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B Risberg

Publications and source records attributed to B Risberg.

At least 91 records · Page 5Linked to original sources

Release of markers of myocardial and endothelial injury following cold cardioplegic arrest in pigs.

Cold cardioplegic arrest causes reperfusion injury to both endothelium and myocardium. We investigated release of troponin-T (TnT), tissue plasminogen activator activity (t-PA) and histamine (HA) from the heart before and after 2h of cold crystalloid cardioplegia in eight Swedish landrace pigs. Coronary sinus blood flow was measured in an external shunt between the coronary sinus and the right atrium. TnT, t-PA and HA were measured concomitantly in arterial and coronary sinus plasma, and the cardiac release was calculated. Cardiac release of TnT increased from 18 (15-25) micrograms/min (median (central 90% percentile)) before cold cardioplegia to maximum 281 (132-510) micrograms/min 30 min after aortic declamping (p < 0.02 vs initial value). t-PA rose from -4 (-52-34) to maximum 249 (75-691) IU/min 2 min after declamping (p < 0.01) and thereafter returned to baseline levels. The net cardiac release of HA was 72 (-80-1321) nmol/min before cardioplegia, rising to 234 (-188-524) after 2 min of reperfusion (p < 0.02) and returning to baseline after 30 minutes. We conclude that the porcine heart releases t-PA, Tn-T and HA during postcardioplegic reperfusion. The differing kinetics of their release may indicate different affection of the myocardium and the endothelium. Tn-T, t-PA and HA are potential markers of myocardial and endothelial injury in the porcine heart.

Animals↗

Adhesions: preventive strategies.

Adhesions, which occur after 67% to 93% of abdominal operations, represent a major clinical problem, resulting in intestinal obstruction, infertility, and pain and incurring considerable economic costs. The magnitude and seriousness of the problem of adhesions have been underappreciated. Moreover, efforts to prevent or reduce adhesions largely have been unsuccessful, hindered by their empirical basis, the lack of good predictive animal models, and the biochemical complexities of adhesiogenesis. The two major strategies for adhesion prevention or reduction are adjusting surgical technique and applying adjuvants. Modifications in technique that all surgeons should implement include minimizing the invasiveness of surgery, minimizing surgical trauma, such as ischemia from peritoneal suturing, and avoiding the introduction of foreign material, e.g., starch glove powder, into the body. Given the adhesiogenic nature of peritoneal repair, however, improvements in surgical technique alone will help decrease but not prevent adhesion formation. Adjuvant therapy is necessary. Adjuvants fall into two main categories, drugs and barriers. Nonsteroidal anti-inflammatory drugs have shown questionable clinical efficacy, possibly because of difficulties in drug delivery. Corticosteroids, alone or with antihistamines, also have had equivocal clinical results and may be immunosuppressive and delay wound healing. Experimentally, fibrinolytics such as tissue plasminogen activator (tPA), administered systemically or intraperitoneally (i.p.), have demonstrated conflicting results and hemorrhagic complications. However, recently, tPA, administered topically in a carboxymethylcellulose (CMC) gel, has been effective in reducing and preventing adhesions in rabbits. Phosphatidylcholine, given i.p. or orally, also has shown promise in animal studies. Barriers, by separating traumatized surfaces for the critical first five to seven days of peritoneal re-epithelialization, are useful adjuvants, and include macromolecular solutions and mechanical devices. Dextran, a macromolecular solution, has been studied widely, but has not demonstrated consistent clinical efficacy and has been largely abandoned as an anti-adhesion barrier. A newly developed hyaluronic acid-phosphate-buffered saline solution applied intraoperatively to protect peritoneal surfaces from indirect surgical trauma effectively and safely reduced adhesions in a large multicenter study of women undergoing gynecological laparotomy. Three recently developed mechanical barriers also have demonstrated clinical progress in adhesion prevention. A bioresorbable membrane consisting of hyaluronic acid and CMC has gained regulatory approval for clinical use in both general and gynecological surgery following demonstration of efficacy and safety in reducing adhesions. A barrier made of expanded polytetrafluoroethylene and another developed from oxidized regenerated cellulose are currently available for gynecological surgery. With continued research, new and improved approaches hopefully will become available to prevent adhesion formation.

Adrenal Cortex Hormones↗

Adhesions: pathogenesis and prevention-panel discussion and summary.

This article summarizes the discussions of the faculty and chairpersons on four major topics on postsurgical adhesions examined at the symposium, "Adhesions: Pathogenesis and Prevention". These topics are: 1) clinical significance; 2) pathogenesis; 3) research status and directions; and 4) recommendations for reduction or prevention. Abdominal postsurgical adhesions develop following trauma to the mesothelium, which is damaged often by surgical handling and instrument contact, foreign materials such as sutures and glove dusting powder, desiccation, and overheating. Postoperative adhesions occur after most surgical procedures and can result in serious complications, including intestinal obstruction, infertility, and pain. A long-term and unpredictable problem, postoperative adhesions impact the surgical workload and hospital resources, resulting in considerable health care expenditures. Although understanding of the pathogenesis of adhesions has improved recently, the molecular mechanisms involved continue to be delineated. Adhesions result from the normal peritoneal wound healing response and develop in the first five to seven days after injury. Adhesion formation and adhesion-free re-epithelialization are alternative pathways, both of which begin with coagulation which initiates a cascade of events resulting in the buildup of fibrin gel matrix. If not removed, the fibrin gel matrix serves as the progenitor to adhesions by forming a band or bridge when two peritoneal surfaces coated with it are apposed. The band or bridge becomes the basis for the organization of an adhesion. Protective fibrinolytic enzyme systems of the peritoneum, such as the plasmin system, can remove the fibrin gel matrix. However, surgery dramatically diminishes fibrinolytic activity. The pivotal events determining whether the pathway taken is adhesion formation or re-epithelialization are therefore the apposition of two damaged surfaces and the extent of fibrinolysis. Research in postsurgical adhesion formation and prevention abounds in a variety of avenues of investigation, including: 1) identification on a molecular level of the components involved in adhesiogenesis and their interactions; 2) clarification of the role of fibrin and fibrinolysis in adhesion formation; 3) standardization of design in preclinical and clinical studies of adhesion formation and prevention; 4) delineation of the relationship between adhesion formation and adhesive complications; and 5) elucidation of efficient, site-specific methods of prophylactic drug delivery. Currently, it seems logical to focus preventive research on development of barriers, fibrinolytic drugs, and selected agents such as phospholipids. The major strategies for adhesion prevention or reduction are adjusting surgical practice and applying adjuvants. Surgeons should adjust their major practices by: 1) becoming aware of the potential adhesive complications of a procedure; 2) minimizing the invasiveness of surgery; and 3) minimizing surgical trauma, ischemia, exposure to intestinal contents, introduction of foreign material into the body, and the use of talc- or starch-containing gloves. Available adjuvants include a newly developed by hyaluronic acid-phosphate-buffered saline solution applied intraoperatively to protect peritoneal surfaces from indirect surgical trauma and three mechanical barriers. One of these, a bioresorbable membrane consisting of hyaluronic acid and carboxymethylcellulose, has demonstrated efficacy and safety in both general and gynecological surgery. The other two barriers, one made of expanded polytetrafluoroethylene and one developed from oxidized regenerated cellulose, are indicated only for use in gynecological surgery.

Humans↗

Adhesions: prevention and complications in general surgery.

OBJECTIVE: To document the incidence of adhesion-related problems and the current concepts on the prevention of adhesions among Swedish surgeons. DESIGN: Postal questionnaire during 1992. SETTING: Sweden. MATERIAL: All surgical units performing abdominal surgery. MAIN OUTCOME MEASURES: Number of patients admitted with or operated on for adhesive small bowel obstruction, methods in use to prevent the formation of adhesions, and costs of adhesion-related complications in abdominal surgery. RESULTS: At least 4700 patients were admitted annually with symptoms of adhesive small bowel obstruction. Of these, 2200 were operated on to relieve the obstruction. No consistent methods were in use to minimise formation of adhesions. Surgical gloves were not washed before operation by 49 of the 84 units that replied and of those only 12 always used powder-free gloves, which gives a likelihood of starch contamination in 70%-82% of all operations. Only 13 (16%) of the units consistently avoided suturing the peritoneum separately. Yearly, at least 1500 laparotomies were complicated by previously formed adhesions. The annual medical expenditure for adhesive small bowel obstruction was more than US $6 million. CONCLUSIONS: Postoperative adhesion formation created substantial morbidity and workload in surgical units. Efforts to reduce the formation of adhesions must be instituted. To start this process, the suturing of peritoneum and the use of powdered gloves could be omitted from clinical practice.

Data Collection↗

Cervex-Brush vs. spatula and Cytobrush. A cytohistologic evaluation.

OBJECTIVE: To compare the efficacy of two cervical smear instruments, Cervex-Brush and spatula plus Cytobrush. STUDY DESIGN: Cervical smears were taken before laser ring biopsies in 213 women, who were randomized for the Cervex-Brush or spatula plus Cytobrush (S+C). The cytologic diagnosis was compared to the histologic diagnosis after laser ring biopsy. RESULTS: The correlation between cytology and histology showed comparable concordance (54% and 42%) for the two devices. In 130 (74 with Cervex-Brush and 56 S+C) patients, histology revealed moderate dysplasia or more advanced lesions. Those cases were further analyzed for smear failures. Negative smears were found in 13 cases (10 in the Cervex-Brush and 3 in the S+C group). This difference in favor of S+C was not, however, statistically significant. Significantly more false negative smears were found when endocervical cells were absent and in patients 30-39 years of age. CONCLUSION: Modern sampling devices, such as the Cervex-Brush and S+C, seem to be equally efficient in obtaining dysplastic squamous cells. Other factors of importance for nonrepresentative cervical smears should be studied in order to improve efficacy.

Adult↗

Cost of bowel obstruction resulting from adhesions.

OBJECTIVE: To assess the direct costs associated with bowel obstruction resulting from adhesions. DESIGN: Prospective study. SETTING: University Hospital, Sweden. SUBJECTS: 57 patients aged 16 years or older who fulfilled the clinical and radiological criteria of bowel obstruction. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Course of, and direct costs associated with, the illness. RESULTS: In 34 of the 57 patients (60%) bowel obstruction was caused by adhesions, and in all 34 the small bowel was obstructed (85% of all cases of small bowel obstruction). 22 of the 42 patients who required a hospital stay of more than 24 hours (52%) had adhesive obstruction, and 10 of these (45%) had to be operated on, 2 of them twice. Major complications occurred in 6 (60%) and one died. In a national perspective, adhesive bowel obstruction may cause 2330 hospital admissions annually, which is associated with an estimated direct cost of about US$13 million. CONCLUSIONS: Adhesions are a serious, common, and costly complication of surgery. Efforts have to be undertaken to control their formation.

Adult↗

Antithrombotic effect of two low molecular weight thrombin inhibitors and a low-molecular weight heparin in a caval vein thrombosis model in the rat.

A sensitive thrombosis model with a high reproducibility was developed in the rat, utilizing stasis of the caval vein and a standardized surgical trauma as the only thrombogenic stimuli. Since no procoagulant substances were used, the results of the present study might be relevant in a clinical situation. The antithrombotic effect of two recently synthesized low-molecular-weight thrombin inhibitors have been compared to dalteparin, (Fragmin) a low-molecular-weight heparin fragment. Each compound was studied at 8 different doses with 10 rats in each group. On a gravimetric basis, the thrombin inhibitor melagatran was twice as potent as dalteparin (ED50 16 and 33 microg/kg per h, respectively). The second thrombin inhibitor, inogatran, had an intermediate effect, with an ED50 of 24 microg/kg per h. No differences in antithrombotic effect were, however, found when the compounds were compared at anticoagulant equivalent doses (same APTT prolongation). A 50% reduction in the mean thrombus weight was obtained when APTT was prolonged to 1.2 to 1.3 times the pretreatment value.

Animals↗

Spontaneous nitroblue-tetrazolium (NBT) reduction related to granulocyte priming and activation.

The aim of the present study was to explore the relationship between the increasing level of spontaneous NBT-reduction and the tendency for PMNs to marginate during experimental hemorrhagic shock in rats. Rat PMNs, isolated on Percoll density gradients or suspended in blood, were examined by chemiluminescence (CL), NBT-test and by their CD-18 expression and F-actin formation. The NBT-test generally produced higher numbers of activated PMNs when the cells were suspended in buffer than in whole blood, probably due to the scavenging properties of blood. The level of spontaneous NBT-reduction of PMNs in blood correlated with the magnitude of the NBT-response to f-MLP stimulation in blood and buffer. On the contrary, there were no significant correlations between spontaneous NBT reduction, CD18 expression and F-actin content. Thus, high levels of spontaneous NBT reduction in blood were associated with priming of the separated PMNs rather than increased rigidity (F-actin) or adhesiveness (CD18).

Actins↗

Fibrinolysis in human peritoneum during operation.

BACKGROUND: A reduced local fibrinolysis seems to be an important mechanism in the formation of adhesions. Peritonitis may cause adhesions, and the aim of the present study was to determine peritoneal fibrinolytic capacity in inflamed and normal peritoneum. METHODS: Biopsy specimens from normal and inflamed human peritoneum were taken at the beginning and end of operation. After extraction plasminogen activator activity (PAA) was determined by using a chromogenic substrate assay in the presence or absence of inhibitory antibodies against tissue-type plasminogen activator (t-PA), urokinase or plasminogen activator inhibitor-1. RESULTS: t-PA exerted 95% of the PAA. PAA was significantly reduced (p < 0.01) during peritonitis (3.0 IU/micrograms protein; range, 0.3 to 4.2) compared with normal peritoneum (7.1 IU/micrograms protein; range, 0.6 to 18.1). A significant reduction (p < 0.05) in PAA occurred during operation both in normal peritoneum (3.8 IU/micrograms protein; range, 0.8 to 8.6) and in peritonitis (0.6 IU/micrograms protein; range, 0.16 to 2.1). Values are given as medians. CONCLUSIONS: The main PAA in human peritoneum was t-PA. The activity was decreasing during operation and reduced in peritonitis. This reduction in PAA might be a local response to inflammation.

Abdomen↗

Clinical experience with a bifurcated endovascular graft for abdominal aortic aneurysm repair.

PURPOSE: The purpose of this study was to test a transfemoral system of bifurcated endovascular graft insertion for aortic aneurysm repair. METHODS: Bifurcated endovascular grafts were inserted through bilateral femoral artery cutdowns in 41 patients. The results were assessed by completion angiography and follow-up computed tomography. RESULTS: The second half of the study included more aneurysms 6 cm or larger (p < 0.05) and more instances of short proximal neck (p < 0.05), proximal neck angulation (p < 0.05), and iliac angulation (p < 0.05). Despite the increasingly challenging anatomy, the results were better in the second half of the study as illustrated by the lower overall combined morbidity/mortality rate (15% vs 50%) and higher overall success rate (85% versus 65%). The mortality rate for the series as a whole was 7.5%. Mean follow-up was 18.8 months for the first 20 patients and 10.9 months for the second 20. The commonest complication in the first half of the study was graft thrombosis (n = 5). This complication was absent from the second half of the study because of routine adjunctive stenting. Two patients died of complications of endovascular repair. In both cases aneurysm rupture on the third postoperative day was associated with coagulopathy and angiographic signs of perigraft leak. CONCLUSION: Aneurysm exclusion with a bifurcated endovascular graft was feasible in a wide range of patients, but when the aneurysm was not entirely excluded from the circulation, the risk of rupture persisted.

Aorta, Abdominal↗

Are self-expanding stents superior to balloon-expanded in dilating aortas? An experimental study in pigs.

OBJECTIVE: To study the stent/vessel interaction and distensibility following the natural increase in vascular diameter using self-expanding and balloon-expanded stents. DESIGN: Open experimental study. SETTING: Animal laboratory, university hospital. MATERIALS AND METHODS: Eight Palmaz (P) and eight Gianturco (G) stents were transluminally placed in the infrarenal aortas of 16 pigs. Pulsatile diameter changes above, at and below the stents were non-invasively monitored with an ultrasound phase-locked echo-tracking system before and immediately after stenting and at 4 and 18 weeks. Blood pressure was registered intra-arterially and stiffness (beta) was calculated. Intravascular ultrasound (IVUS) was performed at 18 weeks. RESULTS: Median weight increased from 20 kg (19-26) to 93 kg (62-130). Diameter of the aorta increased 60%. In group P no pulsatile diameter change could be measured at the stent (beta = infinity). In group G stenting increased stiffness from beta 20.7 (9.2) to 43.2 (8.0) (p < 0.05). After 18 weeks stiffness returned to beta 20.1 (12.4). Expanded, median diameter of the P stents was 7.4 (0.8) mm, not increasing after 18 weeks. Initial diameter of the G stents was 7.8 (1.0) mm, increasing 56% to 12.2 (2.3) mm (p < 0.05). IVUS revealed the G stents to be well attached to the vascular wall, but five P stents were detached within half of the circumference. CONCLUSION: Self-expanding stents follow the pulsatile diameter change of the vessel wall, not adversely affecting distensibility after 18 weeks. They show good attachment despite 56% dilation. In contrast, the balloon-expanded stents do not show pulsatile movement and may detach during vessel diameter increase. This may be of importance when choosing stents for endovascular treatment of abdominal aortic aneurysms.

Animals↗

Heterogeneity of mitotic activity in breast cancer.

The aim of this study was to investigate to what extent mitotic activity index assessments are influenced by tumour heterogeneity. Ten invasive breast carcinomas of varying size were completely embedded, yielding 2-7 paraffin blocks per tumour. From each block, three H&E stained skip sections were cut and, in all sections, the mitotic activity index (MAI) and the mitoses per volume (M/V-)index were assessed. Coefficients of variation were calculated for the three different sampling levels (tumours, blocks, sections). In addition we recorded in how many tumours threshold discrepancies (values on both sides of the prognostic thresholds) occurred. Nested analysis of variance showed that most of the total variance occurred between the tumours. Threshold discrepancies occurred in four (40%) and five tumours (50%) for mitotic activity index and the mitoses per volume index, respectively. However, when grouping all sections from the same tumour and subjectively selecting the one showing the highest proliferation, the section with the highest mitotic activity was selected in nine of the 10 cases. In the other single case a prognostically correct value was still obtained. Thus, there is a noteworthy intra-tumour heterogeneity in mitotic activity in invasive breast cancer. We therefore propose the need to take multiple blocks per tumour and carefully scan all sections for the highest proliferative area.

Analysis of Variance↗

Different fibrinolytic potentials between human umbilical vein endothelial cells and human adult vein endothelial cells.

Endothelial cells play a central role in fibrinolysis due to their production of both tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1). The purpose of this study was to test the hypothesis that the production of t-PA and PAI-1 from human umbilical vein endothelial cells (HUVEC) and from human adult vein endothelial cells (HAVEC) adopt the same pathways for the regulation of fibrinolysis, and that differences in PAI-1 and t-PA production are only quantitative. HUVEC and HAVEC cultures were exposed to phorbol ester (PMA), endotoxin (LPS) or thrombin, singly or in combination with forskolin or H7. The conditioned medium was collected after 16 h and analyzed for t-PA and PAI-1 antigens. The basal production of both t-PA and PAI-1 was significantly higher from HUVEC than from HAVEC. Exposure to PMA, thrombin or forskolin gave a similar response from the two cell types. In contrast, the results from HUVEC and HAVEC differed significantly, not only in magnitude but also in direction, when the cells were exposed to forskolin coincubated with PMA, LPS or thrombin, and in magnitude alone when exposed to LPS only. The results indicate that there are not only quantitative but also qualitative differences in the production of t-PA and PAI-1 from HUVEC and HAVEC. These differences must be taken into account when data from cells of different origin are compared.

Adult↗

Changes in permeability of sheep's lungs by oleic acid are dose dependent.

OBJECTIVE: To evaluate a two-isotope technique to detect graded changes in pulmonary microvascular permeability. DESIGN: Open experimental study. SETTING: University hospital, Sweden. MATERIAL: Fifty-seven sheep. INTERVENTIONS: Catherisation of one carotid artery, pulmonary artery and central vein. Control group 1 (n = 10), control group 2 (n = 12) had an additional pulmonary artery balloon catheter inserted, experimental group 3 (n = 9) was given oleic acid 0.005 mg kg-1 BW, experimental group 4 (n = 12) received oleic acid 0.02 mg kg-1 BW and experimental group 5 (n = 11) 0.05 mg kg-1 BW. Groups 3-5 had all PA catheters. All animals were intubated and ventilated artificially. Duration of experiments was 6 hours. OUTCOME MEASURES: Transferrin was labelled in vivo with 113mIn chloride and erythrocytes with 99mTc following injection of stannous chloride. External gamma counting was corrected for background, decay and scatter. Blood activity was used as reference. Normalised slope index (NSI) and transferrin leak index (TLI) were calculated as measures of pulmonary microvascular permeability. RESULTS: A graded response in both NSI and TLI was found. Insertion of the PA catheter (group 2) significantly increased NSI from (group 1) (1.4 (0.1)) 10(-4) min-1 to (11 (2)) 10(-4) min-1 (p < 0.05). TLI increased significantly from (9 (2)) 10(-4) min-1 to (72 (13)) 10(-4) min-1. Oleic acid increased NSI significantly to (13 (1)) 10(-4) min-1, (32 (2)) 10(-4) min-1 and (61 (5)) 10(-4) min-1 in groups 3-5, respectively. Corresponding values for TLI were (95 (13)) 10(-4) min-1, (162 (6)) 10(-4) min-1 and (228 (26)) 10-4 min-1, respectively. CONCLUSION: The double-isotope technique of external monitoring of permeability changes to protein in the lungs was sensitive to pick up graded increments in leakage, related in a dose-dependent way to lung injury.

Animals↗