PubMed Health⌕ Search

Biomedical subjects

Richard Greenwood

Publications and source records attributed to Richard Greenwood.

At least 19 recordsLinked to original sources
PubMed2006

Modelling and field application of the Chemcatcher passive sampler calibration data for the monitoring of hydrophobic organic pollutants in water.

Passive sampling of dissolved pollutants in water has been gaining acceptance for environmental monitoring. Previously, an integrative passive sampler consisting of a C18 Empore disk receiving phase saturated with n-octanol and fitted with low density polyethylene membrane, was developed and calibrated for the measurement of time weighted average (TWA) concentrations of hydrophobic pollutants in water. In this study, the exchange kinetics were modelled to obtain a better understanding of the mechanism of the accumulation process and to enable the measurement of TWA concentrations of hydrophobic pollutants in the field. An empirical relationship that enables the calculation of in situ sampling rates of chemicals using performance reference compounds was derived and its application was demonstrated in a field study in which TWA aqueous concentrations estimated from sampler data for target analytes were compared with TWA concentrations obtained from spot samples of water collected regularly during the sampler deployment period.

Calibration↗
PubMed2006

Prophylaxis of venous thromboembolism during early inpatient rehabilitation after acquired brain injury: how guidelines change management.

PURPOSE: To establish guidelines for prophylaxis of venous thromboembolism (VTE) in younger adults undergoing early inpatient rehabilitation following acquired brain injury (ABI). METHOD: A two-phase (phase 1: retrospective; phase 2: prospective) observational study was carried out involving patients admitted to an inpatient neurological rehabilitation unit during a 40-month period. In phase 1, VTE prophylaxis was prescribed on an ad hoc basis. In phase 2, prophylaxis was considered in accordance with guidelines agreed locally. The prescribing behaviour in each phase of the study was compared using a VTE risk stratification tool based on expert opinion and a review of the literature. RESULTS: Data were obtained on 94 patients in phase 1 and 23 patients in phase 2. During phase 1, the prophylactic prescribing behaviour of the referring hospitals and our unit after admission were similar ( p = 0.13). In phase 2, our prescribing behaviour had changed compared with that of the referring hospitals, with a significant increase in the proportion of patients on appropriate treatment ( p = 0.01) and a decrease in the numbers under-treated ( p = 0.002). We were also significantly less likely to under-treat ( p = 0.005) and more likely to over-treat ( p = 0.004) after admission during phase 2 compared with phase 1, whilst practice was variable in patients at moderate risk. CONCLUSIONS: Guidelines modify behaviour. They must stratify risk, particularly to avoid inconsistencies in the management of patients at moderate risk. There is a need to establish national guidelines for VTE prophylaxis during early inpatient rehabilitation after ABI; these guidelines should include a risk stratification tool.

Adolescent↗
PubMed2006

Noradrenergic modulation of space exploration in visual neglect.

Visual neglect after stroke is often associated with a failure to explore contralesional space. Here, we show that guanfacine, a noradrenergic agonist that modulates dorsolateral prefrontal cortex, improves leftward space exploration in selected right-hemisphere patients with neglect. The positive effects of guanfacine were associated with extended ability to maintain attention on task. The results suggest that neuropharmacological targeting of intact frontal areas might be one way to enhance cognitive function after damage to posterior brain regions in selected individuals.

Adrenergic alpha-Agonists↗
PubMed2006

Prevalence and correlates of face recognition impairments after acquired brain injury.

Impairments of face recognition after acquired brain injury (ABI) are not restricted to prosopagnosia but commonly arise in association with other cognitive deficits and can be psychosocially debilitating. Despite this, the prevalence and cognitive concomitants of such impairments after ABI have not been systematically investigated. We tested 91 adults with ABI on a range of cognitive measures including several indices of face recognition and learning. The proportion of patients who show impaired performance varied across face learning/recognition tests between 21% and 80%. Principal components analyses indicated orthogonality between impairments of "directed facial processing", associated with memory and visuoperceptual deficits and manifest in slow learning and matching of previously unfamiliar faces, and of "face identification", associated with deficits on verbal tests and manifest in difficulty in naming famous faces. Theoretical and rehabilitative implications are considered.

Adolescent↗
PubMed2006

Prism adaptation changes perceptual awareness for chimeric visual objects but not for chimeric faces in spatial neglect after right-hemisphere stroke.

Prism adaptation can ameliorate some symptoms of left spatial neglect after right-hemisphere stroke. The mechanisms behind this remain unclear. Prism therapy may increase exploration towards the contralesional side, yet without improving perceptual awareness, as apparently for the left side of chimeric face stimuli (Ferber et al. 2003). However, other prism studies suggest that perceptual awareness might be improved (e.g., Maravita et al., 2003). We tested the impact of prism therapy on visual awareness for the left side of chimeric objects as well as chimeric faces, in three neglect patients. Prism therapy dramatically improved awareness for the identity of the left side of chimeric non-face objects, but had no effect on judging expressions for chimeric faces. The latter may thus be unique in showing no prism benefit.

Adaptation, Physiological↗
PubMed2006

Use of the Barthel Index and the Functional Independence Measure during early inpatient rehabilitation after single incident brain injury.

OBJECTIVE: To compare the appropriateness and responsiveness of the Barthel Index and the Functional Independence Measure (FIM) during early inpatient rehabilitation after single incident brain injury. DESIGN: Cohort study. SETTING: A regional neurological rehabilitation unit. PATIENTS: Two hundred and fifty-nine consecutive patients undergoing inpatient comprehensive neurological rehabilitation following a vascular brain injury due to single cerebral infarction (n = 75), spontaneous intracerebral haemorrhage (n = 34) and subarachnoid haemorrhage (n = 43), and 107 patients who had sustained traumatic brain injury. MEASUREMENTS: Admission and discharge FIM total, physical and cognitive scores and the Barthel Index were recorded. Appropriateness and responsiveness in the study samples were determined by examining score distributions and floor and ceiling effects, and by an effect size calculation respectively. Non-parametric statistical analysis was used to calculate the significance of the change in scores. RESULTS: In all patient groups there was a significant improvement (Wilcoxon's rank sum, P<0.0001) in the Barthel Index (mean change score: vascular 3.9, traumatic 3.95) and FIM (mean change score: vascular 17.3, traumatic 17.4) scores during rehabilitation, and similar effect sizes were found for the Barthel Index (effect size: vascular 0.65, traumatic 0.55) and FIM total (effect size: vascular 0.59, traumatic 0.48) and physical scores in all patient groups. In each patient group the cognitive component of the FIM had the smallest effect size (0.35-0.43). CONCLUSIONS: All measures were appropriate for younger (less than 65 years of age) patients undergoing early inpatient rehabilitation after single incident vascular or traumatic brain injury. The Barthel Index and the total and physical FIM scores showed similar responsiveness, whilst the cognitive FIM score was least responsive. These findings suggest that none of the FIM scores have any advantage over the Barthel Index in evaluating change in these circumstances.

Activities of Daily Living↗
PubMed2005

Calibration of the Chemcatcher passive sampler for the monitoring of priority organic pollutants in water.

An integrative passive sampler consisting of a C18 Empore disk receiving phase saturated with n-octanol and fitted with low-density polyethylene diffusion membrane was calibrated for the measurement of time-weighted average concentrations of hydrophobic micropollutants, including polyaromatic hydrocarbons and organochlorine pesticides, in water. The effect of temperature and water turbulence on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water was studied in a flow-through system under controlled conditions. It was found that the absorption of test analytes from water to the sampler is related to their desorption to water. This allows for the in situ calibration of the uptake of pollutants using offload kinetics of performance reference compounds. The sampling kinetics are dependent on temperature, and for most of the tested analytes also on the flow velocity. Sampler-water partition coefficients did not significantly change with temperature.

Calibration↗
PubMed2005

Performance optimisation of a passive sampler for monitoring hydrophobic organic pollutants in water.

The performance of an integrative passive sampler that consists of a C18 Empore disk sorbent receiving phase fitted with low density polyethylene membrane was optimised for the measurement of time-weighted average concentrations of hydrophobic micropollutants in water. A substantial improvement of sampling characteristics including the rate of sampling and the sampling precision was achieved by decreasing the internal sampler resistance to mass transfer of hydrophobic organic chemicals. This was achieved by adding a small volume of n-octanol, a solvent with high permeability (solubility [times] diffusivity) for target analytes, to the interstial space between the receiving sorbent phase and the polyethylene diffusion-limiting membrane.

Adsorption↗
PubMed2005

Spatial working memory capacity in unilateral neglect.

It has been proposed recently that a deficit in keeping track of spatial locations may contribute to the severity of unilateral neglect in some right hemisphere stroke patients. However, performance on traditional spatial working memory (SWM) tasks (e.g. Corsi blocks) might be confounded by failure to encode leftward locations, rather than a true deficit of maintaining locations in SWM. Here we introduced new procedures for circumventing this to measure SWM capacity in neglect. In a first experiment, 20 right hemisphere stroke patients (10 with and 10 without neglect) were tested on a computerized vertical variant of the Corsi task. Sequences of spatial locations in a vertical column were displayed and participants had to tap out the remembered sequence on a touchscreen. Patients with left neglect were impaired on this vertical SWM task compared with all control groups. However, poor performance on this task (as for Corsi blocks) might involve impaired memory for stimulus sequence, or poor visuomotor control of manual responding, rather than reduced SWM capacity per se. A second experiment therefore employed a purer measure of vertical SWM. After the displayed sequence, a single location was now probed visually, with observers judging verbally (yes/no) if it had been in the preceding sequence. Hence order no longer mattered, and no spatial motor response was required. Again, the neglect group was impaired relative to all others, now with very little overlap between the performances of individual neglect patients versus individuals in control groups. Poor performance on the second task, which provides a purer measure of SWM capacity, correlated with severity of left neglect on cancellation tasks (but not on line bisection), consistent with recent proposals that SWM deficits can exacerbate left neglect on visual search tasks when present conjointly. Lesion anatomy indicated that neglect patients with a SWM deficit were most likely to have damage to parietal white matter, plus, in the second experiment, to the insula also. These findings demonstrate that an impairment in SWM capacity can contribute to the neglect syndrome in patients with stroke involving regions within the right parietal lobe and insula.

Adult↗
PubMed2005

An audit of first seizures presenting to an Accident and Emergency department.

OBJECTIVES: To investigate whether patients presenting after a first seizure to an Accident and Emergency (A&E) department were being managed according to consensus recommendations. DESIGN: Retrospective audit. SETTING: UK District General Hospital over 6 months. METHODOLOGY: Hand search of Accident and Emergency notes for diagnoses of "seizure", "fit", "epilepsy" and "epileptic fit", followed by scrutiny of hospital and General Practice (GP) medical notes. RESULTS: Eighty three percent of patients discharged from the A&E department with a letter to take to their general practitioners, but only 20% of those referred directly to the neurology clinic, were lost to follow-up. Of the patients seen as out-patients by a neurologist, the median waiting time to clinic was 22 weeks, 18 weeks longer than recommended. The average time to having an MRI scan and EEG performed were 12 and 15 weeks, respectively. Twenty percent of patients seen by a neurologist were not felt to need further investigation for epilepsy. CONCLUSIONS AND RECOMMENDATIONS: All patients presenting after a first seizure should be directly referred to a neurology clinic from the A&E department. The currently proposed target time to specialist review is unrealistic without significant resource improvements. The provision of diagnostic guidelines and telephone advice by the neurology team prior to discharge from A&E may avoid unnecessary investigation.

Brain Diseases↗
PubMed2004

Religious views of the 'medical' rehabilitation model: a pilot qualitative study.

PURPOSE: To explore the religious beliefs that patients may bring to the rehabilitation process, and the hypothesis that these beliefs may diverge from the medical model of rehabilitation. METHODS: Qualitative semi-structured interviews with representatives of six major religions--Islam, Buddhism, Christianity, Judaism, Sikhism, and Hinduism. Representatives were either health care professionals or religious leaders, all with an interest in how their religion approached health issues. RESULTS: There were three recurrent themes in the interviews: religious explanations for injury and illness; beliefs about recovery; religious duties of care towards family members. The Buddhist, Sikh, and Hindu interviewees described beliefs about karma--unfortunate events happening due to a person's former deeds. Fatalistic ideas, involving God having control over an individual's recovery, were expressed by the Muslim, Jewish, and Christian interviewees. All interviewees expressed the fundamental importance of a family's religious duty of care towards ill or injured relatives, and all expressed some views that were compatible with the medical model of rehabilitation. CONCLUSIONS: Religious beliefs may both diverge from and resonate with the medical rehabilitation model. Understanding these beliefs may be valuable in facilitating the rehabilitation of diverse religious groups.

Attitude to Health↗
PubMed2004

Misdiagnosing the vegetative state after severe brain injury: the influence of medication.

Patients who suffer severe brain damage may be left unaware of self and of the environment and in a permanent vegetative state (PVS). The difficulties in correctly ascertaining unawareness after brain injury have been emphasized by a number of authors. It is well recognized that toxic-metabolic and drug-induced cerebral depression occurs acutely after brain injury. However, less attention has been drawn to the effects of medication months after brain injury and the way in which medication may confound assessment of awareness and, thus, the reliable assessment of long-term prognosis. This paper describes two patients who sustained a severe and well-documented structural brain injury, one hypoxic and one traumatic. Both were unaware when first seen at 3 months post-injury, but both have made useful functional recovery. The paper discusses their progress and how the early prescription of large doses of anti-epileptic drugs, sedatives and anti-spastic agents in these circumstances may result in an initial misdiagnosis of the vegetative state.

Adolescent↗
PubMed2004

Rehabilitation outcomes after brain injury: disability measures or goal achievement?

BACKGROUND: The outcome of rehabilitation interventions following brain injury is commonly rated by disability scales. Goal-setting and achievement are important in inpatient rehabilitation, but seldom assessed as outcomes. OBJECTIVE: To compare the information acquired from using disability ratings and goal attainment/variances as outcome measures in brain injury rehabilitation. SETTING: An inpatient regional neurological rehabilitation unit. SUBJECTS: One hundred and seventy-seven patients admitted after single incident brain injury over a three-year period. MAIN MEASURES: (1) Disability outcomes by the Barthel Index and the Functional Independence Measure, (2) goal achievement and variance distribution, and (3) the influence of diagnosis and demographics on these measures. RESULTS: Patients improved significantly on all disability scales employed (p < 0.0001), with the baseline admission scores being inversely correlated with changes in dependency by discharge (rho approximately -0.4). The median attainment rate of long-term goals was 75% per patient. Nonachievement was most frequently due to cognitive problems (38%), followed by behavioural difficulties and physical limitations (18% each). Goal achievement correlated poorly with disability outcome at discharge (rho < 0.3). Patients who accomplished all their goals tended to be less disabled at admission. Diagnostic groups and demographic factors had little influence on either disability or goal achievement outcomes. CONCLUSIONS: The use of a simple goal achievement and variance coding scheme has been relatively straightforward to incorporate into the daily practice of the unit. It provides useful information on rehabilitation process and outcome after brain injury that is complementary to the utilization of disability measures.

Achievement↗