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Biomedical subjects

S J Jones

Publications and source records attributed to S J Jones.

At least 19 recordsLinked to original sources
PubMed2006

Modification of the home environment for the reduction of injuries.

BACKGROUND: Injury in the home is extremely common, accounting for around a third of all injuries. The majority of injuries of children under five and people aged 75 and over, occur at home. Multifactorial injury prevention interventions have been shown to reduce injuries in the home. However, few studies have focused specifically on the impact of physical adaptations to the home environment and the effectiveness of such interventions needs to be ascertained. OBJECTIVES: To review the evidence for the effect on injuries of modification of the home environment with a primary focus on interventions to reduce physical hazards. SEARCH STRATEGY: We searched The Cochrane Library, MEDLINE, EMBASE, National Research Register and other specialised databases. We also scanned conference proceedings and reference lists. In addition, we contacted experts and trialists in the field. The searches were not restricted by language or publication status. The searches were last updated in December 2004. SELECTION CRITERIA: Randomised controlled trials. DATA COLLECTION AND ANALYSIS: All abstracts were screened by two authors for relevance, outcome and design. Two authors independently assessed methodological quality and extracted data from each eligible study. MAIN RESULTS: We found 18 published and one unpublished trials. Trials were not sufficiently similar to allow pooling of data by statistical analyses, so this review takes a narrative form. Studies were divided into three groups based on the primary population sample; children (five studies), older people (14 studies) and the general population/mixed age group (no studies). None of the studies focusing on children demonstrated a reduction in injuries that might have been due to environmental adaptation in the home; one study reported a reduction in injuries and in hazards but the two could not be linked. Of the 14 included studies in older people, none demonstrated a reduction in injuries due to hazard reduction, although two demonstrated a reduction in falls that could be due to hazard reduction. AUTHORS' CONCLUSIONS: There is insufficient evidence to determine the effects of interventions to modify environmental home hazards. Further interventions to reduce hazards in the home should be evaluated by adequately designed randomised controlled trials measuring injury outcomes. Recruitment of large study samples to measure effect must be a major consideration for future trials.

Accidents, Home↗
PubMed2006

Cortical processing of quasi-periodic versus random noise sounds.

The first objective was to confirm using auditory evoked potentials (AEPs) the findings of magnetoencephalographic studies, that quasi-periodic iterated rippled noise (IRN) elicits a population response in the human auditory cortex which is topographically distinct from that elicited by random noise with a similar overall frequency spectrum. AEPs were recorded at the onset of random noise from silence, at the transition from random noise to IRN with a period of 5 ms, and in the two complementary conditions, IRN onset from silence and the transition from IRN to random noise. An N1/P2 complex was recorded to all four stimuli, that to the transition to IRN being significantly the most anteriorly distributed on the scalp. The second objective was to determine whether the response to the transition to IRN was due to detection of its quasi-periodicity, rather than its spectral "ripples". Virtually no effect was found of applying a 2 kHz low- or high-pass filter, above which it is unlikely that the spectral ripples at intervals of 200 Hz would have been resolved on the cochlear partition. It is concluded that a substantial neuronal population in the auditory cortex is influenced by temporal regularity in sounds, and that this population is equally responsive to spectral frequencies below and above 2 kHz.

Adult↗
PubMed2006

Detection of signals in modulated and unmodulated noise observed using auditory evoked potentials.

OBJECTIVE: To investigate a neurophysiological correlate of the perceptual enhancement of noise-masked sounds when the masking frequencies have a wide spectral bandwidth and are coherently amplitude-modulated. METHODS: Auditory evoked potentials were recorded to 1 kHz tones (200 ms, 61 dBSPL, SOA 3s) occurring in silence or with 80 dB masking noise, which was either wide-band or narrow-band and either unmodulated or 100% amplitude-modulated by a 17.5 Hz square-wave. In a second study, the tones were timed to coincide alternately with the rise and fall of the masker envelope. RESULTS: N1 and P2 potentials recorded to the unmasked tones were abolished in the presence of the unmodulated masker, but were elicited again with lower amplitude and longer latency when the masker was modulated. No significant effect of the masker bandwidth was observed. Latencies were strongly determined by whether the tones coincided with the rise or fall of the masker envelope, indicating that the responses were only evoked when the instantaneous noise level was low. CONCLUSIONS: The findings demonstrate partial correspondence to the threshold reduction to similar stimuli seen in comodulation masking release (CMR). The dependence of latencies on the phase of the masker envelope is consistent with the 'dip-listening' model of CMR. SIGNIFICANCE: Under these conditions the N1/P2 complex can be viewed as a possible neurophysiological correlate of perceptual CMR.

Acoustic Stimulation↗
PubMed2006

Quantification of optic nerve head topography in optic neuritis: a pilot study.

AIMS: To investigate optic nerve head topography in patients with optic neuritis compared to controls using the Heidelberg retina tomograph-II (HRT-II) and to determine if detected changes are related to visual function and electrophysiology. METHODS: 25 patients with a previous single episode of unilateral optic neuritis and 15 controls were studied with HRT-II, visual evoked potentials, and pattern electroretinogram. Patients also had testing of visual acuity, visual field, and colour vision. RESULTS: In affected eyes compared to fellow eyes, there was reduction of both the mean retinal nerve fibre layer (RNFL) thickness at the disc edge (p = 0.009) and the neuroretinal rim volume (p = 0.04). In affected eyes compared to control eyes, the three dimensional optic cup shape measure was increased (p = 0.01), indicative of an abnormal cup shape. There were no other significant differences in HRT-II measures. Within patient interocular difference correlation was used to investigate the functional relevance of these changes and demonstrated associations between RNFL thickness change and changes in visual acuity, visual field, and colour vision. Colour vision change was also associated with change in neuroretinal rim volume. CONCLUSIONS: HRT detects functionally relevant changes in RNFL thickness and neuroretinal rim volume between eyes affected by optic neuritis and unaffected fellow eyes.

Adult↗
PubMed2006

The influence of local politicians on pedestrian safety.

AIM: To determine whether local politicians influence the distribution of traffic calming measures. METHODS: Longitudinal ecological study in two UK cities. Local political constituencies were categorized by representation by members of the cabinet structure as a marker of influence. The density of traffic calming features per political area, adjusted for the historical pattern of road injuries, was compared between cabinet represented and non-represented areas. RESULTS: Traffic calming density was significantly associated with cabinet representation status, adjusted for historical collision risk (risk ratio 2.77, 95% confidence interval 1.37 to 5.61). CONCLUSION: These results support the hypothesis that senior local politicians are effective advocates for enhancing safety in their areas.

Accident Prevention↗
PubMed2005

Traffic calming policy can reduce inequalities in child pedestrian injuries: database study.

OBJECTIVES: To determine whether area wide traffic calming distribution reflects known inequalities in child pedestrian injury rates. To determine whether traffic calming is associated with changes in childhood pedestrian injury rates. DESIGN: Small area ecological study, longitudinal analysis of injury rates with cross sectional analysis of traffic calming and method of travel to school. SETTINGS: Two cities in the United Kingdom. PARTICIPANTS: 4-16 year old children between 1992 and 2000. MAIN OUTCOME MEASURES: Area wide traffic calming distribution by area deprivation status and changes in injury rate/1000. RESULTS: The most deprived fourth of city A had 4.8 times (95% CI 3.71 to 6.22) the number of traffic calming features per 1000 population compared with the most affluent fourth. Injury rates among the most deprived dropped from 9.42 to 5.07 from 1992-94 to 1998-2000 (95% CI for change 2.82 to 5.91). In city B, the traffic calming ratio of the most to least deprived fourth was 1.88 (95% CI 1.46 to 2.42); injury rates in the deprived areas dropped from 8.92 to 7.46 (95% CI for change -0.84 to 3.77). Similar proportions of 9-12 year olds walked to school in both cities. CONCLUSIONS: Area wide traffic calming is associated with absolute reductions in child pedestrian injury rates and reductions in relative inequalities in child pedestrian injury rates.

Accident Prevention↗
PubMed2004

Serial magnetization transfer imaging in acute optic neuritis.

In serial studies of multiple sclerosis lesions, reductions in magnetization transfer ratio (MTR) are thought to be due to demyelination and axonal loss, with later rises due to remyelination. This study followed serial changes in MTR in acute optic neuritis in combination with clinical and electrophysiological measurements to determine if the MTR changes over time mirror the picture in multiple sclerosis lesions, further validating MTR as a marker of tissue integrity. Twenty-nine patients were recruited who had acute optic neuritis for a median of 13 days (range 7-24 days) since the onset of visual symptoms. A clinical examination and measurement of visual evoked potentials (VEP) was performed on each patient. Their optic nerves were imaged with a fat-saturated fast spin echo (FSE) sequence and a magnetization transfer sequence. Twenty-one had multiple subsequent examinations over the course of 1 year. In addition, 27 control subjects had their optic nerves imaged up to three times over 1 year. A blinded observer segmented the optic nerves from the MTR maps. Lesions were defined on the acute FSE images and, from the coordinates, the ratio of mean lesion MTR : healthy nerve MTR (lesion ratio) was calculated for each dataset. The time-averaged mean MTR in control optic nerves was 47.7 per cent units (pu). In diseased optic nerves, baseline mean MTR was 47.3 pu, with a mean lesion ratio of 0.98. The diseased optic nerve MTR and lesion ratio declined over time with a nadir at about 240 days at a mean MTR value of 44.2 pu and mean lesion ratio of 0.91. Subsequently, diseased optic nerve MTR appeared to rise; after 1 year the diseased optic nerve mean MTR was 45.1 pu (mean lesion ratio 0.93), although the difference was not significant compared with the nadir value. For each 0.01 increase in time-averaged lesion ratio logMAR visual acuity recovery improved by 0.03 (95% CI, 0.002, 0.08, P = 0.02). Time-averaged VEP central field latency was shorter by 6.1 ms (95% CI 1.5, 10.7, P = 0.012) per 1 pu rise in time-averaged diseased optic nerve MTR. The early fall in diseased optic nerve MTR is consistent with demyelination and Wallerian degeneration of transected axons. The late nadir compared with studies of multiple sclerosis lesions may have been due to slow clearance of myelin debris. Remyelination may have influenced subsequent MTR changes. The observations support using MTR to monitor symptomatic demyelinating lesions.

Acute Disease↗
PubMed2004

Effectiveness of rugby headgear in preventing soft tissue injuries to the head: a case-control and video cohort study.

OBJECTIVE: To determine if headgear use by rugby players was associated with a reduced risk of head or facial laceration, abrasion, or fracture. METHODS: An emergency department based case-control study in South Wales, UK, with cases being rugby players treated for superficial head and facial injuries and controls being their matched opponents during the game. A review of videos of the 41 games in the 1999 Rugby World Cup was also carried out to compare with the case-control study. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to measure association between exposure (headgear wearing) and outcome (head and facial injuries). RESULTS: In the case-control study, 164 pairs were analysed, with headgear worn by 12.8% of cases and 21.3% of controls. Headgear use was associated with substantial but non-significant reductions in superficial head (OR = 0.43, 95% CI 0.13 to 1.19) and facial (OR = 0.57, 95% CI 0.21 to 1.46) injuries. The video study followed 547 players over 41 games, during which there were 47 bleeding injuries to the head. Headgear use significantly reduced the risk of bleeding head injury in forwards (OR = 0.14, 95% CI 0.01 to 0.99, p = 0.02), but not in backs. There was also a higher risk of facial injury among forwards, but this was not significant. CONCLUSIONS: The combined results suggest that headgear can prevent certain types of superficial head injuries in players at all levels of the game, but the evidence is strongest for superficial head injury in elite forwards. A randomised controlled trial would be the best way to study this further.

Case-Control Studies↗
PubMed2003

A randomized controlled study of modified cobratoxin in adrenomyeloneuropathy.

Adrenomyeloneuropathy is a peroxisomal disorder that causes demyelination, with no proven therapy. Oral modified cobratoxin was assessed in a double-blind, randomized, crossover study of eight patients. Treatment was well tolerated. There were no significant improvements with therapy. The authors do not confirm previous anecdotal reports of dramatic improvement with modified cobratoxin.

Adrenoleukodystrophy↗
PubMed2003

Sensitivity of human auditory evoked potentials to the harmonicity of complex tones: evidence for dissociated cortical processes of spectral and periodicity analysis.

A strong subjective tendency exists for simultaneous sound frequencies forming an harmonic series (integer multiples of the fundamental) to "group" together into a unified auditory percept whose pitch is similar to that of the fundamental. The aim of the study was to determine whether cortical auditory evoked potentials (AEPs) to complex tones differ according to whether the component frequencies of the stimuli are harmonically related or not. AEPs were recorded to continuous complex tones comprising four or more sinusoids. The vertex-maximal "change-potentials" (CP1, CN1, CP2), recorded to a stimulus cycle comprising one harmonic and five inharmonic complexes changing every second, showed no sensitivity to harmonicity, although an additional mismatch negativity was possibly present to the harmonic complex. In a second study the CP2 was significantly attenuated when an harmonic complex changed to a new one in the presence of an unchanging sinusoidal background tone, harmonically related to the first complex but not to the second, and thus becoming perceptually distinct. This, however, might be caused by lateral inhibitory effects not related to harmonicity. In a third experiment, when four concurrent sinusoidal tones came to rest on steady frequencies after a 5-s period of 16/s pseudo-random frequency changes, fronto-centrally maximal "mismatch-potentials" (MN1, MP2), were recorded. Both the MN1 and the MP2 were significantly shorter in latency when the steady frequencies formed an harmonic complex. Since the harmonic complex had a short overall periodicity, equal to that of the fundamental, while that of the inharmonic complex was much longer, the effect might be explained if the latencies of the mismatch-potential are related to periodicity. The perceptual grouping of harmonically related frequencies appears not to be a function of spectral domain analysis, reflected in the change-potentials, but of periodicity analysis, reflected in the mismatch-potentials

Acoustic Stimulation↗
PubMed2003

Socioeconomic variation in injury in children and older people: a population based study.

OBJECTIVES: To compare hospital admission rates for all causes and specific causes of injury in children and the elderly by a measure of economic deprivation. STUDY DESIGN: All emergency admissions for Welsh residents from 1997-99 were located to one of 865 electoral tracts, which were grouped into fifths using a measure of socioeconomic deprivation. Standardised admission rates for all ages and 0-14, 15-75, and 75+ year groups for each quintile were calculated with 95% confidence intervals. RESULTS: There were 90 935 admissions in a population of 2.84 million yielding a crude admission rate of 1601/100 000/year and a standardised rate of 1493/100 000. The ratio of admissions in deprived and affluent areas varied with category of injury and age group. In general, socioeconomic variations in injury rates were much smaller in older people than in children with the exception of pedestrian related injuries where the rates were similar. The largest variations were for injuries sustained in assaults or self inflicted. CONCLUSIONS: The relationship between socioeconomic position and injury varies by cause and age group. This should be considered when developing area based preventive interventions or monitoring the effectiveness of policies to reduce inequalities in injury occurrence.

Adolescent↗
PubMed2003

Routine narrative analysis as a screening tool to improve data quality.

AIM: To determine whether narrative information in emergency department surveillance systems can be systematically interrogated to improve our understanding of the causes of injury. METHODS: Screening algorithms for location, intent, and activity were developed from structured analysis of narrative data from 98999 records. The algorithms were then tested on a 50000 record database containing entries in both of the two narrative fields. A proxy gold standard was defined as the total extract using both code and narrative. Sensitivity and specificity of the emergency department coding and narrative algorithms was calculated. RESULTS: The proportion of records carrying an informative emergency department code was higher in records containing narrative-the percentage of causes coded "not know" dropped by 28.3%. The sensitivity of coded data varied from 42% to 98 % and from 33% to 99% for narrative data. Narrative analysis increased the percentage of home injuries identified by 19%, assaults by 26%, and rugby injuries by 137%. CONCLUSIONS: Using a small amount of narrative is a practical and effective means of developing more informative injury causation data in an emergency department based surveillance system. It allows for internal validation of the codes and for the identification of emerging hazards without adding more "tick boxes" or further burdening data entry clerks.

Algorithms↗
PubMed2003

Are mobile speed cameras effective? A controlled before and after study.

OBJECTIVE: To identify the most appropriate metric to determine the effectiveness of mobile speed cameras in reducing road traffic related injuries. DESIGN: Controlled before and after study which compares two methods for examining the local effectiveness of mobile speed cameras-a circular zone around the camera and a route based method to define exposure at various distances from sites. SETTING: South Wales, UK. SUBJECTS: Persons injured by road traffic before and after intervention. INTERVENTION: Use of mobile speed cameras at 101 sites. MAIN OUTCOME MEASURES: Rate ratio of injurious crashes at intervention and control sites. RESULTS: Camera sites had lower than expected numbers of injurious crashes up to 300 metres using circles and up to 500 metres using routes. Routes methods indicated a larger effect than the circles method except in the 100 metres nearest sites. A 500 metre route method was used to investigate the effect within strata of time after intervention, time of day, speed limit, and type of road user injured. The number of injurious crashes after intervention was substantially reduced (rate ratio 0.49, 95% confidence interval 0.42 to 0.57) and sustained throughout two years after intervention. Significant decreases occurred in daytime and night time, on roads with speed limits of 30 and 60-70 miles/hour and for crashes that injured pedestrians, motorcycle users, and car occupants. CONCLUSIONS: The route based method is the better method of measure effectiveness at distances up to 500 metres. This method demonstrates a 51% reduction in injurious crashes.

Accidents, Traffic↗
PubMed2003

Two cases of quadriparesis following anterior cervical discectomy, with normal perioperative somatosensory evoked potentials.

Two cases illustrate an uncommon failure of perioperative somatosensory evoked potential (SEP) monitoring to detect iatrogenic lesions causing temporary quadriparesis during straightforward cervical surgery. In both cases, anterior cervical discectomy at one or two levels was undertaken with bone graft and titanium implants, and cortical SEP were monitored to alternate stimulation of the left and right median or ulnar nerves. The SEP showed only minor changes during surgery, not considered pathologically significant, and were normal when recorded postoperatively. Both patients, however, experienced marked postoperative limb weakness or paralysis. Motor evoked potentials (MEP) recorded postoperatively to transcranial magnetic stimulation were absent. The clinical motor deficits resolved over the ensuing months. In spite of the normally low incidence of "false negatives," in these two cases SEP monitoring failed to detect a iatrogenic lesion causing moderate to severe, though temporary, motor impairment. Monitoring of MEP may be considered as an alternative to SEP during anterior cervical procedures, while combined monitoring of SEP and MEP may be the ideal.

Aged↗
PubMed2003

Comparison of measured and estimated angles of table tilt at Caesarean section.

BACKGROUND: Lateral maternal tilt reduces aortocaval compression and the consequent cardiovascular instability. METHODS: We measured the angle of table tilt used by 16 anaesthetists during uncomplicated, elective Caesarean section. After initiating anaesthesia, they were asked to position the patient and estimate the angle of tilt, which was then measured. RESULTS: Almost every anaesthetist positioned the patient less than 15 degrees because they overestimated the angle of tilt. When questioned on their knowledge of the current advice for lateral tilt, 11 of the 16 anaesthetists were aware of the 15 degrees recommendation. CONCLUSION: Estimation of the angle of table tilt is unreliable.

Anesthesia, Obstetrical↗