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Biomedical subjects

G A Baker

Publications and source records attributed to G A Baker.

At least 19 recordsLinked to original sources
PubMed2006

Interaction of influenza virus fusion peptide with lipid membranes: effect of lysolipid.

The effect of lysophosphatidylcholine (LPC) on lipid vesicle fusion and leakage induced by influenza virus fusion peptides and the peptide interaction with lipid membranes were studied by using fluorescence spectroscopy and monolayer surface tension measurements. It was confirmed that the wild-type fusion peptide-induced vesicle fusion rate increased several-fold between pH 7 and 5, unlike a mutated peptide, in which valine residues were substituted for glutamic acid residues at positions 11 and 15. This mutated peptide exhibited a much greater ability to induce lipid vesicle fusion and leakage but in a less pH-dependent manner compared to the wild-type fusion peptide. The peptide-induced vesicle fusion and leakage were well correlated with the degree of interaction of these peptides with lipid membranes, as deduced from the rotational correlation time obtained for the peptide tryptophan fluorescence. Both vesicle fusion and leakage induced by the peptides were suppressed by LPC incorporated into lipid vesicle membranes in a concentration-dependent manner. The rotational correlation time associated with the peptide's tryptophan residue, which interacts with lipid membranes containing up to 25 mole % LPC, was virtually the same compared to lipid membranes without LPC, indicating that LPC-incorporated membrane did not affect the peptide interaction with the membrane. The adsorption of peptide onto a lipid monolayer also showed that the presence of LPC did not affect peptide adsorption.

Adsorption↗
PubMed2006

In utero antiepileptic drug exposure: fetal death and malformations.

BACKGROUND: Pregnancy outcomes following in utero exposure to antiepileptic drugs (AEDs) are uncertain, limiting an evidenced-based approach. OBJECTIVE: To determine if fetal outcomes vary as a function of different in utero AED exposures. METHODS: This ongoing prospective observational study across 25 epilepsy centers in the USA and UK enrolled pregnant women with epilepsy from October 1999 to February 2004 to determine if differential long-term cognitive and behavioral neurodevelopmental effects exist across the four most commonly used AEDs. This initial report focuses on the incidence of serious adverse outcomes including major congenital malformations (which could be attributable to AEDs) or fetal death. A total of 333 mother/child pairs were analyzed for monotherapy exposures: carbamazepine (n = 110), lamotrigine (n = 98), phenytoin (n = 56), and valproate (n = 69). RESULTS: Response frequencies of pregnancies resulting in serious adverse outcomes for each AED were as follows: carbamazepine 8.2%, lamotrigine 1.0%, phenytoin 10.7%, and valproate 20.3%. Distribution of serious adverse outcomes differed significantly across AEDs and was not explained by factors other than in utero AED exposure. Valproate exhibited a dose-dependent effect. CONCLUSIONS: More adverse outcomes were observed in pregnancies with in utero valproate exposure vs the other antiepileptic drugs (AEDs). These results combined with several recent studies provide strong evidence that valproate poses the highest risk to the fetus. For women who fail other AEDs and require valproate, the dose should be limited if possible.

Abnormalities, Drug-Induced↗
PubMed2006

A randomized controlled trial of a health promotion education programme for people with multiple sclerosis.

OBJECTIVE: To evaluate the effectiveness of a health promotion education programme for people with multiple sclerosis (the OPTIMISE programme) in terms of increasing the level of health-promoting activity undertaken, improving self-efficacy and enhancing quality of life. DESIGN: A randomized controlled single blinded trial. Non-parametric analysis was undertaken to test for significant differences between treatment and control groups change scores. SUBJECTS AND SETTING: Sixty-two adults (32 treatment and 30 control subjects) with multiple sclerosis of any type, Expanded Disability Status Scale (EDSS) 1-7. INTERVENTION: An eight-week multidisciplinary outpatient health promotion education programme aimed at increasing knowledge, skills and confidence in undertaking health promotion activities. OUTCOME MEASURES: Health Promoting Lifestyle Profile, Self-Rated Abilities for Health Practices Scale and the Short Form 36 Item Health Survey. RESULTS: Following completion of the programme, treatment subjects had significantly higher levels of health promotion activity undertaken (P < 0.01) and self-efficacy for health promotion activities (P < 0.01). These benefits were sustained for at least three months after the programme ceased. Certain domains of quality of life also improved in treatment subjects more than controls (physical P = 0.03, mental health and general health P = 0.01), although only mental health and general health showed further improvement at three months. Participants provided positive feedback regarding the usefulness of the intervention and demonstrated observable changes to their health promotion behaviours. CONCLUSIONS: The OPTIMISE programme produced significant changes in health-promoting behaviours.

Female↗
PubMed2005

Psychological treatments for epilepsy.

BACKGROUND: Psychological interventions such as relaxation therapy, cognitive behaviour therapy, bio-feedback and educational interventions have been used alone or in combination in the treatment of epilepsy, to reduce the seizure frequency and improve the quality of life. OBJECTIVES: To assess whether the treatment of epilepsy with psychological methods is effective in reducing seizure frequency and/or leads to a better quality of life. SEARCH STRATEGY: We searched the Cochrane Epilepsy Group's Specialized Register (July 2005), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2005), and MEDLINE (1966 to March 2005). No language restrictions were imposed. We checked the reference lists of retrieved studies for additional reports of relevant studies. SELECTION CRITERIA: Randomized or quasi-randomized studies assessing one or more types of psychological or behaviour modification techniques for people with epilepsy. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed the trials for inclusion and extracted data. Primary analyses were by intention to treat. Outcomes included reduction in seizure frequency and quality of life. MAIN RESULTS: We found three small trials (50 participants) of relaxation therapy. They were of poor methodological quality and a meta-analysis was therefore not undertaken. No study found a significant effect of relaxation therapy on seizure frequency. One trial found cognitive behavioural therapy to be effective in reducing depression, among people with epilepsy with a depressed affect, whilst another did not. One trial of group cognitive therapy found no significant effect on seizure frequency. Two trials of combined relaxation and behaviour therapy and one of EEG bio-feedback and four of educational interventions did not provide sufficient information to assess their effect on seizure frequency. One small study of galvanic skin response biofeedback reported significant reduction in seizure frequency. Combined use of relaxation and behaviour modification was found beneficial for anxiety and adjustment in one study. In one study EEG bio-feedback was found to improve the cognitive and motor functions in individuals with greatest seizure reduction. Educational interventions were found to be beneficial in improving the knowledge and understanding of epilepsy, coping with epilepsy, compliance to medication and social competencies. AUTHORS' CONCLUSIONS: In view of methodological deficiencies and limited number of individuals studied, we have found no reliable evidence to support the use of these treatments and further trials are needed.

Biofeedback, Psychology↗
PubMed2005

Neuropsychological effects of exposure to anticonvulsant medication in utero.

OBJECTIVE: To investigate the long-term differential drug effects on cognitive functioning in school-aged children exposed to antiepileptic drugs (AEDs) in utero. METHODS: Mothers with epilepsy were recruited from specialist epilepsy clinics and obstetric clinics from the Liverpool and Manchester region. The mothers and their children were recruited without prior knowledge of their AED treatment during pregnancy or the health of the offspring. A battery of neuropsychological tests was applied to each mother-child pair in order to obtain a neuropsychological profile for each child. RESULTS: Neuropsychological investigation was performed on 249 children between the ages of 6 and 16. Children exposed to sodium valproate had a significantly lower verbal IQ when compared to children exposed to other antiepileptic drugs or not exposed at all. The same children were more likely to have an IQ below 69 and more likely to have memory impairment when compared to the other groups. The mothers' IQ, exposure to sodium valproate, and the number of tonic-clonic seizures during pregnancy were significant predictors of verbal IQ in this population. CONCLUSIONS: This retrospective study highlights the potential harmful effects of sodium valproate exposure in utero on neuropsychological development.

Adolescent↗
PubMed2005

The detection of malingering in memory performance: the sensitivity and specificity of four measures in a UK population.

OBJECTIVES: To investigate the validity of a clinical neuropsychological battery for the detection of malingering on tests of memory. METHODS: A simulated scenario design was developed to investigate the effectiveness of a battery of four neuropsychological tests in the detection of malingering; the Coin in the Hand Test (CIH), Autobiographical Memory Index (AMI), Rey I 5-Item Test (RIT),and the Wechsler Mental Control Test (MCT). The performances of patients with an acquired brain injury (N = 40) were compared with two groups of controls instructed either to simulate a head injury performance (N = 40) or do their best (N = 40). RESULTS: The CIH and MCT demonstrated good validity and displayed high sensitivity and specificity. The RIT and the AMI was relatively poor in distinguishing between simulators and patients. CONCLUSIONS: The sensitivity and specificity of all four tests to the detection of malingering has been assessed. Two of the tests the CIH and MCT would be useful as a quick and accurate screening tool for detecting malingering.

Adult↗
PubMed2003

Neuropsychological assessment of a group of UK patients with Cohen syndrome.

Cohen syndrome is a rare autosomal recessive syndrome with a distinctive clinical phenotype that includes mental retardation and a characteristic sociable disposition. Variability in the level of learning disability and the behavioural phenotype is seen in the published literature. In a cohort of Finnish Cohen syndrome patients, severe mental retardation and non-maladaptive behaviour were described. Outside of Finland, autistic-spectrum behaviour has been reported in a few isolated Cohen syndrome patients but in a recent UK study was found to be highly prevalent. We report the results of neuropsychological studies in a group of 16 genetically heterogeneous patients, all with the characteristic clinical features of Cohen syndrome. Of the 9 patients who underwent formal neuropsychological testing, all but one was functioning in the severely mentally impaired range. Of the remaining patients, 3 were below the age of formal testing and 4 had such profound learning and behavioural problems that they were deemed unable to participate in testing. Mild maladaptive behaviour was observed in 13 patients and 3 were documented as having significant maladaptive behaviour. In contrast to the Finnish group of Cohen syndrome patients, this UK study identifies significant neuropsychological impairment combined with maladaptive behaviour as a characteristic of Cohen syndrome. Although autistic-type behaviour was observed, an increased prevalence of autism in Cohen syndrome was not confirmed.

Adolescent↗
PubMed2002

The A-B neuropsychological assessment schedule (ABNAS): the relationship between patient-perceived drug related cognitive impairment and results of neuropsychological tests.

Our intention was to evaluate the relationships between the A-B neuropsychological assessment schedule (ABNAS) as a measure of patient-perceived cognitive effects of antiepileptic drugs (AEDs) and the results of neuropsychological tests. The measure was developed specifically to assess patient-perceived cognitive effects of AED treatment. Evidence of its reliability and validity has been previously documented. In this study 96 patients were included using stratified inclusion-criteria to guarantee variability of performance: 55 patients were included from a 'low risk condition' with respect to possible cognitive effect (i.e. monotherapy carbamazepine within a dose range of 600-1200 mg/day) and 41 patients were included from a 'high risk condition' (i.e. polytherapy of three or two AEDs including either phenytoin, phenobarbitone or a benzodiazepine; treatment with topiramate with a titration speed using 50 mg or higher increments per week and within the first 6 months of treatment). All patients were prospectively assessed using the ABNAS and five neuropsychological tests (all part of the FePsy test system) with proven sensitivity of cognitive effects of antiepileptics: three tasks using reaction-time to measure speed ('simple (visual) reaction-time measurement', 'the binary choice reaction test' and 'the computerized visual searching task'); one test measuring motor speed ('the finger tapping task'); and a memory test ('recognition of words'). The three reaction-time tasks and the finger tapping test were significantly correlated with the ABNAS-score with correlations ranging from 0.22 to 0.35. The highest correlation was with 'simple (visual) reaction-time measurement' (0.35). Discriminant analysis showed that with the neuropsychological tests 61.5% of the patients were correctly identified as having high/low ABNAS-scores. The ABNAS underestimated impairment in 17.8% of the patients ( = low ABNAS-score but impairment on the neuropsychological tests). The present study contributes to the already existing evidence of validity of the ABNAS as a screening instrument for clinical practice as the relationship between the ABNAS-score and results of neuropsychological tests can help to identify who is at risk and needs further referral for neuropsychological assessment. Moreover the correlation between ABNAS-score and those neuropsychological tests that are sensitive for drug-effects may provide a sensitive instrument in early drug-development phases while keeping the burden on financial and time resources to a minimum.

Adult↗
PubMed2001

Effects of fluorescent probe structure on the dynamics at cysteine-34 within bovine serum albumin: evidence for probe-dependent modulation of the cybotactic region.

We have prepared a series of bovine serum albumins (BSA) that have been site-selectively labeled at cysteine-34 with one of four different sulfhydryl-selective boron dipyrromethene difluoride (BODIPY) fluorescent probes (BODIPY FL IA, BODIPY FL C(1) IA, BODIPY 530/550 IA, and BODIPY 493/503 MB). We determine how the choice of extrinsic probe structure dictates the recovered BSA-BODIPY dynamics under thermal (10-80 degrees C) and chemical (0-5M guanidine hydrochloride) denaturation conditions. The results of these experiments show that the global protein dynamics are sensed equally by each fluorescent probe; however, the probe itself influences the local probe dynamics within the cybotactic region that surrounds cysteine-34. Thus, it seems inappropriate to think of these extrinsic fluorescent probes as passive, nonparticipatory viewers of local protein dynamics.

Animals↗
PubMed2001

Psychological treatments for epilepsy.

BACKGROUND: Psychological interventions such as relaxation therapy, cognitive behaviour therapy, EEG bio-feedback and educational interventions have been used alone or in combination in the treatment of epilepsy, to reduce the seizure frequency and improve the quality of life. OBJECTIVES: To assess whether the treatment of epilepsy with psychological methods is effective in reducing seizure frequency and/or leads to a better quality of life. SEARCH STRATEGY: We searched the Cochrane Epilepsy Group trial register, the Cochrane Controlled Trials Register (Cochrane Library Issue 2, 2001), MEDLINE using OVID (1966 - May 2001) and cross references from identified publications. SELECTION CRITERIA: Randomized or quasi-randomized studies assessing one or more types of psychological or behaviour modification techniques for patients with epilepsy. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed the trials for inclusion and extracted data. Primary analyses were by intention to treat. Outcomes included reduction in seizure frequency, and quality of life. MAIN RESULTS: We found three small trials (50 patients) of relaxation therapy. They were of poor methodological quality and a meta-analysis was therefore not undertaken. No study found a significant effect of relaxation therapy on seizure frequency. One trial found cognitive behavioural therapy to be effective in reducing depression, among people with epilepsy with a depressed affect, whilst another did not. One trial of group cognitive therapy found no significant effect on seizure frequency. Two trials of combined relaxation and behaviour therapy and one of EEG bio-feedback and two of educational interventions did not provide sufficient information to assess their effect on seizure frequency. Combined use of relaxation and behaviour modification was found beneficial for anxiety and adjustment in one study. In one study EEG bio-feedback was found to improve the cognitive and motor functions in subjects with greatest seizure reduction. Educational interventions were found to be beneficial in improving the knowledge and understanding of epilepsy, improving compliance to medication and improving social competencies. REVIEWER'S CONCLUSIONS: In view of methodological deficiencies and limited number of patients studied, we have found no reliable evidence to support the use of these treatments and further trials are needed.

Biofeedback, Psychology↗
PubMed2001

The A-B neuropsychological assessment schedule (ABNAS): the further refinement of a patient-based scale of patient-perceived cognitive functioning.

PURPOSE: To provide further evidence of the reliability and validity of the ABNAS as a measure of patient-perceived cognitive side effects of antiepileptic drug treatment. METHODS: The measure was developed specifically to assess patient-perceived cognitive side effects of antiepileptic drug treatment. Evidence of its reliability and validity has been previously documented and this evidence has been further extended by administration of a battery of 400 questionnaires to two groups (200 people with epilepsy, PWE; and 200 controls who do not have epilepsy). The questionnaire packs consisted of the ABNAS, HADS, the everyday memory questionnaire, and the Adverse Events Profile. Data were analysed using MAP-R and SPSS. RESULTS: Further evidence of the psychometric properties of the scale demonstrated that it had excellent reliability (Cronbach's alpha=0.96) and good face, congruent, content and construct validity. The sensitivity of the instrument was demonstrated through analysis of floor and ceiling levels. CONCLUSIONS: The ABNAS is a reliable, tool for the detection of cognitive impairments associated with epilepsy and its treatment. We have provided further evidence of its criterion validity. This measure has the potential to be a useful tool for both clinical practice and clinical trials.

Adolescent↗
PubMed2001

Reliability, validity and responsiveness of a revised scoring system for the Liverpool Seizure Severity Scale.

This report examines the reliability, validity and responsiveness of a revised scoring system for the Liverpool Seizure Severity Scale (LSSS). The revised scoring system was validated using archival data from an observational study and a randomized controlled study. Factor analyses confirmed that a single dimension captured how patients evaluate the severity of their most severe seizures occurring during a recall period. The revised scoring system repositions the severity score to range from 0 (no seizures) to 100 (most severe possible). Scores based on the new system were reliable, had construct validity (known-groups validity), and were responsive to changes in the patients' epilepsy as noted by their physicians. Results suggest that future epilepsy studies assessing seizure severity should incorporate the revised LSSS scoring system and a modified version of the questionnaire that simplifies self-assessment and analyses. The modified version of the LSSS and its scoring system are appended to this report.

Analysis of Variance↗
PubMed2001

Cognitive and behavioural assessments in clinical trials: what type of measure?

This paper provides an overview of the types of neuropsychological and behavioural measures used in randomised controlled trials (RCTS) of antiepileptic drugs (AEDs) in patients with epilepsy. The results of previous systematic reviews are reported in respect of the methods used in clinical trials to assess cognitive and behavioural effects of AED treatment. There were 46 trials incorporating behavioural measures and 40 trials incorporating neuropsychological measures. The evidence supporting the choice of test, and their reliability, validity, and sensitivity to change was minimal. It is concluded that poor reporting of methods and a plethora of both neuropsychological and behavioural measures make it difficult to provide any meaningful comments about the effects of AED treatment. A much more standardised approach to assessing these effects is necessary.

Anticonvulsants↗
PubMed2001

Assessment of quality of life in people with epilepsy: some practical implications.

Growing recognition of the need to assess the impact of epilepsy on psychosocial functioning has led to a number of initiatives to quantify quality of life (QOL) in patients with this condition. To understand the impact of epilepsy and its treatment, physical, social, neuropsychological, and psychological functioning aspects must be considered. It also is apparent from previous research work that measures of QOL should be comprehensive enough to address the question under consideration, but also simple and as brief as possible. A number of QOL measures for assessing the impact of epilepsy and its treatment exist, such as the Washington Psychosocial Seizure Inventory, the Social Effects Scale, the Epilepsy Surgery Inventory, the Quality of Life in Epilepsy (QOLIE) questionnaire, and the Liverpool QOL Battery. These measures have in most cases been shown to be reliable, valid, and sensitive to change, although at the current stage of development, some are better validated than others. It is generally agreed that the best approach is to use a standard generic instrument with disease-specific additions. Selection of a measure already in existence is recommended, as the process of producing a new measure is costly in terms of both resources and time. Some consideration also needs to be given to factors such as the process of administration (e.g., self-completion or administration at interview) or the timing of data collection. Then questions such as the cross-cultural applicability of QOL measures and the real relevance of the changes remain to be answered. It is hoped that, over the next few years, significant progress will be made in addressing these issues.

Adult↗
PubMed2001

The quality of life of older people with epilepsy: findings from a UK community study.

The impact of epilepsy on the quality of life of older people with epilepsy has rarely been investigated. As part of a large prevalence study of epilepsy conducted in one UK Health Region, we investigated the burden of their condition in older compared with younger people. A second analysis compared quality of life in those men and women diagnosed after the age of retirement from the workforce compared with those diagnosed before that age. Data were collected from men and women with epilepsy and from their primary and secondary care physicians. There were few differences between older and younger people with regard to their reported quality of life, though younger people were more likely to report feeling stigmatized by their condition. Older people with epilepsy diagnosed in later life were more anxious and depressed than those diagnosed earlier and their overall perception of quality of life was more likely to be negative. Our data emphasize that older people do not necessarily experience poorer quality of life than younger people, but those first diagnosed in later life do appear to have a quality of life which is more impaired. Consideration should be paid to the important psychosocial consequences of epilepsy in the older person.

Age Factors↗
PubMed2001

The use of the Canadian occupational performance measure as an outcome of a pain management program.

The last three decades have seen the emergence of measures to assess the efficacy of pain management programs. Recently there has been interest in measures that assess clients' perceptions of their own performance. The Canadian Occupational Performance Measure (COPM) (Law et al, 1994, 1998) is an individualized measure designed for use by occupational therapists to detect a self-perceived change in occupational performance problems over time. It may be an important extra dimension to assessing the outcomes of pain management programs. The aim of this study was to ascertain the validity of the COPM as an outcome measure for the Liverpool Pain Management Program. One hundred and six clients were recruited to the study and 87 clients completed a battery of tests including the COPM at baseline, end of program and 3 month follow-up. Results of the study demonstrated that the COPM showed good evidence of concurrent criterion validity and sensitivity to change.

Adult↗