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Biomedical subjects

G Boysen

Publications and source records attributed to G Boysen.

At least 91 records · Page 5Linked to original sources
PubMed1993

Risk factors for stroke in Copenhagen, Denmark. I. Basic demographic and social factors.

The Copenhagen City Heart Study is a prospective study based on a randomly selected sample of an urban population of, initially, 19,698 participants followed since 1976. Risk factor analysis was based on the initial examination of 13,000 persons > or = 35 years old without previous stroke who responded to the first invitation. In the period 1976-1988, 696 initial cases were identified: 584 strokes, 106 transient ischemic attacks and 6 retinal-artery occlusions. We used the regression model of Cox based on a hierarchic system of risk factors that indicated the way they influence each other. This method distinguishes independent risk factors and estimates their causal influences on the risk of stroke. Among the basic variables analyzed in this paper, significant effects were found for age, sex, length of school education and income. There was a tendency for living alone to be a risk factor as opposed to living with someone, while no influence could be demonstrated for family history of stroke.

Adult↗
PubMed1993

Risk factors for stroke in Copenhagen, Denmark. II. Life-style factors.

The objective of the present work was to identify independent life-style factors for stroke and to estimate their causal contribution. The study is based on a random sample of the Copenhagen population selected in 1976 and stratified by age. The present analysis includes 12,961 subjects examined initially, aged 35 or over and without a previous cerebrovascular event, for whom information about life-style factors was recorded between 1976 and 1978. The outcome was the first-in-life stroke or transient ischemic attack during 12 years of follow-up. The events were ascertained at a second examination 5 years later and from hospital records and death certificates through 1988. Cox's regression model was used to estimate the effect on stroke risk of the factors recorded. In the period 1976-1988, 693 initial events were recorded in eligible responders. Among the life-style factors analyzed, a significant, independent effect was found for cigarette smoking, daily consumption of sleeping pills or tranquilizers and body mass index (BMI). There was a tendency for daily alcohol intake to be associated with lower risk, this could not be demonstrated for physical activity at leisure time. Among smokers, stroke risk was influenced by the number of cigarettes smoked, and daily alcohol intake was associated with a significantly lower risk. The effect of smoking decreased with age. BMI in smokers still had a significant effect on stroke risk but neither daily consumption of tranquilizers, nor physical inactivity at leisure time had a significant influence.

Adult↗
PubMed1993

Anticoagulation for atrial fibrillation and stroke prevention.

Nonvalvular atrial fibrillation (NVAF) has a prevalence of about 1% in the 60- to 70-year age group, increasing to above 4% in persons older than 80 years. The yearly stroke incidence in NVAF patients is 3-8%, which is 5-7 times higher than that in age-matched persons in sinus rhythm. In five independent studies of stroke prevention in NVAF patients, anticoagulation therapy resulted in a risk reduction of stroke of about 65%. The risk of intracerebral hemorrhage was 0.3% per year during warfarin therapy compared with 0.1% in the placebo group. In one study aspirin reduced the risk of thromboembolic events by 42% while another study found a nonsignificant effect of aspirin. The following variables were identified as risk factors for stroke in the individual studies: prior myocardial infarction, increasing age, mitral annular calcification, history of hypertension, congestive heart failure and previous arterial thromboembolism. A pooled analysis of risk factors in the placebo-treated patients of the five studies is ongoing.

Age Factors↗
PubMed1993

Thrombolytic therapy in acute ischemic stroke. A Danish pilot study.

BACKGROUND AND PURPOSE: In a feasibility and safety study of thrombolytic therapy in acute ischemic stroke, we explored the usefulness of measurements of regional cerebral blood flow. METHODS: Twenty-three patients with acute ischemic stroke were treated with 100 mg recombinant tissue plasminogen activator infused intravenously over 1 hour. Thrombolytic therapy was initiated 78 to 355 minutes after onset of symptoms. RESULTS: Angiography 16 to 24 hours after treatment in 17 patients showed patient intracranial arteries in 12, partial occlusion of the middle cerebral artery in 3, and total occlusion of the middle cerebral artery in 2. rCBF with 99mTc-hexamethylpropyleneamine oxime intravenously was measured 5 minutes before and within 24 hours after thrombolytic therapy in 12 patients. 10 of the 12 patients showed brain tissue reperfusion and 2, with angiographically documented middle cerebral artery occlusion, showed no reperfusion, thus documenting a relationship between reperfusion measured by regional cerebral blood flow and angiographic patency (P = .015). Three patients died. Patients who were reperfused within 24 hours (documented by repeated regional cerebral blood flow measurements) showed greater clinical improvement on the Scandinavian Stroke Scale the sooner their thrombolytic therapy was started and the more severe their neurological deficits. CONCLUSIONS: Acute cerebral ischemia can be documented by rCBF measurements without delay of thrombolytic therapy, and repeated rCBF measurements can reveal whether cerebral reperfusion has occurred. In our study, early reperfusion was associated with clinical improvement.

Adult↗
PubMed1993

Lifestyle factors and risk of cerebrovascular disease in women. The Copenhagen City Heart Study.

BACKGROUND AND PURPOSE: The purpose of the present analysis was to determine how lifestyle influences the risk of cerebrovascular disease in women participating in the Copenhagen City Heart Study. METHODS: A random sample of a white, lower and middle-class, urban population selected in 1976 was invited to two cardiovascular examinations at 5-year intervals. The present analysis was based on 7060 women invited to an initial examination from 1976 through 1978, aged 35 years or more, and without previous stroke or transient ischemic attack. At the initial examination, potential risk factors were recorded. The 265 first cases of stroke and transient ischemic attack were ascertained at a second examination 5 years later and through hospital records and death certificates through 1988. The Cox regression model was used to estimate the influence of the factors recorded on the risk of cerebrovascular disease. RESULTS: The relative risks of cigarette smoking and lack of physical activity were 1.4 and 1.45; 95% confidence limits, 1.02 to 1.94 and 1.01 to 2.08, respectively). The relative risk of daily consumption of tranquilizers was 1.25 (95% confidence limits, 0.96 to 1.62). No significant influence was found for number of cigarettes, body mass index, or alcohol intake. In postmenopausal women, there was a statistically significant interaction (P < .041) between smoking and hormone replacement therapy. Smokers receiving this therapy had a 28% lower risk of cerebrovascular disease than smokers not receiving it. CONCLUSIONS: The statistically significant and equally potent effects on the risk of cerebrovascular disease were found for cigarette smoking and lack of physical activity. The risk associated with smoking seemed to be influenced by hormonal replacement therapy.

Adult↗
PubMed1993

Neuroprotection by excitatory amino acid antagonist augments the benefit of thrombolysis in embolic stroke in rats.

BACKGROUND AND PURPOSE: The effects of delayed thrombolysis with alteplase and neuroprotection with an excitatory amino acid receptor antagonist and their combination were tested in an embolic stroke model. METHODS: In 61 rats the carotid artery territory was embolized with arterial-like fibrin-rich clots. Hemispheric cerebral blood flow before and after embolization was measured by intra-arterial 133Xe injection method. The animals were assigned to one of the following treatments: (1) vehicle-treated controls (n = 15); (2) dizocilpine 1 mg/kg i.v. 5 minutes after embolization (n = 16); (3) alteplase 20 mg/kg as an intravenous continuous infusion starting 2 hours after embolization (n = 16); and (4) both agents (n = 14). Carotid angiography displayed the site of occlusion of the cerebral arterial tree immediately after and 3 hours after embolization, and the clinical neurological score was assessed after the rats recovered from anesthesia and before the rats were killed. Brains were fixed after 2 days and evaluated neuropathologically; infarct volume affecting cortical and deep brain structures was measured separately. RESULTS: Both alteplase and dizocilpine reduced the total infarct volume (P = .05 and P = .04, respectively, Mann-Whitney tests). Dizocilpine reduced the incidence of cortical infarctions by 48% (P < .001, Fisher's test). Only the combined treatment significantly reduced deep brain infarctions (P = .03, Mann-Whitney test). The combined treatment also improved the clinical score by 83% compared with controls, by 75% compared with the group treated by dizocilpine alone, and by 50% compared with the group treated by alteplase alone. Sixty-seven percent of thrombolytic-treated animals recanalized completely compared with 39% of those given no thrombolytics (P = .05, Fisher's test). The clinical outcome correlated with infarct size (P < .01, Spearman test). CONCLUSIONS: Our results document comparable efficacy of delayed thrombolysis and excitatory amino acid receptor antagonism in this model and suggest that combination of these two therapeutic approaches may yield additional benefit in treatment of thromboembolic stroke, particularly in cases where deep brain (end-artery-supplied) structures are affected.

Animals↗
PubMed1993

Reduction of infarct volume by thrombolysis with rt-PA in an embolic rat stroke model.

Thrombolytic therapy with recombinant tissue plasminogen activator was tested in an embolic stroke model. In rats the internal carotid territory was embolized through the internal carotid artery with 50 microliters thrombin-rich (n = 18), 50 microliters thrombin-poor (n = 17) and 20 microliters thrombin poor (n = 13) suspension of arterial-like microthrombi formed under pressure. Hemispheric cerebral blood flow before and after embolization was measured by intra-arterial 133Xe injection method. Fifteen minutes after embolization 19 animals were treated with tissue plasminogen activator 20 mg kg-1, and 22 animals with saline. Carotid angiography displayed the degree of occlusion of the cerebral arterial supply before and after treatment. Brains were evaluated neuropathologically and infarct volume measured. Cerebral blood flow was reduced 72% after embolization with 50 microliters emboli suspension and 32% after embolization with 20 microliters suspension. The comparison of pre- and post-treatment angiography showed some recanalization in the treated animals, control animals had no recanalization. Thrombolytic therapy reduced the infarct volume from 72.8% to 20.9% of embolized hemisphere volume (p = 0.0037) in the 50-microliters thrombin rich-embolized group, from 22.9 to 9.0 (NS) in the 50-microliters-thrombin-poor-embolized group and from 6.6 to 0.0 (NS) in the 20-microliters-embolized group. One third of treated animals recanalized completely and developed smaller (p = 0.03) infarcts than the non-recanalized. No hemorrhagic complications were observed. Early thrombolytic therapy reduced infarct volume after embolic stroke in this model, this effect was dependent upon recanalization.

Animals↗
PubMed1993

Alteplase therapy in acute ischemic stroke: a Danish pilot study.OFF.

In the period from October 1990 to December 1991, 23 patients with acute ischemic stroke were treated with recombinant tissue plasminogen activator (rt-PA) at a median of 205 min (range 78-355 min) after symptom onset. In this open pilot study rt-PA was given intravenously after an acute CT scan had not shown acute changes. In 12 patients regional cerebral blood flow was measured intravenously using 99mTc-HMPAO before and within 24 h after thrombolytic therapy. Reperfusion of the ischemic area was obtained in 10 patients. In these patients clinical improvement was greater the shorter the delay from symptom onset to initiation of treatment. Three of the 23 patients died, one of a parenchymatous hematoma, one of a large middle cerebral artery infarct, and one of acute myocardial infarction.

Cerebral Infarction↗
PubMed1993

[Apoplexy--the acute stage].

This review concerns the acute phase of stroke. It describes incidence, prevalence, etiology, diagnosis and treatment together with the possibilities for prevention. The incidence of stroke in the Danish population is about 2/1000 person years and has been largely unchanged during the last 20 years. About 85 per cent of strokes are caused by cerebral infarcts, ten percent by intracerebral haemorrhages and about five per cent by subarachnoid bleeding. The incidence increases with age. Up till age 65 years the ratio between men and women is two to one, while the ratio in the oldest age group approaches one to one. The most important risk factors for stroke are smoking, arterial hypertension, previous cerebrovascular disease, heart disease and diabetes mellitus. Till now, no treatment has been documented as effective in reducing the cerebral damage caused by acute stroke. Ongoing controlled clinical trials in the acute state of ischaemic stroke are testing the effect of thrombolytic therapy, treatment with calcium antagonists, glutamate receptor antagonists, aspirin and heparin. The general medical treatment including nursing and physiotherapy in the acute phase is described. Within recent years benefit of various strategies of stroke prevention has been documented.

Acute Disease↗
PubMed1992

Focal reductions of cerebral blood flow in amyotrophic lateral sclerosis: a [99mTc]-d,l-HMPAO SPECT study.

We investigated regional cerebral blood flow (rCBF) using the [99mTc]-d,l-HMPAO technique with brain dedicated high resolution single photon emission computer tomography (SPECT) in 14 consecutive patients with amyotrophic lateral sclerosis (ALS), median age 62 years (45-77). Global CBF, expressed in % relative to the cerebellum, was significantly lower (P less than 0.05) in the ALS group (80.5 +/- 6.7%) than in the control group of 14 age-matched healthy volunteers (87.0 +/- 7.5%). Eight patients (57%) had abnormal rCBF distribution maps with reduced flow, primarily in the frontal lobes. Three of the 8 patients with abnormal rCBF had mild to moderate dementia and another one had mild aphasia. None of the patients with normal rCBF distribution maps had dementia. In the group of ALS patients as a whole rCBF was significantly reduced in the frontal cortex, the hippocampus, and the central white matter. We conclude that reduced rCBF, primarily in the frontal lobes, is a frequent finding in patients with ALS. The decreased rCBF may be associated with cognitive deficits and is most likely caused by neuronal degeneration and reduced metabolic needs.

Aged↗
PubMed1992

A rat model of reproducible cerebral infarction using thrombotic blood clot emboli.

The purpose of this study was the development of a model of embolic stroke with high reproducibility concerning infarct volume. In 37 male Sprague-Dawley rats, the internal carotid artery was embolized with in vitro preformed suspensions of autologous microemboli resembling arterial thrombi. With a method of continuous flow through the carotid arterial catheter, reflux of blood with uncontrolled clotting and embolization was avoided, thereby providing control animals free of ischemic damage. The embolized animals had arterial occlusions on angiograms immediately after embolization and no spontaneous recanalization on angiograms 2 h later. The cerebral blood flow measured by the intra-arterial 133Xe injection method decreased to 21-37% of baseline values. All embolized animals developed hemiparesis with spontaneous circling behavior, embolization with more than 150 microliters clot suspension resulted in hemispherical infarcts. There was a strong statistically significant correlation between amount of emboli, rate of vascular occlusion, and volume of infarcted tissue. This is the first model presented utilizing autologous in vitro microemboli imitating "white" arterial thrombi. The animals developed infarction, resembling human stroke.

Angiography↗
PubMed1992

Gelsolin-derived familial amyloidosis caused by asparagine or tyrosine substitution for aspartic acid at residue 187.

Dominantly inherited familial amyloidosis, Finnish type (FAF) is caused by the accumulation of a 71-amino acid amyloidogenic fragment of mutant gelsolin (GSN). FAF is common in Finland but is very rare elsewhere. In Finland and in two American families, the mutation is a G654A transition leading to an Asp to Asn substitution at residue 187. We found the same mutation in a Dutch family but a Danish FAF family had a G654T mutation, predicting Asp to Tyr at residue 187. We also found the G654T transversion in a Czech family. Using GSN polymorphisms, different haplotypes were found in the Danish and Czech families. We conclude that substitution of the uncharged Asn or Tyr for the acidic Asp at residue 187 creates a conformation that may be preferentially amyloidogenic for GSN.

Alleles↗
PubMed1992

Dose-response of rt-PA and its combination with aspirin in a rat embolic stroke model.

The efficacy and safety of thrombolysis with different dose regimens of recombinant tissue plasminogen activator (rt-PA) and its combination with aspirin was tested in an embolic stroke model. In rats the carotid territory was embolized with a single clot formed in a polyethylene tube and washed with saline. Fifteen minutes after embolization 10 animals were treated with rt-PA 10 mg kg-1; 11 with 15 mg kg-1; 12 with 20 mg kg-1 and 9 with 10 mg kg-1 + 20 mg kg-1 aspirin and 34 animals with saline. Rt-PA 10 mg kg-1 reduced median infarct volume (in percent of the ipsilateral hemisphere volume) from 19.5 to 4.8; rt-PA 15 mg kg-1 to 2.0; rt-PA 20 mg kg-1 to 0.0, while rt-PA 10 mg kg-1 + aspirin resulted in a median infarct volume of 9.5%. Thrombolytic therapy significantly and dose dependently (p = 0.001) reduced the infarct volume, improved the presacrifice clinical score and increased (p = 0.02) angiographically verified reperfusion. There was no additional benefit of coadministration of aspirin.

Animals↗
PubMed1992

Stroke incidence in Copenhagen, 1976-1988.

BACKGROUND AND PURPOSE: Temporal trends in stroke incidence in Denmark have not been previously reported. The Copenhagen City Heart Study is a prospective study based on a randomly selected sample of an urban population of, initially, 19,698 participants followed since 1976. Over a period of 12 years, we studied three important aspects of stroke incidence in 848 identified cases: temporal trends, dependence on age and sex, and comparison of responders and nonresponders. METHODS: The participants were invited to two health examinations at 5-year intervals. The participants who attended at least one of the two examinations are termed responders and those who attended none nonresponders. The cases of first-ever stroke were collected from responders, the National Patient Register, and the National Register of Deaths and were verified by study of hospital records and death certificates. RESULTS: For responders aged 35-64 years and greater than or equal to 65 years, there were no significant changes in the weighted rates in four consecutive 3-year periods. There was a tendency toward decreasing rates among younger women, but not in older women or men. The age- and sex-adjusted rates per 1,000 (based on the Danish population in 1982) in responders in the entire 12-year follow-up period were 1.61 in women, 2.67 in men, and 2.14 in both sexes combined. Stroke incidence rates increased exponentially with age in both sexes, with rates in men generally twice those in women, even in the greater than or equal to 75 years of age group. Age-adjusted rates were higher in nonresponders than in responders. For women, this ratio was 1.7; for men, 1.1. CONCLUSIONS: The stroke incidence in Copenhagen is relatively high and has shown no decreasing tendency over the period 1976-1988.

Adult↗