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Biomedical subjects

D Heathcote

Publications and source records attributed to D Heathcote.

7 recordsLinked to original sources
PubMed2000

Tricyclic drugs for depression in children and adolescents.

BACKGROUND: There is a need to identify effective and safe treatments for depression in children and adolescents. While tricyclic drugs have proven effectiveness in the treatment of depression in adults, individual studies involving children and adolescent have been equivocal. OBJECTIVES: To examine whether orally administered tricyclic antidepressants are superior to placebo in the treatment of child and adolescent depression SEARCH STRATEGY: We searched the literature using CD ROM Silver Platter and On-Line MEDLINE (1966-1997) and Excerpta Medica (June 1974-1997) data bases. Terms used for the search were: the exploded terms child and depression; the Medical Subject Headings of antidepressant drugs, tricyclic and affective disorders; individual tricyclic drugs by name; names of well-known researchers in the field; and school phobia. We searched the trials database of the Cochrane Collaboration Depression, Anxiety and Neurosis Group. Abstracts in English (of English and non-English papers) were reviewed. Bibliographies of previously published reviews and papers describing original research were cross-checked. Current Contents was screened for recent publications. We contacted authors of abstracts describing "work in progress" identified in conference proceedings of the American Academy of Child and Adolescent Psychiatry to determine whether they held data which could be included in the meta-analysis. We have hand searched the Journal of the American Academy of Child and Adolescent Psychiatry to identify randomized controlled trials. SELECTION CRITERIA: Randomized controlled trials comparing the efficacy of orally administered tricyclic medication with placebo in depressed subjects aged 6-18 years. DATA COLLECTION AND ANALYSIS: Most studies reported multiple outcome measures including depression scales and clinical global impression scales. For each study the best available depression measure was taken as the index measure of depression outcome. Predetermined criteria were established to assist in the ranking of measures. Where authors reported categorical outcomes we calculated individual and pooled odds ratios for the odds of improvement in treated compared with control subjects. For continuous outcomes pooled effect sizes were calculated as the number of standard deviations by which the change in depression scores for the treatment group exceeded those for the control groups. MAIN RESULTS: Twelve studies fulfilled the criteria for inclusion in the review, eight from which dichotomous outcome data could be extracted, and eleven from which continuous outcome data could be extracted. Pooled odds ratios calculated from the dichotomous data indicated no advantage of treatment over placebo for children or adolescents (odds ratio = 0.83, 95% confidence interval 0.48 to 1.42). Effect size calculations from the continuous data suggested a statistically significant but small benefit of treatment over placebo in reducing symptoms for the aggregate sample (effect size = -0.38, 95% confidence interval -0.74 to -0.02) with subgroup analyses suggesting a larger benefit among adolescents (effect size = -0.59, 95% confidence interval -1.12 to -0.06), and no benefit among children (effect size = 0.15, 95% confidence interval -0.34 to 0.64). Treatment with a tricyclic antidepressant caused more vertigo (odds ratio = 8.47, 95% confidence interval 1.40 to 51.0), orthostatic hypotension (odds ratio = 4.77, 95% confidence interval 1.11 to 20.49) and dry mouth (odds ratio = 5.19, 95% confidence interval 1.15 to 23.51) than did placebo, but there was no statistically significant difference in other possible adverse effects. REVIEWER'S CONCLUSIONS: Data suggest tricyclic antidepressants are of unlikely benefit in the treatment of depression in pre pubertal children. There is marginal evidence to support the use of tricyclic antidepressants in the treatment of depression in adolescents, although the magnitude of effect is likely to be moderate at best.

Administration, Oral↗
PubMed1999

The lack of standardization of cardiac troponin I assay systems.

The lack of standardization of cardiac troponin I (cTnI) assay systems has meant an inability to compare absolute values between methods, and non-traceability of cTnI measurement in clinical laboratories. The present study tested whether a common calibrator for cTnI would harmonize values between different methods. Twenty fresh-frozen plasma samples and a common calibrator were analyzed in duplicate using the Dade Behring Stratus II, Chiron ACS:180, Abbott AxSYM, and Beckman Coulter Access immunoassay systems. Uncorrected cTnI values varied up to 60-fold between systems, and when correlated to the Stratus, linear regression slopes were 0.97 (ACS:180), 4.86 (AxSYM), and 0.03 (Access), verifying the differences in calibration. After correction for calibration differences by reference to the common calibrator, among-assay CV ranged from 2.7% to 55%, and was >25% for eight samples. However, the exclusion of Access results reduced the CV to 32% with only four outliers. The results show that comparable cTnI values between methods are possible by the use of a common calibrator. The lack of method harmonization for some samples may be due to non-equal antibody immunoreactivity of different plasma cTnI forms. The complete standardization of cTnI measurement requires both a secondary reference material and standardization of manufacturers' cTnI antibodies.

Clinical Chemistry Tests↗
PubMed1995

Efficacy of tricyclic drugs in treating child and adolescent depression: a meta-analysis.

OBJECTIVE: To examine whether tricyclic antidepressants are superior to placebo in the treatment of child and adolescent depression. DESIGN: Meta-analysis of 12 randomised controlled trials comparing the efficacy of tricyclic antidepressants with placebo in depressed subjects aged 6-18 years. MAIN OUTCOME MEASURES: Most studies employed several depression rating scales. For each study the "best available" measure was chosen by using objective criteria, and individual and pooled effect sizes were calculated as the number of standard deviations by which the change scores for the treatment groups exceeded those for the control groups. Where authors had reported numbers "responding" to treatment we calculated individual and pooled ratios for the odds of improvement in treated compared with control subjects. RESULTS: From the six studies presenting data which enabled an estimation of effect size the pooled effect size was 0.35 standard deviations (95% confidence interval of -0.16 to 0.86) indicating no significant benefit of treatment. From the five studies presenting data on the number of "responders" in each group, the ratio of the odds of a response in the treated compared with the control subjects was calculated and the pooled odds ratio was 1.08 (95% confidence interval of 0.53 to 2.17); again indicating no significant benefit of treatment. The pooled sample had more than an 80% chance of detecting a treatment effect of 0.5 standard deviations or greater. There was an inverse relation between study quality and estimated treatment effect. CONCLUSIONS: Tricyclic antidepressants appear to be no more effective than placebo in the treatment of depression in children and adolescents.

Adolescent↗
PubMed1995

Gravitropic responses of the Avena coleoptile in space and on clinostats. I. Gravitropic response thresholds.

We conducted a series of gravitropic experiments on Avena coleoptiles in the weightlessness environment of Spacelab. The purpose was to test the threshold stimulus, reciprocity rule and autotropic reactions to a range of g-force stimulations of different intensities and durations The tests avoided the potentially complicating effects of earth's gravity and the interference from clinostat ambiguities. Using slow-speed centrifuges, coleoptiles received transversal accelerations in the hypogravity range between 0.l and 1.0 g over periods that ranged from 2 to 130 min. All responses that occurred in weightlessness were compared to clinostat experiments on earth using the same apparatus. Characteristic gravitropistic response patterns of Atuena were not substantially different from those observed in ground-based experiments. Gravitropic presentation times were extrapolated. The threshold at 1.0 g was less than 1 min (shortest stimulation time 2 min), in agreement with values obtained on the ground. The least stimulus tested, 0.1 g for 130 min, produced a significant response. Therefore the absolute threshold for a gravitropic response is less than 0.1 g.

Acceleration↗
PubMed1995

Gravitropic responses of the Avena coleoptile in space and on clinostats. II. Is reciprocity valid?

Experiments were undertaken to determine if the reciprocity rule is valid for gravitropic responses of oat coleoptiles in the acceleration region below 1 g. The rule predicts that the gravitropic response should be proportional to the product of the applied acceleration and the stimulation time. Seedlings were cultivated on 1 g centrifuges and transferred to test centrifuges to apply a transverse g-stimulation. Since responses occurred in microgravity, the uncertainties about the validity of clinostat simulation of weightlessness was avoided. Plants at two stages of coleoptile development were tested. Plant responses were obtained using time-lapse video recordings that were analyzed after the flight. Stimulus intensities and durations were varied and ranged from 0.1 to 1.0 g and from 2 to 130 min, respectively. For threshold g-doses the reciprocity rule was obeyed. The threshold dose was of the order of 55 g s and 120 g s, respectively, for two groups of plants investigated. Reciprocity was studied also at bending responses which are from just above the detectable level to about 10 degrees. The validity of the rule could not be confirmed for higher g-doses, chiefly because the data were more variable. It was investigated whether the uniformity of the overall response data increased when the gravitropic dose was defined as (gm x t) with m-values different from unity. This was not the case and the reciprocity concept is, therefore, valid also in the hypogravity region. The concept of gravitropic dose, the product of the transverse acceleration and the stimulation time, is also well-defined in the acceleration region studied. With the same hardware, tests were done on earth where responses occurred on clinostats. The results did not contradict the reciprocity rule but scatter in the data was large.

Acceleration↗