcocaine, and cocaethylene groups. Furthermore, 30- and 60-fold higher doses of benzoylecgonine and ecgonine methyl ester, respectively, were necessary to produce only mild neurobehavioral changes. Benzoylecgonine was not lethal even at doses 100 times greater than cocaine. CONCLUSIONS: These results indicate that benzoylecgonine and ecgonine methyl ester are not as toxic as cocaine, norcocaine, or cocaethylene when administered intravenously to pharmacologically naive rats.

Animals↗

PubMed1998

Change in plasma prolactin and clinical response to haloperidol in schizophrenia and schizoaffective disorder.

There has been a long-standing interest in plasma prolactin as a potential in vivo indicator of blockade of tuberoinfundibular D2 dopamine receptors. Potential relationships between prolactin response and neuroleptic treatment have been obscured by the use of high doses which have caused prolactin to plateau. With lower doses of neuroleptic now commonly in use, prolactin may be more valuable as a correlate of clinical response. In this study, 23 acutely exacerbated schizophrenic and schizoaffective patients were washed out for at least 6 days and were then treated with haloperidol to achieve fixed low to moderate plasma levels under double-blind conditions. Clinical response, plasma prolactin, and haloperidol plasma levels were measured weekly for 3 weeks. Clinical symptoms at endpoint were related to both prolactin change and final prolactin level during haloperidol treatment. Specifically, fewer symptoms at endpoint were associated with a greater increase in prolactin over time and a higher prolactin level at endpoint. Thus, prolactin increase caused by low to moderate doses of haloperidol may be a correlate of endpoint symptomatology. As lower doses of typical neuroleptics are now in use, prolactin response as a predictor of clinical response may have more clinical utility. Further study of prolactin and clinical response to typical neuroleptics should focus on low neuroleptic doses.

Adult↗

PubMed1998

Effects of electroconvulsive therapy on plasma vasopressin and oxytocin.

BACKGROUND: Animal studies suggest that vasopressin has cognitive-enhancing properties and oxytocin may have amnestic effects. A clinical report suggests that the acute increase in oxytocin-associated neurophysin predicts clinical response to electroconvulsive therapy (ECT) in depressed patients. METHODS: Medication-free patients with major depression were randomized to receive right unilateral or bilateral ECT administered with electrical stimulus intensity at either just above seizure threshold or at 150% above seizure threshold. The associations between plasma vasopressin, oxytocin, ECT treatment parameters, clinical outcome, and cognitive effects were assessed. RESULTS: The sample comprised 55 patients. At the second ECT, patients receiving ECT at 150% above initial seizure threshold had significantly greater increases in plasma vasopressin than patients receiving low-dose ECT (ps < .01-.04), with no effects of electrode placement. At the second and ninth ECT treatments, the vasopressin or oxytocin surges were not associated with clinical improvement, seizure duration, time to orientation, or memory test performance. There were inverse trend-level associations between the acute surge in oxytocin levels at the ninth ECT and clinical response, contradicting a report in the literature. CONCLUSIONS: Overall, these findings do not support the hypothesis that diencephalic seizure propagation is central to the mechanism of action of ECT.

Cognition↗

PubMed1998

Hostility is associated with a heightened prolactin response to meta-chlorophenylpiperazine in abstinent cocaine addicts.

The prolactin (PRL) response to the administration of serotonin (5HT) agonists is an index of central nervous system 5HT activity. This index is blunted in association with hostile aggression in personality and depressive disorder patients without substance abuse. We tested whether the PRL response to the oral administration of the partial 5HT agonist meta-chlorophenylpiperazine (MCPP), 0.35 mg/kg, was associated with a measure of trait hostility, the Buss Durkee Hostility Inventory (BDHI), in cocaine addicts who were completing a 3-week detoxification and rehabilitation program. We also tested whether the cocaine addicts differed from healthy volunteers on their PRL, cortisol (CORT) or temperature responses to MCPP. The PRL response to MCPP was positively associated with the total score on the BDHI. There were, however, no differences in the neuroendocrine or temperature responses to MCPP between the cocaine-dependent group and the healthy volunteers once age effects were controlled for.

Adult↗

PubMed1998

Chronic ethanol administration down-regulates cannabinoid receptors in mouse brain synaptic plasma membrane.

The effects of chronic ethanol (EtOH) consumption on the central nervous system may be related in part to its action on biological membranes by altering various receptor functions. In the current study, we examined the effects of chronic EtOH (4 day inhalation) on cannabinoid receptors (CB1) labeled with [3H]CP55,940 in synaptic plasma membranes (SPM) isolated from mouse brain. Our results indicate the presence of a high level of CB1 receptors in controls (Bmax=12.0+/-0.3 pmol mg-1 protein) which decreased significantly (-58%) in SPM from mouse brain chronically exposed to EtOH. This effect occurs without any changes in the receptor affinity (Kd=2. 3+/-0.3 nM for control and 2.9+/-0.3 nM for EtOH group, P>0.05). Dissociation kinetic results showed a dissociation rate constant (K-1) of 0.09+/-0.01 min-1 for control and this dissociation rate constant decreased significantly in the chronic EtOH treated mice brain (0.05+/-0.01 min-1, P<0.05). The competition studies with anandamide resulted in a substantial decrease in [3H]CP55,940 binding in both the control and EtOH group, with a decrease (P<0.05) in the Ki values in the SPM of chronic EtOH exposed mice. Hill transformation analysis showed an nH close to one in control (0. 92+/-0.01). This did not change significantly after chronic EtOH (0. 95+/-0.01) administration, which indicates the existence of a single class of receptor for [3H]CP55,940 binding in SPM from control and EtOH treated mice. The observed down-regulation of CB1 receptors by chronic EtOH may indicate the involvement of cannabinoid receptors in EtOH tolerance and dependence.

Administration, Inhalation↗

PubMed1998

Effect of chronic ethanol exposure on mouse brain arachidonic acid specific phospholipase A2.

The enzyme phospholipase A2 (PLA2), which catalyzes the hydrolysis of an ester bond at the sn-2 position of 1,2-sn-diacylglycerols, has been suggested to play an important role in regulating cellular functions. Although ethanol (EtOH)-induced activation of PLA2 activity was reported previously by us in mouse brain (Hungund et al., Neurochem Int 25: 321-325, 1994), its subcellular localization and biochemical properties have not been investigated. Therefore, in the present study, we examined the subcellular localization and characterization of EtOH-activated PLA2 activity in mouse brain. The results indicated that EtOH treatment decreased the specific activity of PLA2 for the first 48 hr, and then the activity increased and reached a peak level in both cytosol (1.6-fold) and membrane (1.7-fold) fractions at 96 hr of exposure. Specific activity was found to be higher in the membrane fraction than in the cytosol. Using differential density gradient centrifugation, subcellular localization of the membrane-associated PLA2 revealed that most of the EtOH-activated PLA2 specific activity was associated with the synaptic membrane (44%) followed by the nuclear membrane (13%). No significant increase in the PLA2 specific activity of mitochondrial and microsomal membranes was observed. No activity was detected in the myelin membrane. PLA2 specific activity of membranes from control and EtOH-exposed mouse brain exhibited preference for arachidonic acid over linoleic acid at the sn-2 position of glycero-3-phosphocholine (PC). No detectable PLA2 specific activity was found when PC containing oleic acid at the sn-2 position was used as a substrate. The present results also indicated that the PLA2 specific activity of membrane from control and EtOH-exposed mouse brain was insensitive to dithiothreitol, strongly stimulated by Ca2+, enhanced by glycerol, and inhibited by the cytosolic PLA2 (cPLA2) inhibitor methyl arachidonyl fluorophosphonate with an IC50 value of 3.33 microM. In summary, results suggest that the properties of EtOH-activated PLA2 activity found in mouse brain membrane fraction are similar to those of cPLA2 found in variety of cells, including mammalian brain.

Alcoholism↗

PubMed1998

Cerebrospinal fluid concentrations of somatostatin and biogenic amines in grown primates reared by mothers exposed to manipulated foraging conditions.

BACKGROUND: In an earlier study, infant primates were nursed by mothers randomly assigned to variable foraging demand (VFD) or nonvariable foraging conditions (non-VFD). A group of grown VFD-reared subjects demonstrated elevations of cisternal cerebrospinal fluid (CSF) corticotropin-releasing factor concentrations and decreased CSF cortisol levels vs non-VFD counterparts. To further characterize neurobiological sequelae of disturbed early rearing, CSF concentrations of serotonin, dopamine, and norepinephrine metabolites (5-hydroxyindoleacetic acid, homovanillic acid, and 3-methoxy-4-hydroxyphenethyleneglycol [MHPG], respectively) and of somatostatin were determined. METHODS: Second CSF taps were obtained from the previously studied cohort of 30 subjects and from 28 age-matched ad libitum-reared control subjects. Relevant assays were performed. RESULTS: All neurochemicals assayed except MHPG were elevated in the VFD-reared compared with non-VFD subjects. In the VFD group, statistically significant positive correlations between corticotropin-releasing factor and each neurochemical was found, except for MHPG. In the non-VFD subjects, no significant correlations with corticotropin-releasing factor were observed. No effect of age was evident. CONCLUSIONS: Reducing the predictability of maternal foraging demand during early rearing was associated with elevations of cisternal somatostatin and of serotonin and dopamine metabolite concentrations in grown offspring. The corticotropin-releasing factor elevations reported previously were positively correlated with all the elevated CSF parameters of the current study. The findings support the notion that adverse early rearing experiences in primates have longstanding and complex effects on a range of neurochemicals relevant to emotional regulation. Replication in prospective age-controlled studies is warranted.

Animals↗

PubMed1998

Cerebrospinal fluid vasopressin levels: correlates with aggression and serotonin function in personality-disordered subjects.

BACKGROUND: Animal studies suggest that central vasopressin plays a facilitatory role in aggressive behavior. To examine this possibility in humans, the relationship between cerebrospinal fluid (CSF) arginine vasopressin (AVP) and indices of aggression and central serotonin system function was examined in personality-disordered subjects. METHODS: We used CSF (AVP), CSF 5-hydroxyindoleacetic acid, and the prolactin response to d-fenfluramine challenge (PRL[d-FEN]) as central indices of vasopressin and serotonergic system function, respectively, in 26 subjects who met the DSM-IV criteria for personality disorder. Measures of aggression and impulsivity included the Life History of Aggression assessment and the Barratt Impulsiveness Scales. RESULTS: The CSF AVP level was correlated directly with life history of general aggression and aggression against persons and inversely with PRL[d-FEN] responses (but not with CSF 5-hydroxyindoleacetic acid), which in turn was correlated inversely with these 2 measures of life history of aggression. The positive relationship between CSF AVP and life history of aggression remained even when the variance associated with PRL[d-FEN] responses in these subjects was accounted for. CONCLUSION: Central AVP may play a role in enhancing, while serotonin plays a role in inhibiting, aggressive behavior in personality-disordered individuals. In addition to the possibility of central AVP and serotonin interacting to influence human aggression, central AVP may also influence human aggressive behavior through a mechanism independent of central serotonin in personality-disordered subjects.

Adult↗

PubMed1998

Acute tryptophan depletion attenuates the 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 pretreatment with and without acute tryptophan depletion (ATD) in six physically healthy male volunteers. Compared to pretreatment with SHAM-ATD, ATD pretreatment attenuated the PRL response to d-FEN Challenge in all subjects. These data suggest that PRL responses to cl-FEN challenge reflect to a substantial degree the activity of newly synthesized 5-HT.

Adult↗

PubMed1998

Prevention of lithium nephrotoxicity in a novel one-hour model in rats.

It is well established that lithium can cause morphologically visible damage to the kidneys of humans and animals. Although the clinical significance of its nephrotoxicity is debatable, it would be desirable to find a method to prevent lithium's effect on the kidneys. Toward this end, we have developed a novel method for producing nephrotoxicity that will be useful for research on prevention. A single, large, toxic dose of lithium chloride (LiCl) caused necrosis of the distal convoluted tubules, which was visible by light microscopy in 30 min, had fully developed in 1 h, and had disappeared by the next day. The lesions were seen after i.p. or i.v. injections of fasted rats of three different strains. Equivalent doses of NaCl, KCl, MgCl2 and combinations thereof had no such effect, nor did they inhibit nephrotoxicity when incorporated into the LiCl solution. However, relatively small doses of LiCl injected by any route 3 or 24 h beforehand prevented the nephrotoxicity. The mechanism of prevention is not known, but it does not involve reduction of lithium levels in the kidneys.

Animals↗

PubMed1998

Lithium for prepubertal depressed children with family history predictors of future bipolarity: a double-blind, placebo-controlled study.

BACKGROUND: Because of negative studies of TCAs for prepubertal major depressive disorder (PMDD) and because of the potentially high switch rate of PMDD to prepubertal bipolarity (BP), it was hypothesized that lithium would be efficacious treatment for PMDD in children who also had family history (FH) predictors of future BP. METHODS: A double-blind, placebo-controlled, and pharmacokinetically dosed study of lithium for PMDD with FH predictors of future BP was performed. Random assignment was stratified by FH of BP-I or mania versus loaded/multigenerational (L/M) FH of MDD without BP-I or mania. Comprehensive assessments were done during a six week outpatient protocol that included weekly serum lithium levels. RESULTS: Mean age was 10.7+/-1.2 years; 17 subjects were randomized to active and 13 to placebo; 80% had FH of BP-I or mania (40% of parents had BP-I or mania); and 20% had FH of L/M MDD. Using both intent to treat with last observation carried forward (n = 30) and completer (n = 24) analyses, there were no significant differences on continuous or categorical measures between active and placebo groups. Mean serum lithium level was 0.99+/-0.16 mEq/l. There were no significant differences between mean total daily dose or mean serum lithium levels between responders and non-responders. LIMITATIONS: Four subjects on active drug were discontinued because of dose-limiting side effects (three were cognitive impairment). Future studies of treatment for PMDD should consider alternative drugs. CLINICAL RELEVANCE: Lithium was not significantly more efficacious than placebo for PMDD with FH predictors of future BP.

Adolescent↗