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Biomedical subjects

P Bright

Publications and source records attributed to P Bright.

At least 19 recordsLinked to original sources
PubMed2003

Objects and their actions: evidence for a neurally distributed semantic system.

An influential model of conceptual knowledge claims that objects are represented in a distributed network of cortical areas that store information about different types of attributes, such as form, colour, and motion (A. Martin et al., 2000, in: The Cognitive Neurosciences, 2nd ed., MIT Press, Cambridge). Two specific claims of this account are that (a) the motions and actions associated with objects (along with other attributes) are automatically activated whenever the object concept is evoked and (b) topographically distinct neural regions are responsible for motion/action attributes pertaining to objects in the categories of tools and animals. We used fMRI to examine the neural activation associated with conceptual processing of nouns referring to animals and tools and for verbs referring to tool-associated actions (e.g., drilling, painting) and biological actions (e.g., walking, jumping). We found that object names and their associated actions activated the same set of neural regions (left fusiform gyrus, superior and middle temporal cortex) consistent with the claim that word tool and animal concepts implicitly activate the actions associated with them. However, there was no evidence of category specificity for either objects or actions, with essentially the same activations for the form and motion attributes of both living and nonliving categories.

Adult↗
PubMed2002

Interpretation of occupational peak flow records: level of agreement between expert clinicians and Oasys-2.

BACKGROUND: Oasys-2 is a validated diagnostic aid for occupational asthma that interprets peak expiratory flow (PEF) records as well as generating summary plots. The system removes inconsistency in interpretation, which is important if there is limited agreement between experts. A study was undertaken to assess the level of agreement between expert clinicians interpreting serial PEF measurements in relation to work exposure and to compare the responses given by Oasys-2. METHOD: 35 PEF records from workers under investigation for suspected occupational asthma were available for review. Records included details of nature of work, intercurrent illness, drug therapy, predicted PEF, rest periods, and holidays. Simple plots of PEF and the Oasys-2 generated plots were available. Experts were advised that approximately 1 hour was available to review the records. They were asked to score each work-rest-work (WRW) period and each rest-work-rest (RWR) period for evidence of occupational effect. At the end of each record scores of 0-100% were given for evidence of "asthma" and "occupational effect" for the whole record. Kappa values were calculated for each scored period and for the opinions on the whole record. The scores were converted into four groups (0-25%, 26-50%, 51-75%, 76-100%) and two groups (0-50% and 51-100%) for analysis. This is relevant to scores produced by Oasys-2. Agreement between Oasys-2 scores and each expert was calculated. RESULTS: 24 of 35 records were analysed by seven experts in the allotted time. For whole record occupational effect, median kappa values were 0.83 (range 0.56-0.94) for two groups and 0.62 (0.11-0.83) for four groups. For asthma, median kappa values were 0.58 (0-0.67) and 0.42 (0.15-0.70) for two and four groups respectively. For all WRW and RWR periods kappa values were 0.84 (0.42-0.94) and 0.70 (0.46-0.87) respectively. Agreement between Oasys-2 and individual experts showed a median kappa value of 0.75 (0.50-0.92) for two groups and 0.50 (0.39-0.70) for four groups. Kappa values for the median expert score v Oasys-2 were 0.75 for two groups and 0.67 for four groups. Agreement was poor for records with intermediate probability, as defined by Oasys-2. CONCLUSION: Considerable variation in agreement was seen in expert interpretation of occupational PEF records which may lead to inconsistencies in diagnosis of occupational asthma. There is a need for an objective scoring system which removes human variability, such as that provided by Oasys-2.

Asthma↗
PubMed2002

Recording flow in the first second of a maximal forced expiratory manoeuvre: influence of frequency content.

The frequency content of the first second of the maximum forced expiratory manoeuvre (MFEM) was measured to determine if the currently accepted frequency limit of 20 Hz for MFEM is adequate for recording peak expiratory flow (PEF). The frequency response of a Fleisch pneumotachograph (PT) was measured and used to record MFEM from 24 patients attending a lung-function laboratory and 26 normal volunteers. The first 1.024 s of the signal recorded at 1,000 Hz for that blow with maximum PEF, underwent fast Fourier transformation using a triangular window function, applied after 0.75 s to reduce flow linearly to zero. All the frequencies above a set limit were removed, followed by inverse transformation to reconstitute the blow. The limits for this frequency cut-off were progressively varied from 100 Hz down to 15 Hz, with the resulting PEF being compared with the PEF from the reconstituted blow with no frequency reduction. The average+/-SD age for the group was 47+/-18 yrs and the average PEF was 450+/-187 L x min(-1), which, when expressed as a standardized residual, was 0.1+/-2.1, with a range from -4.5-3.9 indicating a good spread around normal values. Average rise time to PEF was 83+/-38 ms and dwell time >90% PEF was 45+/-25 ms. Cut-off >20 Hz reduced the mean PEF of the group by 8.5 L x min(-1) (95% confidence limit 5.5-11.4 L x min(-1)), whereas cut-off >30 Hz reduced mean PEF by 4.4 L x min(-1) (2.6-6.2). In the present study subjects, 30 Hz was on the 95th percentile of frequencies for defining the upper limit for 98% of the power spectrum for the first second of the blow. It has been shown that there are frequencies >20 Hz that contribute to peak expiratory flow enough to influence readings made using conventional hand-held peak expiratory flow meters, such as the mini-Wright. Devices used for recording flow from a maximum forced expiratory manoeuvre should therefore have an adequate frequency response of up to 30 Hz.

Adult↗
PubMed2001

Computerized planimetry versus clinical assessment for the measurement of cervical ectopia.

OBJECTIVE: As part of a study to assess the role of cervical ectopia in the acquisition of cervical infections, we determined the reliability of cervical ectopia measurements made by computer planimetry and by clinical (visual) assessment. STUDY DESIGN: We conducted pelvic examinations of 1004 women seeking contraceptive services at two health centers in Baltimore. After application of acetic acid, clinicians estimated the relative area of ectopia by visual inspection and took cervical photographs. Two independent raters measured the absolute and relative areas of ectopia from the digitized images by means of an analytic software program. Agreement levels between raters, between multiple readings by the same rater, and between the two measurement methods were quantified by means of the intraclass correlation coefficient and weighted kappa. RESULTS: Intrarater agreement was excellent for computer planimetry measurements of the absolute (intraclass correlation coefficient, 0.97) and relative (intraclass correlation coefficient, 0.89) areas of ectopia. Interrater agreement was also high for computer planimetry measurements of the absolute (intraclass correlation coefficient, 0.83) and relative (intraclass correlation coefficient, 0.85) areas of ectopia. Agreement levels were moderate between clinician assessment and computer planimetry measurements of the relative area of ectopia (kappa = 0.48), but agreement was better when clinical assessment was limited to observations by a single, experienced clinician. CONCLUSION: Measurement of cervical ectopia by computer planimetry was highly reliable and appears appropriate for assessment of the role of ectopia in the acquisition of cervical infections. Clinical assessment of cervical ectopia may be used when computer planimetry is not available.

Cervix Uteri↗
PubMed2001

Learning and memory: recent findings.

Recent findings from neuroimaging, event-related potential and lesion investigations reflect a rapidly emerging view that the memory system is widely distributed throughout the cortex. It is clear that the pattern of cortical involvement during encoding and retrieval of memories is critically dependent on the nature and complexity of task demands. This has implications, both for existing models of memory function, and in the methodology of future investigations and the issues they address. No consensus has yet been reached on a number of issues, perhaps most notably the role of the hippocampus in retrieval, but advances in measurement techniques should enable some of these matters to be resolved. Further work must address the complex dynamics of the memory system, the extent to which the same regions underlie different functions, and how different regions interact and reflect common functions.

Animals↗
PubMed2001

OASYS-3: improved analysis of serial peak expiratory flow in suspected occupational asthma.

Serial peak expiratory flow (PEF) records are useful for the screening and diagnosis of patients with occupational asthma. We have presented work on a method based on linear discriminant analysis (OASYS-2) and have now tried to improve on this technique and investigate the repeatabilities of expert interpretation. 268 serial PEF records made by workers with possible occupational asthma were divided into four sets. The first two were development sets; development set 1 was used to develop a discriminant analysis to match the human expert, who scored each complex (a sequence of work days, then rest days, then work days, or its counterpart: rest-work-rest) for its likelihood of having a work-related effect. This was modelled using 729 new measurements from each complex, together with the 50 measurements originally used in the development of OASYS-2. Linear discriminant analysis is a statistical technique which can refine from a large number of indices a narrower range that best predict a known outcome. Combinations of these indices are weighted and used to assign outcomes for novel cases. Models were produced containing a combination of measurements that generated scores best matching the expert. Development set 2 was used to test the model. Sets 3 and 4 were "gold standard" sets where the diagnosis had been made independently of the PEF record. Set 3 was used to set the cut-off for an occupational effect, the sensitivity and specificity for the combined model was determined from the fourth (gold standard) set. The fourth set was also used to determine the sensitivity and specificity of the human expert. The repeatability of the human expert re-scoring the same complexes had a weighted kappa score of 0.71. OASYS-3 was 100% repeatable. Comparing the scores awarded to whole records by the new (OASYS-3) and OASYS-2 analysis methods with the scores awarded by the human expert revealed mean (95% CI) differences of -0.28 (0.30, -0.26) and -0.34 (-0.37, -0.31) respectively. Hence both OASYS-3 and OASYS-2 tended to score records less positively for work-related changes in PEF than the expert. OASYS-3 scored complexes marginally better than OASYS-2. The sensitivity of OASYS-3 was better than OASYA-2 (82% and 75% respectively) for an equivalent specificity (94%). The sensitivity of the human expert was 100% with a specificity of 93%. OASYS-3 provides an objective method of interpreting serial peak flow records with a sensitivity and specificity approaching that of a human expert and is a modest improvement on OASYS-2.

Adult↗
PubMed1999

Different origin of auditory and phonological processing problems in children with language impairment: evidence from a twin study.

This study investigated the heritability of auditory processing impairment, as assessed by Tallal's Auditory Repetition Test (ART). The sample consisted of 37 same-sex twin pairs who had previously been selected because one or both twins met criteria for language impairment (LI) and 104 same-sex twin pairs in the same age range (7 to 13 years) from the general population. These samples yielded 55 children who met criteria for LI, who were compared with 76 children whose language was normal for their age (LN group). We replicated earlier work showing that group LI is impaired relative to group LN on ART. However, there was no evidence of a heritable influence on ART scores: Correlations between twins and their co-twins were reasonably high for both MZ and DZ twins, suggesting that performance is more influenced by shared environment than genetic factors. Analyses of extreme scores gave a similar picture of nonsignificant group heritability. In contrast, a test of phonological short-term memory, the Children's Nonword Repetition Test (CNRep), gave high estimates of group heritability. In general, CNRep was a better predictor of low language test scores than ART, but ART did make a significant independent contribution in accounting for variance in a test of grammatical understanding.

Adolescent↗
PubMed1999

A double-blind placebo-controlled study of the effect of inhaled beclomethasone dipropionate for 2 years in patients with nonasthmatic chronic obstructive pulmonary disease.

Treatment of chronic obstructive pulmonary disease (COPD) with inhaled and oral corticosteroids is common, although their exact role is unclear. Previous studies suggest these drugs may reduce decline in lung function in this group of patients. We report a study investigating the effect of inhaled beclomethasone diproprionate (BDP) on lung function and symptoms in a group of patients with COPD. Treatment was given for 2 years, and the decline in FEV1 in individual patients calculated over this period. Ninety-eight patients were randomized for the study, 59 completing 2 years of treatment. Patients withdrawn had more severe airflow obstruction. Decline in FEV1, measured both prior to and after bronchodilator, was less in patients receiving inhaled BDP, although the differences failed to reach statistical significance except in a subgroup of patients with more severe airflow obstruction. Exacerbation rates were also reduced by inhaled BDP, but again the differences failed to reach conventional levels of statistical significance. The results of this study are consistent with previous published work, but further insight into the long-term role of corticosteroids in COPD await the publication of large studies which have recently been completed. Although the changes seen in this study and others are numerically small, the rate of decline in FEV1 returned to normal levels expected from age-related decline, and hence such treatment combined with other strategies may well have a significant role in the long-term treatment of this condition.

Administration, Inhalation↗
PubMed1999

Development of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma. Midlands Thoracic Society Research Group.

If asthma is due to work exposures there must be a relation between these exposures and the asthma. Asthma causes airway hyperresponsiveness and obstruction; the obstruction can be measured with portable meters, which usually measure peak expiratory flow, or sometimes forced expiratory volume in 1 second (FEV1). These can be measured serially (for instance 2 hourly) over several weeks at and away from work. Once occupational asthma develops, the asthma will be induced by many non-specific triggers common to non-occupational asthma. The challenge is to identify changes in peak expiratory flow due to work among other non-occupational causes. Standard statistical tests have been found to be insensitive or non-specific, principally because of the variable period for deterioration to occur after exposure, and the sometimes prolonged time for recovery to occur, such that days away from work may initially have lower measurements than days at work. A computer assisted diagnostic aid (Oasys) has been developed to separate occupational from non-occupational causes of airflow obstruction. Oasys-2 is based on a discriminant analysis, and achieved a sensitivity of 75% and a specificity of at least 94%; therefore peak expiratory flow monitoring combined with Oasys-2 analysis is better to confirm than to exclude occupational asthma. A neural network version in development has improved on this. Both have been based on expert interpretation of peak flow measurements plotted as daily maximum, mean, and minimum, with the first reading at work taken as the first reading of the day. Oasys has been evaluated with independent criteria against measurements made in a wide range of occupational situations. Oasys is sufficiently developed to be the initial method for the confirmation, although less so for exclusion of occupational asthma.

Asthma↗
PubMed1998

The use of a neural network to detect upper airway obstruction caused by goiter.

Goiter is a common condition and can cause upper airway obstruction (UAO), which may be difficult to detect. We have studied maximal expiratory and inspiratory flow volume loops using a neural network to see if this offers a better way to identify patients with UAO. The flow-volume loops from 155 patients with goiter were assessed by a human expert and sorted into those with and without UAO. The reliability of this assessment was judged by using two observers who repeated the sorting 8 wk apart. A set of 46 patients with loops suggesting UAO and a set of 51 patients with normal flow loops were taken from these 155, and the loops from a further 50 subjects with airflow limitation caused by chronic obstructive pulmonary disease were used for training and testing the neural network. Novel and standard indices were derived from the loops and used by the neural network. The kappa score for agreement between each of the observers and the original classification were 0.5 and 0.46, respectively, with the agreement between the observers at each reading of 0.58 and 0.68. The neural network found that a combination of four novel scores for flatness of the expiratory loop, the moment ratio, and the FEV1/PEF ratio was best at identifying UAO with a kappa score of 0.81, a sensitivity of 88%, specificity of 94% and an accuracy of 92%. We conclude that a neural network using only six indices taken from the expiratory limb of a flow-volume loop was better than human experts at identifying flow loops with UAO.

Adult↗
PubMed1997

Occupational asthma due to chrome and nickel electroplating.

BACKGROUND: Exposure to chromium during electroplating is a recognised though poorly characterised cause of occupational asthma. The first series of such patients referred to a specialist occupational lung disease clinic is reported. METHODS: The diagnosis of occupational asthma was made from a history of asthma with rest day improvement and confirmed by specific bronchial provocation testing with potassium dichromate and nickel chloride. RESULTS: Seven workers had been exposed to chrome and nickel fumes from electroplating for eight months to six years before asthma developed. One subject, although exposed for 11 years without symptoms, developed asthma after a single severe exposure during a ventilation failure. This was the only subject who had never smoked. The diagnosis was confirmed by specific bronchial challenges. Two workers had isolated immediate reactions, one a late asthmatic reaction, and four a dual response following exposure to nebulised potassium dichromate at 1-10 mg/ml. Two of the four subjects were also challenged with nebulised nickel chloride at 0.1-10 mg/ml. Two showed isolated late asthmatic reactions, in one at 0.1 mg/ml, where nickel was probably the primary sensitising agent. Four workers carried out two hourly measurements of peak expiratory flow over days at and away from work. All were scored as having occupational asthma using OASYS-2. Breathing zone air monitoring was carried out in 60 workers from four decorative and two hard chrome plating shops from workers with similar jobs to those sensitised. No measurement exceeded the current occupational exposure standard for chromate or nickel, the mean levels of chromate exposure for jobs similar to those of the affected workers were 9-15 micrograms/m3. CONCLUSION: Chrome used in electroplating is a potential cause of occupational asthma. Sensitivity to chrome in electroplaters may occur in situations where exposure levels are likely to be within the current exposure standards. There may be cross reactivity with nickel. Inhalation challenge with nebulised potassium dichromate solution is helpful in making the specific diagnosis where doubt exists.

Adult↗
PubMed1996

The measurement of hand preference: a validation study comparing three groups of right-handers.

Three groups of right-handers were identified using the Edinburgh Handedness Inventory. Exclusive strong right-handers (Rs: N = 18) reported that they always used the right hand for eight or more of the 10 activities, and usually used the right hand for the remainder. Exclusive weak right-handers (Rw: N = 15) usually used the right hand for three or more activities, and always used the right hand for the remainder. Predominant right-handers (Rp: N = 18) preferred the right hand for most items, but used the left hand for at least one activity. These groups did not differ on three measures of relative skill of the two hands: peg-moving, tapping and dotting. Groups Rs and Rw were also indistinguishable in terms of the hand used for reaching for cards placed in different spatial positions. However, the reaching measure did discriminate group Rp, which included some individuals who reached predominantly with the left hand. It is concluded that preference batteries should quantify degree of hand preference in terms of the number of activities for which a preference is shown, ignoring the distinction between 'usually' and 'always'. The behavioural reaching measure shows promise as a method for providing a unitary scale of hand preference.

Adult↗
PubMed1995

The performance of Mini Wright peak flow meters after prolonged use.

The accuracy of 84 new and 35 old Mini Wright peak flow meters were tested using a servo-controlled pump system. The 95% confidence limits for flow measurement across the range of the new meters was between +/- 151 min-1 at the lower end of the range and +/- 28 l min-1 at the top of the range. The readings for 22 (63%) of the old meters (age range 1-13 yr) were within these 95% confidence limits. For the remaining 13 old meters (age range 1-13 yr) whose readings were not within these limits, there were 11 meters with readings falling below and two meters with readings above these limits. Twelve of these old meters were washed and retested and there was no significant change in their readings. Twenty of the new meters were retested after 1 yr of continuous use and their readings were significantly higher with a median value of 5 l min-1 across the range, although only two of these 20 meters had readings outside the 95% confidence limits set from the 84 new meters. It is concluded that whilst Mini Wright meters aged up to 14 yr can give readings which are as good as new meters, some meters demonstrate significant changes in readings after only 1 yr and washing did not correct this change. It is recommended that clinicians prescribing peak expiratory flow (PEF) meters should be responsible for checking the patient's meter as well as their PEF readings at clinic visits.

Disinfection↗
PubMed1995

Occupational asthma due to glutaraldehyde and formaldehyde in endoscopy and x ray departments.

BACKGROUND: Glutaraldehyde is the best disinfectant for fibreoptic endoscopes. It is also used in the processing of x ray films. A number of studies have reported eye, nose, and respiratory symptoms in exposed workers. Three individual case reports of occupational asthma in endoscopy workers and a radiographer have also been published. We describe a further seven cases of occupational asthma due to glutaraldehyde in endoscopy and x ray departments, together with exposure levels measured during the challenge tests and in 19 endoscopy and x ray departments in the region. METHODS: Eight workers were referred for investigation of suspected occupational asthma following direct or indirect exposure to glutaraldehyde at work. They were investigated by serial measurements of peak expiratory flow (PEF) and specific bronchial provocation tests. Glutaraldehyde levels were measured using personal and static short and longer term air samples during the challenge tests and in 13 endoscopy units and six x ray darkrooms in the region where concern about glutaraldehyde exposure had been expressed. Three of the workers investigated with occupational asthma came from departments where glutaraldehyde air measurements had been made; the others came from other hospitals or departments. RESULTS: The diagnosis of occupational asthma was confirmed in seven workers, all of whom had PEF records suggestive of occupational asthma and positive specific bronchial challenge tests to glutaraldehyde. Bronchial provocation testing was negative in one worker who was no longer exposed and who had a less clearcut history of occupational asthma. Three workers also had a positive specific bronchial challenge to formaldehyde. The mean level of glutaraldehyde in air during the challenge tests was 0.068 mg/m3, about one tenth of the short term occupational exposure standard of 0.7 mg/m3. The levels obtained in the challenge chamber were similar to those measured in 13 endoscopy suites and six x ray darkrooms where median short term levels were 0.16 mg/m3 during decantation in endoscopy suites and < 0.009 mg/m3 in darkrooms. CONCLUSIONS: Glutaraldehyde can cause occupational asthma. The exposure levels measured in the workplace suggest that sensitisation may occur at levels below the current occupational exposure standard.

Adult↗
PubMed1995

Differences in output from corticosteroid inhalers used with a volumatic spacer.

Corticosteroid inhaler therapy using a spacer device is commonly used as an important part of asthma management. Increasingly, generic corticosteroid inhalers are being used with spacer devices. We have therefore tested whether these generic inhalers yield equivalence in dose when compared to the established inhalers. We measured the in vitro output, discharged into a Volumatic spacer from beclomethasone dipropionate inhalers (250 micrograms.puff-1) made by three manufacturers, Allen & Hanburys, 3M and Baker Norton. The output from 20 of each type of inhaler was sampled, in random order, by a computer driven pump system. Beclomethasone was absorbed onto a coded filter, which was analysed independently for drug content. The output per puff differed significantly between the inhalers of each manufacturer, with a 36% difference between the highest output from the Allen & Hanburys device and the lowest output device. We conclude that there are important differences in output from these inhalers when used with a spacer, and that substitution of one device with another will not necessarily give equivalent therapy to the patient.

Adrenal Cortex Hormones↗
PubMed1994

A strong association between mefloquine and halofantrine resistance and amplification, overexpression, and mutation in the P-glycoprotein gene homolog (pfmdr) of Plasmodium falciparum in vitro.

Stepwise selection for increased mefloquine resistance in a line of Plasmodium falciparum in vitro resulted in increased resistance to halofantrine and quinine, increased sensitivity to chloroquine, and amplification and overexpression of the P-glycoprotein gene homolog (pfmdr1). A point mutation (tyrosine to phenylalanine) noted at amino acid 86 in pfmdr1 in the mefloquine-resistant line W2mef was amplified in more resistant lines derived from it by in vitro selection pressure with mefloquine. Conversely, lines selected for increased chloroquine resistance exhibited a revertant phenotype that was sensitive to mefloquine and halofantrine. These lines also demonstrated increased sensitivity to quinine, loss of amplification of pfmdr1, loss of the mefloquine/halofantrine phenylalanine-86 mutation, and selection for a tyrosine-86 mutation previously associated with chloroquine resistance. These findings provide strong evidence for pfmdr1 mediating cross-resistance to halofantrine and mefloquine in P. falciparum in vitro.

ATP Binding Cassette Transporter, Subfamily B, Mem↗