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Biomedical subjects

T Purcell

Publications and source records attributed to T Purcell.

12 recordsLinked to original sources

Perceptual and physiological responses to the visual complexity of fractal patterns.

Fractals have experienced considerable success in quantifying the complex structure exhibited by many natural patterns and have captured the imagination of scientists and artists alike. With ever widening appeal, they have been referred to both as "fingerprints of nature" and "the new aesthetics." Our research has shown that the drip patterns of the American abstract painter Jackson Pollock are fractal. In this paper, we consider the implications of this discovery. We first present an overview of our research from the past five years to establish a context for our current investigations of human response to fractals. We discuss results showing that fractal images generated by mathematical, natural and human processes possess a shared aesthetic quality based on visual complexity. In particular, participants in visual perception tests display a preference for fractals with mid-range fractal dimensions. We also present recent preliminary work based on skin conductance measurements that indicate that these mid-range fractals also affect the observer's physiological condition and discuss future directions based on these results.

Arousal↗

Symptoms are a poor indication of severity of reflux in Barrett's oesophagus

AIMS: Patients with Barrett's oesophagus have increased acid and duodenogastric reflux and impaired motility compared with non-Barrett's patients with reflux disease. Impaired sensitivity to acid infusion and distension have also been described, but the relationship of this visceral response to symptoms is unclear. A symptom index was used to compare Barrett's and non-Barrett's patients with reflux. METHODS: Patients with reflux (DeMeester score above 14) were studied with 24-h pH monitoring and manometry. An event marker recorded symptom events. An event was positive if it corresponded to a period greater than 10 s within 2 min either side of the drop in pH. The symptom index was calculated as the number of symptoms with pH less than 4/total number of symptoms x 100. RESULTS: Eighteen patients with Barrett's oesophagus were compared with 58 non-Barrett's patients with significant reflux. CONCLUSIONS: Patients with Barrett's oesophagus have a low symptom index compared with non-Barrett's patients with reflux disease. This occurs despite a near 100 per cent increase in acid exposure in the Barrett's group. Symptoms are thus no guide to the severity of reflux in patients with Barrett's oesophagus. Proof of efficacy of therapeutic modalities may need physiological rather than symptom-based confirmation.

Journal Article↗

Static splinting of extensor tendon repairs.

In a prospective review we assessed the results of extensor tendon injuries managed postoperatively with a static splint. Thirty-three patients with 44 injured digits were assessed 4 months after primary tendon repair, using the Strickland-Glogovac criteria. Patients were managed in a static splint, the duration of which was guided by the zone of injury. Four months after repair, excellent or good results were obtained in 95%. Overall it was found that static splinting was an effective and safe method of management after extensor tendon repair.

Adolescent↗

Next of kin clinics.

Explore the source record for details and available documents.

Ambulatory Care Facilities↗

Tobacco control activities of primary-care physicians in the Community Intervention Trial for Smoking Cessation. COMMIT Research Group.

OBJECTIVE: To compare tobacco control practices of physicians and their staff in Intervention communities with those in Comparison communities of the Community Intervention Trial for Smoking Cessation (COMMIT). DESIGN: COMMIT was a randomised trial testing community-based intervention for smoking cessation carried out over four years. SETTING: Eleven matched pairs of communities assigned randomly to Intervention and Comparison conditions. PARTICIPANTS AND INTERVENTIONS: Physicians in the Intervention communities participated in continuing medical education (CME). Training for office staff focused on tobacco control and office intervention "systems". OUTCOME MEASURES: Smoking control attitudes and practices reported by primary-care physicians in the 22 communities, smoking policies, and practices of 30 randomly selected medical offices in each community, and patient reports of physician intervention activities. RESULTS: Response rates to the physicians' mail survey were 45% and 42% in Intervention and Comparison communities, respectively. Telephone interviews of office staff had response rates of 84% in both conditions. Physicians in Intervention communities were more likely to attend training than those in Comparison communities (53% and 26%, respectively (P<0.0005)). In both conditions, training attendees perceived themselves as being better prepared to counsel smokers than non-attendees (P < or = 0.01) and reported more activity in smoking intervention. Intervention communities carried out more office-based tobacco control activities (P = 0.002). Smokers in Intervention communities were more likely to report receiving reading material about smoking from their physicians (P = 0.026). No other differences in physician intervention activities were reported by smokers between the Intervention and Comparison communities. CONCLUSIONS: The COMMIT intervention had a significant effect on some reported physician behaviours, office practices, and policies. However, most physicians still did not use state-of-the-art smoking intervention practices with their patients and there was little, or no, difference between patient reports of intervention activities of physicians in the Intervention and Comparison communities. Better systems and incentives are needed to attract physicians and their staff to CME and to encourage them to follow through on what they learn. The recently released Agency for Health Care Policy and Research clinical practice guideline for smoking cessation and other standards and policies outline these systems and offer suggestions for incentives to facilitate adoption of these practices by physicians.

Adult↗

Nuclear magnetic resonance analysis of methotrimeprazine (levomepromazine) hydroxylation in humans.

Two monohydroxylated metabolites of methotrimeprazine (levomepromazine), which previously have been identified in plasma and urine from psychiatric patients, were synthesized by nonenzymatic, FeCl2-catalyzed oxidation, isolated, and purified by preparative reversed-phase HPLC. Mass spectrometric analysis gave identical spectra for the two compounds, but did not reveal the positions of the OH groups. However, 1H NMR spectroscopy at 200 MHz demonstrated that one of the compounds, which had the shortest GC retention time on an OV-17 column, was hydroxylated in the 3-position on the phenothiazine nucleus, and that the other derivative was hydroxylated in the 7-position. The metabolism of methotrimeprazine differs, therefore, from that of its congener chlorpromazine, which is hydroxylated mainly in the 7-position in humans.

Biotransformation↗

Prolonged treatment with D-penicillamine: effects on adjuvant arthritis in the rat.

The effects of long term D-penicillamine treatment on adjuvant arthritis in the rat were determined in order to establish a possible approach to the laboratory evaluation of anti-rheumatic drugs. Oral pretreatment (1-3 months) followed by continued through-treatment on a daily basis (100 mg/kg p.o.) failed to modify the parameters tested: viz. (a) body weight changes; (b) primary paw lesions; (c) secondary hind paw lesions; (d) secondary forepaw, ear and tail lesions; (e) the number of 'responders'. Autopsy showed no macroscopic abnormalities in the lungs, heart, thymus, liver, spleen, adrenal glands, kidneys and gastro-intestinal tract. These results are discussed in relation to previous findings whereby rat adjuvant arthritis, in addition to other experimental immune reactions, has been suggested as an indicator for D-penicillamine activity.

Administration, Oral↗

Antrafenine: anti-inflammatory activity with respect to oedema and leucocyte infiltration in the rat.

Antrafenine effectively suppressed carrageenan paw oedema in the rat (ED 40 = 24 mg/kg p.o) in the dose range of 10-40 mg/kg p.o, approximating that of phenylbutazone. Antrafenine was superior to phenylbutazone with respect to inhibition of exudate volume and total leucocyte infiltration in carrageenan and calcium pyrophosphate dihydrate crystal pleurisies. The effect of antrafenine on leucocytes was most striking, significant suppression being observed at each dose tested (10, 20, 40 mg/kg p.o), whereas phenylbutazone showed significant activity only at the relatively elevated dose of 40 mg/kg p.o. These observations suggest that antrafenine merits further investigation with respect to its anti-inflammatory effects.

Animals↗

In vitro studies on 6-fluoronoradrenaline at several peripheral sympathetic neuroeffector junctions.

A comparison of the effects of noradrenaline and 6-fluoronoradrenaline has been made at several peripheral sympathetic neuroeffector junctions. In the rat vas deferens preparation in the presence of 1 microM cocaine, 6-fluoronoradrenaline was found to be about 9 times more potent than noradrenaline as an agonist at presynaptic inhibitory alpha 2- adrenoceptors. In the rabbit aorta, 6-fluoronoradrenaline had approximately one tenth of the potency of noradrenaline in stimulating the postsynaptic alpha 1-adrenoceptors. Furthermore 6-fluoronoradrenaline, in contrast to previous reports, appears to be a substrate for the neuronal uptake process since exposure to cocaine potentiated the inhibition of the twitch response of the vas deferens by 6-fluoronoradrenaline. In addition, 6-fluoronoradrenaline increased the spontaneous outflow of radioactivity from rabbit pulmonary artery strips prelabelled with 3H-noradrenaline and this increase was blocked by cocaine (30 microM). These results demonstrate that 6-fluoronoradrenaline is a preferential alpha 2-adrenoceptor agonist which is a substrate for the neuronal uptake process in peripheral sympathetically innervated smooth muscle preparations.

Animals↗

The angular function of orientation illusions induced by projected images of tilted real object scenes.

Tilt aftereffects induced by line gratings are maximal when the test and inducing stimuli have an angular separation of 10 degrees-15 degrees. Similar effects induced by prismatically tilted real-object scenes have been found to increase monotonically with scene tilt. The difference between these two angular functions of aftereffect (that induced by gratings and that induced by real objects) has been attributed to the 'meaning' inherent in the real-object scenes. The preliminary experiments described here suggest that tilt aftereffects and illusions induced by projected slides of tilted real-object scenes have angular functions similar to that induced by a line grating. Hence, the monotonically increasing angular function obtained in the prism studies is not necessarily determined by the use of real-object scenes.

Female↗