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Biomedical subjects

L E Linder

Publications and source records attributed to L E Linder.

63 records · Page 4Linked to original sources
PubMed1978

Reversibility of the blood-brain barrier dysfunction induced by acute hypertension.

An acute hypertensive episode of short duration (less than 3 min) induced by i.v. injection of angiotensin in rats resulted in a blood-brain barrier dysfunction that was rapidly reversible. Thus, no macroscopic extravasation was seen when Evans blue was given 10 or 20 min after angiotensin. A faint fluorescence (Evans blue-albumin) was seen in the walls of some intracerebral arterioles in a few rats given the tracer 10 min after angiotensin.

Acute Disease↗
PubMed1978

Cerebrovascular permeability in acute arterial hypertension. Effect of unilateral ligation of the common carotid artery.

Ligation of the right common carotid artery prevented protein extravasation in the homolateral cerebral hemisphere when a blood pressure increase was induced by bicuculline or amphetamine. In addition to a blood pressure increase these two drugs induce a vasodilatation, which makes the resistance vessels particularly vulnerable to the mechanical stress of high intravascular pressure. The ratio between the mean arterial blood pressure in the femoral artery and the carotid artery distal to the ligation was approximately 0.5; slightly higher after than prior to the pressure increase.

Acute Disease↗
PubMed1977

The pressure-flow relations of the canine brain in acute mechanically induced arterial hypertension at different levels of cerebral blood flow.

Cerebral pressure-flow relations were studied in anaesthetized dogs during acute arterial hypertension, induced by compression of the thoracic aorta. In one group of animals steady state measurements were made with the radioactive gas elimination method. In another group the immediate changes of blood flow at a blood pressure change, as indicated by variations in the cerebral venous oxygen saturation, were studied with continuous oximetric analyses of the superior sagittal sinus blood. The initial blood flow was varied by variations of the arterial carbon dioxide tension of injections of papaverine. At low or normal blood flows autoregulation was efficient up to pressures around 180-200 mmHg, while at higher flows the upper autoregulatory pressure limit was found at lower blood pressures. Above the autoregulatory limit-irrespective of the control flow level-there was a rise in blood flow and a decrease in cerebrovascular resistance.

Animals↗
PubMed1977

Mechanisms for closure of the human urethra during intravaginal electrical stimulation.

The effect of intravaginal electrical stimulation (IVS) on the urethral pressure profile (UPP) before and during succinylcholine blockade or spinal anaesthesia was studied in patients with stress incontinence and in patients with clinically normal urethral function. During succinylcholine blockade, the UPP was lowered to 74% and during spinal anaesthesia to 39% of the original maximal UPP. IVS could not influence the UPP during succinylcholine blockade, while the UPP could be restored during spinal anaesthesia when the stimulation strength was increased 3 to 4 times. The following conclusions were arrived at: 1) The urethral effect of IVS is due to activation of somatic nerves and not to activation of nerves supplying smooth muscles or direct activation of striated and smooth muscles. 2) The more pronounced depression of the UPP during spinal anaesthesia compared to succinylcholine blockade should be caused by the loss of nervous activity of the smooth muscles. 3) The fact that the UPP could be restored during spinal anaesthesia indicates that activation of somatic efferents can compensate for the loss of striated and smooth muscle activity. Therefore, IVS can control incontinence in partial lower motor neuron lesions, provided a sufficient number of efferent neurons are preserved.

Adult↗
PubMedDate not supplied

Effect of four dental varnishes on the colonization of cariogenic bacteria on exposed sound root surfaces.

The aim of this study was to evaluate the effect of four different dental varnishes on the colonization of mutans streptococci, total streptococci and lactobacilli on exposed sound root surfaces. Sixty-five individuals were randomly allotted to one of four groups for treatment with Cervitec((R) ) varnish containing 1% chlorhexidine and 1% thymol, a thymol varnish or one of two different fluoride varnishes, Fluor Protector and Duraphat. The varnish was applied to three buccal root surfaces in each patient at baseline and after 1 week. Dental plaque from the root surfaces was collected and analysed on four different occasions: at baseline, after 1 week, 1 month and 6 months. The Cervitec varnish caused a statistically significant reduction in the number of mutans streptococci over time. The reduction was significant at 1 week and 1 month relative to baseline. The numbers of total streptococci and lactobacilli were not significantly affected by treatment with Cervitec. No statistically significant difference over time was found for mutans streptococci, lactobacilli or total streptococci after treatment with the fluoride varnishes or the thymol varnish.

Analysis of Variance↗
PubMedDate not supplied

Phenothiazine-mediated protection of the blood-brain barrier during acute hypertension.

The phenothiazine dixyrazine (5 mg . kg-1 i.v.) had minimal, transient hypotensive effects but significantly reduced the leakage of 125I labelled serum albumin in conscious rats subjected to acute hypertension provoked by i.v. adrenaline or bicuculline. By contrast, dixyrazine did not protect the blood-brain barrier during osmotic stress induced by intracarotid infusion of 2 M urea. The diameters of pial arteries and veins were continuously measured with a multichannel videoangiometer through a closed cranial window in anesthetized rats before and after i.v. injection of dixyrazine (5 mg . kg-1). No change in vessel diameter was observed except for a transient autoregulatory dilatation of arteries in response to a slight transitory decrease in the blood pressure. It is concluded that dixyrazine probably protects the blood-brain barrier during mechanical stress by modifying the endothelial cell membrane.

Acute Disease↗
PubMedDate not supplied

Material thrombogenicity in central venous catheterization: a comparison between soft, antebrachial catheters of silicone elastomer and polyurethane.

In order to compare two types of long, soft central venous catheters with the same stiffness, 39 silicone elastomer (SE) and 36 polyurethane (PU) catheters were inserted in 75 patients via basilic or cephalic veins punctured at the cubital fossa. Mean duration of catheterization was 10.5 days. Scanning electron microscopy revealed that the SE catheters to have a more uniform, but somewhat rougher surface topography than the PU catheters. The platelet adhesion in vitro to the SE catheters was four times higher than to the PU catheters. The incidence of clinical thrombophlebitis in the arm veins was 36% with the SE catheters, and 5.5% with the PU catheters (p less than 0.01). No significant differences were found between the SE and PU catheters regarding the number and size of radiologic thrombi in the peripheral and central veins, catheter occlusion rate, and platelet adhesion to the inner side of the catheter tip at withdrawal. Platelet adhesion in vivo correlated with the duration of catheterization in both groups of catheters. Mechanical trauma to the vein endothelium seems to be of vital importance in thrombus formation, but not in the induction of clinical thrombophlebitis.

Adolescent↗