Biomedical subjects
L Atkinson
Publications and source records attributed to L Atkinson.
Mental retardation and WAIS-R scatter analysis.
In an earlier article, the psychometric properties of Wechsler Adult Intelligence Scale-Revised (WAIS-R) subtest difference scores were explored using a sample with IQ < 80. Data were offered which allowed the practitioner to determine whether the difference between two subtests was statistically reliable. This article represents an extension of the earlier work. It presents a set of reliability estimates for the difference between a single WAIS-R subtest and the mean of all subtests, and permits the clinician to determine whether the difference obtained by a particular examinee is statistically significant.
Mental retardation and WAIS-R difference scores.
This article explores the psychometric properties (reliabilities, standard deviations and measurement errors) of Wechsler Adult Intelligence Scale--Revised (Wechsler, 1981) subtest difference scores. The sample consisted of 290 subjects with IQ less than 80. Results demonstrated less than satisfactory difference score reliability and disproportionate measurement error. Nevertheless, neither property was so inadequate as to render cautious profile interpretation impossible. The tabled values can help clinicians working with developmentally delayed clients interpret differences between subtest scores based on statistically reliable discrepancies.
Concurrent use of the Wechsler Memory Scale-Revised and the WAIS-R.
The Wechsler Memory Scale-Revised (WMS-R) is often used in combination with the Wechsler Adult Intelligence Scale-Revised (WAIS-R). The clinician must determine whether variation between Indexes and IQs is due to measurement error, or whether it reflects real discrepancies in underlying abilities. This article presents a table of statistically significant differences between WMS-R Indexes and WAIS-R IQs. Although psychometric difficulties and procedural limitations render the tabled values somewhat inaccurate, the values can nevertheless be used to augment clinical decision.
Development and application of a multiple typing system for Clostridium difficile.
A combination of bacteriocin, bacteriophage, and plasmid typing techniques was used to differentiate strains of Clostridium difficile. A typing set of 20 bacteriocin-producing strains was established after 400 isolates of C. difficile were screened for the ability to produce bacteriocin. These strains were used to type a collection of 114 isolates of C. difficile. Forty-six (40%) of the 114 isolates were typeable, and 31 typing patterns were distinguishable. Plasmid typing of the same 114 isolates of C. difficile showed that 67 (59%) of the isolates carried up to four plasmids ranging from 7 to 60 kb in size, although most strains contained only one or two plasmids. Twenty different plasmid typing patterns were observed among the isolates. A combination of bacteriocin and plasmid typing provided 77% typeability. Fifteen (13%) of the 114 strains were typeable with five bacteriophages isolated in our laboratory, but the increase in typeability of strains over that obtainable by plasmid and bacteriocin typing was only 1.8%. Isolates that were nontypeable by bacteriocins, plasmids, or phages could be divided into two groups on the basis of positive or negative cytotoxin production. This further division of strains would increase the typeability potential by 7%; i.e., the ability to differentiate strains would rise from 77 to 84%, or perhaps 86%, if phage typing were included. We conclude that more than one of the techniques reported in this paper must be used to achieve an acceptable level of typeability of this species.
Use of population-specific parameters in generating WAIS-R short forms.
One method of increasing the validity of WAIS-R short forms in estimating the standard WAIS-R Full Scale IQ is by using population-specific parameters in generating WAIS-R short forms. Three studies were conducted to evaluate (1) the contribution of age-scaled scores in generating accurate short-form Full Scale IQ, (2) the psychometric properties (validity and reliability) of WAIS-R subtests with a heterogeneous psychiatric population and subsequent development of short forms based on these properties, and (3) the validity of these short forms with respect to Silverstein's (1982) and Cyr and Brooker's (1984) 2- and 4-subtest combinations. Analyses showed (1) the use of age-scaled scores did not increase validity, (2) different subtest combinations were generated based on the population-specific parameters, and (3) increases in validity occurred for some short forms derived from the clinical sample. Despite increases in validity, clinicians and researchers are cautioned about the use of short forms in clinical practice.
The British Picture Vocabulary Scale: constructing confidence intervals to evaluate change.
The practitioner is often faced with the situation where a client has been administered a test more than once, and it must be determined whether variation in the scores obtained is either due to real change or merely reflects imprecision in measurement. This paper offers a table of standard errors of prediction, and confidence levels based thereon, which can help in making this decision where the British Picture Vocabulary Scale is used. The table is based on the normative data provided in the manual.
The requirement for platelets in allergen-induced late asthmatic airway obstruction. Eosinophil infiltration and heightened airway responsiveness in allergic rabbits.
In these studies, we have used an allergic rabbit model to investigate the role of platelets in the late asthmatic response (LAR) by depleting platelets with a guinea pig antirabbit platelet antiserum (APAS). Allergen exposure of immunized rabbits pretreated with normal guinea pig serum (NGPS) to serve as a control resulted in an early- and late-phase obstructive airway response that persisted for 6 h. When the immunized animals were pretreated with APAS, the magnitude of the LAR in terms of dynamic compliance was reduced by 86.2% (p less than 0.03), but there was no difference in the early response curve. Allergen challenge of animals treated with NGPS resulted in an increased bronchial responsiveness to inhaled histamine: PD50 Cdyn geometric mean +/- SEM before, 2.36 mg/ml (3.43-1.64); after, 0.60 mg/ml (0.67-0.54) (p less than 0.01). PD50 RL before, 1.78 mg/ml (2.4-1.32); after, 0.58 mg/ml (0.81-0.47) (p less than 0.05). In contrast, when animals were treated with APAS, there was a significant inhibition of allergen-induced airway hyperresponsiveness to inhaled histamine: PD50 Cdyn geometric mean +/- SEM before, 1.42 mg/ml (2.06-0.98); after, 1.10 mg/ml (1.41-0.86) (p less than 0.4). PD50 RL before, 1.62 mg/ml (2.22-1.39); after, 1.05 mg/ml (1.35-0.82) (p greater than 0.4). Analysis of bronchoalveolar lavage fluid revealed an increase in the number of neutrophils and eosinophils after allergen exposure in control animals (p less than 0.01). However, in animals rendered thrombocytopenic, the number of eosinophils, but not neutrophils, was significantly reduced (p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)
Reliability and validity of ratio developmental quotients from the Cattell Infant Intelligence Scale.
The test-retest reliability and predictive validity of developmental quotients (DQs) derived from the Cattell Infant Intelligence Scale as administered to children with mental retardation over 30 months of age was assessed. When DQs of 36 children assessed twice with the Cattell were compared, scores were highly correlated, with no significant difference between them, indicating impressive test score stability. When DQs of 47 youngsters assessed once with the Cattell and once with the Stanford-Binet, Form L-M, were compared, scores were significantly correlated but significantly discrepant. These results were compared to previous findings (Goldstein & Sheaffer, 1988) on the Bayley Scales of Infant Development as a predictor of Stanford-Binet IQ. The DQs derived from the Bayley were superior to Cattell DQs in predicting Stanford-Binet IQ.
Intellectual and adaptive functioning: some tables for interpreting the Vineland in combination with intelligence tests.
A set of tables was provided with the differences necessary for statistical significance between the Vineland Adaptive Behavior Scales and the Bayley Scales of Infant Development. McCarthy Scales of Children's Abilities, Stanford-Binet Intelligence Scale (4th ed.), and all current Wechsler intelligence scales. This information may be beneficial in determining whether discrepancies in the Vineland and measures of intelligence can be attributed to chance alone or whether they represent real differences. In light of normative sampling diversity, regression effects, and procedural factors, which result in varying and indeterminate error in the tables, the tables can only augment clinical decision, not replace it.
Generalizability of WAIS-R factor structure within and between populations.
We investigated the reliability of the factor structure of the Wechsler Adult Intelligence Scale-Revised (WAIS-R). The WAIS-R subtests, as administered to 146 head-injured males, were factor analyzed. Two- and three-factor solutions were extracted that were consistent with past findings. Congruence coefficients were computed to determine degree of association between factor structures from all samples reported in the literature. All coefficients were impressive. Also, congruence coefficients based on factor structures derived from different samples within the same population were compared to coefficients based on different samples from different populations. No significant discrepancies emerged. Apparently, the slight factor structure variation that does exist is due to chance data fluctuation rather than to systematic population bias. This reflects well on the robustness of the WAIS-R factor structure.
Modification of allergen-induced airway obstruction and airway hyperresponsiveness in an allergic rabbit model by the selective platelet-activating factor antagonist, BN 52021.
Allergen challenge of eight ragweed-immunized rabbits elicited a prolonged airway obstruction that was evident during the 6-hour study period. Airway responsiveness to histamine was enhanced 24 hours after allergen exposure (geometric mean of the 50% reduction in effective dose [ED50] of dynamic compliance [Cdyn] before challenge, 3.46 mg/ml, decreased to 0.52 mg/ml after challenge, p less than 0.01; pulmonary resistance ED50 geometric mean before challenge, 3.50 mg/ml, decreased to 0.65 mg/ml after challenge, p less than 0.05). In a random crossover study, the selective platelet-activating factor antagonist, BN 52021 (60 mg/kg, orally, 1 hour before allergen challenge), significantly reduced the allergen-induced airway obstruction (p less than 0.005). In addition, pretreatment with BN 52021 reduced the associated increased airway responsiveness induced by allergen exposure (prechallenge Cdyn ED50, 1.93; after challenge, 2.13 mg/ml; pulmonary resistance ED50, 1.91 mg/ml before challenge and 1.69 mg/ml after challenge). These present observations suggest a role for platelet-activating factor in the pathogenesis of allergen-induced airway obstruction and in the development of airway hyperresponsiveness in an allergic rabbit model.
Toxic reaction to inhaled paint fumes.
An acute confusional state was observed to follow heavy exposure to polyurethane gloss paint fumes in a previously healthy 60 year old man. This state remitted over a 3-day period, but was followed by transient bone marrow suppression and evidence of liver cell damage. The corroborated absence of other toxins and the temporal association of exposure to paint fumes suggest that a volatile paint component was responsible. White spirit is the major volatile solvent in polyurethane gloss paint. Ingestion of related aliphatic hydrocarbons has been reported to cause nausea, drowsiness and hepatotoxicity, but these symptoms have not previously been documented following excessive inadvertent inhalation of paint fumes.
Differential classification in school refusal.
It has been argued that school refusal may not be a unitary syndrome, but a common presenting symptom founded on differing underlying dynamics. The paper explores this hypothesis empirically. The clinical files of 100 refusers were scored for several variables which could potentially differentiate between school refusal subtypes, and for several commonly accepted beliefs about school refusal. The data were subjected to a variety of analyses, culminating in cluster analysis. Cluster (C) 1 consisted of children who feared separation from dependent, overprotective mothers. C2 youngsters were perfectionistic and depressed. They dominated mothers who had been deprived in childhood. C3 consisted of extensively disturbed children from multiproblem families, who had suffered early separation or loss, and who were fearful and depressed.
Clinical experience with ciprofloxacin: analysis of a multi-practice study.
In a multi-practice study of 113 patients treated with ciprofloxacin (mean daily dosage, 995 mg per day; mean duration of treatment, 9.6 days) for a variety of infections, 14 were microbiologically proven. Of these, bacteriologic cure and/or improvement resulted in 92.9% of cases. For all 113 infections, clinical cure and/or improvement resulted in 97.1% of cases. A total of 17 infections were classified as chronic. Therapy with ciprofloxacin was discontinued in three (2.6%) of 113 patients because of adverse effects. Overall, there were 5/113 (4.4%) adverse reactions (ADRs). Only one ADR was related definitely to ciprofloxacin therapy. Two ADRs were definitely not related; in two the relationship was uncertain. Two patients of the five (40%) elected to continue ciprofloxacin therapy despite mild side effects.
The emergency burr hole in cranial trauma.
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The management of intracranial arteriovenous malformations.
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Alexithymia: a comparative study of three self-report measures.
This study evaluates and compares the psychometric properties of the three self-report measures of alexithymia - a hypothetical personality construct thought to be associated with hypochondriasis, somatization disorder and a variety of other medical and psychiatric disorders. Two hundred and nine college students were administered the Schalling-Sifneos Personality Scale (SSPS), MMPI alexithymia scale (MMPI-A), Toronto Alexithymia Scale (TAS), and two measures of functional somatic symptoms. Results indicated that the TAS is internally consistent and sensitive to reports of somatic symptoms. In contrast, the SSPS and MMPI-A were found to have response and/or gender biases, poor internal reliabilities, and no systematic relationship with somatic symptoms. In addition, factor analysis showed the TAS to have a stable, replicable factor structure, while the SSPS demonstrated little factor stability. These findings suggest that the TAS is the most psychometrically sound measure of the alexithymia construct.