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Biomedical subjects

P Marsden

Publications and source records attributed to P Marsden.

At least 37 records · Page 2Linked to original sources
PubMed1990

Quantitative assessment of diagnostic ability.

This paper describes variables critical to diagnostic thinking that are based on research by Bordage and Grant & Marsden on the diagnostic thinking of medical students and experienced doctors. The purpose of the study is to use their findings to develop an inventory of diagnostic thinking. A 56-item diagnostic thinking inventory was initially developed; each item contains a stem followed by a 6-point, semantic differential scale. The inventory is designed to measure two aspects of diagnostic thinking: the degree of flexibility in thinking and the degree of knowledge structure in memory. The specific goal of the study is to determine which items discriminate best between weaker and stronger diagnosticians and to reduce the inventory to only those items which significantly contribute to the overall score. Thirty subjects from nine groups, each representing a distinct phase of medical education and clinical practice, participated, namely first- and third-year clinical medical students, house officers, senior house officers, registrars, senior registrars, consultants, trainees in general practice, and general practitioners, all from the UK (n = 270). Discrimination indices were calculated for each item. The revised version of the inventory contains 41 items. All the subjects found the exercise meaningful and the resulting scores showed variance and discrimination. The inventory will eventually be used to assess individual student's and clinician's diagnostic thinking and to plan ways of improving their diagnostic thinking.

Clinical Competence↗
PubMed1990

The learning needs in diabetes of general practitioners.

The aim of the study was to determine the learning needs of General Practitioners (GPs) in diabetes. A postal questionnaire was sent to all GPs in South East Thames Region (England). The level of interest in continuing professional education in diabetes is sufficient to merit production of tailored learning materials and opportunities. Eighty-three percent of GPs would definitely or probably avail themselves of the opportunity even if they did have to pay. This percentage represents a figure of over 780 GPs. They are most keen to learn the clinical and other skills associated with diabetes and its management. A large number, 71%, requested education on retinal examination and adjustment of insulin, 56% on adjustment of tablet therapy, and 51% on the management of children with diabetes. Individual study materials, backed up by small group meetings and video material would be the most appreciated format. A course of study divided into half-hourly periods adding up to a total of about 5 h might be the most widely acceptable format. GPs would most like to study with other GPs from local practices and with hospital staff. Group work might best be designed to incorporate both an experienced GP, if one were available, and a consultant. The materials themselves might also best be designed and written by such a partnership.

Diabetes Mellitus↗
PubMed1989

Senior house officers and their training. I. Personal characteristics and professional circumstances.

To assess the experience and perceptions of training of senior house officers in medicine a population survey of senior house officer training was conducted on senior house officers, registrars, senior registrars, and consultants in six medical specialties in South East Thames region by interview and postal questionnaire. The overall response rate was 72%, varying from 62% to 83% according to status and from 61% to 80% according to specialty. Although most of the 226 senior house officer respondents were aged 28 or under (168/225), had been qualified for four years or less (168/225) and were British (176/223), a quarter were older and had been qualified for five years or more; in all, 17 other nationalities were represented. Twenty two were aged over 33, and 17 had been qualified for more than 10 years. Thirty five senior house officers worked more than the mode of the distribution of duty rotas (one in three). Among postgraduate qualifications achieved or pursued, those related to general practice were highly represented (164 examinations); 111 senior house officers intended becoming general practitioners, 63 non-teaching hospital consultants, and 34 university or NHS teaching staff. Analysis of career progression showed that an appreciable number (31/221) had had more than three senior house officer posts. The findings indicate that the main implications for training and education are time for study, careers advice, and revision of educational programmes.

Adult↗
PubMed1989

Senior house officers and their training. II. Perceptions of service and training.

Aspects of teaching and learning at senior house officer level in South East Thames region were investigated by analysis of the responses of consultants, senior registrars, registrars, and senior house officers to a postal questionnaire. Responses to sections about who teaches senior house officers, how senior house officers learn, and the relation between the service and training elements of these posts varied significantly, according to the status of the respondents; certain grades commonly overestimated their own contribution when compared with the estimates of the other grades. Although the replies of senior house officers showed that they were taught by various grades, 47% of this group did not regard the consultant as their main teacher. Senior registrars and registrars rather than consultants were regarded by senior house officers as best at teaching (63% v 48% respectively). Consultants and registrars were considered to require more commitment to training, personal educational training, and to be more approachable. Inquiry about teaching methods used most by senior house officers showed absence of a systematic approach to training. Only about half of senior house officers cited ward rounds with consultants. Views on the relation between training and service were significantly different among grades, but there was general dissatisfaction. Overall, the findings disclosed the ineffectiveness of senior house officer training posts. This arises from lack of a clear distinction between training and service elements, of educational training for teachers, of a clear contractual obligation to teach im the consultant grade, and of allotted time for training and study for the teachers and senior house officers respectively. Reversal of these current trends is needed for senior house officer posts to fulfil their main training function.

Attitude of Health Personnel↗
PubMed1988

Primary knowledge, medical education and consultant expertise.

We have studied the knowledge of students and clinicians that they actually used to follow up four problems in general medicine. Some unexpected similarities and differences in their readily accessible or primary knowledge were found in groups from first-year clinical medical students to consultants. There is no linear increase in the quantity of primary knowledge with experience, but qualitative changes are very much more important. At all levels individuals show a remarkable dissimilarity in the knowledge they use to solve clinical problems, so that the bulk of personal knowledge used is individual. Comparatively rarely do people use the same knowledge to solve any one clinical problem. However, there is evidence of a general tendency towards increasing uniformity in knowledge as a result of the medical school years. After houseman level, individuality increases again. These changes result in consultants achieving an identical profile to first-year clinical medical students in terms of the extent to which their primary knowledge bases are held individually or in common. These findings suggest that consultant expertise is actually based on individual experience rather than a common core of knowledge. The influence of medical school in providing such a common knowledge base is (1) limited and (2) reversed by clinical practice. The results suggest the necessity for increased vocational and practice-oriented components in medical education, particularly in postgraduate education.

Clinical Competence↗
PubMed1987

The structure of memorized knowledge in students and clinicians: an explanation for diagnostic expertise.

This paper provides for the first time evidence of a consistent difference in the memory structures of novice and expert clinicians. The diagnostic performance of first- and third-year clinical medical students, senior house officers, registrars and consultants on four clinical problems in general medicine was studied. Comparisons were made of all diagnostic interpretations offered and the forceful features (personally important pieces of information which act as a key to particular memory structures which in turn give rise to the clinical interpretation) from which these were derived. Results demonstrate that the numbers of interpretations made and the numbers of forceful features identified did not differ significantly between groups (P greater than 0.05). However, the actual interpretations made in three out of four cases, and the actual forceful features identified in all cases, did differ significantly between groups (P less than 0.05). The numbers of interpretations made by all groups were large and demonstrated enormous variability. Highly individualized multiple responses to clinical information are associated with easy diagnoses. We conclude that there is no difference between groups of differing clinical experience in the breadth of thought but that there are marked differences in the precise content and structure of thought. This allows coherent explanation of variation in diagnostic expertise with clinical experience. The significance of the findings is discussed.

Clinical Competence↗
PubMed1984

The role of the routine clinical history.

Twenty-two final year clinical medical students, twenty-two pre-registration house physicians and twenty-two post MRCP (U.K.) registrars were studied during the clinical interview by the method of videotape-stimulated recall. It was found that the course of the clinical interview was determined by three thinking processes. There was no significant difference between the students, house offers and registrars in the extent to which their interviews displayed these thinking processes. Taking all subjects together, however, there was a significant difference in overall frequency of usage of the processes. The results show that students and doctors largely conduct the clinical interview according to either demands of their own interpretation of clinical information as it is gathered or the requirements of the routine but usually by a combination of both. The active role of the interviewer in following his/her own interpretative needs is the most important feature of our findings. The routine inquiry was used by all groups as a failsafe or background search mechanism. Increased knowledge of these thinking processes among students and teachers of medicine may lead to a more realistic and efficient balance in the teaching and learning of the clinical history.

Education, Medical, Graduate↗
PubMed1984

A clinical evaluation of a prototype positron camera for longitudinal emission tomography.

A multiwire proportional-chamber positron camera, developed at the Rutherford Laboratory, has been evaluated at The Royal Marsden Hospital. The prototype camera consists of two opposing 30 X 30 cm2 chambers. Longitudinal tomograms of a positron-emitting radioactive distribution placed between the detectors are obtained via back-projection and 2D-deconvolution. Due to the limited stereoscopic angle achieved with stationary detectors, only five planes parallel to the detector faces are reconstructed. A selection of images is presented of phantoms using 68Ga and of patients using 18F, 18F fluorodeoxyglucose and Na124I, to illustrate the tomographic performance of the positron camera. A comparison between back-projected and deconvoluted images shows that the 2D-deconvolution process, which includes filtration of image noise, successfully removes the background due to scattered photons. The spatial resolution achieved depends on the half-height frequency cut-off used in the filtering process, and this parameter was chosen according to the count density in the back-projected images. A qualitative visual comparison was made between the positron images and equivalent single photon studies on the same patient. The results justify further development of this new detector, especially for use with generator-produced positron-emitting radionuclides. Three-dimensional deconvolution resulted in improved tomographic performance for phantom data, but was less successful for patient data. These problems associated with limited-angle tomography will be overcome by multi-view acquisition. This study has shown that a relatively low-cost positron imaging system can be used for routine organ imaging. Further developments in hardware and software should yield images which are superior to those from single-photon planar or tomographic studies.

Bone Marrow↗
PubMed1983

Epidemiological study of prevalence of chlorpropamide alcohol flushing in insulin dependent diabetics, non-insulin dependent diabetics, and non-diabetics.

An epidemiological study was carried out to compare the prevalence of facial flushing in non-diabetics, patients with insulin dependent diabetes, and patients with non-insulin dependent diabetes in response to 40 ml sherry taken 12 hours after 250 mg chlorpropamide or placebo, administered double blind in randomised order. A flush after chlorpropamide but not placebo was reported by 6.2% of non-diabetics (17/273), 9.7% of insulin-dependent diabetics (14/145), and 10.5% of non-insulin dependent diabetics (25/239), excluding those receiving long term chlorpropamide treatment. The differences were not significant. This response was unrelated to age, sex, body mass index, and family history of diabetes in all three groups. Patients taking long term chlorpropamide, however, showed a significantly (p less than 0.01) higher prevalence of flushing after both chlorpropamide and placebo (56.3%; 9/16) compared with the rest of the non-insulin dependent diabetics (16.7%; 40/239), the insulin dependent diabetics (6.9%; 10/145), and the non-diabetics (5.9%; 16/273). Patients receiving long term chlorpropamide would be expected to flush with sherry after a placebo tablet because of therapeutic plasma concentrations of the drug. It is concluded that there is no evidence of an increased prevalence of chlorpropamide alcohol flushing in response to the single challenge test in non-insulin dependent diabetics compared with insulin dependent diabetics and non-diabetics except in selected patients taking chlorpropamide long term. This study does not support the hypothesis that the chlorpropamide alcohol flush is a specific marker for a subtype of non-insulin dependent diabetes.

Adult↗
PubMed1982

Clinical problem solving: the beginning of the process.

The diagnostic thinking process is often described as one of hypothesis generation and testing. Yet descriptions of the clinical problem solver's thinking prior to generation of the first diagnostic hypothesis are lacking. This paper reports a study of this phase in students, house officers and registrars. Theories of pattern recognition are seriously questioned. It is shown that these subjects make immediate active interpretative or evaluative responses to initial items of clinical information elicited. These responses cannot be described as 'diagnostic hypotheses', but are important working interpretations. Implications for teaching are discussed.

Diagnosis↗
PubMed1981

Rapid adaptation of pituitary responsiveness to TRH in the post-surgical state. The role of free T3.

In eight clinically and biochemically euthyroid patients undergoing routine major non-thyroidal surgery preoperative and daily postoperative serum concentrations of total and free thyroid hormones were measured. Thyrotrophin-releasing hormone (TRH) tests were performed preoperatively and on the first 3 postoperative days. There was a significant fall in mean serum total and free triiodothyronine (T3) concentrations on the postoperative days and mean reverse T3 concentrations rose reciprocally. There was no significant change in mean basal thyroid-stimulating hormone (TSH) values, but there was a significant increase in the mean TSH-response to TRH on the first postoperative day. The mean TSH response than declined sequentially until day 3 while mean free T3 concentrations remained significantly depressed. Mean serum free thyroxine(T4)concentrations remained normal during the study. Intrapituitary conversion of T4 to T3 or other down regulatory mechanisms could explain this rapid adaptation of the pituitary axis.

Adaptation, Physiological↗
PubMed1980

A method for the preparation of human thyroxine-binding globulin; its importance in the establishment of an accurate and specific radioimmunoassay.

Pure thyroxine-binding globulin (TBG) is required in radioimmunoassay to prepare monospecific antisera, [125I]TBG and as primary standard. Homogeneous TBG was prepared by a three-stage affinity chromatography procedure; it could not be dissociated into subunits and its molecular weight by SDS polyacrylamide gel electrophoresis was 59 000. The amino acid composition was in agreement with two earlier reports. The secondary structure determined by circular dichroism in the far U.V. showed it to contain 24% each of alpha-helix and beta-pleated sheet. Serum TBG was determined by a 24-h radioimmunoassay using polyethyleneglycol to separate bound and free TBG. Serum TBG (mg/l, mean +/- S.D.) was: normal men 15.3 +/- 2.11 (n = 34), normal women 18.4 +/- 2.72 (n = 32) (P less than 0.005), in women on oral oestrogens 24.0 +/- 5.0 (n = 23), in normal pregnancy 38.6 +/- 3.0 (n =37), in cord blood 21.7 +/- 3.5 (n = 25) (P less than 0.001) and in euthyroid subjects aged over 60 years 17.8 +/- 4.5 (P n.s.). In women with thyroid disease TBG was reduced in hyperthyroidism: 15.5 +/- 2.5 (n = 28) and elevated in hypothyroidism: 21.0 +/- 4.0 (n = 25). Wider use in TBG-assay of non-denatured TBG of proven composition and structure should decrease the scatter in reference ranges and improve its value as a routine thyroid function test as both a primary measurement and as the T4 : TBG ratio.

Adolescent↗
PubMed1980

The accuracy and standardization of TBG kits.

Three kits for measurement of serum thyroxine-binding globulin (TBG) were compared with a reference radioimmunoassay in forty-three normal euthyroid subjects. The Corning Immophase kit gave similar results to those with the reference method with satisfactory precision and accuracy. The Behringwerke AG RIA-gnost kit gave results with adequate but lower correlation with the reference method (r = 0.80) than that of the Corning kit trial (r = 0.92). The mean value was significantly greater than the reference method mean, indicating that the Behringwerke kit was inaccurately standardized. The CEA-Sorin TBG kit (Eurotope services) gave results with a poor correlation against the reference method (r = 0.59). The mean value was also significantly greater than the reference mean indicating that this kit is both inaccurately standardized and less precise than the other two. It is stressed that TBG-kits need to be periodically standardized against reference methods in the absence of properly validated primary standards in all batches.

Adolescent↗
PubMed1977

In-vitro studies of normal human thyroid cells: responses to thyrotrophin and dibutyryl cyclic AMP.

Follicular cells isolated from normal human thyroid tissue have been cultured for up to 140 h with bovine thyrotrophin (TSH) or dibutyryl cyclic AMP (DBcAMP). Both compounds induced marked reorganization of the cells into three-dimensional follicular structures, whilst non-supplemented cells assumed a monolayer form. Cultures treated initially with TSH or DBcAMP showed a greater iodide uptake capacity, in comparison with unsupplemented cultures, in which iodide uptake was markedly diminished after 24 h. The release of tri-iodothyronine (T3) and thyroxine (T4) into the medium was determined by radioimmunoassay. Both TSH- and DBcAMP-treated cells showed a significant increase in iodothyronine output compared with unsupplemented control cells. In contrast to the "classical" TSH-induced depression of the T4:T3 ratio in vivo, an increase in the ratio was observed for both TSH- and DBcAMP-supplemented cells in vitro. The ratio was also significantly greater after TSH than after DBcAMP, and possible implications of this findings are discussed.

Bucladesine↗