| 1. |
- Lindgren, Arne, et al.
(författare)
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Plasma homocysteine in the acute and convalescent phases after stroke
- 1995
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Ingår i: Stroke: a journal of cerebral circulation. - 1524-4628. ; 26:5, s. 795-800
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Stroke patients frequently manifest moderate hyperhomocysteinemia. In most published studies, plasma homocysteine was measured at least 1 month after stroke (or the interval was not reported). To determine whether plasma homocysteine concentrations change in the acute phase, we compared acute-phase values with both convalescent-phase and control values. METHODS: Plasma homocysteine concentrations were measured in the acute phase (mean, 2 days after stroke onset) in 162 first-ever stroke patients aged 50 years or more (median, 75 years) and again at a median interval of 583 days (range, 460 to 645 days) after stroke onset in a subgroup of 17 patients, with values for 60 age-matched subjects serving as controls. Twenty of the control subjects were reexamined 2 to 3 years after their initial examination. RESULTS: The median plasma homocysteine concentration was 13.4 mumol/L in the patient group compared with 13.8 mumol/L for control subjects (NS, Mann-Whitney U test) and increased from 11.4 mumol/L in the acute phase to 14.5 mumol/L in the convalescent phase in the subgroup of patients examined twice (P < .01, Wilcoxon signed rank test). In the 20 reexamined control subjects, no significant change over time in plasma homocysteine concentration was found. CONCLUSIONS: The post-acute-phase increase in plasma homocysteine may explain why higher values were obtained for stroke patients than for control subjects in previous studies. Possible reasons for the variation in plasma homocysteine concentrations over time are (1) an acute-phase reduction secondary to a decrease in plasma albumin and (2) an increase in plasma homocysteine during the convalescent phase due to modified vitamin intake and/or lifestyle. The timing of plasma homocysteine measurements relative to stroke onset is a factor to be considered in the interpretation of results.
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| 2. |
- Lindgren, Arne, et al.
(författare)
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Tissue plasminogen activator and plasminogen activator inhibitor-1 in stroke patients
- 1996
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Ingår i: Stroke: a journal of cerebral circulation. - 1524-4628. ; 27:6, s. 1066-1071
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Abnormal endogenous fibrinolytic activity may be a risk factor for stroke. Since the possible variation of tissue-type plasminogen activator (TPA) antigen and plasminogen activator inhibitor-1 (PAI-1) antigen concentrations over time after stroke has been rarely studied, it was examined in plasma from stroke patients in the acute and convalescent phases of the disease and in a control group. METHODS: Plasma concentrations of TPA and PAI-1 were determined in 135 stroke patients and in 77 control subjects. All but 4 patients were examined within 7 days after stroke onset, and 32 patients and 18 control subjects were reexamined 2 to 4 years later. RESULTS: In the acute phase, stroke patients had significantly higher TPA (median, 10 micrograms/L) and PAI-1 (median, 14 micrograms/L) antigen concentrations, compared with control subjects (median values, 6 micrograms/L [P = .0001] and 8 micrograms/L [P < .01], respectively); TPA levels were higher in both the cerebral infarction (n = 122) and cerebral hemorrhage (n = 12) subgroups, whereas PAI-1 levels were higher in the cerebral infarction subgroup only. Stepwise logistic regression analysis (with correction for age, sex, history of hypertension, diabetes mellitus, and heart disease) showed TPA antigen level to be an independent discriminator between the cerebral infarction subgroup and control subjects (P = .0001), whereas the corresponding difference for PAI-1 antigen levels just failed to reach significance (P = .05). TPA antigen levels were correlated with concentrations of serum cholesterol (Spearman's rho = 0.15; P < .05), serum triglyceride (rho = 0.33; P = .0001), and plasma homocysteine (rho = 0.19; P < .01). PAI-1 antigen levels were correlated with serum triglyceride levels only (rho = 0.41; P = .0001). At reexamination after 2 to 4 years, neither TPA nor PAI-1 levels had changed significantly from the baseline values. CONCLUSIONS: In stroke patients, high TPA antigen concentrations may indicate an activation of the fibrinolytic system or may be due to a delayed clearance of TPA complexed with inhibitors. High PAI-1 antigen concentrations in patients with cerebral infarction represent increased fibrinolytic inhibition. The findings in this longitudinal study suggest that TPA and PAI-1 antigen concentrations both differ little between the acute and convalescent phases after stroke.
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| 3. |
- Lindgren, Björn, et al.
(författare)
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Measurement and calculation of guide vane performance in expanding bends for wind-tunnels
- 1998
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Ingår i: Experiments in Fluids. - : Springer. - 0723-4864 .- 1432-1114. ; 24, s. 265-272
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Tidskriftsartikel (refereegranskat)abstract
- The design of guide vanes for use in expanding bends was investigated both experimentally and numerically. The primary application in mind is the use of expanding corners in wind-tunnels for the purpose of constructing compact circuits with low losses. To investigate the performance of guide vanes in realistic situations expansion ratios between 1 and 3 were tested in the experiments. These were carried out in an open wind-tunnel specially built for the present purpose. The experimental results demonstrated that suitably designed guide vanes give very low losses and retained flow quality even for quite substantial expansion ratios. For wind-tunnel applications expansion ratios around 1.3 seem appropriate, Optimization of a guide vane design was done using a two-dimensional cascade code, Mises. A new vane optimized for an expansion ratio of 4/3 gave a two-dimensional total pressure-loss coefficient as low as 0.041 for a chord Reynolds number of 200,000.
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| 4. |
- Lindgren, Stefan, et al.
(författare)
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Immunsvar och inflammation vid Crohns sjukdom. Snart mojligt driva diagnostiken langre och utveckla mer specifika lakemedel
- 1999
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Ingår i: Läkartidningen. - 1652-7518. ; 96:1-2, s. 52-55
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Tidskriftsartikel (refereegranskat)abstract
- The chronic inflammation in Crohn's disease may be caused by aggressive response to bacterial antigens normal to the gut. Genetic and environmental factors modify the inflammatory response evoked by damage to the mucosal gut barrier. Genetic factors may also determine the subsequent course of chronic inflammation. Further elucidation of the pathogenesis might improve our understanding of the heterogenous nature of Crohn's disease, thus enabling the disease to be subtyped and individualised therapy directed primarily at down-regulation of helper T-cell-1 response to be developed.
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| 5. |
- Merlo, Juan, et al.
(författare)
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Utilization of cardiovascular drugs (blood pressure lowering drugs, lipid lowering drugs and nitrates) and mortality from ischaemic heart disease and stroke. An ecological analysis based on Sweden's municipalities
- 1999
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 1432-1041 .- 0031-6970. ; 55:1, s. 69-76
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To perform an ecological study in an effort to generate questions concerning the preventive impact of various cardiovascular drugs on mortality from stroke and ischaemic heart disease (IHD) in the community, and to explore the association between sales of nitrates and mortality from stroke and IHD. METHODS: Out-patient drug utilization (sales) of blood pressure lowering drugs, lipid lowering drugs and nitrates were categorized in four groups of equal size by quartiles and compared with mortality from IHD and stroke, using the group of municipalities with the lowest utilization as reference, from 1989 to 1993 in 283 of Sweden's 288 municipalities, by Poisson regression. Adjustments were made for population size, age and gender proportions, the utilization rate of cardiovascular drugs other than the tested drug group and location of the municipality. RESULTS: Compared with the group of municipalities with the lowest sales and adjusting only for population size, mortality from IHD and stroke increased with the extent of utilization of blood pressure lowering drugs and nitrates. In contrast, mortality decreased with increased utilization of lipid lowering drugs. After further adjustments by percentage of men, age structure, geographical location (mid-points) of the municipalities, and, as a proxy for cardiovascular disease, the sales of cardiovascular drugs other than the tested drug group, the increased risk associated with blood pressure lowering drugs disappeared, and there was a dose-response association between sales of diuretics and old antihypertensives and decreasing mortality, sales of nitrates continued to be associated with an increased risk, and the low mortality risk associated with sales of lipid lowering drugs persisted. CONCLUSION: Lipid lowering drugs may have a preventive impact in the general population, but the preventive impact of blood pressure lowering drugs, with the exception of diuretics and old antihypertensives, may be low in many municipalities. The safety of nitrates needs more investigation at the individual level.
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| 6. |
- Roijer, Anders, et al.
(författare)
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Cardiac changes in stroke patients and controls evaluated with transoesophageal echocardiography
- 1997
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 31:6, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- In stroke patients several cardiac changes associated with embolism can be detected with transoesophageal echocardiography. Potential major cardiac embolic sources (e.g. atrial fibrillation, thrombi of left ventricle/atrium, vegetation, myxoma, dilated cardiomyopathy) have a causal relationship to embolism. Other changes with no certain causal relationship are regarded as potential minor cardiac embolic sources (e.g. atrial septal aneurysm, patent foramen ovale, mitral annular calcification, mitral valve prolapse, protruding atheroma of the aorta). We compared the prevalences of major and minor potential cardiac embolic sources in a stroke population with that in controls. One hundred and twenty-one patients with first-ever stroke were compared with 68 randomly selected controls. All subjects underwent magnetic resonance imaging of the brain, carotid ultrasound and transthoracic/transoesophageal echocardiography. The patients were slightly older (mean age 70.7 +/- 10.3 years) than the controls (65.5 +/- 15.5 years) (p < 0.05). Potential major cardiac embolic sources were found in 27% of the patients and in 4% of the controls (p < 0.001). The most common major potential embolic source was atrial fibrillation, detected in 22/121 patients. Fifteen of these also had spontaneous echocontrast in the left atrium. Eleven left atrial thrombi were found (four of these patients had atrial fibrillation and seven had sinus rhythm). A history of heart disease was more common in patients with a potential major cardiac embolic source or a carotid artery stenosis (77%) than in those patients without (44%) (p < 0.01). After excluding subjects with a major potential cardiac embolic source and/or carotid artery stenosis, no differences in the prevalence of minor potential cardiac embolic sources were found between patients (55%) and control subjects (47%) (p = NS). Even when subjects without a major potential cardiac embolic source or a carotid artery stenosis were categorized into three age groups (35-54, 55-74 and > 74 years) the prevalence of potential minor cardiac embolic sources did not differ between patients and controls. To conclude, major potential cardiac embolic sources are more common in an older population with first-ever stroke than in a comparable control group. However, potential minor cardiac embolic sources did not differ in prevalence in the patients compared with controls. Certain changes (e.g. atrial septal aneurysm) might have a potential embolic role in younger stroke patients but in our study no difference was found between older stroke patients and controls.
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| 7. |
- Roijer, Anders, et al.
(författare)
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Potential cardioembolic sources in an elderly population without stroke. A transthoracic and transoesophageal echocardiographic study in randomly selected volunteers
- 1996
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Ingår i: European Heart Journal. - 1522-9645. ; 17:7, s. 1103-1111
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Tidskriftsartikel (refereegranskat)abstract
- Transoesophageal echocardiography renders a better image than transthoracic echocardiography of cardiac changes especially at the atrial level, and of atherosclerotic changes in the aorta. Although several studies on stroke patients have included transthoracic and transoesophageal echocardiography, the relevance of the reported findings remains unclear because of limited information on the prevalence of cardiac changes related to cardioembolism in a control population without stroke. In order to define a non-hospitalized group of volunteers without previous stroke or transient ischaemic attack, we randomly selected a group of 68 volunteers (mean age 65.4 years). These volunteers were divided into two groups: the elderly group, 65 years or older (n = 38) and the younger group, younger than 65 years (n = 30). The subjects underwent transthoracic and transoesophageal echocardiography, sonography of the carotid arteries, and magnetic resonance imaging of the brain. The prevalences of atrial septal aneurysm, patent foramen ovale, mitral annulus calcification, and protruding plaque in the aorta were investigated. We found atrial septal aneurysm in 13%, patent foramen ovale in 22%, protruding plaque in the aorta in 7%, and mitral annular calcification in 22% of the 68 subjects. No significant differences were found between the two age groups with the exception of mitral annular calcification, which was seen more often in the older group (P < 0.001). Total cardiac changes related to thromboembolism (including three cases with atrial fibrillation in the older group and other less common cardiac embolic sources) were more common in the older than in the younger group (23/38 vs 9/30; P < 0.05). If mitral annular calcification was excluded, no difference was found between the elderly and the younger group, 14/38 vs 8/30; ns. Even when subjects with a history of heart disease or a pathological ECG were omitted, no differences between the two age groups were found. The causal relationship between a possible embolic source and a clinical embolic event remains unsettled. The high prevalence of cardiac changes in a control population has to be considered when evaluating the significance of similar findings in patients with stroke.
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| 8. |
- Wirestam, Ronnie, et al.
(författare)
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The perfusion fraction in volunteers and in patients with ischaemic stroke
- 1997
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Ingår i: Acta Radiologica. - 1600-0455. ; 38:6, s. 961-964
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Tidskriftsartikel (refereegranskat)abstract
- The fractional volume of capillary blood, i.e. the perfusion fraction f, was measured with the aid of an echo-planar imaging protocol originally designed for the measurement of water diffusion. In healthy volunteers, reasonable f values were obtained. In patients with cerebral ischaemic stroke, a marked decrease in the f value was seen in the infarcted region as compared with corresponding values in the contralateral hemisphere. We suggest that perfusion-fraction measurements may add to the diagnostic value of water-mobility examinations in patients with ischaemic disease.
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