Biomedical subjects
Publications and source records attributed to P B Pynsent.
The maximum pullout force in the distal metaphysis of cadaver femurs was investigated using a commercially available, pneumatically inserted staple. In paired studies, a significantly greater pullout force was required in the power-driven staples than in an almost identical sized hand-driven staple. A nonlinear relationship was shown to exist between staple-leg length and maximum pullout force.
We describe a computer-based interview system for patients with back pain. The system uses a light-pen for the patient--computer interface. The questionnaire consists of over 200 multiple and single choice questions. Graphic presentations are used to identify pain patterns. The procedure has been well accepted by patients and is in routine clinical use in several hospitals.
A microcomputer-based system has been designed to interview patients with a view to investigating and establishing common syndromes of back and leg pain. In a randomized crossover validation study, 50 consecutive outpatients were interviewed by the computer and had a conventional clerking by a doctor. The conventional clerking made minor errors in 3.75% of questions answered and major errors in 0.90%. The computer made minor errors in 6.75% of questions and major errors in 5.45%. The majority of the computer errors were due to inadequate question design. These have been corrected, and it is anticipated that the computer will now have an overall rate of 94% correct answers and be sufficiently accurate to pursue the aim of clinical syndrome identification.
The reproducibility between observers of physical signs in patients with low-back pain was investigated. Fifty patients were examined by two surgeons and another sample of 33 patients was examined by a surgeon and a physiotherapist. Continuous data on five signs were analyzed by Pearsons' correlation coefficient, and binary data on 54 signs were analyzed by the Kappa agreement coefficient. Reliable signs consisted of measurements of lordosis and flexion range, determination of pain on flexion and lateral bend, nearly all measurements associated with the straight leg raising test, determination of pain location in the thigh and legs, and determination of sensory changes in the legs. Signs of root tension showed better agreement when qualified with a description of where the pain was experienced. Bony tenderness was more reliable than soft tissue tenderness.
Between 1965 and 1973 a total of 808 McKee-Farrar metal-on-metal cemented total hip arthroplasties were performed in the Norfolk and Norwich Hospital. Of these, 230 surviving arthroplasties have been reviewed at average follow-up of 13.9 years. There were good or excellent results in 49% of the arthroplasties as judged by the Harris hip score with 78% of these having little or no pain. A comprehensive radiographic analysis was undertaken and a survivorship study of 81% of the total number of prostheses is presented.
The glucose concentrations of the blood plasma and aqueous humour were measured in 56 cataract patients. The sodium concentration and colour of the lenses were determined after extraction. The mean plasma and aqueous glucose levels were 5.8 and 3.2 mM respectively in non-diabetic patients, while the values for diabetics were 14.2 and 7.8 mM. The sodium concentration of the lenses from non-diabetic patients appeared to consist of two distributions around 30 and 170 mM, corresponding to nuclear and cortical cataracts respectively. Only two lenses from the non-diabetic patients had sodium concentrations in the range 60-120 mM. In diabetic patients, however, 80% of the extracted lenses had sodium concentrations in this intermediate range. The data indicate that the osmotic stresses induced in the lenses of diabetic and non-diabetic patients are different. The diabetic lenses were also distributed in the middle range when nuclear colour was graded on a scale from I to V, while normal lenses were again normally distributed at either end of the scale.
Six measurements of joint mobility were made in a group of 446 normal adolescents. A method of measuring hip and knee rotation is presented. All these data are normally distributed, and would suggest that joint hypermobility lies at the end of the normal spectrum. There was a weak but significant correlation between each of the different measures of joint mobility except elbow hyperextention. Criteria for joint laxity are discussed in this age group, and the importance of quantitative techniques of measuring joint mobility are emphasised.
Mechanical abnormalities of the patellofemoral joint are among the many causes that have been suggested for adolescent knee pain. This study seeks to identify these factors. Measurements of joint mobility and lower limb morphology were made on 446 pupils at a comprehensive school, 136 of whom had suffered knee pain in the previous year. The pupils with symptoms enjoyed sporting activities significantly more than their symptom-free contemporaries. Joint mobility, the Q-angle, genu valgum and anteversion of the femoral neck were not significantly different between those pupils with and those without anterior knee pain. Data on lower limb morphology of normal adolescents are presented. Examination of 52 hospital outpatients aged 13 to 36 years with anterior knee pain produced results comparable with those for the pupils. It is concluded that chronic overloading, rather than faulty mechanics, is the dominant factor in the genesis of anterior knee pain in adolescent patients.
A microcomputer based system has been designed to obtain spatial information for orthopaedic measurements, using three potentiometers as the transducer. Both hardware and software are described, including algorithms for converting the raw data to lengths and angles in three dimensional space.
Otis urethrotomy is an empirical procedure when used in the treatment of recurrent urinary tract infection and the urethral syndrome. Sixty-four female patients were randomised into two treatment groups. One group had cystoscopy alone and the other cystoscopy and Otis urethrotomy. The patients were assessed pre-operatively and at 6 weeks after surgery both symptomatically and by urodynamic testing. There was no significant difference in the results obtained in the two groups. We conclude that Otis urethrotomy has no advantage in the routine treatment of patients with lower urinary tract symptoms.
Explore the source record for details and available documents.
1. The electrical resistance of the perfused frog lens was measured using separate internal current passing and voltage measuring electrodes. 2. The resistance values obtained using voltage clamp and direct and alternating current techniques were in good agreement. 3. The voltage transients induced in response to current steps were multi-exponential in form. Increasing the external K concentration reduced both the amplitude of the voltage response and the rise time. 4. The impedance characteristics were investigated in more detail using alternating current analysis techniques. 5. In an equivalent-circuit modelling study it was assumed that there were two major pathways for current flow in the lens. The first through the surface membranes and the second through the inner fibre membranes via the narrow extracellular spaces. 6. The experimental impedance loci could not be adequately fitted by a simple two time constant model and a third time constant was introduced which may represent diffusion polarization effects in the extracellular spaces. 7. The three time constant model gave good and consistent fits to impedance data from a number of preparations. 8. The form of the impedance loci was also dependent on the external K concentration, but the only fitted parameter which changed consistently with external K was the surface membrane resistance (Rs).
Explore the source record for details and available documents.
1. Simultaneous intracellular (Vi) and extracellular (Ve) recordings have been made from photoreceptor cells in the retina of the cephalopod Sepiola atlantica. 2. The depolarization of the distal (rhodopsin containing) membrane (Vm) was derived from the Vi and Ve records. 3. All three potentials had very similar time courses in response to short flashes of low intensity but the Vi and Vm responses were much greater in amplitude. 4. At high intensities the amplitudes of Vi and Ve were similar but the wave forms were quite different and it was postulated that a voltage-sensitive potassium conductance change in the proximal membranes of the cell was mainly reponsible for the observed differences. 5. The wave forms of the three responses following long (500 msec) flashes were quite different at all intensities tested. At high intensities there was a slow sag phase in the Vi response, that was mirrored by a slow rise phase in the Ve responses. The reconstructed Vm response was flat during this period of change in the other two responses. 6. The recoveries to the base line of all responses following both long and short flashes were similar in that at high intensities they consisted of at least two phases. The fast phase had a time constant less than 1 sec and the slow component had a time constant of greater than 10 sec. 7. The maximum rates of change of voltage (dV/dt) in both short and long flash responses were linear over a much wider range of intensity values than were the response amplitudes and the rates continued to increase after the peak response amplitude had saturated. 8. The characteristics of the cephalopod responses were compared with those from vertebrate rods and cones and several marked similarities were found.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.