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Biomedical subjects

L Norgren

Publications and source records attributed to L Norgren.

At least 145 records · Page 8Linked to original sources
PubMed1987

Hemodynamic effects of dopamine during thoracic epidural analgesia in man.

The cardiovascular effects of dopamine were studied before and during thoracic epidural analgesia (TEA) in eight patients prior to abdominal aortic surgery. Dopamine was infused at rates of 2, 4, and 8 micrograms X kg-1 X min-1. Mean plasma dopamine concentration increased proportionally to the infusion rate. Before TEA, dopamine 8 micrograms X kg-1 X min-1 decreased systemic vascular resistance 4 +/- 4 mmHg min X 1-1 (m +/- SD) (P less than 0.05), but increased mean arterial pressure 15 +/- 12 mmHg (P less than 0.01), cardiac output 1.9 +/- 1.0 1 X min-1 (P less than 0.01), heart rate 10 +/- 9 beats X min-1 (P less than 0.05), and plasma norepinephrine concentration 544 +/- 252 pg X ml-1 (P less than 0.01). After the induction of TEA, which extended above the T2 dermatome and below the L2 dermatome, saline and albumin were infused to maintain central venous and pulmonary capillary wedge pressures. TEA reduced mean arterial pressure from 96 +/- 18 to 55 +/- 8 mmHg (P less than 0.01), cardiac output from 4.7 +/- 0.9 to 3.9 +/- 0.9 1 X min-1 (P = 0.05), systemic vascular resistance from 21 +/- 6 to 14 +/- 3 mmHg min X 1-1 (P less than 0.05), and plasma norepinephrine concentration from 394 +/- 141 to 207 +/- 73 pg X ml-1 (P less than 0.01). The plasma epinephrine concentration was reduced 49% after the induction of TEA.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Incidence of deep vein thrombosis in bedridden non-surgical patients.

In order to detect deep vein thrombosis (DVT), 101 patients with acute medical or infectious disorders were examined with the 125I-fibrinogen uptake test. All patients were bedridden on admission and were scanned daily from the second to the eighth day. Thirteen patients developed a positive fibrinogen uptake test. Thus, if a positive test is interpreted as DVT, the incidence of DVT was 13% in our bedridden patients. Of the patients admitted because of heart disease or pneumonia 20% had DVT, but only 4% of those admitted with other diagnoses. Other clinical "risk factors" studied, could not identify patients who developed DVT.

Acute Disease↗
PubMed1987

Postjunctional alpha-adrenoceptors in human superficial epigastric arteries and veins.

A pharmacological characterization of the postjunctional alpha-adrenoceptors in human superficial epigastric artery and vein was performed, using several alpha-adrenoceptor subtype selective agonists, and the antagonists prazosin (alpha 1) and rauwolscine (alpha 2). In the arteries prazosin fulfilled the criteria for a competitive antagonism in concentrations 10(-9)-10(-7) M, giving a pA2-value of 9.17 in the Schild plot. Rauwolscine in concentrations 10(-8)-10(-6) M caused less pronounced but significant dextral shifts of the noradrenaline (NA) concentration-response curves. In the veins rauwolscine behaved like a competitive antagonist (10(-8)-10(-7) M). The pA2-value was 9.16. Prazosin 10(-9) M displaced the NA concentration-response curve, but higher concentrations (10(-8) and 10(-7) M) caused no further displacement. Prazosin reduced the Emax-values in the veins. In the arteries the rank order of potency for the agonists was: cirazoline (alpha 1) greater than NA greater than naphazoline (alpha 2) greater than guanfacine (alpha 2) greater than phenylephrine (alpha 1). The intrinsic activities of clonidine (alpha 2), ST 587 (alpha 1), B-HT 920 (alpha 2) and B-HT 933 (alpha 2) were too low to allow meaningful comparisons to be made. The rank order of potency in the veins was: NA greater than clonidine (alpha 2) greater than naphazoline (alpha 2) greater than guanfacine (alpha 2) greater than phenylephrine (alpha 1) greater than B-HT 920 (alpha 2) greater than cirazoline (alpha 1) greater than B-HT 933 (alpha 2). The intrinsic activity of ST 587 was low.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Comparative effects of some calcium-channel blockers on human peripheral arteries and veins.

We investigated the effects of five different calcium-channel blockers (CCBs), verapamil, nifedipine, diltiazem, flunarizine and lidoflazine, on contractions evoked in vitro by noradrenaline (NA) in small human arteries and veins from the epigastric region. Vessels were obtained from patients without obvious vascular diseases undergoing surgery because of inguinal hernias. The human superficial epigastric artery has previously been shown to contain mainly alpha 1-adrenoceptors, whereas in the vein alpha 2-adrenoceptors predominate. In experiments where NA (10(-5) M) was added non-cumulatively, it was found that nifedipine was the most potent relaxant agent in both arteries and veins, but that this drug showed no preference for any type of vessel. In contrast verapamil (10(-6) M) and (10(-5) M) diltiazem, flunarizine and lidoflazine inhibited the NA-induced contractions to a significantly greater extent in the arteries than in the veins. Comparison between diltiazem and nifedipine on contractions induced by cumulative addition to NA showed that both drugs had significantly more depressive effects on arteries than on veins if the vessels were contracted by relatively high concentrations of NA (10(-6) and 10(-5) M). The results thus confirm the clinical finding that CCBs have more pronounced effects on the arterial than on the venous side of the circulation. They do not support the view that CCBs are more effective inhibitors of alpha 2- than alpha 1-adrenoceptor mediated contraction in isolated human blood vessels.

Adult↗
PubMed1987

Contractile response in isolated human groin lymphatics.

Lymphatics from the human superficial groin removed at operation in 21 patients (one with lymphedema) were examined in vitro. Histochemically no nerves were identified with either specific catecholamine fluorescence or immunoreactivity to tyrosine hydroxylase or dopamine beta-hydroxylase. Ring preparations of the lymphatics were mounted in tissue baths and isometric induced contractions were recorded after administration of K+ (124 mM), acetylcholine, selected amines and prostanoids. Noradrenaline (NA), adrenaline, dopamine, and acetylcholine had no or only weak contractile effects. In some segments, serotonin induced contractions. Prostaglandin E2 showed no contractile effect and prostaglandin F2 alpha induced contraction in most of the tested lymphatics. The prostaglandin-endoperoxide analogue U44069 uniformly elicited marked concentration-dependent contraction. In the lymphatic segment from the patient with lymphedema, a slightly greater contractile response to NA and serotonin was observed. The results overall suggest an absence of sympathetic innervation and contraction-mediating alpha adrenergic receptors in human superficial groin lymphatics, and support that certain prostanoids may be important regulators of human lymphatic contractility.

Acetylcholine↗
PubMed1986

The effect of pneumatic antishock garments in the treatment of lethal combined hepatic and caval injuries in rats.

Thirty rats were subjected to a standardized lethal hepatic and retrohepatic caval vein injury. The animals were divided into six groups. In addition to controls (I), the animals were treated with a pneumatic antishock garment (PASG) (II), massive intravenous (III), or intra-aortic (IV), saline infusion, or PASG in combination with either massive intravenous (V) or intra-aortic (VI) saline infusion. Intravenous and intra-aortic infusion of saline led to a median survival time of 13 min and 37 min, respectively, not statistically different from the control group. Nine of ten animals who had the combined treatment with PASG and infusion of saline developed a fulminant pulmonary edema. The treatment with PASG alone, however, prolonged survival time significantly from a median survival time of 10 min in the control group, to greater than 120 min in the treated group.

Animals↗
PubMed1986

Effects of alpha-adrenoceptor subtype-selective antagonists on the human saphenous vein in vivo.

The effects of the alpha-adrenoceptor subtype-selective antagonists prazosin (alpha 1) and yohimbine (alpha 2) on the saphenous vein of six healthy male subjects were investigated in vivo. The drugs were infused locally into the congested (40 mmHg), long saphenous vein constricted by simultaneous local infusion of noradrenaline (NA). Prazosin 10(-9) M (concentration in the infusion solution, infusion rate 0.3 ml min-1) did not reduce the NA-induced venoconstriction, but at a concentration of 10(-8) M there was a significant reduction; in two subjects no response to NA could be elicited in the presence of 10(-8) M prazosin. Prazosin 10(-7) M caused no further reduction of the NA effect compared to that produced by 10(-8) M in three of the subjects, whereas in one, prazosin 10(-9), 10(-8) and 10(-7) M caused a dose-dependent blockade. Yohimbine, 10(-9), 10(-8) and 10(-7) M caused a dose-dependent reduction of the NA-induced venoconstriction in all subjects. The results suggest that the human saphenous vein is endowed with functionally important populations of both alpha 2- and alpha 1-adrenoceptors.

Adrenergic alpha-Antagonists↗
PubMed1986

Follow-up evaluation of venous morphologic factors and function after thrombectomy and temporary arteriovenous fistula in thrombosis of iliofemoral vein.

Fifty-seven patients (58 post-thrombotic legs) treated with venous thrombectomy and temporary arteriovenous fistula for thrombosis of the iliofemoral vein were evaluated in a follow-up study regarding clinical, morphologic and functional aspects nine to ten months after thrombectomy. There were 33 men and 24 women, between 15 and 84 years of age (a mean of 51 years). The results of clinical examination revealed that 75 per cent of the patients had a good and 20 per cent a fair result of the treatment. No ulcers of the leg or venous claudication had developed. Venography (53 legs) demonstrated 61 per cent patency rate of the iliofemoral segment, although post-thrombotic changes were noted in 23 per cent. Venous femoral pressure measurement was normal in 82 per cent of 28 legs examined despite some proximal stenosis or occlusion. A good venous emptying with plethysmography was achieved in 29 per cent and foot volumetry showed normal peripheral venous function in 29 per cent. The results of this follow-up study, however short, reveal that venous patency can be restored to a high extent with good clinical result. Functionally, these patients may be at high risk for having sequelae develop later.

Adolescent↗
PubMed1986

Effect of ticlopidine and prostaglandin E on endotoxin-induced pulmonary platelet sequestration in vivo.

Prostaglandin E1 has earlier been shown to decrease pulmonary platelet trapping (PPT) following shock. This experiment was performed to evaluate a new method to study PPT in vivo, and to study the effect of prostaglandin E1 and a new antiplatelet drug (ticlopidine) on PPT in rabbits after i.v. administration of endotoxin. Following platelet labeling with In-111, the rabbits were placed under a scintillation camera for continuous measuring of the activity distribution for 40 minutes. The first five minutes represented reference values, whereafter endotoxin E. coli was injected i.v. The following 2-4 minutes showed a sudden increase of radioactivity over the lungs and a simultaneous decrease over the heart, indicating PPT in the nontreated animals, followed by a slow decrease to almost preshock values during the following 30 minutes. Animals receiving prostaglandin E1 showed a significantly lower activity peak in the lungs after the administration of endotoxin, while the corresponding peak in ticlopidine-treated animals did not differ from that seen in the nontreated animals. In all groups, endotoxin caused a decrease in platelet count, but it was significantly lower in the PGE1-treated animals. The results have shown that this diagnostic model for PPT is reliable and may be used for evaluation of the effect on platelet aggregation in vivo of different drugs.

Alprostadil↗
PubMed1985

Low prevalence of abdominal aortic aneurysm in hypertensive patients. A population-based study.

The prevalence of abdominal aortic aneurysms (AAA) was estimated by ultrasonography in hypertensives in the age group 50-70 years in geographically defined population. Only one case of AAA was found among 245 patients. This rather unexpected result implies a probability of less than 5% that the true prevalence of AAA is as high as 2% in hypertensives. Our population-based study indicates a lower prevalence than earlier studies based on necropsies and is an example of research cooperation between primary health care and specialized hospital care.

Aged↗
PubMed1985

Revascularization of popliteal and below-knee arteries with polytetrafluoroethylene.

The expanded polytetrafluoroethylene (PTFE) graft (Gore-tex) is the most frequently used synthetic graft when an alternative to autologous saphenous vein is required. Early results have been encouraging. In the present paper we report on 6 years of results from 153 above-knee (AK) femoropopliteal bypass grafts, 74 below-knee (BK) femoropopliteal bypass grafts, and 54 femorotibial/peroneal bypass grafts. The main indication for the vascular reconstruction was severe ischemia. Preventive antibiotics were given to 95% of the patients. Minimum observation time was 1 year after implantation. There was no operative death. Graft infection was seen in less than 5% of patients. The 6-year cumulative limb salvage rate was 87% for patients with severe ischemia in the AK femoropopliteal bypass group, 59% for those in the BK femoropopliteal bypass group, and 57% for those in the femorotibial/peroneal bypass group. The graft patency rate was 88% at 2 years and 78% at 6 years for the AK femoropopliteal bypass group, for whom the operative indication was disabling claudication, and 81% and 68%, respectively, when the indication for the vascular procedure was severe ischemia. The cumulative graft patency rate was 53% and 43% at 2 and 6 years, respectively, after implantation of BK femoropopliteal bypass grafts and 43% and 39% for femorotibial/peroneal bypass procedures. The expanded PTFE (Gore-tex) graft seems therefore to be a good alternative when an autologous vein is not available, even for reconstructions well below the knee joint.

Adult↗
PubMed1985

A neurophysiologic investigation of thoracic outlet syndrome.

Earlier reports have been conflicting as regards the value of neurophysiologic measurements in the diagnosis of thoracic outlet syndrome (TOS), presumably due to differences in selection of patients and in selection and standardization of neurophysiologic tests. The object of the present study was to assess the value of extensive conventional neurophysiologic measurements for the diagnosis of brachial plexus compression in patients with clinical TOS as determined from standardized criteria. The results are discussed in the light of expected neurophysiologic findings at different degrees of brachial plexus compression.

Adolescent↗
PubMed1984

An experimental method for in vivo studies of pulmonary platelet sequestration.

It has been reported in earlier in vitro studies that soft tissue trauma and endotoxin-induced shock causes pulmonary platelet trapping (PPT). This paper describes a noninvasive in vivo technique for dynamic studies of PPT in rabbits. Autologous platelets were labeled with 111In and reinfused into the animals. The following day, the rabbits were anesthetized and placed in a supine position under a scintillation camera. Continuous measurement of the activity distribution in the animal was performed for 35 min. The first 5 min represented a preshock measurement, whereafter endotoxin E. coli was injected IV. The following 2-3 min showed a sudden increase of radioactivity in the lungs indicating PPT, and thereafter a slow decrease to almost the preshock level. A simultaneous decrease in the number of platelets and the radioactivity in peripheral blood also indicated the induction of PPT. This study clearly shows that PPT can be detected in vivo with an easy, noninvasive scintillation camera method.

Animals↗
PubMed1984

The postjunctional alpha-adrenoceptors of the human saphenous vein.

The postjunctional alpha-adrenoceptors in human long saphenous vein were characterized using alpha-adrenoceptor subtype selective agonists and antagonists. The order of potency for the alpha-adrenoceptor agonists used was: Clonidine (alpha 2) greater than BHT-920 (alpha 2) greater than naphazoline (alpha 2) greater than guanfacine (alpha 2) greater than cirazoline (alpha 1) greater than phenylephrine (alpha 1) greater than ST 587 (alpha 1) greater than BHT-933 (alpha 2). Clonidine had the same potency as noradrenaline (NA), but was 52 times more potent than phenylephrine (pEC50 7.09 and 5.37, respectively). Phenylephrine and guanfacine had intrinsic activities that did not differ from that of NA, whereas the intrinsic activities of the other agonists were significantly lower. The highly selective alpha 1-adrenoceptor antagonist prazosin in concentrations 10(-9)-10(-7) M was unable to cause a significant shift of the NA concentration response (cr) curve to the right. However, the alpha 2-adrenoceptor antagonists yohimbine and rauwolscine in concentrations 10(-8)-10(-6) M shifted the NA cr-curve towards higher concentrations. No concentration of any antagonist used significantly attenuated the maximum contraction. The slope of the regression line in the Schild plot differed significantly from unity for rauwolscine but not for yohimbine, and the pA2-values were 9.00 and 8.27, respectively. These results suggest that the contraction mediating alpha-adrenoceptors in the human saphenous vein are mainly of the alpha 2-type. However, the low slope value of the Schild plot for rauwolscine may indicate the presence of a small population of alpha 1-adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1984

Pharmacological characterization of postjunctional alpha-adrenoceptors in isolated human omental arteries and veins.

The alpha-adrenoceptors in human omental arteries and veins were characterized and compared. In the arteries both prazosin (pA2 9.48) and rauwolscine (pA2 7.19) displaced the noradrenaline (NA) concentration-response (cr) curve towards higher concentrations without reduction of maximum. Neither clonidine, nor oxymetazoline had any consistent contractile effects. Phenylephrine had a lower potency than NA, but a similar intrinsic activity. In the veins, both prazosin (pA2 9.72) and rauwolscine (pA2 8.11) displaced the NA cr-curve towards higher concentrations, but also significantly depressed maximum. Clonidine and oxymetazoline contracted veins from 3 out of 7 and 4 out of 6 patients, respectively. Their pD2-values were similar to that of NA, but their intrinsic activities were significantly lower. NA was more potent than phenylephrine in these vessels, and there was no significant difference in intrinsic activity. The results suggest that in human omental arteries, the postjunctional alpha-adrenoceptors are mainly of the alpha 1-type, even if a small population of alpha 2-adrenoceptors cannot be excluded. In omental veins, there seems to be a functionally important population of postjunctional alpha 2-adrenoceptors occurring together with a population of alpha 1-adrenoceptors.

Adolescent↗
PubMed1984

Postjunctional alpha 1- and alpha 2-adrenoceptors mediating contraction in isolated human groin arteries and veins.

By means of selective agonists and antagonists for alpha 1- and alpha 2-receptors, the alpha-receptor subtypes in human groin arteries and veins were characterized and compared. In the arteries the alpha 1-receptor blocker prazosin caused a concentration-dependent parallel displacement of the noradrenaline (NA) concentration-response (cr) curve without reduction of maximum (pA2 = 9.86); the selective alpha 2-receptor antagonist rauwolscine in the concentration 10(-8) M caused a right-ward shift of the NA cr-curve without reduction of Emax, but 10(-7) M and 10(-6) M caused little or no further shift. In the veins, the two antagonists had the opposite effects. Rauwolscine caused a concentration-dependent right-ward shift of the NA cr-curve without depression of maximum (pA2 = 9.03); prazosin 10(-9) M significantly displaced the NA cr-curve, whereas 10(-8) M and 10(-7) M caused little or no further shift. The responses to the alpha 2-receptor agonist clonidine in the arteries were too small to allow calculations of pEC50 values; in the veins contractions were elicited in all vessel segments investigated (pEC50 = 6.24). Phenylephrine, selective for alpha 1-receptors, was significantly more potent in arteries than in veins. NA was significantly more potent in veins than in arteries. It is concluded that in human groin vessels, there is a functional predominance of alpha 1-receptors in the arteries and of alpha 2-receptors in the veins.

Adrenergic alpha-Agonists↗