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Biomedical subjects

M Britton

Publications and source records attributed to M Britton.

At least 55 records · Page 3Linked to original sources
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

Do-not-resuscitate orders in Swedish medical wards.

In a nation-wide survey, procedures related to do-not-resuscitate (DNR) orders in Swedish medical wards were investigated by means of a questionnaire given to internists-in-charge. The response rate was 89% (286 out of 323), of whom all but 2% (seven individuals) stated that DNR orders were used in their wards. The most common procedure was an oral direction to the nurse, who documented the order in the nurses' day-to-day work sheet. The DNR orders were signed by 28% of the physicians. A wide range of symbols and code words were used, and there was considerable disagreement regarding the meaning of a DNR order. Such orders were often associated with withdrawal and withholding of life-sustaining treatments other than cardiopulmonary resuscitation. Most physicians stated that they never discuss DNR order with the patients, and that only in a minority of DNR decisions do they involve family members. There was considerable conflict with regard to DNR ordering procedures not only between internists in different hospitals, but also within individual hospitals.

Documentation↗
PubMed1990

Very high blood pressure in acute stroke.

In a study sample consisting of 388 unselected, consecutive acute stroke patients, 27 with systolic blood pressure greater than or equal to 200 mmHg and diastolic blood pressure greater than or equal to 115 mmHg were compared with the other 361 patients. The patients with high blood pressure were younger (65 vs. 73 years) and much more often had a history of hypertension (78 vs. 42%). Cardiac and vascular hypertensive manifestations were more frequent, particularly when only those patients with a history of hypertension were compared in the two groups. Alcohol abuse was mentioned in a higher proportion of hypertensives in the summaries of their medical records. No definite conclusions could be drawn with regard to the size and location of the brain lesions. Clinical symptoms did not differ between the groups, neither did the proportion of patients who could be discharged from hospital immediately. Mortality was higher in the high blood pressure group (30 vs. 14%, P less than 0.05). Thus the characteristics of patients with very high blood pressure were: younger age, much more frequent and severe previous hypertension. Alcohol abuse might be an important factor. The type, size and location of the brain lesion itself could not be statistically related to the high blood pressure, but very large lesions, particularly haemorrhages, might be associated with a reactive blood pressure response.

Age Factors↗
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↗
PubMed1988

The total cost of care and the use of pharmaceuticals in the management of rheumatoid arthritis: the Medi-Cal program.

Medicaid claims data were analyzed to investigate the prevalence and cost of rheumatoid arthritis (RA) in the Medi-Cal program. It was estimated that approximately 24,000 Medi-Cal recipients receive treatment for RA each year. The sample of Medi-Cal RAs studied averaged more than $2500 annually in total direct health care expenditures. The total cost of RA to Medi-Cal is projected to be $19.26 million (+/- $0.90 million) annually. Inclusion of possible gastrointestinal side effects of drug therapy increases the total cost to $20.49 million (+/- $0.91 million). While only 6.5% of the sample of RAs were hospitalized and 4.9% received nursing home care annually, these services are estimated to account for nearly 70% of RA-related expenditures. Less than 7% of Medi-Cal RAs receive disease modifying antirheumatic drugs (DMARDs). More than 75% of Medi-Cal RAs received aspirin or NSAIDs. These relieve pain and inflammation, but have not been demonstrated to halt the process of joint destruction.

Anti-Inflammatory Agents↗
PubMed1985

Circulatory manifestations and risk factors in patients with acute cerebrovascular disease and in matched controls.

The occurrence of various circulatory manifestations and risk factors was evaluated in a consecutive series of 209 patients admitted for acute cerebrovascular disease (CVD) and 209 control patients admitted for acute surgical disorders. Old and recent myocardial infarction, atrial fibrillation, congestive heart failure and reduced arterial blood pressure in the big toe were all much more frequently noted in CVD patients than in their matched controls. Hypertension, diabetes mellitus, overweight, high haemoglobin values, were also overrepresented in the CVD patients. Male CVD patients had a higher alcohol consumption than their controls. These findings implicate that CVD in old age is strongly related to both hypertension and a generalized atherosclerosis. The heavy accumulation of primary risk factors, many of which are considered to be primarily associated with atherosclerosis among elderly stroke victims, may indicate their contribution to a progressive atherosclerotic process still in operation.

Age Factors↗
PubMed1984

Platelet aggregation and plasma levels of acetylsalicylic acid in stroke patients on long-term treatment with an enteric-coated aspirin formulation.

Enteric-coated formulations of acetylsalicylic acid (ASA) should be advantageous in prophylaxis after stroke because they cause fewer gastrointestinal side effects. However, the absorption of unchanged ASA and the effectiveness of these formulations have been questioned, which prompted the present investigation. Fourteen elderly stroke patients on long-term medication with enteric-coated ASA 1.5 g daily and four patients on placebo were studied. When tested with arachidonic acid platelet aggregation was completely inhibited in all ASA subjects whereas it was normal in the controls. Plasma samples, drawn every 1/2 h for 6 h after tablet intake, were analyzed by HPLC. The presence of ASA was short lasting with a mean peak concentration of 55 mumol/l reached after 2-3.5 h. Salicylic acid (SA) appeared later, having a mean peak value of 591 mumol/l after 2.5-6 h. Thus, absorption of ASA as well as inhibition of platelet aggregation were confirmed during long-term medication with enteric-coated ASA.

Aged↗
PubMed1984

Diagnostic errors discovered by CT in patients with suspected stroke.

We assessed the frequency of stroke diagnostic errors revealed by CT in 197 patients. In five patients, CT was an emergency procedure. In the other 192 patients, CT was used to check diagnosis based on routine investigations. All but eight diagnoses (4%) were thereby confirmed. Either hemorrhage was discovered where an ischemic lesion had been suspected (2 cases) or the reverse (3 cases). Disorders other than stroke were found in three patients--subdural hematoma, hydrocephalus, and suspected tumor. Thus, few but important errors were revealed by the CT investigations.

Adult↗
PubMed1983

Prognosis in acute stroke with special reference to some cardiac factors.

Neurological assessments were done regularly during hospitalization in 283 consecutive patients (mean age 73 yr) with acute cerebrovascular disease treated at the Stroke Unit of Serafimerlasarettet. A preplanned investigation program and strict criteria for diagnosis and treatment were followed. Hospital mortality was 18%. Patients with a major cerebral infarction or haemorrhage often died very early during the hospital period and deaths due to complications increased significantly during the second week. Multivariate analysis regarding mortality showed that a low neurological score and heart failure were the most important factors for the short-term prognosis. In those patients with cerebral infarction, ambulatory capacity and ECG-diagnosed bundle branch block added significantly to the prognostic power of the neurological score. Among the 227 patients discharged alive, 1 and 2-yr mortality was 14 and 18% respectively. Here, the most important long-term prognostic factors were age and ST changes on the ECG. Again, considering only patients with cerebral infarction (N = 190), bundle branch block was found to be the single most useful predictive factor. Prognostication in acute ischemic stroke should thus be based not only on neurological findings but on careful evaluation of associated cardiac disease, especially in the long-term perspective.

Acute Disease↗