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Biomedical subjects

L Norgren

Publications and source records attributed to L Norgren.

At least 73 records · Page 4Linked to original sources
PubMed1997

Endovascular abdominal aortic aneurysm repair induces significant alterations in surface adhesion molecule expression on donor white blood cells exposed to patient plasma.

OBJECTIVE: To determine the response of white blood cells in endovascular aortic aneurysm repair. MATERIALS AND METHODS: Seven patients treated with an endoluminal procedure (AAA-E) and seven patients undergoing conventional surgery (AAA-C) were included (all males, aged 52-80 years). A panel of monoclonal antibodies against CD11a, CD11b, CD11c, CD18 and L-selectin was used. To determine the surface receptors on both circulating and sequestered white blood cells, plasma from the patients and cells from healthy donors were combined for flow-cytometry. RESULTS: The expression of CD11a adhesion molecules only showed slight variations regarding granulocytes, but was more pronounced on monocytes, however, without significant differences between the two patient groups, CD11b, CD11c and CD18 molecules on both granulocytes and monocytes were significantly upregulated 60 min after the endovascular procedure compared to conventional aneurysm repair, and L-selectin molecules were by this time correspondingly cleaved off. CONCLUSION: Endovascular aneurysm repair differed significantly from conventional aneurysm surgery with peak adhesion molecule expression 60 min after balloon deflation, probably caused by release of tumour necrosis factor-alpha (TNF-alpha).

Aged↗
PubMed1997

Venous thrombectomy for iliofemoral vein thrombosis--10-year results of a prospective randomised study.

OBJECTIVES: To study if venous thrombectomy prevents late post-thrombotic sequelae, venous obstruction reflux, and improves venous physiology following an acute iliofemoral venous thrombosis. DESIGN: Prospective randomised controlled study. MATERIAL: Thirty patients returned for follow-up 10 years after an acute iliofemoral venous thrombosis initially treated with conventional anticoagulation treatment (medical group, n = 17) or with thrombectomy combined with a temporary arteriovenous fistula and anticoagulation (surgical group, n = 13). Clinical assessment, radionuclide angiography, duplex ultrasound and venous physiology tests were performed. RESULTS: Leg swelling was recorded in 12 (71%) and leg ulcers in three (18%) of the medical patients and in, respectively, six (46%) and one (8%) of the surgical patients. The surgical patients had less severe sequelae (class 0-2). Radionuclide angiography demonstrated that the iliac vein was more commonly occluded following medical (59%) than following surgical (17%) treatment (p < 0.05). Duplex examination demonstrated slightly (n.s.) more reflux in the femoral and popliteal veins in the medical group. Venous physiology (occlusion plethysmography, foot volumetry, and foot vein pressures) did not show any significant differences, although the medical group tended to have a more severe pathology. CONCLUSION: Venous thrombectomy improves venous patency and possibly reduces venous reflux and post-thrombotic sequelae as compared to anticoagulation treatment.

Acute Disease↗
PubMed1997

Chronic venous insufficiency--a well-known disorder with many question marks.

Chronic venous insufficiency (CVI) is a common disorder found in many parts of the world. The pathophysiology of this condition is only partly elucidated, and even the development of varicose veins remains unexplained. Microcirculation is greatly affected by CVI, which occasionally induces skin changes and ulcers. Although varicose veins are a common symptom of CVI, they are absent in many patients. Thus, clinical examination is often insufficient for the diagnosis of CVI. Furthermore, the treatment of a common disorder such as CVI is frequently inadequate. The author discusses the overfrequent use of varicose vein surgery, where compression treatment would seem more appropriate and effective, and the current status of compression in the treatment of deep vein incompetence. He recommends that the various manifestations of CVI should be more thoroughly classified. He also examines how sclerotherapy is used to various extents in different countries. Finally he discusses the use of various drugs in the treatment of CVI. It is clear that the pathophysiology and the treatment of CVI must be further examined, in particular to determine whether prevention is possible.

Chronic Disease↗
PubMed1997

The need for clinical trials of endovascular abdominal aortic aneurysm stent-graft repair: The EUROSTAR Project. EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair.

EUROSTAR (EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair, EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience. As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a "Retrieval and Analysis Study" for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.

Angioplasty↗
PubMed1997

Biological responses to endovascular treatment of abdominal aortic aneurysms.

PURPOSE: To review the findings of two studies investigating the apparent differences in inflammatory responses demonstrated in patients undergoing endovascular as opposed to classic surgical treatment of abdominal aortic aneurysms (AAAs). METHODS: The clinical course of seven patients treated with an endoluminal procedure (AAA-E) and seven patients undergoing conventional surgery (AAA-C) were compared (all men; ages 52 to 80 years). Blood samples were taken pre-, intra-, and postoperatively for up to 7 days. Inflammatory responses were assessed from measurement of interleukins (IL)-1 beta, IL-6, IL-8, and tumor necrosis factor (TNF-alpha); complement proteins C1q, C4, C5a, and terminal complement complexes, C5b-C9; and C-reactive proteins. Granulocyte and monocyte surface adhesion molecule expression was determined indirectly using a panel of monoclonal antibodies against CD11a, CD11b, CD11c, CD18, and L-selectin in donor white blood cells exposed to patient plasma. RESULTS: In six of the AAA-E patients, blood pressure decreases were recorded during the introduction of the device. Elevated body temperature was sustained for 2 to 5 days postoperatively in the AAA-E group. IL-6 levels were significantly higher in AAA-C patients (p < 0.0005), while TNF-alpha release was recorded in the AAA-E group only. CD11b, CD11c, and CD18 molecules on both granulocytes and monocytes were significantly upregulated 60 minutes after the endovascular procedure compared to conventional surgery. CONCLUSIONS: Endovascular aortic aneurysm repair apparently induces a significant inflammatory response, mainly involving TNF-alpha release, which differs from open AAA repair. These inflammatory responses, which may be related to the observed intraprocedural blood pressure decreases, could be caused by cell activation arising from intra-aneurysmal device manipulation.

Aged↗
PubMed1997

Inflammatory response to aorto-bifemoral graft surgery.

OBJECTIVE: To evaluate the systemic release of major cytokines and complemental activation during elective aorto-bifemoral bypass surgery and the influence on the postoperative course. DESIGN: Prospective randomised study. SETTING: University hospital, Sweden. PATIENTS: Fourteen consecutive patients with aorto-iliac occlusive disease were randomised to receive either a bifurcated e PTFE graft with stretch properties or a collagen coated Dacron graft. MAIN OUTCOME MEASURES: Immunologic parameters were assessed and included the cytokines TNF alpha (tumor necrosis factor), IL-6, IL-8, S-IL-2R and complemental factor C5a. Furthermore, acute plasma proteins, including C-reactive protein, and the different white blood cell fractions were determined. Sampling was performed frequently during surgery and postoperatively up to one month. RESULTS: An increase of serum-TNF alpha levels was observed early after declamping. This response preceded an increase of IL-6 levels and of C-reactive protein. No release of IL-8 was identified. A significant correlation between TNF alpha, IL-6 and C-reactive protein was observed (p < 0.001). A positive correlation was also observed for the degree of surgical trauma (blood loss). No significant differences between the two graft materials were encountered. The complemental system was also involved in the acute reactions and a marked increase of C5a levels was noted. A decrease of S-IL-2R levels as well as lymphocyte concentrations was also observed postoperatively and was interpreted as a downregulation of the immune-system in the immediate postoperative course. CONCLUSIONS: The results demonstrate an early and generalized inflammatory response during and after aortic surgery with involvement of different cytokines as well as the complemental system. TNF alpha appears to play a central role in the release of other cytokines, but IL-6 seemed to correlate best with later development of nonvascular complications. Few differences were found between the different grafts and the response seems to be influenced by other factors such as the surgical procedure and ischaemia/reperfusion injury.

Aged↗
PubMed1996

Surface adhesion molecule expression on human blood cells induced by vascular graft materials in vitro.

The expression of surface adhesion molecules on granulocytes, monocytes (CD11a, CD11b, CD11c, CD18, L-selectin), and platelets (P-selectin, gpIIb-IIIa) was determined after incubation with different graft surfaces [expanded polytetrafluoroethylene (ePTFE) or woven Dacron]. Woven Dacron grafts upregulated the CD11b and CD11c surface antigens on both granulocytes and monocytes. Both graft materials demonstrated increased expression of CD11a and CD18 adhesion molecules on white blood cells at 30 min, followed by a downregulation. Maximum L-selectin expression was seen at 120 min on granulocytes and at 90 min on monocytes without differences between the graft materials. A rapid downregulation of gpIIb-IIIa complexes on platelets was noticed, while no expression of platelet P-selectin molecules was observed. In conclusion, both graft materials induced alteration of the white blood cell adhesion molecule expression, but the intensity and time course were dependent on the cell type and the graft material, suggesting that different mechanisms might be implicated. The expression of platelet surface antigens was less clearly influenced. The clinical significance of an enhanced cell surface antigen receptor expression caused by woven Dacron (CD11b, CD11c) has to be further studied. However, determination of adhesion molecule expression might offer possibilities to predict biocompatibility.

Blood Platelets↗
PubMed1996

Aortobifemoral surgery induces complement activation and release of interleukin-6 but not tumour necrosis factor-alpha.

The aim of the present study was to determine the inflammatory response by an extended analysis of complement in 16 patients undergoing aortobifemoral bypass surgery. The patients were randomized to receive either a bifurcated expanded polytetrafluoroethylene graft (n = 8; group I) or a collagen-impregnated knitted Dacron graft (n = 8; group II) to determine whether differences in graft surface properties might influence the inflammatory response during and after the procedure. The following components of complement: C1q, C4, C3, C3d, C5a and terminal complement complexes were all analysed. C-reactive protein and interleukin-6 were also determined to assess the acute phase response. The complement data were corrected for haemodilution, which was assessed from alpha 2-macroglobulin concentrations. A significant decrease of C1q (P < 0.0001) and an increase in C5a (P < 0.0005) was observed in both groups. C4 and C3 levels showed slight fluctuations in group I, whereas in group II these proteins increased significantly (P < 0.05, P < 0.005, respectively) between 2 and 7 days after surgery. Terminal complement complexes remained unchanged in both groups. Interleukin-6 levels peaked at 12-24 h and the C-reactive protein at 24-72 h. Higher interleukin-6 levels (P < 0.05) were found in group II 6 h after surgery compared with group I; no release of tumour necrosis factor-alpha was identified. An early inflammatory response was found in all patients. The patterns of the complement proteins varied with a C1q depletion and a C5a increase, interpreted as complement activation. Whether the variations between the two graft groups represent any differences in graft surface properties has to be further elucidated.

Aged↗
PubMed1996

Biological responses differ considerably between endovascular and conventional aortic aneurysm surgery.

OBJECTIVES: To determine the inflammatory responses in endovascular abdominal aortic aneurysm (AAA) repair and their relation to clinical findings. DESIGN: Prospective non-randomised study. SETTING: University Hospital, Department of Surgery. PATIENTS AND METHODS: Seven patients treated with an endoluminal procedure (AAA-E) and seven patients undergoing conventional surgery (AAA-C) were included. Inflammatory parameters were assessed by measurements of the cytokines interleukin (IL)-1 beta, IL-6, IL-8 and Tumour Necrosis Factor-alpha (TNF-alpha); analyses of complement proteins C1q, C4, C3, C5a and Terminal Complement Complexes (TCC); haematologic parameters and determination of C-reactive protein (CRP). RESULTS: In six of seven patients in the AAA-E group blood pressure decreases were recorded during introduction of the device. IL-6 and CRP levels were found to be significantly higher in AAA-C patients compared to the AAA-E group. On the other hand, high TNF-alpha levels were recorded in the AAA-E group. Less consumption of the complement proteins C1q, C4 and C3 was observed in AAA-E compared to AAA-C patients. Increased C5a levels were recorded in the AAA-C group, whereas only slight fluctuations were noticed in the AAA-E group. TCC levels were unchanged in both groups. CONCLUSION: Endovascular aortic aneurysm repair induced a significant inflammatory response, mainly involving TNF-alpha and differing from the findings during open AAA repair. These inflammatory responses were probably related to blood pressure decreases during the procedures. On the other hand, conventional repair induced responses related to the more extensive surgical trauma and reperfusion injury.

Aged↗
PubMed1996

NADPH-diaphorase expression of endothelial cells during four weeks' healing of a stretch-ePTFE graft: an experimental porcine study.

Endothelial Nitric Oxide Synthase (eNOS) mediates the conversion of L-argine to NO and citrulline, which requires Nicotinamide Adenine Dinucleotide Phosphate (NADPH) as an essential cofactor. Evidence has been given that NOS accounts for the NADPH-diaphorase activity. The aim of the present study was to identify the histochemical and immunocytochemical appearance of NADPH-diaphorase and von Willebrand factor (factor VIII) respectively, in endothelial cells (ECs) during healing of stretch-expanded polytetrafluoroethylene (ePTFE) arterial grafts. On six Swedish domestic pigs an iliac bypass was bilaterally performed using 6 mm stretch-ePTFE grafts. The animals were allowed to survive one, two or four weeks. After explanation the grafts were prepared for NADPH-diaphorase histochemistry and factor VIII immunohistochemistry. Positive staining for the two identification markers was demonstrated after two weeks, whereas a more intense staining was seen after four weeks at the proximal and distal anastomoses, indicating maturation by time. No stained cells were observed at the mid-region of the grafts at any time. The cells differed from normal ECs, the former being less intense which may reflect immature ECs and probably a decreased expression of NO. In conclusion, the present study suggests tha NADPH-d histochemistry can be used to identify ECs. Whether a lower expression of NO compared to normal cells also means a reduced function, capable of causing adverse events has to be further evaluated.

Animals↗
PubMed1996

Quantitative analysis of heparin retention on heparin bonded knitted Dacron grafts after exposure to shear stress in vitro.

OBJECTIVE: To analyse the quantity of heparin retention on heparin bonded collagen coated knitted Dacron grafts (HCD) and heparin bonded knitted Dacron grafts without interluminal collagen coating (HD) after they had been exposed to shear stress in an artificial circulation model. EXPERIMENTAL DESIGN: A comparative study. SETTING: University Hospital, Department of Surgery. METHODS: HCD grafts were exposed to shear stress during 2, 24, 48, and 168 hours, and HD grafts during 1, 2, 3 and 4 weeks. Heparin retention on the graft walls was determined by a method based on the measurements of total sugars. RESULTS: HCD grafts showed no loss of heparin from the graft-surface when exposed to a flow of 200 ml/min up to 168 hrs. HD grafts demonstrated an initial loss of heparin from 8 mg/g to 3 mg/g/graft-segment within one week after which the level was stable during the remaining three weeks. CONCLUSION: Based on the present experimental setting it seems reasonable to conclude that the heparin-collagen layer remains stable but heparin alone is partly washed out by shear stress. To measure the release of heparin under the influence of the bloodstream including mechanisms for the slow degradation of collagen, a more sensitive method for heparin analysis is required.

Blood Vessel Prosthesis↗
PubMed1996

Dilatation of aorto-bifemoral knitted Dacron grafts after a mean implantation of 5 years.

OBJECTIVE: To evaluate the dilatation-rate of a reverse locknitted Dracon graft. EXPERIMENTAL DESIGN: Comparative study, a follow-up after 5 years. SETTING: Department of Surgery, University Hospital. PATIENTS: During 1987 to 1990, 105 patients underwent elective aorto-bifemoral bypass surgery for aorto-iliac occlusive disease. Nineteen patients received a reverse locknitted Dacron graft. During follow-up in 1993 ten patients were available for evaluation of graft-diameter. For comparison 14 patients who received a wrap knitted Dacron graft (12 collagen impregnated and two uncoated) operated during the same time period were randomly chosen. INTERVENTION: CT-scan evaluation. RESULTS: A significantly lower increase (a mean aortic body dilatation of 6.8%) of the graft-size was found for this reverse locknitted Dacron (p < 0.001) compared to two wrap knitted Dacron grafts (collagen impregnated and uncoated knitted Dacron) (31.0% and 37.8% respectively). At the femoral level mean dilatation rates of respectively, 2.5%; 23.8% and 31.7% were found. Mural thrombus was observed in three grafts. No false aneurysms, graft degradation or graft occlusions were observed. CONCLUSION: It was concluded that reverse locknitted Dacron dilates to a minimum, however, further studies are needed to evaluate the relation of graft-composition/structure and dilatation.

Aged↗
PubMed1995

Metabolic response of granulocytes and platelets to synthetic vascular grafts: preliminary results with an in vitro technique.

The metabolism of granulocytes as well as platelets evoked by incubation with different synthetic vascular grafts was monitored during 6-h batch experiments using microcalorimetry. Standard knitted Dacron grafts, ePTFE-grafts, knitted Dacron grafts with collagen impregnation, and knitted Dacron grafts with external collagen-coating were used. The heat production per cell was calculated. A rapid increase of metabolic activity followed by a gradual decrease was demonstrated with both granulocyte suspension and platelet concentrate. Significant differences were obtained between the materials with a maximum response of Dacron grafts with collagen impregnation for both granulocyte and platelet response. The materials had different surface morphologies regarding cell adhesion after incubation as demonstrated with scanning electron microscopy with more pronounced adhesion on the collagen-impregnated grafts. The results suggest that microcalorimetry may be useful for the evaluation of cellular reactions on different biomaterials. However, further studies have to reveal the specificity of the reactions.

Animals↗
PubMed1995

Reticuloendothelial system function in acute liver injury induced by D-galactosamine.

AIMS/METHODS: Reticuloendothelial system function, as assessed by clearance of radiolabelled bacteria, was evaluated in acute liver injury induced by D-galactosamine in rats, and compared with that after 70% liver resection model. RESULTS: Reticuloendothelial system function was significantly impaired in both instances, but the extent and the pattern of reticuloendothelial system impairment differed in the two models. While the elimination rate of the radiolabelled bacteria (k-value) decreased in both the liver resection and D-galactosamine groups (19% and 52%, respectively), the corrected phagocytic index (alpha) increased in 70% liver resection (247%), indicatine increased activity among the remaining reticuloendothelial system cells of the liver. Estimation of subserosal organ blood flow showed decreased flow to the cecum and distal small intestine (correction of intesting) in both groups, whereas it was significantly increased (477%) in the remaining parts of the liver in the liver resection group. CONCLUSIONS: These findings show that reticuloendothelial system activity is deranged in both these groups, which may explain the increased occurrence of bacterial complications observed in corresponding clinical conditions.

Animals↗