PubMed Health⌕ Search

Biomedical subjects

O Evans

Publications and source records attributed to O Evans.

18 recordsLinked to original sources
PubMed2003

A cluster randomised controlled trial of smoking cessation in pregnant women comparing interventions based on the transtheoretical (stages of change) model to standard care.

OBJECTIVES: To evaluate the effectiveness in helping pregnant women stop smoking of two interventions (Pro-Change for a healthy pregnancy) based on the transtheoretical model of behaviour change (TTM) compared to current standard care. DESIGN: Cluster randomised trial. SETTING: Antenatal clinics in West Midlands, UK general practices. PARTICIPANTS: 918 pregnant smokers INTERVENTIONS: 100 general practices were randomised into the three trial arms. Midwives in these practices delivered three interventions: A (standard care), B (TTM based self help manuals), and C (TTM based self help manuals plus sessions with an interactive computer program giving individualised smoking cessation advice). MAIN OUTCOME MEASURES: Biochemically confirmed smoking cessation for 10 weeks previously, and point prevalence abstinence, both measured at 30 weeks of pregnancy and 10 days after delivery. RESULTS: There were small differences between the TTM arms. Combining the two arms, the odds ratios at 30 weeks were 2.09 (95% confidence interval (CI) 0.90 to 4.85) for 10 week sustained abstinence and 2.92 (95% CI 1.42 to 6.03) for point prevalence abstinence relative to controls. At 10 days after delivery, the odds ratios were 2.81 (95% CI 1.11 to 7.13) and 1.85 (95% CI 1.00 to 3.41) for 10 week and point prevalence abstinence respectively. CONCLUSIONS: While there is a small borderline significant increase in quitting in the combined intervention arms compared with the controls, the effect of the intervention is small. At 30 weeks gestation and at 10 days postnatal, only about 3% of the intervention groups achieved sustained cessation, with numbers needed to treat of 67 (30 weeks of gestation) and 53 (10 weeks postnatal) for one additional woman to achieve sustained confirmed cessation. Given also that the intervention was resource intensive, it is of doubtful benefit.

Adolescent↗
PubMed2002

A multidimensional model of the quality of life in older age.

The broad aim of the research presented here was to define the constituents and indicators of quality of life (QoL) in older age, in order to offer a more multidimensional and useful model of quality of life, based on the perspectives of older people themselves. This paper focuses on the extent to which self-evaluations of global QoL are influenced by health, psychological and social variables, and social circumstances. It reports the results of a national survey of the quality of life in people aged 65 and over, living at home in Britain. Multiple regression analysis with the self-evaluation of quality of life rating as the dependent variable showed that the overall model (Model 9) of QoL indicators explained 26.7% of the variance in quality of life ratings. This is sizeable given the amorphous nature of this concept. The main independent predictors of self-rated global quality of life were: social comparisons and expectations, personality and psychological characteristics (optimism-pessimism), health and functional status and personal and neighbourhood social capital. These variables explained the highest proportion of the variance between groups in their quality of life ratings. Socio-economic indicators contributed relatively little to the model.

Aged↗
PubMed2001

HPLC determination of cyanuric acid in swimming pool waters using phenyl and confirmatory porous graphitic carbon columns.

The chlorinated salts of cyanuric acid have found an important role in recreational swimming pool waters across the United States. Upon application to pool water, they can (1) release disinfectant chlorine or (2) stabilize the free available chlorine by acting as chlorine reservoirs in the form of cyanuric acid, preventing the photolytic destruction of residual chlorine by sunlight. Recommended levels of the cyanuric acid stabilizer are in the 10-100 mg/L concentration range according to the National Swimming Pool Foundation (San Antonio, TX). Two isocratic HPLC methods with UV detection (213 nm) employing phenyl and porous graphitic carbon (PGC) columns and phosphate buffer eluents (pH 6.7 and pH 9.1, respectively) were developed to accurately measure cyanuric acid in swimming pools. The two methods allowed fast separation and detection of the stabilizer in 4 (phenyl) and 8 (PGC) min. Both methods offered practical sensitivities with method detection limits of 0.07 (phenyl) and 0.02 mg/L (PGC). Neither one of the two methods required the use of sample cleanup cartridges. They exhibit chromatograms with excellent baseline stability enabling low-level quantitation. Most important, the PGC column had a useful lifetime of five months and 500 sample analyses/column. Eleven pool water samples were fortified with 4.8-50.0 mg/L stabilizer, and the average recovery was 99.8%. Finally, statistical analysis on the relative precisions of the two methods indicated equivalence at the 0.05 critical level.

Chromatography, High Pressure Liquid↗
PubMed2001

Reliability of measurement of angular movements of the pelvis and lumbar spine during treadmill walking.

BACKGROUND AND PURPOSE: Angular movements of the pelvis and lumbar spine are thought to play an important role in walking. However, little is known about the amount of unpredictable variability in measurement of these movements during human walking. The aim of the present study was to determine the retest reliability of measuring the angular movements of the pelvis and lumbar spine during unimpaired familiarized treadmill walking. METHOD: Retest reliability for 26 subjects without pathology was determined over a one-week interval. Subjects walked on a treadmill at self-selected or a slower speed while measurements of the three-dimensional angular movements were taken with a computer-based video analysis system. RESULTS: The frontal plane movements of pelvic list and lumbar lateral flexion (relative to the pelvis) could be measured with high retest reliability at both self-selected and slow walking speeds (intraclass coefficient (ICC) (2, 1) > or = 0.81). In contrast, transverse and sagittal plane movements demonstrated moderate reliability at both speeds (0.37 < or = ICC (2, 1) < or = 0.76). Averaging the measurement over six strides resulted in increased observed reliability (self-selected walking speed summary Pearson's r = 0.71, slow walking speed summary Pearson's r = 0.79) compared to taking the measurement based on a single stride (self-selected walking speed summary Pearson's r = 0.63, slow walking speed summary Pearson's r = 0.67). Unlike pelvic and lumbar movements (relative to the pelvis), the measurement of lumbar movements (relative to the global reference frame) appeared to depend on whether subjects were walking at self-selected or slow speeds. CONCLUSIONS: Measurement of pelvic list and lumbar lateral flexion (relative to the pelvis) could be applied with confidence to hypothesis testing about individuals or groups. Movements in the transverse and sagittal planes are unlikely to be appropriate in hypothesis testing about individuals and hence clinical practice, but may still have experimental applications in hypothesis testing about groups.

Adult↗
PubMed2001

Social support at work, heart rate, and cortisol: a self-monitoring study.

This study assessed the influence of work social support on self-monitored heart rate, blood pressure, and salivary cortisol recorded on 3 work days and 2 leisure days from 61 nurses and 32 accountants (40 men, 53 women). Heart rate and blood pressure were higher during the day at work than in the evening or on leisure days. Cortisol was higher on leisure than work days and was lower in the evening than in the day. Low social support at work was associated with elevated heart rate during the daytime and evening of work days, an effect that persisted after controlling for psychological distress, age, sex, smoking, and physical activity. Work social support was not related to cortisol on work days, but on leisure days cortisol was elevated among individuals reporting high social support. There were few differences between men and women, and no important occupational effects.

Accounting↗
PubMed2000

An HPLC method with UV detection, pH control, and reductive ascorbic acid for cyanuric acid analysis in water.

Every year over 250 million pounds of cyanuric acid (CA) and chlorinated isocyanurates are produced industrially. These compounds are standard ingredients in formulations for household bleaches, industrial cleansers, dishwasher compounds, general sanitizers, and chlorine stabilizers. The method developed for CA using high-performance liquid chromatography (HPLC) with UV detection simplifies and optimizes certain parameters of previous methodologies by effective pH control of the eluent (95% phosphate buffer: 5% methanol, v/v) to the narrow pH range of 7.2-7.4. UV detection was set at the optimum wavelength of 213 nm where the cyanuric ion absorbs strongly. Analysis at the lower pH range of 6.8-7.1 proved inadequate due to CA keto-enol tautomerism, while at pHs of <6.8 there were substantial losses in analytical sensitivity. In contrast, pHs of >7.4 proved more sensitive but their use was rejected because of CA elution at the chromatographic void volume and due to chemical interferences. The complex equilibria of chlorinated isocyanurates and associated species were suppressed by using reductive ascorbic acid to restrict the products to CA. UV, HPLC-UV, and electrospray ionization mass spectrometry techniques were combined to monitor the reactive chlorinated isocyanurates and to support the use of ascorbic acid. The resulting method is reproducible and measures CA in the 0.5-125 mg/L linear concentration range with a method detection limit of 0.05 mg/L in water.

Ascorbic Acid↗
PubMed1999

Cluster randomised controlled trial of expert system based on the transtheoretical ("stages of change") model for smoking prevention and cessation in schools.

OBJECTIVES: To examine whether a year long programme based on the transtheoretical model of behaviour change, incorporating three sessions using an expert system computer program and three class lessons, could reduce the prevalence of teenage smoking. DESIGN: Cluster randomised trial comparing the intervention to a control group exposed only to health education as part of the English national curriculum. SETTING: 52 schools in the West Midlands region. PARTICIPANTS: 8352 students in year 9 (age 13-14 years) at those schools. MAIN OUTCOME MEASURES: Prevalence of teenage smoking 12 months after the start of the intervention. RESULTS: Of the 8352 students recruited, 7444 (89.1%) were followed up at 12 months. The intention to treat odds ratio for smoking in the intervention group relative to control was 1.08 (95% confidence interval 0.89 to 1.33). Sensitivity analysis for loss to follow up and adjustment for potential confounders did not alter these findings. CONCLUSIONS: The smoking prevention and cessation intervention based on the transtheoretical model, as delivered in this trial, is ineffective in schoolchildren aged 13-14.

Adolescent↗
PubMed1998

High-performance liquid chromatography of selected organic peroxides with oxidative amperometric detection.

Reversed-phase high-performance liquid chromatography with oxidative amperometric detection was optimized for the determination of several organic peroxides in drinking water under ideal conditions. The determinations were performed under isocratic conditions using acetonitrile and methanol as the organic modifiers with 0.05 M potassium phosphate buffer solution. The oxidative amperometric response of the organic peroxides was dependent on the concentration of organic modifier and the electrode potential. The optimum electrode potential (EOxAPP), for the simultaneous determination of the organic peroxides was approximately +1.150 +/- 0.05 V versus the Ag/AgCl reference electrode. The maximum analytical signal for butan-2-one peroxide and tert-butyl hydroperoxide, when using acetonitrile, was obtained with 20% v/v organic modifier. For cumene hydroperoxide, the maximum analytical signal was achieved with approximately 35% v/v acetonitrile. The retention time of cumene hydroperoxide, on an octyldecylsilane column (250 x 4 mm id), decreased sharply from > 100 to < 10 min when the organic modifier concentration was varied from 5 to 50% v/v. The retention time of butan-2-one and tert-butyl hydroperoxide, under the same conditions, varied by < 10 min. The calibration curves for the aliphatic peroxides and aromatic peroxide were linear from 2 to 200 ng and from 0.2 to 200 ng injected, respectively.

Chromatography, High Pressure Liquid↗
PubMed1997

Perceptions of control over work: psychophysiological responses to self-paced and externally-paced tasks in an adult population sample.

This experiment tested the hypothesis that perceptions of control over work pace would modulate cardiovascular reactions to mental stress tests. One hundred and thirty two adults aged 30-65 years (64 men and 68 women) were randomized to self-paced and externally-paced task conditions. The self-paced group carried out visual matrix problem solving and mirror tracing tasks at their own pace. Work pace requirements were imposed on the externally-paced group, with performance requirements being set to equate those in the self-paced condition. This was done to equate work demands. Blood pressure (assessed with the Finapres), heart rate, cardiac baroreceptor reflex sensitivity, skin conductance, respiration rate and tidal volume were monitored. Behavioural performance of the mirror tracing task was comparable in the two conditions, but the externally-paced group attempted more problems and made more errors on the visual matrix task. Systolic blood pressure reactions to mirror drawing were greater in the external than self-paced conditions (mean increases of 27.5 +/- 16.1 vs. 23.1 +/- 18.5 mmHg, P < 0.025), and electrodermal responsivity was also heightened in the externally-paced group (P < 0.05). No differences were recorded in diastolic blood pressure, heart rate, baroreflex sensitivity or respiratory parameters. Results are discussed in relation to the literature on control and physiological stress responsivity, and their implications for understanding the health consequences of lack of control at work are considered.

Adult↗
PubMed1996

Cardiovascular risk and responsivity to mental stress: the influence of age, gender and risk factors.

BACKGROUND: Exaggerated cardiovascular and neuroendocrine responses to mental stress may enhance cardiovascular disease risk. Coronary heart disease and hypertension increase in prevalence with advancing age, whereas the excess male/female ratio declines in later middle age. Psychosocial factors may contribute to these changing risk profiles. The hypothesis that cardiovascular and neuroendocrine stress responses are associated with age and gender differences in cardiovascular disease risk was tested. METHOD: 132 healthy men and women from younger (30-40 years) and older (55-66 years) age bands were selected at random from general practice lists. They performed a series of mental stress tests during which blood pressure, heart rate, cardiovascular baroreflex sensitivity, cortisol, respiration patterns and electrodermal activity were monitored. A submaximal exercise test was performed and psychological characteristics were assessed by questionnaire. RESULTS: At rest, systolic and diastolic blood pressure was higher in men than in women, while cardiac baroreflex sensitivity was greater in younger than in older participants. Blood pressure responses to tasks were substantial, with changes from the baseline averaging 18.6/8.11, 26.0/13.5 and 40.7/19.0 mmHg for computerized problem solving, mirror drawing and speech tasks, respectively. Men and women in the older age band did not differ from each other in blood pressure, heart rate or baroreflex sensitivity responses. Systolic blood pressure responses (mean +/- SEM) were larger in older than in younger women (mean peak difference 6.87 +/- 2.67 mmHg), and in the younger male compared with the younger female groups (mean peak difference 7.20 +/- 2.97 mmHg). Diastolic blood pressure and heart rate responses to mental stress were larger in younger than in older age participants of both sexes. Baroreflex sensitivity was inhibited during behavioural tasks, with significantly greater suppression in younger than in older groups (5.28 +/- 0.52 and 2.62 +/- 0.35 ms/mmHg, respectively). Cortisol responses were greater in men than in women, but did not vary with age. Across the entire sample, systolic blood pressure responsivity was negatively related to the expression of anger. Among older men, heightened blood pressure responses were associated with elevated fasting low-density lipoprotein cholesterol levels, and with lower concentrations of high-density lipoprotein cholesterol. CONCLUSIONS: Systolic blood pressure stress responsivity increases with age in women but not in men. Other data do not support the notion that stress responsivity mediates age and gender differences in cardiovascular disease risk. However, in middle-aged men, ex-aggerated cardiovascular stress responsivity is associated with an unfavourable risk profile.

Adult↗
PubMed1995

Cardiovascular stress reactivity and job strain as determinants of ambulatory blood pressure at work.

OBJECTIVE: To test the hypothesis that cardiovascular reactivity to laboratory mental stressors interacts with job strain in predicting blood pressure at work. DESIGN: Ambulatory monitoring of blood pressure and heart rate was carried out for an 8-h period on a work day and on an equivalent non-work day in 49 male firefighters. METHODS: Participants were recruited from a larger cohort (n = 90) on the basis of showing high or low systolic reactions to mental arithmetic 15-24 months previously, coupled with high or low ratings of perceived job strain (high demand-low control). Four groups were tested: low job strain-low systolic reactors (n = 12), low job strain-high systolic reactors (n = 12), high job strain-low systolic reactors (n = 12) and high job strain-high systolic reactors (n = 13). RESULTS: Systolic blood pressure (SBP) was higher on work than non-work days, and diastolic blood pressure and heart rate were higher at work in the morning but not in the afternoon. These effects were due partly to posture and physical activity differences between the two days. Neither job strain nor laboratory reactivity independently predicted ambulatory blood pressure. However, SBP was significantly higher during the afternoon at work in the high job strain-high systolic reactors than in the other groups. This was independent of baseline SBP, and was not due to differences in posture or activity at the time of recordings. Ambulatory SBP reactivity (difference between ambulatory values and workplace resting levels) in the afternoon at work was also elevated significantly in high job strain-high systolic reactors compared with in the other groups. CONCLUSIONS: The results support the hypothesis that individual differences in the appraisal of work stress modulate the relationship between stress reactivity and ambulatory blood pressure.

Adult↗
PubMed1993

Control over work pace, job strain and cardiovascular responses in middle-aged men.

OBJECTIVE: To assess the effects of control over work pace on cardiovascular stress responses in healthy middle-aged men. DESIGN: The study involved administration in the laboratory of visual matrix and mirror drawing tasks, the pace of tasks being either under the control of the subject (self-paced) or determined externally (externally paced). The work demands in the two conditions were equated. METHOD: Forty men aged 55-65 years were randomly assigned to self-paced or externally paced conditions. Blood pressure (recorded continuously using the Finapres), heart rate, cardiac baroreflex sensitivity, salivary cortisol, skin conductance and breathing pattern were monitored at rest, during task performance and at recovery following tasks. RESULTS: Blood pressure and heart rate responses were significantly greater under the externally paced than self-paced conditions. The mean increase in blood pressure during the visual matrix task averaged 19.8/9.4 versus 34.1/15.5 mmHg for the self- and externally paced conditions, and 28.2/13.7 versus 41.8/19.5 mmHg in response to mirror drawing, respectively. Performance of the matrix task was less accurate under externally paced than self-paced conditions, but the two groups did not differ in mirror drawing. A reduction in baroreflex sensitivity and increases in cortisol, respiration rate, tidal volume and skin conductance responses were recorded during tasks, but these responses did not distinguish the two groups. Men were divided on the basis of reported job strain associated with their regular work, using the demand-control model. Blood pressure and heart rate responses were particularly pronounced among men reporting high job strain who were allocated to the externally paced condition. CONCLUSIONS: Middle-aged men showed greater stress-related cardiovascular responses when they performed tasks at a pace that they could not control. This pattern may be relevant to the mechanisms through which job strain (high demands associated with low control) influences cardiovascular disease risk.

Aged↗
PubMed1987

Magnetic resonance imaging of mesial temporal sclerosis: case reports.

Two patients with uncontrollable complex partial seizures had normal findings on pre- and postinfusion computed tomography scans. Magnetic resonance imaging demonstrated, in both patients, a lesion in the temporal lobe suggestive of mesial temporal sclerosis. One patient underwent temporal lobectomy, and the radiologic diagnosis was verified. In patients with complex partial seizures, magnetic resonance imaging appears to be able to noninvasively localize temporal lobe lesions in preparation for surgical intervention.

Adolescent↗
PubMed1987

Objective assessment of limb movement in children with cerebral palsy.

A preliminary report of a method for assessing the quality of movement in children with cerebral palsy, using an accelerometer, is presented. Able-bodied and disabled children performed a simple task, and there were marked differences between the two groups. Whilst the technique requires further development, it is hoped that accelerometry may eventually provide an objective tool to enable rigorous testing of various therapeutic procedures in cerebral palsy.

Acceleration↗
PubMed1987

Medical and social service provision for families of children with NTD.

The supply of services to the families of children with spina bifida participating in the South Wales longitudinal study was reviewed. Initially general information and contact with other mothers were the commonest needs; as the children grew older the need for practical, material and financial help took priority. Parents were, generally, very satisfied with support provided by hospital staff with whom they had frequent, regular contact. Contact with health visitors and social workers was considered insufficient and unsatisfactory. Mothers of more severely disabled children were most likely to receive visits, but some saw none and contact with the social services decreased as the children got older. The locally organised parents association (SWASBAH) was able to provide information, financial assistance, holiday accommodation, and contact with others in a similar position; all of which were common, but otherwise inadequately met, needs. Despite improvements, particularly in financial benefits, over the course of the study, at 18 years parents appeared largely unsupported as they faced major changes in their children's lives. Throughout the study support from SWASBAH and the interviewer appeared to far outweight the statutory, non-medical, support.

Adolescent↗
PubMed1986

Hormonal responses to a graded mental workload.

Three mental arithmetic tests of graded difficulty were presented to eight young male volunteers on consecutive days. The effort compensation patterns were investigated using urinary catecholamines and salivary cortisol. A significant increase in adrenaline excretion was found in response to all three tests. Urinary adrenaline was partially graded according to the level of difficulty of the tests. The response patterns to mental workload also included a significantly lower noradrenaline/adrenaline ratio and a higher adrenaline/dopamine ratio after the tests. No significant increase was found after the tests for noradrenaline and dopamine. Changes in salivary cortisol concentration during the tests were graded with respect to test difficulty between the easiest and both of the more difficult tests. Salivary cortisol concentration changes are proposed as the basis for field observations involving mental workload. It is concluded that mental workload causes distinguishable effort compensation patterns and that under certain conditions urinary adrenaline and salivary cortisol allow one to distinguish different mental workload levels.

Adult↗
PubMed1986

The fathers of children with spina bifida.

Health, employment, marital outcome and involvement with the child, of fathers with spina bifida (IF) and with "normal" controls (CF), were analysed at intervals from birth to 18 years. By 10 years IF had poorer reported health than did CF. By 18 years IF had more specific health problems, many being psychosomatic in nature, than CF or index and control mothers. This pattern was also reflected in the GHQ scores; IF had a significantly higher incidence of symptoms than CF. Practical involvement of IF and CF was generally little different but at 18 years 30% of IF were still involved in their child's "personal care". Employment and income amongst IF and CF did not differ in the early years. By 18 years, significantly more IF were claiming invalidity benefit, while they were also more likely to be the family's only wage-earner. Our evidence suggests that IF suffered surprisingly severely as a result of emotional strain. Both the psychological and practical problems could be alleviated to the benefit of all family members.

Adult↗