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Biomedical subjects

T Cooper

Publications and source records attributed to T Cooper.

At least 73 records · Page 4Linked to original sources
PubMed1992

Impedance plethysmography and thrombo-embolic disease.

This study compares the results of impedance plethysmography with lower limb venography in 68 patients referred for investigation of clinical deep vein thrombosis, and with the results of ventilation/perfusion isotope scans in 125 patients with suspected pulmonary embolism. Impedance plethysmography had a sensitivity of 100% and a specificity of 61% for the detection of thromboses involving popliteal or more proximal veins (30 patients), but a sensitivity of 90% and a specificity of 68% in the detection of thrombosis at any level, because of a low sensitivity in the detection of isolated calf vein thrombosis (60% in 10 patients). It is a non-invasive, portable and low-cost technique and, in centres where anticoagulation is only given to patients with popliteal or more proximal thrombosis, venography may only be necessary if impedance plethysmography is positive. It may also be of value in the assessment of patients with suspected pulmonary embolic disease and an indeterminate ventilation/perfusion lung scan.

Humans↗
PubMed1992

Low dose oral haloperidol and blood levels in Alzheimer's disease: a preliminary study.

Nineteen patients with probable Alzheimer's disease who manifested psychosis or behavioral disturbance received 0.5 to 5 mg per day of oral haloperidol, with blood levels drawn on a stable daily dose. Oral dose correlated strongly with haloperidol blood levels assessed by radioimmunoassay (r = 0.82, p = .0001). The stronger correlation observed between oral dose and blood level compared with most studies in schizophrenia may be related to the fact that virtually all the Alzheimer's patients were neuroleptic naive, without the alterations in absorption and metabolism known to occur in schizophrenics receiving long-term neuroleptic treatment. Compared with oral dose, blood levels showed stronger relations to changes in symptoms and to changes in severity of extrapyramidal side effects. These preliminary data suggest that the utility of monitoring haloperidol blood levels in patients with Alzheimer's disease merits further investigation.

Aged↗
PubMed1991

Serial dexamethasone suppression tests and plasma dexamethasone levels. Effects of clinical response to electroconvulsive therapy in major depression.

Serial 1-mg dexamethasone suppression tests with concurrent plasma dexamethasone assessments were conducted in 58 patients with endogenous depression treated with electroconvulsive therapy (ECT). Plasma cortisol levels decreased significantly from pretreatment to immediately posttreatment, and they declined further during the first week after the ECT course, when patients remained drug free. Plasma dexamethasone levels showed an opposite pattern of progressive increases over these three time points. The progressive changes in plasma dexamethasone and cortisol levels seen during the week after ECT indicate that alterations in the bioavailability of dexamethasone and in hypothalamic-pituitary-adrenal axis function may be incomplete immediately after the ECT course. This may partly account for previous inconsistencies in serial dexamethasone suppression test findings with this treatment modality. The major finding was that clinical response was associated with increased plasma dexamethasone levels, whereas changes in cortisol levels were independent of clinical outcome. With ECT, changes in plasma dexamethasone levels may be more related to changes in clinical state than changes in postdexamethasone cortisol levels. The extent to which clinical recovery with other treatments in depression is associated with altered bioavailability of dexamethasone and perhaps other compounds is unknown and in need of investigation.

Age Factors↗
PubMed1991

Mood responses of remitted schizophrenics to methylphenidate infusion.

To investigate the mood response of schizophrenic subjects to psychostimulant challenge, 29 neuroleptic-treated subjects (22 with schizophrenia and 7 with schizoaffective disorder) in clinical remission received two infusions, one with methylphenidate 0.5 mg/kg and the other with normal saline, under double-blind conditions. Twenty-five of these subjects were withdrawn from neuroleptics and given a second set of double-blind infusions. Infusion mood responses were classified as euphoric, neutral, mixed or dysphoric. Subjects were also rated as either psychotic symptom activators to the infusion or no change in psychotic symptoms. Overall response by mood category was as follows: 35.2% euphoric, 50% neutral, 5.6% mixed and 9.3% dysphoric. Mood responses were not correlated with sex, methylphenidate plasma levels or diagnostic distinctions between schizophrenia and schizoaffective disorder. Although they occurred infrequently, dysphoric and mixed mood responses were associated with high rates of psychotic activation. Comparing subjects on and off neuroleptics, subjects on neuroleptics had more euphoric responses than the same subjects off neuroleptics. This increased number of euphoric responses in subjects taking neuroleptics compared to off neuroleptics suggests that neuroleptic treatment status may be an important factor in assessing psychostimulant use in schizophrenia patients.

Adolescent↗
PubMed1991

Noradrenergic function in obsessive-compulsive disorder: behavioral and neuroendocrine responses to clonidine and comparison to healthy controls.

To evaluate noradrenergic (NE) function in obsessive-compulsive disorder (OCD), behavioral, physiological, and neuroendocrine responses to the alpha 2-adrenergic agonist clonidine were examined in 18 patients with OCD and 10 healthy subjects. Subjects received single i.v. doses of 2 micrograms/kg of clonidine administered under double-blind, placebo-controlled, random-assignment conditions. Following clonidine, but not following placebo, patients transiently experienced a significant reduction of obsessions and compulsions. Significant drowsiness and a reduction in anxiety were also noted, but the antiobsessional effect appeared independent of the soporific and antianxiety effects. Growth hormone (GH), cortisol, and 3-methoxy-4-hydroxyphenylglycol responses to clonidine did not differentiate patients from healthy controls. Blood pressure and pulse in response to clonidine did not differ between groups. Improvement in OCD symptoms after clonidine significantly correlated with GH response to clonidine, suggesting specific noradrenergic mediation. This finding lends only partial support for a primary defect of noradrenergic function in OCD.

Adolescent↗
PubMed1991

Glucocorticoid level and neuropsychiatric symptoms in homosexual men with HIV infection.

OBJECTIVE: There is a controversial literature suggesting that stress, anxiety, and depression are harmful to the immune system and therefore to health. Preclinical studies indicate that activation of the hypothalamic-pituitary-adrenal (HPA) axis by stress may be responsible for immunocompromise. The goal of this study was to assess this phenomenon in human immunodeficiency virus (HIV) infection. METHOD: Homosexual men in the community who did not meet modified Centers for Disease Control criteria for acquired immune deficiency syndrome (AIDS) were recruited for the study; 113 of the men were HIV positive and 77 were HIV negative. Very few of the men studied suffered from depression or anxiety disorder at the time of the first assessment. Twenty-four-hour urinary free cortisol levels were obtained from the 112 HIV-positive and 75 HIV-negative men whose 24-hour urine volumes were 500 ml or more. Cortisol levels were correlated with measures of medical, immunological, neurological, and psychiatric status. RESULTS: Small but significant correlations between 24-hour urinary free cortisol and medical status, level of depression, and level of anxiety were found in the HIV-positive group. There was no relationship between cortisol level and the number of CD4+ or CD8+ T lymphocytes or the CD4-CD8 ratio. CONCLUSIONS: Although HPA activation may be associated with stress in cases of HIV infection, it does not seem to be associated with further loss of CD4+ T lymphocytes. Subjects with HIV infection with the most evidence of medical complications may also be the most anxious and depressed.

Adult↗
PubMed1991

A case report of cimetidine-induced clozapine toxicity.

Cimetidine may decrease concomitant medication clearance by inhibiting the oxidative system of cytochrome P-450. The authors report increased serum clozapine levels and adverse side effects during clozapine and cimetidine treatment but not during clozapine and ranitidine treatment in a patient with chronic paranoid schizophrenia.

Adult↗
PubMed1991

Ventilation agents--what agents are currently used?

A survey of radiologists and nuclear physicians in 360 hospitals in the UK was undertaken to assess the current use of pulmonary ventilation agents. Replies were received from 340 (94%) hospitals. Of these, 200 (59%) provided lung scanning. The agents used for ventilation studies were Tc-labelled aerosols (118, 59%), 81Krm (58, 29%), 133Xe (42, 21%) and 127Xe (4, 2%). Nine (4.5%) hospitals performed perfusion scintigraphy without providing ventilation imaging. Thirty-two (16%) hospitals used more than one agent for ventilation imaging.

Humans↗
PubMed1990

Dopaminergic sensitivity and cocaine abuse: response to apomorphine.

Ten male patients with chronic cocaine abuse received a single dose of the dopamine agonist apomorphine. Self-ratings of cocaine craving, depression, and anxiety decreased in response to apomorphine. Neuroendocrine response was consistent with central dopaminergic stimulation. Patients in the "craving" phase of the cocaine abuse cycle differed in behavioral but not neuroendocrine response to apomorphine from patients in the "crash" phase. Decrease in cocaine craving correlated with decrease in plasma homovanillic acid (pHVA). Total cocaine consumption correlated negatively with baseline prolactin and pHVA levels and inversely with peak change in prolactin following apomorphine. Patients had blunted neuroendocrine response to apomorphine in comparison to historical normal controls. Implications for the "dopamine" hypothesis of cocaine abuse are discussed.

Adult↗
PubMed1990

Model for the kinetics of imipramine and its metabolites in adolescents.

A kinetic model for imipramine (IMI) has been developed, based upon a study of 16 teenagers who received IMI 4-5 mg/kg/day for treatment of a major depressive disorder. Serial measurements of plasma concentrations of IMI, desmethylimipramine (DMI), 2-hydroxy-IMI, and 2-hydroxy-DMI were made. Mean residence times, volumes of distribution, clearances of IMI and DMI, and rate constants for formation and elimination of the hydroxy metabolites were determined from a multicompartment model fitted to the concentration-time data. Mean residence time for DMI was significantly longer than for IMI (47.1 +/- 21.2 vs. 13.4 +/- 4.8 h, p less than 0.001). A different volume of distribution for IMI and DMI was not supported by the data. Clearance of DMI was considerably slower than that of IMI (0.67 +/- 0.45 vs. 2.18 +/- 1.33 l(kg.h), p less than 0.001). A statistically significant increase in mean residence time with increasing age during adolescence was found (r = 0.57, p less than 0.05).

Adolescent↗
PubMed1990

Conditioned learning in alcohol dependence: implications for cue exposure treatment.

A review of the literature pertinent to cue exposure treatment in alcohol dependence is presented. Psychological models of relapse, based on conditioning and social learning theories, are critically evaluated. In particular, attention is drawn to the potential implications for cue exposure research and treatment of an interaction between Pavlovian and operant conditioning, problems with the application of the concepts of arousal and craving and the importance of a systems model to understand physiological responses. It is concluded that no study has so far demonstrated a link between conditioned responses to alcohol-related cues and relapse, an assumption on which cue exposure treatment is based. Further, the evidence for the effectiveness of cue exposure as a treatment is lacking. Promising research directions are identified.

Alcohol Drinking↗
PubMed1990

Effects of trihexyphenidyl on plasma chlorpromazine in young schizophrenics.

This study investigated the effects of trihexyphenidyl on chlorpromazine (CPZ) plasma levels and clinical state in 20 relatively young schizophrenic patients diagnosed using the DSM-III. Spontaneous changes in CPZ plasma levels over time were also examined. Trihexyphenidyl significantly increased CPZ plasma levels (average 41%) but did not produce clinical change. The trihexphenidyl-induced increase in CPZ plasma levels was independent of CPZ oral dosage and of CPZ plasma levels. Chlorpromazine plasma levels decreased non significantly (about 13%) over the four weeks following steady state, but there was marked inter-subject variability, and CPZ levels rose in some subjects. Although identical CPZ doses produced widely variable plasma levels, CPZ plasma levels correlated significantly with oral dose. The views that antiparkinsonian drugs interfere with neuroleptic efficacy, and do so by lowering neuroleptic plasma levels, are questioned.

Adolescent↗
PubMed1990

Human Xq24-Xq28: approaches to mapping with yeast artificial chromosomes.

One hundred twenty-seven yeast strains with artificial chromosomes containing Xq24-Xqter human DNA were obtained starting from a human/hamster somatic cell hybrid. The clones were characterized with respect to their insert size, stability, and representation of a set of Xq24-Xqter DNA probes. The inserts of the clones add up to 19.3 megabase (Mb) content, or about 0.4 genomic equivalents of that portion of the X chromosome, with a range of 40-650 kb in individual YACs. Eleven clones contained more than one YAC, the additional ones usually having hamster DNA inserts; the individual YACs could be separated by extracting the total DNA from such strains and using it to retransform yeast cells. One of the YACs, containing the probe for the DXS49 locus, was grossly unstable, throwing off smaller versions of an initial 300-kb YAC during subculture; the other YACs appeared to breed true on subculture. Of 52 probes tested, 12 found cognate YACs; the YACs included one with the glucose-6-phosphate dehydrogense gene and another containing four anonymous probe sequences (DX13, St14, cpx67, and cpx6). Xq location of YACs is being verified by in situ hybridization to metaphase chromosomes, and fingerprinting and hybridization methods are being used to detect YACs that overlap.

Animals↗
PubMed1990

Dose and blood levels of haloperidol in treatment of mania.

Three doses of haloperidol, 10 mg/day, 30 mg/day, and 80 mg/day, were compared in 47 newly admitted manic patients. There was no difference in outcome within 6 weeks among the three doses. Four blood levels of plasma and red blood cell (RBC) haloperidol and reduced haloperidol showed no linear or curvilinear relationships to clinical response.

Adult↗
PubMed1989

Clozapine pharmacology and tardive dyskinesia.

Clozapine, an atypical neuroleptic, does not cause extrapyramidal symptoms of Parkinsonism and dystonia and appears to have a reduced or absent capacity to produce tardive dyskinesia. 37 subjects, most with chronic schizophrenia, were treated with clozapine and TD outcome was analyzed. A subset of these subjects underwent plasma and CSF studies. TD response was heterogenous, but a proportion of patients improved with clozapine treatment. Neurochemical data differed from published reports of classical neuroleptics with the most robust effect produced by clozapine seen in CSF norepinephrine levels. Other neurochemical data and implications for the mechanism of clozapine in TD are reviewed.

Adolescent↗