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Biomedical subjects

M Britton

Publications and source records attributed to M Britton.

At least 19 recordsLinked to original sources
PubMed1992

Cost effectiveness of primary stroke prevention in atrial fibrillation: Swedish national perspective.

OBJECTIVE: To assess the potential effects of primary prevention with anticoagulants or aspirin in atrial fibrillation on Swedish population. DESIGN: Analysis of cost effectiveness based on the following assumptions: about 83,000 people have atrial fibrillation in Sweden, of whom 22,000 would be potential candidates for treatment with anticoagulants and 55,000 for aspirin treatment; the annual 5% stroke rate is reduced by 64% (with anticoagulants) and 25% (with aspirin); incidence of intracranial haemorrhage of 0.3%, 1.3%, or 2.0% per year; direct and indirect costs of a stroke of Kr180,000 and Kr90,000; estimated annual cost of treatment is Kr5030 for anticoagulants and Kr100 for aspirin. SETTING: Total Swedish population. MAIN OUTCOME MEASURES: Direct and indirect costs of stroke saved, number of strokes prevented, and cost of preventive treatment. RESULTS: Depending on the rate of haemorrhagic complications 34 to 83 patients would need to be treated annually with anticoagulants to prevent one stroke; 83 patients would need to be treated with aspirin. Giving anticoagulant treatment only would reduce costs by Kr60 million if the incidence of intracranial haemorrhage were 0.3% but would imply a net expense if the complication rate exceeded 1.3%. The total savings from giving anticoagulant (22,000 patients) and aspirin (55,000 patients) treatment would be Kr175 million per year corresponding to 2 million pounds per million inhabitants each year. CONCLUSIONS: Treatment with anticoagulants and, if contraindications exist, with aspirin is cost effective provided that the risk of serious haemorrhage complications due to anticoagulants is kept low.

Aged↗
PubMed1992

Diet as a source of phospholipid esterified 9,11-octadecadienoic acid in humans.

1. Diene-conjugated fatty acids are one of the products of free-radical attack upon lipids and therefore have been used as markers of such attack. The major diene-conjugated fatty acid in human tissue and serum is an isomer of linoleic acid (9,12-octadecadienoic acid), namely 9,11-octadecadienoic acid. Diet may be another source of this isomer, raising questions as to its value as a free-radical marker. The aim of this study was to determine the importance of diet as a source of 9,11-octadecadienoic acid in phospholipid esterified fatty acids in human serum. 2. Foodstuffs rich in 9,11-octadecadienoic acid were identified. Fourteen subjects volunteered to alter their diets, either increasing ('high diet') or decreasing ('low diet') their intake of these foodstuffs for 3 weeks. Where subjects undertook both diets, a washout period of at least 3 weeks was allowed between phases. 3. Seven-day diet histories were kept and scored with respect to their content of 9,11-octadecadienoic acid. The concentrations of 9,11-octadecadienoic acid and linoleic acid in serum phospholipids were measured by h.p.l.c. with u.v. detection. 4. The percentage molar ratio of 9,11-octadecadienoic acid to linoleic acid was calculated. The percentage molar ratio rose significantly on the 'high diet' [1.3(0.4) versus 1.9(0.7), P = 0.01, mean (SD)] and fell significantly on the 'low diet' [1.6(0.4) versus 1.1(0.4), P = 0.004, means (SD)]. There was a significant correlation between the change in dietary intake of 9,11-octadecadienoic acid and the change in the percentage molar ratio (r = 0.829, P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Mortality and recurrences during eight years following stroke.

A total of 388 patients, of mean age 73 years, with acute cerebrovascular disease (CVD) evaluated in a non-intensive Stroke Unit, and a sample of 209 age- and sex-matched similarly acutely admitted patients with surgical diseases were followed up for 5-8 years. The CVD patients had a 21-day hospital mortality of 13%, and 66% mortality during the entire study period, compared to 2% and 48%, respectively, in controls. Old age had only a minor effect on the initial mortality. However, long-term mortality increased markedly with age. The initial mortality in 120 stroke recurrences was 50%. In CVD patients heart diseases were common causes of death, and circulatory diseases were most predominant of all (86%), with an accumulation during the first months after the occurrence of the initial CVD event. These figures clearly show that stroke patients constitute a group with high risk of stroke recurrence and death. Despite declining figures for stroke mortality, and most probably also for case fatality rate after first stroke episodes, much work remains to be done within the field of secondary prevention after stroke.

Adult↗
PubMed1992

Echocardiographic findings and the increased risk of stroke in nonvalvular atrial fibrillation.

We studied whether cardiac abnormalities contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation (NVAF). M-mode and 2D echocardiography were performed in four age- and gender-matched groups: 20 stroke patients with NVAF, 20 patients with NVAF who had not suffered a previous stroke, 20 stroke patients with sinus rhythm, and 40 healthy controls. Their mean age was 77 years. The two groups with atrial fibrillation differed from healthy controls in that they had more 2D-echocardiographic findings of severe left-ventricular-wall-motion abnormalities (p < 0.05) and tended more often to have enlarged left ventricles, and hypertrophic and congestive cardiomyopathy. Left atrial diameter was 47 mm compared to 41 and 39 mm in the two groups with sinus rhythm (p < 0.001). Intracardiac thrombi were only found in the two atrial-fibrillation groups (with stroke: 15% without stroke: 5%). Aortic sclerosis was common in all groups (30-60%), as was mitral annulus calcification (10-20%). The only significant difference between the two atrial-fibrillation groups was a higher frequency of earlier ischemic heart disease in the stroke group. Both atrial-fibrillation groups had cardiac abnormalities predisposing for embolic as well as thrombotic stroke.

Aged↗
PubMed1991

Wavelength dependence of pulsed laser ablation of calcified tissue.

Pulsed laser ablation of calcified biological tissue was studied at several wavelengths in the near-ultraviolet, visible, near- and mid-infrared regions of the spectrum. The primary tissue model was bovine shank bone, while human arterial calcified plaque and normal human artery wall were also studied at selected wavelengths for comparison. Laser irradiances were on the order of MW/mm2, fluences ranged up to 1000 mJ/mm2, and repetition rates varied between 0.3-10 Hz. Spot sizes on the tissue surface ranged from 150 to 850 microns. Laser craters made with wavelengths between lambda = 295 nm and lambda = 375 nm and in the lambda = 3 microns region exhibited the highest quality ablation with clean, sharp cuts following closely the spatial contour of the incident beam. Craters drilled with visible wavelengths between lambda = 450 nm and lambda = 590 nm were generally larger than the incident laser beam spot, irregular in shape and often surrounded by large flakes of tissue debris. Ablation fluence thresholds increased with wavelength through the visible wavelengths and into the mid-infrared, but dropped to their lowest values near lambda = 3 microns. Fluence thresholds obtained with the tissue under a 1 mm depth of saline were approximately twice air thresholds. Ablation yields also varied with wavelength, probably due to increased scattering in the visible region, and were the same under saline as in air.

Absorption↗
PubMed1991

Pathogenetic mechanism of stroke in non-valvular atrial fibrillation: follow-up of stroke patients with and without atrial fibrillation.

Stroke patients with brain infarction and non-valvular atrial fibrillation (NVAF, n = 88) or sinus rhythm (SR, n = 188), treated at a population-based stroke unit, were studied for 5 years. Within 1 month, 13% of NVAF and 2% of SR patients (P less than 0.01) had either a stroke recurrence or systemic embolism. After 5 years, the corresponding figures were 26 and 25%, respectively. The 1-month and 5-year mortality values were 35 and 78% in the NVAF group vs. 7 and 52% in the SR group (P less than 0.01). Age, ischaemic heart disease and function group on arrival at the hospital were independent risk factors for death. The main cause of death was ischaemic heart disease in the NVAF group, and complications to the initial stroke or a stroke recurrence in the SR group. Thus a higher risk of death, stroke recurrence and peripheral embolism was evident only during the first month after stroke.

Aged↗
PubMed1990

Coagulation factors and the increased risk of stroke in nonvalvular atrial fibrillation.

We studied whether hemostatic abnormalities contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation. Hemostatic function was studied in four age-matched groups: 20 patients with nonvalvular atrial fibrillation and a previous ischemic stroke, 20 patients with nonvalvular atrial fibrillation without a previous stroke, 20 stroke patients with sinus rhythm, and 40 healthy controls. Both groups with nonvalvular atrial fibrillation had significantly higher concentrations of von Willebrand factor, factor VIII:C, fibrinogen, D-dimer (a fibrinolytic product), beta-thromboglobulin, and platelet factor 4; a significantly higher fibrinogen/antithrombin ratio; and significantly higher spontaneous amidolytic activity than the healthy controls. Prekallikrein levels were significantly lower in both groups with nonvalvular atrial fibrillation. Stroke patients with sinus rhythm had normal hemostatic function, normal concentrations of platelet-related factors, and a slightly increased concentration of fibrinopeptide A compared with the healthy controls. Both groups with nonvalvular atrial fibrillation differed from the stroke patients with sinus rhythm as they did from the healthy controls. No difference in hemostatic function was seen between the nonvalvular atrial fibrillation patients with and without a previous ischemic stroke. Thus, alterations in hemostatic function may contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation.

Acute-Phase Reaction↗
PubMed1979

Sulindac in ankylosing spondylitis. Double-blind evaluation of sulindac and indomethacin.

Ankylosing spondylitis affects about 1% of the population. In the past, evaluation of therapy in the management of this disease has been hampered by the lack of availability of objective criteria for following the condition. By using recently developed measurements of spinal mobility and other variables we have compared sulindac, a recently introduced nonsteroidal antiinflammatory drug, and indomethacin in a double-blind six-month parallel study of 30 patients. Sulindac and indomethacin have comparable efficacy and tolerance. Advantages of sulindac include a twice-a-day dose regimen.

Double-Blind Method↗
PubMed1979

Arrhythmias in patients with acute cerebrovascular disease.

Cardiac disease is common in patients with cerebrovascular disease (CVD) and cerebral lesions as such may influence cardiac activity and rhythm. To study the indication for continuous ECG surveillance of patients with CVD, 100 consecutive patients admitted to a medical stroke unit were investigated with 24-hour Holter recordings. The patients' mean age was 73 years and 70% of them had a history of heart disease. Twenty-three patients had chronic atrial fibrillation and 55% of the remainder showed ventricular ectopic activity. Serious ventricular arrhythmias were comparatively rare and mainly seen in association with signs of congestive heart failure and acute myocardial infarction. A prolonged Q-T interval was registered in two-thirds of the patients but there was no significant association between this finding and ventricular ectopic activity. Close observation for cardiac complications is important in patients with CVD and continuous ECG surveillance is indicated in selected high-risk patients.

Aged↗
PubMed1979

A stroke unit in a medical department. Organization and the first 100 patients.

A non-intensive stroke unit of 10 beds has been started in the Medical Department, Serafimerlasarettet, Stockholm. The aim is to make diagnostic and therapeutic studies in unselected stroke patients. Patients with suspect cerebrovascular disease in the Casualty Department are admitted to the unit non-selectively and without any age limit. Relevant physical findings and laboratory data are followed and registered by code on special charts to make evaluation by computer possible. A preplanned investigative programme is adhered to. Strict criteria for diagnosis and treatment are followed. The experience and results from the first 100 patients treated in the Stroke Unit indicate that the unit is a good basis for both education and research.

Acute Disease↗