Biomedical subjects

Mark Gardner

Publications and source records attributed to Mark Gardner.

5 recordsLinked to original sources

PubMed2007

Hopping, skipping or jumping to conclusions? Clarifying the role of the JTC bias in delusions.

INTRODUCTION: There is substantial evidence that patients with delusions exhibit a reasoning bias--known as the "jumping to conclusions" (JTC) bias--which leads them to accept hypotheses as correct on the basis of less evidence than controls. We address three questions concerning the JTC bias that require clarification. Firstly, what is the best measure of the JTC bias? Second, is the JTC bias correlated specifically with delusions, or only with the symptomatology of schizophrenia? And third, is the bias enhanced by emotionally salient material? METHODS: To address these questions, we conducted a series of meta-analyses of studies that used the Beads task to compare the probabilistic reasoning styles of individuals with and without delusions. RESULTS: We found that only one of four measures of the JTC bias--"draws to decision"--reached significance. The JTC bias exhibited by delusional subjects-as measured by draws to decision--did not appear to be solely an epiphenomenal effect of schizophrenic symptomatology, and was not amplified by emotionally salient material. CONCLUSIONS: A tendency to gather less evidence in the Beads task is reliably associated with the presence of delusional symptomatology. In contrast, certainty on the task, and responses to contradictory evidence, do not discriminate well between those with and without delusions. The implications for the underlying basis of the JTC bias, and its role in the formation and maintenance of delusions, are discussed.

Bias↗

PubMed2006

Clinical pharmacology of multiple doses of lasofoxifene in postmenopausal women.

Lasofoxifene, a next-generation selective estrogen receptor modulator, is undergoing phase 3 clinical development for osteoporosis. This study evaluated daily lasofoxifene for 14 days in healthy postmenopausal women. A loading dose of 5 times the daily dose was followed by daily doses of 0.01 mg (n = 8), 0.03 mg (n =8), 0.1 mg(n = 16), 0.3 mg (n =9), 1 mg (n = 8), or placebo (n = 16). Samples were collected for pharmacokinetic and pharmacodynamic assessments. Lasofoxifene was well tolerated; study drug-associated adverse events were mild and unrelated to dose. There was a predictable increase in plasma concentrations of lasofoxifene with dose. Pharmacokinetic parameters included mean half-life of 165 hours, mean area under the plasma concentration-time curve from time 0 to 24 hours ranging from 1.67 ng x h/mL to 137 ng x h/mL, and mean maximum observed plasma concentration ranging from 0.09 ng/mL to 6.43 ng/mL. Lasofoxifene partially suppressed luteinizing hormone, follicle-stimulating hormone, low-density lipoprotein, and N-telopeptide.

Administration, Oral↗

PubMed2006

Peaceful ending.

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Humans↗

PubMed2005

Effect of lasofoxifene on the pharmacokinetics of digoxin in healthy postmenopausal women.

Lasofoxifene is in late-stage development for the prevention and treatment of osteoporosis. Digoxin is commonly prescribed for arrhythmias and congestive heart failure, has a narrow therapeutic index, and may be coadministered with lasofoxifene. This study was conducted to determine the effect of lasofoxifene (4-mg loading dose on day 11 followed by 0.5 mg/d on days 12-20) on the steady-state pharmacokinetics of digoxin (0.25 mg/d on days 1-20) in 12 healthy postmenopausal women. On days 10 and 20, blood and urine samples were collected for 24 hours to determine digoxin concentrations. The 90% confidence interval (CI) of least squares mean ratio for maximum concentration (C(max)) and area under the plasma concentration-time curve (AUC) was calculated. Lasofoxifene had no effect on digoxin plasma pharmacokinetics with a ratio (90% CI) of 95.4% (84.6%-107%) and 103% (97.7%-108%) for C(max) and AUC(0-24), respectively. The ratio of the percentage of dose eliminated unchanged in urine in 24 hours was 127% (116% to 142%). Coadministration of lasofoxifene had no effect on the steady state pharmacokinetics of digoxin.

Aged↗

PubMed2002

Attentional demands of continuously monitoring orientation using vestibular information.

The aim of this series of experiments was to determine whether attention is normally required for continuously processing vestibular information concerning orientation, or is required only when orientation is disrupted (eg by vestibular dysfunction or by conflicting visual and vestibular orientation cues). In the first two studies, healthy subjects were passively oscillated, and indicated when they perceived they were passing through their starting position. There was only weak evidence for interference between performance on this 'continuous orientation monitoring task' and on concurrent mental tasks. However, a third study showed that when patients with vestibular imbalance carried out the continuous orientation monitoring task their performance on a concurrent mental arithmetic task was substantially impaired. This dual task interference was correlated with inaccuracy in judging orientation on the continuous orientation monitoring task, which in turn correlated with severity of recent vestibular symptomatology (assessed by questionnaire). In a fourth experiment, disorientation was induced in healthy subjects by rotating the visual field about the line of sight. Bidirectional interference was observed between monitoring orientation (assessed by accuracy in setting a rod to the perceived vertical) and performance of an arithmetic task. Dual task interference was correlated with baseline levels of disorientation induced by the visual field, as indicated by inaccuracy in judging the visual vertical. These findings suggest that monitoring orientation makes significant demands upon cortical processing resources when disorientation is induced, whether the disorientation results from deficient sensory functioning or from ambiguous perceptual information.

Adult↗