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Biomedical subjects

M Maxwell

Publications and source records attributed to M Maxwell.

At least 37 records · Page 2Linked to original sources
PubMed1996

Mechanisms of heading perception in primate visual cortex.

When we move forward while walking or driving, what we see appears to expand. The center or focus of this expansion tells us our direction of self-motion, or heading, as long as our eyes are still. However, if our eyes move, as when tracking a nearby object on the ground, the retinal image is disrupted and the focus is shifted away from the heading. Neurons in primate dorso-medial superior temporal area responded selectively to an expansion focus in a certain part of the visual field, and this selective region shifted during tracking eye movements in a way that compensated for the retinal focus shift. Therefore, these neurons account for the effect of eye movements on what we see as we travel forward through the world.

Animals↗
PubMed1996

Clinical benchmarking: results into practice.

Describes the way benchmarking data are used in a district general hospital to influence clinical practice. Wirral Hospital Trust is a site for the Electronic Patient Record Project; as such there is a large amount of patient based data available for research and internal benchmarking. Includes working examples of internal benchmarking which have been used by both clinicians and hospital management to improve hospital effectiveness. Discusses the ways in which this information is being used to develop initiatives such as clinical pathway development.

Critical Pathways↗
PubMed1995

Preparation of casein using carbon dioxide.

The effects of pressure, temperature, residence time, and mass of skim milk on some characteristics of casein, prepared by precipitation with high pressure CO2, were examined in a batch reactor. For a 500-g milk sample, precipitation occurred at pressures > 2760 kPa and temperatures > 32 degrees C. Residence time was not significant and was held at 5 min. Yields were maximum at 2750 to 5520 kPa and at 38 to 49 degrees C for a 500-g milk sample. The resulting whey had a pH of 6.0. The casein product had an acceptable appearance and had greater solids, ash, and Ca contents than commercial acid caseins. Particle size distribution studies showed that the mean particle size was sensitive to precipitation pressure and temperature and was similar to that of acid caseins produced under laboratory conditions. The HPLC studies of the casein and whey fractions showed that precipitation by CO2 did not result in fractionation of casein or whey proteins to their component proteins.

Animals↗
PubMed1995

Care of patients with selected health problems in fundholding practices in Scotland in 1990 and 1992: needs, process and outcome.

BACKGROUND: At the time of the introduction of fundholding, a number of potential benefits and concerns about fundholding were debated. AIM: A study was undertaken to compare process and outcome of care in patients with different levels of physical, social and psychological need in 1990 and 1992 in six fundholding groups in Scotland. METHOD: Patients aged 16 years and over consulting with a range of marker conditions in 1990 and 1992 completed a pre-consultation health status questionnaire asking about physical, social and psychological problems, and a postconsultation satisfaction/enablement questionnaire asking about their ability to cope, and understand their illness. Main outcome measures were consultation length and satisfaction/enablement score. RESULTS: Of patients attending in the study period, 39% consulted for one or more marker condition. The proportion of patients reporting social problems rose between 1990 and 1992 for 11 out of 12 conditions. Overall, consultation lengths remained constant. Patients wanting to discuss social problems had significantly longer consultations than those reporting no social problems or problems they did not wish to discuss. The proportion of patients expressing enablement dropped for eight conditions and rose for four between 1990 and 1992. The decrease in the proportion expressing enablement remained after controlling for the rise in the percentage reporting social problems. Patients who had social problems they did not wish to discuss but a general health questionnaire score of five or more were the group reporting lowest enablement. Significantly more patients with pain, skin problems and digestive problems reported social problems and significantly fewer of them reported enablement in 1992 compared with 1990. Patients with diabetes, angina, chronic bronchitis and problems seeing fared relatively well over the study period. Some patients with psychosocial problems fared poorly (they had relatively short consultations and were unlikely to express an ability to cope/understand their illness). CONCLUSION: The issue of whether benefits to some patient groups from recent health service changes may be matched by disadvantage to other groups, for example those with clinical problems with no financial incentive to provide pro-active care or with psychosocial difficulties, is discussed.

Acute Disease↗
PubMed1994

Evaluating care of patients reporting pain in fundholding practices.

OBJECTIVE: To compare quality of care between 1990 and 1992 in patients with self diagnosed joint pain. DESIGN: Questionnaire and record based study. SUBJECTS: Patients identified at consecutive consultations during two weeks in 1990, 1991, and 1992. SETTING: Six practice groups in pilot fundholding scheme in Scotland. MAIN OUTCOME MEASURES: Length of consultation; numbers referred or investigated or prescribed drugs; responses to questions about enablement and satisfaction. RESULTS: About 15% of patients consulted with joint pain each year. 25% (316) of them had social problems in 1990 and 37% (370) in 1992; about a fifth wanted to discuss their social problems. Social problems were associated with a raised general health questionnaire score. The mean length of consultation for patients with pain was 7.6 min in 1990 and 7.7 min in 1992. Patients wishing to discuss social problems received longer consultations (8.5 min 1990; 10.4 min 1992); but other patients with social problems received shorter consultations (7.4 min; 7.2 min). The level of prescribing was stable but the proportion of patients having investigations or attending hospital fell significantly from 1990 to 1992 (31% to 24%; 31% to 13% respectively). Fewer patients responded "much better" to six questions about enablement in 1992 than in 1990. Enablement was better after longer than shorter consultations for patients with social problems. CONCLUSIONS: Quality of care for patients with pain has been broadly maintained in terms of consultation times. The effects of lower rates of investigation and referral need to be investigated further.

Drug Prescriptions↗
PubMed1994

Abnormalities of renal physiology in systemic sclerosis. A prospective study with 10-year followup.

OBJECTIVE: To evaluate the prognostic value of measurements of renal plasma flow and circulating vasoactive hormones in patients with systemic sclerosis (SSc). METHODS: Renal plasma flow (para-aminohippurate [PAH] clearance) and levels of selected circulating hormones (plasma renin activity [PRA] and serum aldosterone and catecholamines) were assessed in 57 SSc patients under the following conditions: at rest, in response to cold, while in upright position, and in response to sodium depletion. Survival was assessed 10.7 years after testing (20 patients had died). RESULTS: Both unstimulated and stimulated PRA clearance rates were frequently elevated. Resting PAH clearances were usually abnormally low. PAH clearances and levels of aldosterone and catecholamines did not change during cold stimulation. Supine PRA levels following acute sodium depletion correlated with survival (P < 0.008). CONCLUSION: The frequent finding of elevated PRA and reduced PAH values reflects clinically the high frequency of renovascular disease noted histopathologically in SSc. Isolated decreases in PAH and elevations in PRA, however, did not predict renal crisis. Changes in PAH clearances were not demonstrable during cold stimulation. An abnormally high supine PRA after sodium depletion correlated with improved survival.

Adolescent↗
PubMed1993

General practice fundholding: observations on prescribing patterns and costs using the defined daily dose method.

OBJECTIVE: To compare prescribing patterns between a group of fundholding practices and a group of non-fundholding practices in north east Scotland using a method which provides more accurate statements about volumes prescribed than standard NHS statistics. DESIGN: The pharmacy practice division of the National Health Service in Scotland provided data for selected British National Formulary sections over two years. Each prescription issued was converted using the World Health Organisation "defined daily dose" mechanism. SETTING: Six fundholding groups (nine practices) in Grampian and Tayside regions and six non-fundholding practices in Grampian. RESULTS: During the past two years both fundholding and control practices reduced the volume of their prescribing for the classes of drug analysed. The unit costs of drugs in some classes, however, rose substantially, contributing to higher costs per patient. The unit costs rose more in the control practices (24%) than in the fundholding practices (11% in Tayside, 16% in Grampian). CONCLUSION: The use of defined daily doses helped identify cost and volume trends in specific areas of prescribing in fundholding and control practices. The basis on which funds are set needs improving, and defined daily doses may prove useful for setting volume targets within drug classes for all practices, whether fundholding or not.

Age Factors↗
PubMed1993

Expression of androgen and progesterone receptors in primary human meningiomas.

Meningiomas are common brain tumors that show a predilection for females and become more aggressive during pregnancy and menses. The existence of gender-specific hormone receptors in meningiomas has long been a matter of controversy; the recent cloning of androgen, estrogen, and progesterone receptors has facilitated their direct evaluation. The authors have demonstrated the expression of androgen and progesterone receptor messenger ribonucleic acid and protein product in nine primary human meningiomas by Northern blot analysis. Cellular localization was achieved by in situ hybridization analysis. Estrogen receptor expression was not detected. Normal adult meninges were shown to express very low levels of both androgen and progesterone receptors.

Female↗
PubMed1993

The chief scientist reports ... Evaluation of the Scottish shadow fund-holding project: first results.

This paper reports preliminary findings from the action research evaluation of the Scottish shadow fund-holding project. Fifty doctors looking after 84,000 patients in six groups negotiated and managed a paper fund for six months, and then a real fund for six months. First analyses of quantitative data suggest that the numbers of prescriptions written, investigations done and referrals made remained stable over the period of study. The length of time spent at consultations varied apparently independently of holding a fund. Patient satisfaction with actions taken by doctors and their feelings of benefit from consultations were high throughout the study, but a consistent and significant shift from very satisfied to satisfied categories was noted in all practices for most variables surveyed during the course of 1990-91. Analyses to explain this are continuing. Qualitative study identified benefits in terms of a greater understanding of the costs of activities, and new working patterns between hospital, general practice and administrative staff have led to progressive work in contracting for quality of patient care. At the same time, the lack of sophistication of fund setting needs to be addressed; equity issues will become relevant as fund-holding reaches a larger proportion of practices. The pressures on those taking leading roles in administration are high, and this is confirmed by parallel quantitative work. Further information is becoming available on both prescribing and the care of selected 'marker' conditions, and these will be the subject of further reports.

Contract Services↗
PubMed1992

Expression of insulin-like growth factors I and II and their receptor mRNAs in primary human astrocytomas and meningiomas; in vivo studies using in situ hybridization and immunocytochemistry.

These studies demonstrate the expression of IGF-1, IGF-11, and their respective receptor mRNAs in primary human astrocytomas and meningiomas. In situ hybridization and immunocytochemistry have localized a strong expression of both IGF-1 and IGF-11 mRNAs and of their protein products in the tumor cells of astrocytomas and meningiomas. The expression of IGF-1 and IGF-11 mRNAs in the tumor cells was accompanied by the co-expression of their respective type-1 and type-11 IGF receptor mRNAs. Control, non-malignant human brain expressed IGF-1 mRNA and IGF-1 and IGF-11 receptor mRNAs. There was no significant expression of IGF-11 MRNA in the control brain specimens. Control pachymeninges (dura mater) expressed low levels of IGF-1 mRNA and IGF-1 receptor mRNA. There was no significant expression of IGF-11 and IGF-11 receptor mRNAs in pachymeninges. The co-expression of IGFs and their receptors in brain tumors may contribute in their development and maintenance. The strong inappropriate expression of IGF-11 mRNA and its protein product in the tumor cells of astrocytomas and meningiomas, but not in normal brain specimens, may serve as molecular markers for the early detection of these tumors.

Astrocytoma↗
PubMed1992

Effect of the expression of transforming growth factor-beta 2 in primary human glioblastomas on immunosuppression and loss of immune surveillance.

Glioblastomas are malignant brain tumors that are attended by an immunosuppressed state. The authors have studied the expression of transforming growth factor-beta 2, which is known to have potent immunosuppressive and angiogenic properties. Transforming growth factor-beta 2 messenger ribonucleic acid and its protein product are both found to be greatly overexpressed in these tumors and are absent from normal brain tissue. The overexpression of this growth factor may contribute to the escape of neoplastic astrocytes from immune surveillance and, furthermore, to the immunosuppressed state that is characteristic of many of these patients.

Astrocytoma↗
PubMed1992

The chief scientist reports ... The Scottish general practice shadow fund-holding project--outline of an evaluation.

After the agreement in January 1989 between the Minister of Health at the Scottish Office, Mr Michael Forsyth, and six groups of General Practitioners (GPs) in the Grampian and Tayside Regions of Scotland to embark on a 'shadow fund-holding' project, the Government agreed to promote an independent evaluation of the scheme. As a result, the Department of General Practice at Edinburgh University was invited to present plans to evaluate the working of and results of the scheme. Consultations with the Minister and Health Department officials, the general practices concerned, and staff of the two Health Boards involved took place during the first three months of 1990, and an outline protocol for the evaluation was approved and funded through the Chief Scientist Organisation for a three-year period from April 1990. It was agreed by all involved that piecemeal publications of results during the period of the research would be inappropriate, but with other attempts to evaluate fund-holding now being reported elsewhere in the UK, it has been agreed that an outline of issues being explored and the methods being used would be in the general interest. This paper first outlines the principal areas in which the evaluation is being focused, then describes the general methods being used, and finally comments on some of the problems encountered with the evaluation. The project should be seen as a descriptive beginning to what may well be a period of around a decade needed to appreciate the full implications of any major change in the organisation of health service provision.

Family Practice↗
PubMed1991

Case-control study of leukaemia and non-Hodgkin's lymphoma in children in Caithness near the Dounreay nuclear installation.

OBJECTIVE: To examine whether the observed excess of childhood leukaemia and non-Hodgkin's lymphoma in the area around the Dounreay nuclear installation is associated with established risk factors, or with factors related to the plant, or with parental occupation in the nuclear industry. DESIGN: Case-control study. SETTING: Caithness local government district. SUBJECTS: 14 cases of leukaemia and non-Hodgkin's lymphoma occurring in children aged under 15 years diagnosed in the area between 1970 and 1986 and 55 controls matched for sex, date of birth, and area of residence within Caithness at time of birth. MAIN OUTCOME MEASURES: Antenatal abdominal x ray examination; drugs taken and viral infections during pregnancy; father's occupation; father's employment at Dounreay and radiation dose; distance of usual residence from the path of microwave beams, preconceptional exposure to non-ionising radiation in the father; and other lifestyle factors. RESULTS: No raised relative risks were found for prenatal exposure to x rays, social class of parents, employment at Dounreay before conception or diagnosis, father's dose of ionising radiation before conception, or child's residence within 50 m of the path of microwave transmission beams. Results also proved negative for all lifestyle factors except an apparent association with use of beaches within 25 km of Dounreay. However, this result was based on small numbers, arose in the context of multiple hypothesis testing, and is certainly vulnerable to possible systematic bias. CONCLUSION: The raised incidence of childhood leukaemia and non-Hodgkin's lymphoma around Dounreay cannot be explained by paternal occupation at Dounreay or by paternal exposure to external ionising radiation before conception. The observation of an apparent association between the use of beaches around Dounreay and the development of childhood leukaemia and non-Hodgkin's lymphoma might be an artefact of multiple testing and influenced by recall bias.

Case-Control Studies↗
PubMed1991

Expression of angiogenic growth factor genes in primary human astrocytomas may contribute to their growth and progression.

Astrocytomas are highly malignant brain tumors and are among the most neovascularized solid tumors. We have investigated the expression of the angiogenic growth factors acidic fibroblast growth factor and transforming growth factor-alpha, together with its receptor epidermal growth factor receptor, in 30 primary astrocytomas. Both acidic fibroblast growth factor and transforming growth factor-alpha, together with epidermal growth factor receptor, are found to be greatly overexpressed in these tumors when compared with normal brain. This overexpression of angiogenic growth factors may underlie the intense neovascularization characteristic of astrocytomas.

Angiogenesis Inducing Agents↗
PubMed1991

Coronary vasoconstriction induced by vasopressin. Production of myocardial ischemia in dogs by constriction of nondiseased small vessels.

BACKGROUND: We studied the effect of intracoronary administration of arginine-8-vasopressin on blood flow in nondiseased coronary arteries and determined whether this vasoconstriction was severe enough to produce ischemia in 30 dogs. METHODS AND RESULTS: In group 1 (n = 6), after vasopressin administration coronary blood flow was decreased by 41% (p less than 0.002) without changes in heart rate or aortic pressure, and left ventricular ejection fraction measured by radionuclide angiocardiography was decreased by 18% (p less than 0.0005). In group 2 (n = 6), ischemia was confirmed by measurement of transmural pH changes. Administration of vasopressin decreased subendocardial pH of the infused zone from 7.40 +/- 0.03 to 7.31 +/- 0.07 (p less than 0.01). The subendocardial pH of the zone not infused with vasopressin did not change. To overcome the intrinsic regulation of blood flow, operating primarily in small coronary arteries, we hypothesized that vasopressin must increase resistance primarily in large rather than small coronary arteries. After intracoronary infusion in group 3 (n = 6), however, most (94%) of the increase in resistance during vasopressin administration was explained by an increase of resistance in small coronary arteries. In group 4 (n = 9), vasopressin decreased coronary blood flow by 50% and decreased local shortening by 90% at a time when systemic hemodynamics were unchanged. Coronary constriction induced by vasopressin, or the recovery from it, also was not altered by cyclooxygenase blockade. CONCLUSIONS: Thus, vasopressin produces myocardial ischemia by constricting small, nondiseased coronary arteries severely enough to overcome the competition from normal coronary regulation, and this ischemic event is not mediated by prostaglandin products.

Animals↗