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Biomedical subjects

Andrew Smith

Publications and source records attributed to Andrew Smith.

117 records · Page 7Linked to original sources
PubMed2001

Caffeine levels in saliva: associations with psychosocial factors and behavioural effects.

The present study had two main aims. The first was to examine associations between psychosocial factors, health-related behaviours, regular level of caffeine consumption, time of day and levels of caffeine in saliva following acute caffeine challenges. The second aim was to determine whether individual differences in changes in performance following ingestion of caffeine were related to levels of caffeine in saliva. One hundred and forty-four young adults participated in the study. Questionnaires were administered prior to the study to measure psychosocial characteristics, health-related behaviours and habitual levels of caffeine consumption. Two double-blind acute caffeine challenges were then carried out 1 week apart. Volunteers were given either placebo or 1.5 or 3 mg/kg of caffeine on each occasion. The challenges were carried out at 8 : 00, 11 : 00, 14 : 00 or 18 : 00 h so that the impact of time of day could be assessed. In the week between the two challenges the volunteers consumed either caffeinated or decaffeinated products. This allowed investigation of the effects of caffeine withdrawal on caffeine metabolism. Prior to each caffeine challenge volunteers performed a range of tasks, and a baseline saliva sample was taken. The tasks were repeated 1 h after ingestion of the caffeine, with saliva samples being taken at the start and end of the 1 h test battery. The results showed that the level of caffeine in the saliva was a good indicator of the dose of caffeine consumed and of compliance with the withdrawal manipulation. Caffeine levels were not influenced by time of day, habitual caffeine consumption, psychosocial factors or health-related behaviours. Individual differences in caffeine levels in saliva were not related to the individual variation in the effects of caffeine on performance. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2001

The effects of caffeine on simulated driving, subjective alertness and sustained attention.

There is evidence that caffeine increases alertness and reduces fatigue. This may be especially so in low arousal situations (e.g. working at night or for prolonged hours). Caffeine has also been found to improve performance on vigilance tasks and simple tasks requiring sustained response. Again, these effects are often clearest when alertness is reduced, although there is evidence that benefits may still occur when the individual is unimpaired. Most studies to date have investigated the behavioural effects of caffeine in laboratory experiments using artificial tasks. In the current study 3 mg/kg caffeine was found to improve steering accuracy in a 1 h simulated drive. Measures of mood and performance on a sustained attention task also showed the benefits of caffeine. These findings suggest that laboratory results reflect a general benefit of caffeine that may also be observed in real-life situations. Other evidence examining the effects of caffeine on performance efficiency over the working day has shown the benefits of caffeine consumption on measures of sustained attention and alertness. This study also provided evidence suggesting that caffeine is often consumed when alertness is low to maximise alertness and performance efficiency. The implications of these findings for road safety are also considered. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗
PubMedDate not supplied

The nurse practitioner's role in day case pre-operative assessment.

This article discusses the benefits of developing a nurse practitioner role in day case surgery through an appropriate education programme and a multidisciplinary support group. The authors found that the expanded role can work well in this setting and benefit patients.

Ambulatory Surgical Procedures↗
PubMedDate not supplied

Full-field breast tomosynthesis.

Breast tomosynthesis is a 3-dimensional (3-D) imaging technology that involves acquiring images of a stationary compressed breast at multiple angles during a short scan. The individual images are then reconstructed into a series of thin high-resolution slices that displayed individually or in a dynamic ciné mode. Tomosynthesis can reduce or eliminate the tissue overlap effect. While holding the breast stationary, images are acquired at a nsumber of different x-ray source angles. Objects at different heights in the breast project differently for each angle. The final step in the tomosynthesis procedure is reconstructing the data to generate images that enhance objects from a given height by appropriate shifting of the projections relative to one another. There are 3 specific areas in tomosynthesis system requirements that warrant a closer review: detector efficiency and dose, field of view, and equipment geometry. The breast is compressed in a standard way. While holding the breast stationary, the x-ray tube is rotated over a limited angular range. A series of low dose exposures are made every few degrees, creating a series of digital images. Typically, the tuben is rotated about +/-15 degrees, and 11 exposures are made every 3 degrees during a total scan of a few seconds. The individual images are projections through the breast at different angles and these arewhat are reconstructed into slices. There are 2 basic tomosynthesis system designs that diiffer in the motion of the detector during acquisition. One method moves the detector in concert with the x-ray tube so as to maintain the shadow of the breast on the detector. An altemate method is to keep the detector stationary relative to the breast platform. The tomosynthesis reconstruction process consists of computing high-resolution images whose planes are parallel to the breast support plates. Typically, these images are reconstructed with slice separation of 1 mm; thus, a 5 cm compressed breast tomosynthesis study will have 50 reconstructed slices. The reconstructed tomosynthesis slices can be displayed similarly to computed tomography (CT) reconstructed slices. Tomosynthesis could resolve many of the tissue overlap reading problems that are a major source of the need for recalls and additional imaging in 2-D mammography exams.

Breast↗