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Biomedical subjects

P Greenfield

Publications and source records attributed to P Greenfield.

7 recordsLinked to original sources
PubMed1997

Survey of the information given to patients about blood transfusion and the need for consent before transfusion.

There is no current requirement in the United Kingdom to provide patients with information about blood transfusion or to seek their written consent to transfusion. To study patients' attitudes to these questions, a questionnaire survey was carried out on 51 patients during an admission to hospital in which they received a blood transfusion. The patients in this survey, although mostly satisfied about the information they were given before they were transfused, would have welcomed more general information about transfusion, mainly because of concerns about the risk of viral infections. Nearly 40% of patients thought that written consent should be obtained before transfusion, but the ethical and practical aspects of this issue are complex. Further debate would be required before implementation of written consent to transfusion could be considered as a routine policy.

Adolescent↗
PubMed1996

Do diurnal changes in loading affect the interpretation of MRI scans of the lumbar spine?

We tested the hypothesis that the visual interpretation of magnetic resonance imaging (MRI) scans of the asymptomatic lumbar spine are affected by diurnal changes in fluid exchange in the intervertebral discs. Ten male subjects carried a 20-kg backpack in the intervening 3-h period between two MRI scans of the lumbar spine. After the subjects arrived at the MRI center (within 45 min of awakening), they lay on a bed for 45 min. The first set of MRI scans were obtained. Each subject was then fitted with a 20-kg backpack. After they walked for 3 h, the pack was removed, and a second set of MRI scans were obtained immediately. The sets of MRI scans were reviewed by three radiologists: none of the three radiologists found differences in the interpretation of the MRI scans. On the basis of these results, diurnal changes in fluid exchange in the asymptomatic intervertebral disc (exaggerated in our case by the backpack) are undetectable by visual reading of MRI scans.

Adult↗
PubMed1994

Calcium alginate immobilized hybridomas grown using a fluidized-bed perfusion system with a protein-free medium.

Hybridoma SPO1 cells were immobilized in calcium alginate beads and were further grown in a fluidized-bed perfusion system with a protein-free medium. The presence of serum in the steps of entrapment was shown to be helpful for the preservation of cell viability. Each step during immobilization was investigated with respect to the extent of cell damage caused. The immobilization process using small beads caused a lower cell viability initially but allowed a higher rate of cell growth subsequently, compared to those in large beads. In a perfusion system for the continuous production of monoclonal antibodies (MAb), the viable cell density reached 2 x 10(7) cells per ml of beads with a viability of 40%. Compared with the cells in suspension culture, the immobilized SPO1 cells showed higher viable cell based specific rates of substrate uptake (glucose and glutamine) and of MAb production. A significant drop in the formation of lactate after the cell growth entered a steady state suggested a higher activity of the Tricarboxylic Acid Cycle in the cells when the cell density became high.

Alginates↗
PubMed1983

Evoked potential and preferential looking estimates of visual acuity in pediatric patients.

Pattern visual evoked potentials (VEPs) and behavioral visual acuity measured with forced-choice preferential looking techniques (FPL) were obtained from 172 pediatric patients between the ages of 4 months and 10 years. More children younger than 2 years of age successfully completed monocular testing by pattern VEP than by FPL methods. For children older than 2 years, we were equally successful in completing each of the two tests. Of those children who completed both tests, the VEP results agreed with Snellen, Allen, and "E" acuity measures more often (66%) than did the FPL results (50%). Both tests were more sensitive than Allen single characters in detecting interocular acuity differences in children younger than 3 years of age.

Age Factors↗