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Biomedical subjects

N Vaughan

Publications and source records attributed to N Vaughan.

15 recordsLinked to original sources
PubMed2006

Sensitivity of markers of DNA stability and DNA repair activity to folate supplementation in healthy volunteers.

We have previously reported that supplementation with folic acid (1.2 mg day(-1) for 12 week) elicited a significant improvement in the folate status of 61 healthy volunteers. We have examined effects of this supplement on markers of genomic stability. Little is known about the effect of folate supplementation on DNA stability in a cohort, which is not folate deficient. Preintervention, there was a significant inverse association between uracil misincorporation in lymphocyte DNA and red cell folate (P < 0.05). In contrast, there were no associations between folate status and DNA strand breakage, global DNA methylation or DNA base excision repair (measured as the capacity of the lymphocyte extract to repair 8-oxoGua ex vivo). Folate supplementation elicited a significant reduction in uracil misincorporation (P < 0.05), while DNA strand breakage and global DNA methylation remained unchanged. Increasing folate status significantly decreased the base excision repair capacity in those volunteers with the lowest preintervention folate status (P < 0.05). Uracil misincorporation was more sensitive to changes in folate status than other measures of DNA stability and therefore could be considered a specific and functional marker of folate status, which may also be relevant to cancer risk in healthy people.

Adult↗
PubMed2005

Workplace protection of air-fed visors used in paint spraying operations.

Air-fed visors are commonly used for protection against exposure to airborne isocyanates during paint spraying. Protection levels for this class of equipment are theoretically adequate, yet isocyanate sensitization in this occupation still occurs. The work reported here set out to establish the level of respiratory protection that is achieved during real paint spraying activities when air-fed visors are used. The work also examined the effects of reduced air supply flow rates on this type of respiratory protection. The workplace study highlighted common problems that occur when attempting to measure protection factors, and process and interpret the collected data. Many of the environments included in this study did not exhibit challenge concentrations high enough to reliably measure the workplace protection factor of this class of device. When detection limits are taken into consideration, the remaining field data suggest that an assigned protection factor in the region of 40 may be appropriate. When well maintained and used in accordance with the manufacturer's instructions, air-fed visors are capable of providing a good level of respiratory protection. The protection given by air-fed visors is strongly dependent on the air flow supplied to them. Laboratory measurements demonstrate that protection falls as the air supply falls. This is a gradual process and does not suddenly occur at any particular air supply flow. Observations made during the field tests indicate that there may be other activities associated with the spraying process that need to be taken into consideration when looking for sources of respiratory sensitization.

Aerosols↗
PubMed2005

Meaningful workplace protection factor measurement: experimental protocols and data treatment.

Workplace performance measurement of respiratory protective equipment (RPE) is fundamental to the understanding of how well wearers are protected. It forms the basis for guidance on which the selection of appropriate equipment is based. However, the measurement of this performance is open to many sources of interference and inaccuracy, reducing the value and relevance of the results, and is most difficult for devices providing the highest levels of protection. In this paper, a method for critically assessing collected workplace protection factor (WPF) data is validated. This method rejects unreliable data, using criteria based on the detection limits of the analytical measurement system. An iterative approach is also described which arrives at a supportable estimate of given non-parametric percentiles of the distribution of measured WPFs [such as the fifth percentile, conventionally taken to be the assigned protection factor (APF)]. Further pragmatic criteria, based on a combination of experimental experience and consideration from first principles, are suggested as the basis for any future studies of RPE performance. These will maximize the chances of valid measurements being made, and also provide insight into the level of confidence which can be placed on any of the results. A consequence of these criteria is that typical working environments and measurement methods are incapable of generating WPF data which can be considered reliable.

Calibration↗
PubMed2002

Food intake and body measurements of Atlantic bottlenose dolphins (Tursiops truncates) in captivity.

The food consumption (recorded in kg of individual fish species), body length and mass of 11 Atlantic bottlenose dolphins kept first at Windsor Safari Park, UK (1979-1993/1994), and later at Harderwijk Marine Mammal Park, The Netherlands (1993/1994-1995) are reported. This broad-scale, longitudinal study is based on historical data that were originally recorded for short-term husbandry purposes. The chemical composition and caloric value of the diet were variable and were not recorded. The food intake quantities should therefore be viewed as rough weight estimates of what wild conspecifics might eat (depending on their diet). The average annual food consumption of adult males and non-pregnant, non-lactating females was approximately 2000 kg of fish (estimated at 176 x 10(5) kJ). Food consumption showed little increase during gestation, but was 58-97% higher during lactation than during similar periods in non-reproductive years. All six calves began to eat solid food within a year of birth although suckling continued for 14-37 months after birth. The pattern of food intake of mothers and calves varied substantially between suckling periods. No seasonal changes in food consumption were detected, although there were small seasonal changes in water temperature. Births occurred at various times of year, since the timing of mating varied between years. The animals' body length increased rapidly during the first 3 years of life after which the growth rate decreased. Body length reached asymptote at approximately 270 cm. Adults of both sexes weighed around 260 kg. The relationship between standard body length (in cm) and body mass (in kg), although based on a small sample size (n = 16), can be expressed as body mass = 17.261e(0.0156(body length-100)). Animals weighing 155-225 kg consumed between 2 and 4% of their body mass per day.

Animal Husbandry↗
PubMed2001

The influence of three acoustic alarms on the behaviour of harbour porpoises (Phocoena phocoena) in a floating pen.

Harbour porpoise bycatch may be reduced by deterring porpoises from nets acoustically. In this study, two harbour porpoises were subjected to three acoustic alarms. The effect of each alarm was judged by comparing the animals' position and respiration rate during a test period with that during a baseline period. The XP-10 alarm produced 0.3 s tonal signals randomly selected from a set of 16 with fundamental frequencies between 9 and 15 kHz, with a constant pulse interval of 4.8 s (duty cycle 6%). The 2MP alarm produced 0.3 s tonal signals randomly selected from a set of 16 with similar fundamental frequencies but with random pulse intervals of between 2 and 5 s (duty cycle 8%). The frequency spectra and source levels of the 2MP and XP-10 alarms varied depending on the signal selected. The HS20-80 alarm produced a constant, but asymmetrical frequency modulated sinewave between 20 and 80 kHz with total pulse duration of 0.3 s. with random pulse intervals of between 2 and 5 s (duty cycle 4.6%). The porpoises reacted to all three alarms by swimming away from them and by increasing their respiration rate. The XP-10, which on average had the highest source level, had the strongest effect.

Acoustics↗
PubMed1999

Magnetic resonance guided general surgery.

Image guided surgery can be defined as the intraoperative use of a radiologicai technique to give the surgeon information not available from direct inspection or palpation of the surgical field. This information may then be used to change the course of an operative procedure. Magnetic resonance (MR) imaging has the potential to be the most useful radiologicai technique in the developing field of image guided surgery.

Journal Article↗
PubMed1997

Comet assay in human biomonitoring studies: reliability, validation, and applications.

The comet assay (single-cell gel electrophoresis), which measures DNA strand breaks at the level of single cells, is very easily applied to human lymphocytes, and therefore lends itself to human biomonitoring studies. For the examination of DNA base oxidation (a specific marker of oxidative damage), the assay is modified by including a stage at which the DNA is incubated with a suitable lesion-specific endonuclease. Here we report on the reliability and reproducibility of this approach, from the level of comparing results from duplicate gels prepared from the same sample of cells, up to an assessment of the natural intra- and interindividual variability in lymphocyte DNA damage measured in groups of normal, healthy human volunteers. We applied the assay in investigations of human disease and occupational exposure of factory workers.

Analysis of Variance↗
PubMed1997

Perseveration and wandering as a predictor variable after brain injury.

Perseveration and wandering are well recognized sequelae of traumatic brain injury. They are believed to arise as a constellation of behaviours from lesions involving the frontal, temporal, or parietal lobes or subcortical motor regions. Attention and memory deficits are believed to contribute to the presence of perseveration and wandering. Patients who perseverate and/or wander after brain injury tend to have poorer outcomes and slower rates of progress. This prospective study is based on 32 consecutive admissions to a brain injury rehabilitation unit over a 4-month period. For each patient data was collected on perseverative behaviours, wandering, Functional Independence Measure, total number of rehabilitative days, supervision requirement at discharge and discharge disposition. Perseveration and wandering were assessed using the Agitated Behaviour Scale and clinical observations of the primary physician, physical and occupational therapist and speech-language pathologist. Correlations between perseverative and wandering behaviours were made with the variables identified.

Adult↗
PubMed1995

Insulin dependent diabetes mellitus and deliberate self-harm.

Patients who deliberately harm themselves can present with a variety of disorders. The case is reported of a patient who deliberately self-harms by inducing hypoglycaemic episodes. This patient has placed great demands on the emergency services over the last 9 years. Early involvement by senior accident and emergency staff is advised.

Diabetes Mellitus, Type 1↗
PubMed1991

Barriers to mobility: physically-disabled and frail elderly people in their local outdoor environment.

This paper reports the results of a central government funded two-year project which investigated problems associated with the mobility of physically handicapped people in their external physical environment. Whilst most people who possess below average physical capacity would, even in the most ideal of physical surroundings, experience mobility problems, such inherent personal difficulties are being aggravated by street environments exhibiting symptoms of neglect. Although the difficulties experienced by people in this study can be seen partly as a function of their physical disabilities even elderly people who could be considered as reasonably able-bodied, were reporting difficulty in their local area. A number of the environmental difficulties people reported can be related to existing legislation not being enforced whilst in others to the need for legislation to be entered on to the statute book.

Aged↗
PubMedDate not supplied

Physically disabled and frail elderly: assessing their external environments.

The study reported here forms part of a 2-year government-funded research project concerned with the mobility problems of physically disabled, blind and frail elderly in their external environment. The research grew out of a set of ideas, formulated by Central Government in Wales, which suggested that the Principality has a higher proportion of disabled people than England, Scotland or Northern Ireland, and that of the particularly extreme nature of the Welsh terrain probably presented serious difficulties to these categories of people as they attempted to move around in their external environments. Although difficulties experienced by respondents in this study can be partly attributed to their physical disabilities even elderly people, who were reasonably able-bodied, reported problems in moving around in their local areas. Some of the barriers to mobility, described in this project, are a function of existing legislation not being enforced, while others require new legislation to be enacted.

Activities of Daily Living↗