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Biomedical subjects

G Boysen

Publications and source records attributed to G Boysen.

At least 127 records · Page 7Linked to original sources
PubMed1989

Hemodilution increases cerebral blood flow in acute ischemic stroke.

We measured cerebral blood flow in 10 consecutive, but selected, patients with acute ischemic stroke (less than 48 hours after onset) before and after hemodilution. Cerebral blood flow was measured by xenon-133 inhalation and emission tomography, and only patients with focal hypoperfusion in clinically relevant areas were included. Hemodilution was done according to the hematocrit level: for a hematocrit greater than or equal to 42%, 500 ml whole blood was drawn and replaced by the same volume of dextran 40; for a hematocrit between 37% and 42%, only 250 ml whole blood was drawn and replaced by 500 cc of dextran 40. Mean hematocrit was reduced by 16%, from 46 +/- 5% (SD) to 39 +/- 5% (SD) (p less than 0.001). Cerebral blood flow increased in both hemispheres by an average of 20.9% (p less than 0.001). Regional cerebral blood flow increased in the ischemic areas in all cases, on an average of 21.4 +/- 12.0% (SD) (p less than 0.001). In three patients, a significant redistribution of flow in favor of the hypoperfused areas was observed, and in six patients, the fractional cerebral blood flow increase in the hypoperfused areas was of the same magnitude as in the remainder of the brain. In the last patient, cerebral blood flow increased relatively less in the ischemic areas. Our findings show that cerebral blood flow increases in the ischemic areas after hemodilution therapy in stroke patients. The marked regional cerebral blood flow increase seen in some patients could imply an improved oxygen delivery to the ischemic tissue.

Acute Disease↗
PubMed1988

Inhibition of platelet function by low-dose plain and micro-encapsulated acetylsalicylic acid.

The effect of two acetylsalicylic acid (ASA) formulations, plain (Magnyl) and micro-encapsulated (Globentyl), on platelet aggregation, thromboxane formation, and bleeding time was studied in 12 healthy volunteers in a randomized double-blind cross-over study. All subjects were treated with Magnyl and Globentyl (75 mg daily) in periods of 2 weeks, separated by a wash-out period of 2 weeks. Both drugs significantly depressed platelet aggregation and thromboxane formation and prolonged bleeding time without difference in mode of action of the drugs. It is concluded that significant inhibition of platelet activity may be achieved by low-dose ASA treatment with micro-encapsulated as well as with plain formulations.

Adult↗
PubMed1988

Postoperative cerebrovascular accidents in general surgery.

In a prospective study of postoperative complications, strokes occurred in 6 out of 2463 patients (0.2%) who underwent non-cardiac, non-carotid artery surgery. The patients who experienced cerebrovascular accidents, including three cases of transient ischemic attack, were significantly older than the rest of the group (mean age 79 years versus 65 years) and had manifestations of atherosclerosis in at least one organ preoperatively. Significant predictors of risk for postoperative cerebrovascular accidents were previous cerebrovascular disease, heart disease, peripheral vascular disease, and hypertension. Cerebrovascular accidents occurred late in the postoperative period, 5-26 days after surgery, and were not directly related to surgery and anesthesia. They were more frequent after acute than after elective operations. Precipitating factors for some of the stroke incidents were rapid atrial fibrillation and postoperative dehydration.

Adult↗
PubMed1988

Danish very-low-dose aspirin after carotid endarterectomy trial.

The effect of very-low-dose aspirin as an antithrombotic agent was evaluated blindly in 301 patients who had recently undergone carotid endarterectomy. After randomization, 150 patients received aspirin and 151 received placebo. The two groups were comparable with regard to age, sex, blood pressure, previous cerebrovascular events, and smoking habits. The effect of the study medication on platelet aggregation was measured twice in each patient during the first 2 months and at each follow-up visit; the dose was individually adjusted. In 76% of the patients receiving aspirin, 50 mg/day gave satisfactory platelet inhibition, 13% needed 60 mg/day, 8% needed 70 mg/day, and 3% needed 100 mg/day. Platelet aggregation was found to be inhibited in only 1.2% of the measurements in the patients receiving placebo. Observation during treatment averaged 21 months; total intention-to-treat follow-up averaged 25 months. For the combined outcome events of transient ischemic attack, stroke, acute myocardial infarction, and vascular death, aspirin reduced risk by 11% (95% confidence limits: -38% to 48%, p greater than 0.1). Thus, there was no significant effect of very-low-dose aspirin in our trial.

Aspirin↗
PubMed1988

Stroke incidence and risk factors for stroke in Copenhagen, Denmark.

Stroke incidence in Copenhagen, Denmark was recorded in a random population sample of 19,327 persons invited for two health examinations with 5 years' interval from 1976 to 1983. Stroke incidence increased exponentially with age. After adjustment to the age and sex distribution of the Danish population in 1980, the estimated incidence of first stroke was 1.41/1000 women and 2.48/1000 men; the total incidence was 1.94/1000 population. Risk factor analysis was based on the initial examination of 13,088 persons greater than 35 years old without previous stroke who responded to the first invitation, in whom 295 first strokes were subsequently observed. We used the regression model of Cox. However, our use of this model differs from the somewhat automatic procedures normally used to develop prognostic models. Evaluation of the causative effect of a particular risk factor requires that the direction of mutual influences between the factor in question and other risk factors is established/postulated. Among the 16 potential risk factors for stroke we examined, significant effects were found for age, sex, household income, smoking habits, systolic blood pressure, diabetes, plasma cholesterol concentration, ischemic heart disease, and atrial fibrillation. No significant effect could be demonstrated for a positive family history of stroke, years of school education, marital status, alcohol consumption, daily use of tranquilizers, body mass index, or postmenopausal hormone treatment.

Adult↗
PubMed1987

Evaluation of the regional cerebral vasodilatory capacity before carotid endarterectomy by the acetazolamide test.

To estimate the regional perfusion pressure and possibly the stump pressure during carotid endarterectomy, cerebral blood flow (CBF) measurements including a vasodilatory test were performed preoperatively. CBF was measured by 133Xe inhalation and emission tomography. An intravenous dose of 1g acetazolamide (Diamox) was used as cerebral vasodilator. Thirty-six patients with a clinical history of previous strokes (9 cases) or transient ischaemic attacks (27 cases) were studied. Nine of the patients showed occlusion of the contralateral internal carotid artery (ICA). The percent flow increase induced by Diamox in the ipsilateral hemisphere correlated to the ICA pressure was measured before clamping (n = 32, r = 0.55, p less than 0.001). In 12 of the 36 patients, Diamox caused a significant change in the flow distribution indicating a restricted regional vasodilatory capacity and a reduced regional perfusion pressure. In addition, these 12 patients showed a low stump pressure (less than 50 mmHg). However, 8 additional patients had uniform CBF increases at the Diamox test, but showed low stump pressures. It is concluded, that preoperative tests of the cerebral vasodilational capacity can be used to identify most patients with a low ICA pressure, and a substantial fraction of patients that will develop a low stump pressure upon ICA clamping during operation. In these patients with abnormal Diamox tests surgical reconstruction is particularly indicated, but, at the same time the perioperative risks are presumably highest in this group.

Acetazolamide↗
PubMed1987

Abnormalities in spinal neurons and dorsal root ganglion cells in Tangier disease presenting with a syringomyelia-like syndrome.

A woman with homozygous Tangier disease had progressive syringomyelia-like neuropathy. She died with cardiac failure at age 61. A sural nerve biopsy taken at age 60 had shown lipid storage in Schwann and interstitial cells, and a pronounced loss of unmyelinated fibers. The neurons of the L5 spinal ganglion and, to a lesser extent, all neurons of the sacral spinal cord, contained large lipid inclusions which in electron micrographs differed from those in Schwann and satellite cells. There was no storage material in glial cells. The neuronal inclusions were membrane-bound and consisted of electron-dense and electron-lucent components. There was evidence of neuronal death in the spinal ganglion, and a diameter histogram showed that small cytons had preferentially been lost. The inclusions probably were secondary lysosomes or residual bodies, and resembled giant lipofuscin granules. Nevertheless, they were uncolored and displayed weak autofluorescence as compared to the aging pigment in control ganglia. It is tentatively suggested that the syringomyelia-like neuropathy in Tangier disease represents a lysosomal storage disorder preferentially affecting small dorsal root ganglion cells.

Diagnosis, Differential↗
PubMed1987

Torture and its treatment.

Physical and psychological torture of political detainees and prisoners is currently practiced in more than 90 countries. Types of torture and the diagnosis and treatment of torture victims are described based on the experience of Copenhagen's Rigshospitalet.

Denmark↗
PubMed1987

Neurologic symptoms and hysterectomy: a retrospective survey of the prevalence of hysterectomy in neurologic patients.

Eleven percent of the 272 women aged 25-45 years admitted consecutively to a neurologic department in 1980-1984 had undergone hysterectomy. The population was divided into two groups according to the discharge diagnoses. Among women with discharge diagnoses usually associated with no objective neurologic findings, the frequency of hysterectomy was 14%, compared with 5.4% in women discharged with diagnoses indicating organic neurologic disease. Gynecologic and psychiatric admissions were more frequent in the former than in the latter group. Of the 30 hysterectomized women, only six had had malignant or premalignant changes in the uterus, whereas in 22 cases the removed organs had been normal. These results suggest that a somatization disorder might have been the underlying cause for the hysterectomy as well as for the symptoms and complaints leading to referral to the neurologic service. Awareness of this problem is important in order to avoid unjustified surgery.

Adult↗
PubMed1986

Carotid surgery, cognitive function, and cerebral blood flow in patients with transient ischemic attacks.

Psychological testing, cerebral blood flow (CBF) measurement, and computed tomographic scan were performed before and 3 months after operation in 31 patients subjected to endarterectomy of the internal carotid artery (ICA) because of transient ischemic attacks and in 11 control patients operated on for atherosclerosis of the lower extremities. In preoperative psychological testing both carotid surgery patients and controls performed somewhat below the normal level for their age group. Postoperatively, cognitive functions improved in the carotid surgery group but not in the control group. The improvement was related to the laterality of the operation, being more marked in verbal tests in patients with left ICA operation and in visuospatial tests in patients with right ICA operation. Postoperatively regional CBF improved in 2 patients only. Hence the intellectual improvement could not be related to changes in CBF. Intellectual deterioration in patients with internal carotid atherosclerosis may be delayed or terminated by surgical abolition of the source of multiple cerebral embolizations.

Adult↗
PubMed1986

Chronic pain treatment with intravenous lidocaine.

In a few uncontrolled studies intravenous lidocaine has been used in the treatment of chronic pain. In a controlled study we used intravenous lidocaine in 18 patients with severe chronic pain states due to various but mainly neurological diseases. After the infusion of lidocaine 14 patients (78%) had significant pain relief ranging from 2 hours to 25 days. There was no significant effect of placebo infusion with isotonic saline. The mechanism of the pain relieving ability of intravenous lidocaine is unknown.

Double-Blind Method↗