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P Dunkley

Publications and source records attributed to P Dunkley.

15 recordsLinked to original sources
PubMed2000

GFAP phosphorylation studied in digitonin-permeabilized astrocytes: standardization of conditions.

Cycles of assembly/disassembly of the intermediate filaments of astrocytes are modulated by the phosphorylation of glial fibrillary acidic protein (GFAP). The sites on GFAP are localized at the N-terminal where they are phosphorylated by cAMP-dependent and Ca(2+)-dependent protein kinases. Phosphorylation of GFAP has been investigated in brain slices, astrocyte cultures, cytoskeletal fractions and purified systems. Here we describe a different approach to study GFAP phosphorylation. We show that permeabilization of astrocytes in culture with digitonin allows direct access to the systems phosphorylating GFAP. Conditions for the permeabilization were established with an assay based on the exclusion of Trypan blue. Incubation of permeabilized cells with cAMP and Ca(2+) increased the phosphorylation state of GFAP. Immunocytochemistry with anti-GFAP showed that permeabilized astrocytes retained their typical flat, fibroblast morphology and exhibited well preserved glial filaments. On incubation with cAMP the filaments apparently condensed to form long processes. The results suggest the approach of studying structural changes in glial filaments in parallel to protein phosphorylation, in the presence of specific modulators of protein kinases and phosphatases has considerable potential.

Adenosine Triphosphate↗
PubMed2000

Effect of intracorporeal-extracorporeal instrument length ratio on endoscopic task performance and surgeon movements.

HYPOTHESIS: Better endoscopic task performance and more ergonomic movements of a surgeon's dominant upper limb can be achieved within a certain range of intracorporeal-extracorporeal instrument length ratio. DESIGN: Investigating the effect of 3 intracorporeal-extracorporeal instrument length ratios (240:120 mm, level 1; 180:180 mm, level 2; and 120:240 mm, level 3) on efficiency and quality of a standardized endoscopic task (intracorporeal surgeon's knot). Ten surgeons tied 360 knots inside a trainer in a random sequence. Task efficiency was measured by the execution time, which was recorded for each knot. Task quality was measured by the knot quality score, derived from the force-extension curves obtained by distraction of each knot in a tensiometer. Motion analysis parameters were obtained at the elbow and shoulder joints using a 3-dimensional motion analysis system (Kinemetrix Model 5.0-3D/3MBM; Medical Research Ltd, Leeds, England). The Kruskal-Wallis and Mann-Whitney tests were used for analysis. RESULTS: The level 3 ratio had the lowest knot quality score (P = .07) and longest execution time (P<.05). The range of movement at the elbow was significantly greater with the level 3 ratio than with the level 1 ratio (P<.05). The level 3 ratio also resulted in the widest range of movement at the shoulder (P<.05 for level 2 vs 3; P = .06 for level 1 vs 3). The median angular velocity was 329.5 degrees/s, 360 degrees/s, and 530 degrees/s for levels 1, 2, and 3, respectively (P = .10). CONCLUSIONS: Intracorporeal-extracorporeal instrument length ratio below 1.0 degrades task performance and is associated with a wider range of movement at the elbow and shoulder and a higher angular velocity at the shoulder.

Biomechanical Phenomena↗
PubMed1999

Surgical simulation: an animal tissue model for training in therapeutic and diagnostic bronchoscopy.

A series of surgical simulation exercises has been developed using an animal model to allow trainees to practise basic instrument handling and develop psychomotor skills in bronchoscopy, without risk to patients. A pig model was found to be most suitable. After suitable preparation the model can be used for diagnostic and therapeutic exercises in bronchoscopy, including lavage, biopsy and the removal of various foreign bodies. The model is a safe, inexpensive and convenient means of bronchoscopic training for otolaryngology trainees. For the trained specialist who has to remove bronchial foreign bodies infrequently, the model is a useful way of maintaining skills.

Animals↗
PubMed1998

Technique training: endoscopic percutaneous tracheostomy.

Percutaneous tracheostomy is being used increasingly in the intensive care unit and endoscopic control of this procedure affords an improved level of safety. Training in such new minimal access techniques can be a significant risk factor in patient outcome. Surgical simulation provides training which minimizes this risk. We present a method of training in percutaneous endoscopic tracheostomy using a simulation model based on animal tissue. Our experience with this model is reported.

Animals↗
PubMed1997

Psychomotor skills for endoscopic manipulations: differing abilities between right and left-handed individuals.

OBJECTIVE: The objective of this study was to compare the psychomotor aptitudes relevant to endoscopic manipulations between right-handed and left-handed subjects. SUMMARY BACKGROUND DATA: There has been little research on the psychomotor performance in relation to minimal access surgery and there are no psychomotor tests to evaluate aspects of psychomotor abilities relevant to endoscopic manipulations. METHODS: A microprocessor-controlled psychomotor tester was developed for objective evaluation of endoscopic performance. The task involved negotiating ten target holes with a probe under videoscopic imaging. Subjects consisted of two groups of 10 medical students: right- and left-handed. After a prestudy familiarization session, each subject performed two test runs with one hand, followed by two runs with the other hand. These test runs were repeated 1 week later. The outcome measures were the total execution time, force on backplate, angular deviations, error rate, and first-time accuracy. RESULTS: A significant difference in the error rate and first time accuracy was observed between subjects (p < 0.001 and p < 0.001, respectively) and between the dominant and nondominant hands (p < 0.001 and p < 0.025, respectively), with no significant change with practice. Right-handed subjects performed better with either hand in terms of error rate (p < 0.001) and first time accuracy (p < 0.001). Practice improved the execution time (p < 0.001) and the degree of angular deviations (p < 0.02). CONCLUSIONS: Right-handed subjects perform less errors and exhibit better first time accuracy. The parameters that improve with practice reflect the positive effect of training, whereas others, such as errors rate and first time accuracy which do not, reflect innate abilities.

Endoscopy↗
PubMed1995

Comparison of direct vision and electronic two- and three-dimensional display systems on surgical task efficiency in endoscopic surgery.

Task efficiency and knot strength was evaluated under standardized conditions using direct vision and electronic imaging with two-dimensional (2-D) and three-dimensional (3-D) systems. Three operators with different endoscopic surgical experience tied a surgeon's knot with standard endoscopic instruments using the three different visual systems in random order. Each operator tied 20 knots with each visual system. Median task efficiency (defined as the time to complete the knot) was 35.0 (interquartile range (i.q.r.) 30.3-43.8) s for direct vision and 53.0 (i.q.r. 45.3-62.8) s and 53.5 (i.q.r. 45.0-64.8) s for 2-D and 3-D imaging respectively (P < 0.05). With respect to direct vision, this represented an overall degradation of task efficiency with the use of electronic imaging of 52 per cent, with no detectable difference between 2-D and 3-D imaging. The knot strength, representing the degree of tightening, was weaker with electronic imaging but the difference was not significant due largely to variation between the three operators.

Clinical Competence↗
PubMed1972

The ANA today.

Explore the source record for details and available documents.

American Nurses' Association↗
PubMedDate not supplied

Coaxial curved instrumentation for minimal access surgery.

New coaxial curved and bayonet instruments have been designed which permit controlled dissection and directional change of the functional tip, blunt dissection and lift retraction. The instruments are introduced into the peritoneal and thoracic cavities through flexible re-usable metal cannulae. The excellent ergonomic properties of the new instruments have been confirmed by their use in major laparoscopic and thoracoscopic operations. Coaxial instruments enhance the scope of minimal access surgery and have distinct advantages over the traditional straight instruments.

Biomechanical Phenomena↗