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Biomedical subjects

G E Powell

Publications and source records attributed to G E Powell.

At least 19 recordsLinked to original sources
PubMed1996

Vegetative state and responses to sensory stimulation: an analysis of 24 cases.

A meta-analysis was performed on data from 24 single-case experimental studies evaluating the immediate effects of sensory stimulation treatment on patients in vegetative state following traumatic brain injury. Response to treatment was evaluated by time sampling behaviour pre- and post-treatment, and examining for changes in behaviour that suggested increased arousal. In this analysis the relative effectiveness of different treatment protocols was examined. The effects of variables such as age, gender and time since injury on magnitude of behaviour change was examined; also whether there was a relationship between response to treatment and outcome in terms of whether patients emerged from vegetative state or not. Analyses showed that multimodal stimulation produced greater behavioural changes than unimodal stimulation, and the use of personally salient stimuli in multimodal stimulation the greatest changes of all. Age and gender both showed effects on the magnitude of the behaviour change, but time since injury did not. Patients who did not emerge from the vegetative state were no less likely that those who did to produce statistically significant changes in behaviour in response to treatment. The paper includes a discussion of general issues concerning vegetative state.

Adolescent↗
PubMed1996

Behavioural differences between patients who emerged from vegetative state and those who did not.

This paper reports on a meta-analysis of behavioural data gathered using single case research methodology, while evaluating the immediate effects of a treatment (sensory stimulation) on 24 individuals diagnosed as being in vegetative state following trauma. The data derived from time sampling have been used to compile measures of behavioural change in response to environmental events, which are referred to as arousal profiles. In addition to this, interviews were conducted regularly to elicit structured observations from the nursing staff concerning behavioural changes that they had observed. The subjects were divided into two groups according to whether they had emerged from vegetative state or not at the time the meta-analysis commenced. Statistically significant differences were found between the outcome groups in terms of modal arousal profile characteristics; one profile type was characteristic only of those that emerged. The two groups could also be differentiated by the mean recovery curves derived from the interview data. Behavioural differences between the outcome groups have been found which are detectable while the patients are in vegetative state. These findings have prognostic potential.

Adolescent↗
PubMed1996

Constructing arousal profiles for vegetative state patients--a preliminary report.

Arousal profiles are a method that we have developed for using data derived from time sampling to examine how behaviours such as the frequency with which the eyes are observed open, and the frequency of spontaneous movements, vary in the periods immediately before and immediately after sensory stimulation treatment. We believe changes in such behaviours reflect changes in arousal. The use of this new technique is illustrated with examples from a pilot study using data from 15-day treatment blocks, gathered for 10-minute periods immediately before and after sensory stimulation treatment from three patients using single-case research methods. The patients were diagnosed as being in vegetative state following traumatic brain injury. The possible significance of the differing characteristics of the profiles is discussed.

Adult↗
PubMed1989

Methanogenesis from ethanol by defined mixed continuous cultures.

Methanogenesis from ethanol by defined mixed continuous cultures was studied. Under sulfate-free conditions, a Desulfovibrio strain was used as the ethanol-degrading species producing acetic acid and hydrogen. In a two-membered mutualistic coculture, the hydrogen was converted to methane by a Methanobacterium sp. and pH was maintained at neutrality by the addition of alkali. Introduction of a third species, the acetate-utilizing Methanosarcina mazei, obviated the need for external pH control. Methanogenesis by the co-and triculture was studied at various dilution rates in the steady state. The mutualistic coculture performed like a composite single species, as predicted from the theory of mutualistic interactions. Coupling between the mutualistic coculture and the acetate-utilizing methanogen was less tight. Increasing the dilution rate destabilized the triculture; at low dilution rates, instability was soon recovered, but at higher dilution rates imbalance between the rates of production and removal of acetic acid led to a drop in pH. Flocs formed in the triculture. An annulus of the Methanobacterium sp. and Desulfovibrio sp. was retained around the Methanosarcina sp. by strands of material probably derived from the Methanosarcina sp.

Journal Article↗
PubMed1987

Relationships between neuropathology and cognitive functioning in temporal lobectomy patients.

Cognitive functions were examined before operation and 4 weeks after operation with respect to pathology in 40 patients who underwent temporal lobectomy for epilepsy. Hippocampal sclerosis was associated with febrile convulsions, an earlier onset of regular seizures, poorer preoperative intelligence and with a tendency towards greater cognitive improvement across the operation than found in patients with tumour-like malformations or non-specific pathology. Damage to the amygdala was associated with a poorer outcome for the retention in memory of verbal and non-verbal material. The absence of any specific abnormality in the resected tissue was not associated with a poorer cognitive outcome 4 weeks after the operation.

Adult↗
PubMed1987

Lateralisation of memory functions in epileptic patients by use of the sodium amytal (Wada) technique.

Lateralisation of speech and memory functions was determined in 27 patients, being assessed for surgical treatment of unilateral temporal lobe epilepsy, using the sodium amytal procedure. The most common outcome with regard to language was the retention of normal left hemisphere dominance, regardless of handedness or side of lesion. In contrast, memory functions were most often to be found only in the unaffected hemisphere, also regardless of handedness or side of lesion. A lesion of either hemisphere appeared capable of interfering with language and verbal memory functions in an unexpectedly high proportion of patients.

Adolescent↗
PubMed1985

The new Maudsley series of temporal lobectomy. I: Short-term cognitive effects.

Cognitive effects of temporal lobectomy for the relief of focal seizures were examined in 59 adult cases (29 left and 30 right). Verbal and non-verbal intelligence and memory were tested pre-operatively and four weeks post-operatively. Slight, non-significant differences between left and right cases pre-operatively were added to by slight, non-significant differences in change across the operation, to produce some significant post-operative differences--right cases being significantly higher on verbal IQ and lower on non-verbal IQ, for example. Variation in cognitive outcome was related to certain subject variables. Those who showed no deterioration or more improvement across the operation tended to be younger, less intellectually able pre-operatively, had an earlier first seizure and an earlier onset of regular seizures. The implications of these results for a model of the effects of temporal lobectomy are discussed.

Adolescent↗
PubMed1984

Serial position, rehearsal and recall in temporal lobe epilepsy.

Two auditory forms of the serial position curve (SPC) were administered to three groups of 20 subjects: normal and neurotic controls and chronic temporal lobe epileptics. In contrast to expectation, epileptics were especially poor on the recency portion of the curve. Evidence from a further 30 cases of temporal lobe damage suggested that the epileptics had rehearsed earlier items at the expense of later ones.

Adult↗
PubMed1983

The clinical description of forty-eight cases of sexual fetishism.

This study surveys the discharge register of a large London teaching hospital over 20 years and presents data on its 48 cases of clinical sexual fetishism. An attempt was made to answer two questions: (1) What are the clinical problems these patients present? They have more to do with the perception of fetishes as personally or socially unacceptable than with 'objective' restrictions placed on sexual activity. (2) What is the classification used to describe? The data have not enabled any conclusions to be drawn about the existence of particular fetishist syndromes. Certainly, a fifth or more of the sample had fetishes for clothes or rubber or rubber items, or wore or stole a fetish or fetishes; but this information is insufficient to allow one to assume that these patients had something significant in common, and leaves open the question of what more precisely each individual was attracted to.

Adolescent↗
PubMed1980

Self-report of memory skills after temporal lobectomy: the effect of clinical variables.

Forty-eight patients who had undergone unilateral temporal lobectomy for the relief of focal epilepsy 6 months to 6 years prior to contact were asked to rate themselves on a questionnaire designed to look at "real-life" memory skills. The temporal lobe patients, as a group, saw themselves as having poorer memories than normals, but only 3 out of 43 items showed significant differences between right-and left-sided lobectomy patients. Our hypotheses that age at operation, reduction in seizure frequency and time since operation (in the left temporal lobe patients only) would determine the extent of subject complaint of memory were fully confirmed. In addition, sex of the patient was found to be a significant variable. The status of subjective and objective measures of memory as indices of "real-life" memory skills is discussed.

Adult↗
PubMed1980

A very short version of the Minnesota Aphasia Test.

A very short version of the Minnesota Differential Diagnosis of Aphasia Test is described. It is standardized on 86 aphasics and reduces the original 43 subtests to just four; takes less than 15 minutes to give; correlates by over 0.9 with the total full test; and misclassified only 13 per cent of subjects. These four subtests are identifying objects named serially (A4), oral reading of words (B8), naming pictures (C13) and written spelling (D6). This extensive shortening is made feasible by the high degree of redundancy in the original full version. The test is designed to detect asphasia in general, and not to partition aphasics typologically, for which the full Minnesota is required.

Aphasia↗
PubMed1979

The relationship between intelligence and verbal and spatial memory.

Administered the Logical Memory Test (LM) and the Rey-Osterreith Test (RO), which have been assumed to pertain to verbal and spatial cognitive functioning, to 150 Ss referred for neuropsychological screening. Ss also were administered the short version of the WAIS, plus Digit Span. It was found that LM did relate more to verbal IQ than to spatial IQ and vice-versa for RO. It was not clear exactly what aspect of cognitive functioning Digit Span was tapping. The clinical implications of the study are that LM scores must be viewed in the light of verbal IQ level, and RO scores interpreted in relation to both spatial IQ and age. Data are presented that can be used for the statistical interpretation of an individual case test scores.

Adolescent↗