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Biomedical subjects

C M MacLeod

Publications and source records attributed to C M MacLeod.

At least 19 recordsLinked to original sources
PubMed2001

Isolated diastolic heart failure as a cause of breathlessness in the community: the Arbroath study.

The aim of this study was to examine the prevalence of exercise limitation due to diastolic heart failure among patients felt to have cardiac breathlessness by their general medical practitioner but not referred to hospital. We found that 18% of patients had a simple investigated profile compatible with isolated diastolic dysfunction as a cause of their symptoms. Symptoms appeared to pre-date major cardiac events (infarction; stroke; arrhythmia) that dominated the subsequent clinical course. The patients in this group have adverse cardiovascular risk profiles. Obesity was a common co-morbidity which may impair detailed 2-D echocardiographic assessment.

Adult↗
PubMed2000

Taking the "text" out of context effects in repetition priming of word identification.

Repetition priming of masked word identification is reduced when initial exposure to target words is in a text rather than in a word list. We demonstrate that there is nothing special about the text context that reduces priming. In Experiment 1, target words read in normal text or in rapid serial visual presentation (RSVP) text--either coherent or scrambled--produced similarly reduced priming, relative to the same words read aloud in a list. In Experiment 2, the delay was decreased between study and test for words presented in text, but they still displayed less priming than did words presented in a study list and tested after an equivalent delay. In Experiment 3, presenting study list words in RSVP to prevent reading each word aloud diminished priming to the same level as that in the text context. We conclude that presenting a target in context prevents it from being encoded and responded to as distinctively as when presented in isolation.

Attention↗
PubMed2000

Direct versus indirect tests of memory: directed forgetting meets the generation effect.

Subjects read 20 words and generated 20 others from definitions during a 40-item study phase. Production of each word was followed by an instruction to remember or to forget that word. In free recall, a direct test of memory, words that had been generated were recalled much better than words that had been read. The remember-forget instructional manipulation affected read words but not generated words. In speeded word reading, an indirect test of memory, all studied words showed priming, but read words showed more priming than generated words. Here, the effect of remember versus forget instructions appeared only for generated words. These dissociations of a direct and an indirect test indicate that two powerful encoding manipulations affect separable processes to which these tests are differentially sensitive.

Adult↗
PubMed1999

Implicit activation of alcohol concepts by negative affective cues distinguishes between problem drinkers with high and low psychiatric distress.

This study tested the hypothesis that negative affective (NEG) cues activate alcohol concepts more strongly in problem drinkers with high rather than low psychiatric distress (PD) and that a parallel difference applies to activation of NEG concepts by alcohol cues. A lexical decision task assessed memory activation in 36 problem drinkers with high vs. low scores on the Symptom Checklist-90. High PD drinkers displayed activation in each condition; low PD drinkers displayed inhibition. Activation of alcohol concepts by NEG cues correlated with intensity of PD, bias to drink in NEG states, and confidence to avoid drinking in these states. Results corroborate in vivo cue reactivity studies and indicate a functional difference between problem drinkers with high and low PD.

Adult↗
PubMed1999

Negative priming for obsessive-compulsive checkers and noncheckers.

Negative priming--the slowing of a response to an item that was recently ignored--was investigated in three groups: obsessive-compulsive disorder (OCD) checkers, OCD noncheckers, and nonclinical control participants. All groups performed both a standard negative priming task, selecting targets based on a perceptual feature (i.e., color), and a modified negative priming task, selecting targets based on a semantic feature (i.e., referent size). All three groups demonstrated significant negative priming in both tasks, although the negative priming was much larger in the novel, semantic task than in the common, perceptual one. The findings suggest that patients with OCD do not demonstrate impairments in negative priming, contrary to earlier claims (Enright & Beech, 1990, 1993a, 1993b; Enright, Beech, & Claridge, 1995).

Adult↗
PubMed1999

The item and list methods of directed forgetting: test differences and the role of demand characteristics.

In directed forgetting, the item method presents instructions to remember or to forget individual items; the list method presents a single mid-list instruction to forget the first half of the list. Initial free recall was better for remember (R) words than for forget (F) words under both methods. Offered 50 cents for each additional F word, subjects could recall almost no more items, eliminating a demand characteristics explanation. On a yes/no recognition test, only the item method showed directed forgetting. Retrospective instruction identification was good except for F words under the list method, where performance was at chance. There was no evidence of speed-accuracy tradeoff on the recognition or instruction identification tests. These results bring together the major findings concerning directed forgetting and support a method-based theoretical distinction.

Humans↗
PubMed1999

Clinical use of benzodiazepines and decreased memory activation in anxious problem drinkers.

Clinical use of benzodiazepines (BZDs) may improve treatment outcome in anxious problem drinkers. Decreased activation of alcohol-related memories by negative affective cues may partly explain the beneficial effects of BZDs. To explore this possibility, the present study assessed semantic priming of alcohol words by negative affective words in anxious problem drinkers who received their standard dose of BZD and in unmedicated controls. Two groups of nine subjects each were matched on levels of anxiety, alcohol use, and alcohol dependence before performing a lexical decision task. Medicated subjects displayed significantly less activation than did unmedicated subjects on trials containing negative affective primes and alcohol-related targets, but displayed equivalent activation on control trials with neutral, categorized words. Degree of activation also correlated with a drug's affinity for the BZD receptor. These preliminary results suggest that BZD-induced amnesia may contribute to the therapeutic effects of these drugs in anxious problem drinkers.

Adult↗
PubMed1998

The influence of attention at encoding on direct and indirect remembering.

The relation between attention at encoding and direct (i.e., recognition) versus indirect (i.e., rapid reading) remembering was investigated. In Experiments 1 and 2, color of print indicated whether to read an individual word aloud or to ignore it. This attentional manipulation reduced direct but not indirect remembering for the ignored words relative to the attended words. Apparently direct remembering is extremely dependent on attention at encoding. In Experiment 3, however, presenting two words simultaneously at study, with color now signifying which word to read and which to ignore, eliminated this dissociative effect of attention. Ignored words were not remembered on either test, although attended words were remembered well on both. Mere exposure is not sufficient to produce indirect remembering: Stimuli must be attended. Ignoring one stimulus in favor of processing another stimulus that is simultaneously presented and equally salient may prevent even the minimal attentional requirements of indirect remembering from being met, let alone the more stringent requirements of direct remembering.

Analysis of Variance↗
PubMed1998

Training on integrated versus separated Stroop tasks: the progression of interference and facilitation.

Two experiments examined the course of interference and facilitation in the Stroop (1935) task during training. Two versions of the task were compared: integrated (e.g., the word RED in the color green) and separated (e.g., green asterisks above the word RED). Stimuli were congruent (RED in red), incongruent (GREEN in red), or neutral (XXX in red). Over 5-day (Experiment 1) and 10-day (Experiment 2) training sessions, facilitation due to congruence was small, stable, and equivalent in both task versions. In contrast, interference declined sharply on the integrated task over Days 1-3, then slowed to parallel the gradual decline on the separated task. Finally, training on the color naming task did not affect a word reading task administered after training. These findings imply that (a) Stroop interference initially reflects two problems--overcoming integration and managing two conflicting information sources; (b) with practice, the larger integration problem is solved relatively quickly, rendering the integrated and separated tasks quite comparable thereafter; and (c) facilitation and interference in the Stroop task may be independent. These results challenge extant theories of the Stroop effect, which do not predict such effects.

Adult↗
PubMed1998

Presenting two incongruent color words on a single trial does not alter Stroop interference.

Two experiments showed that having two incongruent words present on a single Stroop trial (e.g., both red and green in blue, say "blue") did not alter interference relative to having only one incongruent word. This was true whether the two incongruent words were presented successively at several stimulus onset asynchronies (Experiment 1) or simultaneously in adjacent positions (Experiment 2). We argue that the first word captures attention and "locks out" others, preventing additional interference.

Adult↗
PubMed1996

Word frequency effects on recall, recognition, and word fragment completion tests.

In 3 experiments, the effect of word frequency on an indirect word fragment completion test and on direct free-recall and Yes-no recognition tests was investigated. In Experiment 1, priming in word fragment completion was substantially greater for low-frequency words than for high-frequency words, but free recall was unaffected. Experiment 2 replicated the word fragment completion result and showed a corresponding effect in recognition. Experiment 3 replicated the low-frequency priming advantage in word fragment completion with the set of words that P.L. Tenpenny and E.J. Shoben (1992) had used in reporting the opposite pattern in word fragment completion. Using G. Mandler's (1980) dual-process theory, the authors argue that recognition and word fragment completion tests both rely on within-item integration that influences familiarity, whereas recall hinges on elaboration that influences retrievability.

Humans↗
PubMed1995

Psychosis and substance abuse: cause, effect or coincidence?

An association between substance abuse and major psychiatric illness is increasingly well recognised, but most studies have been conducted in the USA and have focussed upon patients with schizophrenia rather than other disorders. We conducted a survey of 38 consecutively admitted patients with DSM-III-R functional psychoses. A semi-structured substance abuse interview was administered and a urine specimen for drug metabolite screening requested. The prevalence of cigarette smoking (63%) and current illicit drug use (26%) were higher than general population norms. The 16 subjects with schizophrenia and related disorders were more likely to smoke cigarettes than the 22 patients with an affective disorder (p = 0.008, odds ratio 8.4, 95% Cl 1.3-69.6), and showed tendencies to more illicit drug and alcohol consumption. Illicit drug users were more likely to have a forensic history and less likely to have entered further education. Substance abuse is common among patients with psychoses, particularly in those with schizophrenia and related disorders. All psychotic patients should have a detailed drug history taken, and therapeutic attempts made to reduce consumption.

Adult↗
PubMed1993

Drugs used in the acutely ill patient.

Critical care encompasses many different areas of medicine, from pulmonary and cardiac medicine to anesthesia and neuropsychiatry. Each discipline has somewhat unique approaches to pharmacology. The therapeutic modalities are discussed in the textbooks and journals that are specific for that discipline. Therefore, the pharmacology and therapeutics needed by the physician or medical personnel who provide critical care services are not easily accessed in a timely fashion. The intent of this monograph is to provide a readily accessible format for information regarding the pharmacology of drugs used frequently in the critical care arena. This information includes categorization of drugs by therapeutic and pharmacologic classification, mechanisms of action of the drugs, frequent or unusual adverse effects that attend the use of the drugs, and indications for use of the agents that are acceptable to the medical community as described in the medical literature. Tables are provided to outline the most common doses of the drugs, their routes of administration, expected onset of action where applicable, mechanisms and times for elimination, and duration of action. Tables are also included to describe frequent or expected drug interactions, which increase dramatically as the number of concomitant drugs used increases. The drugs that are amenable to monitoring, and the optimal methods to provide such monitoring, are outlined. Common developing signs or symptoms in patients during stays in a critical care environment are outlined in terms of differential diagnosis and drugs capable of causing those signs or symptoms. Drugs overlap in terms of therapeutic indication, and this fact is handled by inclusion of a table of drug classification that shows the therapeutic categories in which the drugs are included. The drug is discussed in only one area, with cross-references in other areas. All indications for use of a particular drug in the area of critical care are outlined in the appropriate subsection for each drug. This monograph may be used to determine a drug-related cause for a given clinical manifestation, to predict dosing and duration of action for a given patient with possible organ dysfunction, to understand the mechanism of action for a drug and so choose additional therapy that will not interfere or overlap with the drug, to learn guidelines for monitoring drug therapy, or to select drugs that will not potentiate adverse drug effects by negative drug interactions.(ABSTRACT TRUNCATED AT 400 WORDS)

Critical Care↗
PubMed1993

Blood levodopa levels and unified Parkinson's disease rating scale function: with and without exercise.

We studied 10 regular exercising men with Parkinson's disease on levodopa (LD) under two conditions--no exercise and vigorous exercise started 1 hour after LD ingestion. We compared LD levels and motor scores on the Unified Parkinson's Disease Rating Scale (UPDRS). There was a high degree of agreement between plasma LD level and the patients' UPDRS scores 30 minutes later (mean Eta2 = 0.84) in both conditions, with no difference between the two. We conclude that LD levels accurately reflect UPDRS motor function in these patients, and that vigorous exercise started 1 hour after LD ingestion does not influence LD or motor scores.

Aged↗
PubMed1990

Diurnal blood pressure in patients with mild-to-moderate hypertension treated with once-daily benazepril hydrochloride.

This study evaluated the blood pressure effects of administration of once daily oral benazepril hydrochloride, a new angiotensin-converting enzyme (ACE) inhibitor, for mild-to-moderate hypertension. After a 2 to 4 week placebo baseline period, patients with diastolic blood pressure between 95 and 114 mm Hg, were randomized to receive either placebo or benazepril hydrochloride, 5, 10, 20, or 40 mg, once daily in double-blind fashion for 28 days. Blood pressure was measured predose and at 1, 2, 3, 4, 6, 8, 12, 16, 20, and 24 hours after the dose during inpatient observation days at the end of the placebo baseline period, and on the first and last day of the double-blind treatment period; and 24 hours after the dose at weekly outpatient visits. All doses of benazepril hydrochloride resulted in clinically important reductions in diastolic and systolic blood pressures that lasted between 12 and 24 hours after both the first dose, and following the last dose after 4 weeks of treatment. The findings indicate that benazepril hydrochloride may be clinically useful as once-daily monotherapy in many patients with hypertension.

Administration, Oral↗
PubMed1989

Pharmacokinetic evaluation of the terfenadine-theophylline interaction.

Based on results of studies of a possible terfenadine-theophylline interaction on file with Merrell Dow, Inc., a randomized, crossover study was undertaken to determine if there were a pharmacokinetic interaction between these two medications. Seventeen normal volunteers were randomized to receive theophylline or a theophylline-terfenadine combination for 14 days, followed by a 2-week washout period, with crossover to the other treatment for 14 days. Serum theophylline concentrations were measured on the last day of each treatment phase for determination of pharmacokinetic parameters. No differences were found in elimination rate constant, elimination half-life, area under the concentration-time curve, time to peak concentration, or maximum theophylline concentration. It is concluded that concomitant terfenadine therapy does not affect the pharmacokinetic profile of theophylline in healthy male volunteers.

Adult↗