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Biomedical subjects

L G Friberg

Publications and source records attributed to L G Friberg.

At least 19 recordsLinked to original sources
PubMed2003

Pharmacological inhibition of plasma coagulation and platelet activation during experimental long-term perfusion.

OBJECTIVE: During extracorporeal circulation, initial contact between blood and the artificial surface of the circuit induces an overall activation of the hemostatic system. The objective of this study was to investigate the combined effect of epoprostenol (PGI (2) ), nitric oxide (NO) and nafamostat mesilate (FUT-175, a serine protease inhibitor), on plasma coagulation and platelet activation during experimental long-term perfusion. DESIGN: Two identical extracorporeal life support (ECLS) circuits were primed with fresh, heparinized human blood, and circulated for 24 h. FUT was given with a bolus dose of 85 mg/l blood at the initiation of the experiment and thereafter as a continuous infusion of 14 mg/l/h. PGI (2), at a rate of 2.4 microg/l/h, was also administered to the experimental circuit, and 120 ppm NO gas was added to the oxygenator sweep gas. The other circuit was used as a control. RESULTS: Higher platelet count and platelet membrane expression of GPIb were found in the experimental circuits as compared with control circuits. The levels of thrombin/antithrombin III complex (TAT) and prothrombin fragment 1 + 2 (F1 + 2) increased significantly over time in the control circuits but remained low in the experimental circuits. Plasma levels of plasminogen activator inhibitor 1 (PAI-1) decreased rapidly in both circuits but were higher in the control circuits at each time point studied. CONCLUSION: The activation of platelets and of the coagulation system encountered during extracorporeal perfusion is consistently inhibited by a combination of PGI (2), NO and FUT-175. The combination of these drugs appears to be more effective than each drug separately.

Antithrombin III↗
PubMed2000

Influence of hemofiltration on plasma cytokine levels and platelet activation during extra corporeal membrane oxygenation.

OBJECTIVE: Extra corporeal circulation of human blood is used daily in lifesaving procedures such as open-heart surgery and extracorporeal membrane oxygenation (ECMO). But extracorporeal circulation also induces activation of various cascade reactions in the blood. The objective of this study was to evaluate the effects of hemofiltration on cytokine release and removal as well as on platelet activation and consumption. MATERIAL AND METHODS: Two complete ECMO systems, each of them holding a hollow fiber oxygenator, a bladder box, PVC tubing and a roller pump were perfused for 24 h with fresh, heparinized human blood. A hemofilter was added to one of the paired systems. Blood samples were collected from both circuits before start, and at 0.5, 1, 3, 12 and 24 h of perfusion. A total of 8 paired experiments was performed. RESULTS: The plasma concentration of interleukin (IL)1beta, IL-6 and IL-8, as well as of IL-1 receptor antagonist (IL-1ra) increased over time in both systems, but consistently lower levels were observed in the filter circuits compared to the controls. Only minor parts of these cytokines could be assayed in the ultrafiltrate. No significant difference in platelet count and platelet membrane expression of glycoprotein Ib was observed between the circuits. CONCLUSIONS: By adding a hemofilter to the ECMO circuit, it is possible to reduce the plasma concentration of interleukins without significantly affecting platelet activation and consumption.

Cytokines↗
PubMed1998

Induced cell trauma during in vitro perfusion: a comparison between two different perfusion systems.

The purpose of this study was to compare blood cell activation during in vitro long-term perfusion using 2 parallel in vitro extracorporeal membrane oxygenation (ECMO) systems. We compared two substantially different perfusion systems, an assistance respiratoire extra corporelle (AREC) system on one hand, containing an AREC pump, silicon tubing, and a hollow-fiber oxygenator, and a centrifugal pump system, on the other hand, containing a Biomedicus centrifugal pump, PVC tubing, and a membrane oxygenator. We measured the platelet count using an automated blood cell counter. Platelet activation was evaluated using a flow cytometric technique for the platelet membrane expression of glycoproteins and ELISA for the plasma concentration of beta-thromboglobulin (beta-TG), a platelet specific protein released into the blood upon platelet activation. The neutrophil count was assayed using an automated blood cell counter and the plasma concentration of cytokines using an ELISA kit. A significant difference between the two systems was observed in terms of the platelet membrane expression of glycoprotein (GP)Ib (p=0.0001) and GPIIb/IIIa (p=0.0037), indicating a lower degree of platelet activation in the AREC system. The concentration of neutrophils was significantly lower in the centrifugal system (p=0.002) compared to the AREC system. The neutrophil membrane expression of CD11b was significantly lower (p=0.0067) in the AREC system, indicating a lower degree of neutrophil activation compared to the centrifugal pump system. A significantly lower degree of hemolysis, as expressed by plasma hemoglobin, was observed in the AREC pump system (p=0.0491). In conclusion, lower degrees of the platelet membrane expression of GPIb and GPIIb/IIIa and of the neutrophil membrane expression of CD11b were observed in the AREC system, indicating a lower degree of platelet and neutrophil activation in this system. No significant difference between the two systems as to the plasma concentration of interleukin (IL)-1beta, IL-6, or IL-8 could be recorded. Further studies are warranted to specify the role of each individual component of the two systems.

Blood Platelets↗
PubMed1998

Cytokine release during long-term extracorporeal circulation in an experimental model.

The objective of this study was to determine the degree of leukocyte activation, as measured by cytokine release, in circulating blood during experimental extracorporeal circulation. Complete in vitro extracorporeal membrane oxygenation (ECMO) circuits were used, and 9 experiments were performed. Whole blood stored at 37 degrees C was used as the control. Blood samples were withdrawn before the start of perfusion and at 24 h of perfusion. Statistically significant releases of interleukin (IL)-1beta, IL-8, and IL-1 receptor antagonist were observed in the perfusion circuits compared to both the control blood and baseline values. Also, increases in plasma tumor necrosis factor (TNF)alpha and IL-6 were seen after 24 h of perfusion although these changes did not reach statistical significance. These results indicate that extracorporeal circulation induced leukocyte activation and cytokine release. These reactions might, as an additional trauma, deteriorate the situation in an already severely ill patient. A search for methods to counteract this untoward activation seems warranted.

Adult↗
PubMed1998

The effect of albumin priming solution on platelet activation during experimental long-term perfusion.

The objective of this study was to evaluate the effect of albumin priming on platelet consumption and activation during long-term perfusion. Two identical in vitro extracorporeal membrane oxygenation circuits were used; one was primed with Ringer's solution containing human serum albumin, the other with Ringer's solution only. Fresh heparinized human blood was pooled, divided between the two systems and circulated for 24 h at 37 degrees C. Platelet count, plasma concentration of betathromboglobulin (BTG), platelet membrane density of glycoprotein (GP) Ib and of GPIIb/IIIa were assayed before the start and at 0.5, 1, 3, 12 and 24 h of perfusion. In total, seven experiments were performed. We found that during the first hour of perfusion, slightly higher platelet counts (p = 0.058) and lower BTG values (p = 0.0005) were observed in the circuits primed with albumin, compared to the control circuits. No statistically significant differences were observed for the platelet membrane expression of GPIb and GPIIb/IIIa. We conclude that albumin priming appears to transiently prevent platelet consumption and activation during long-term perfusion.

Extracorporeal Membrane Oxygenation↗
PubMed1998

The influence of a serine protease inhibitor, nafamostat mesilate, on plasma coagulation, and platelet activation during experimental Extracorporeal Life Support (ECLS).

INTRODUCTION: During extracorporeal circulation the contact between blood and the artificial surface of the circuit induces several changes in the hemostatic system. The objective of the present study was to assess the effect of a serine protease inhibitor--Nafamostat mesilate (FUT-175)--on coagulation and on platelets during experimental extracorporeal circulation. METHODS: Two identical Extra Corporeal Life Support (ECLS) circuits were primed with fresh, heparinized human blood and circulated for 24 h. FUT-175 was added to one of the paired circuits and the other was used as a control. The following FUT-175 concentrations were employed: (1) 7.1 mg/l/h, (2) 14.2 mg/l/h, (3) 14.2 mg/l/h + 85.5 mg given as an initial bolus, (4) 28.5 mg/l/h + 171 mg given as an initial bolus. Blood samples were collected from the circuits before the start of the perfusion and at 0.5, 1, 3, 12, and 24 h of perfusion, and analysed for platelet count, plasma betathromboglobulin (beta-TG), platelet membrane glycoprotein (GP) Ib and GPIIb/IIIa expression, thrombin/antithrombin III complex (TAT), prothrombin fragment 1+2 (F1+2), fibrinogen, D-dimer, and plasminogen activator inhibitor 1 activity (PAI-1). RESULTS: Significantly higher platelet membrane GPIb expression and lower plasma beta-thromboglobulin levels were observed in the circuits holding FUT-175, suggesting a lower degree of platelet activation. Also, a reduced activation of the coagulation system was observed in the "FUT-circuits", as reflected by the levels of F1+2 and TAT, and the PAI-1 activity that was rapidly inactivated. CONCLUSION: FUT-175 reduces the activation of platelets and plasma coagulation in an in vitro ECLS model.

Anticoagulants↗
PubMed1998

The effect of cardiopulmonary bypass on blood cell filterability in children undergoing cardiac surgery.

BACKGROUND: The extended use of cardiopulmonary bypass (CPB) in cardiac surgery is limited because of damage to blood which in adults has been assessed by alterations in blood cell rheology. Blood trauma assessment in children is difficult because of the restrictions in sample volume and frequency but needs to be established from time to time in order to study the tolerance to new surgical and extracorporeal techniques. MATERIALS AND METHODS: Fourteen pediatric patients undergoing cardiac surgery with CPB for congenital heart disease corrections were studied. Whole blood, red blood cell and white blood cell rheology (filterability) were monitored before, during and after CPB using the St. George filtrometer that used small amounts of blood. RESULTS: The results showed that all the rheologic parameters were altered during the blood trauma of CPB and were outside the reference values before, during and after CPB. CONCLUSIONS: This suggested that blood cell rheologic disturbances did not recover soon after CPB and this may be of interest in long term follow-up to understand responses and recovery patterns to disease and interventions associated with pediatric heart surgery using CPB.

Blood Cell Count↗
PubMed1996

Nitric oxide in the oxygenator sweep gas reduces platelet activation during experimental perfusion.

BACKGROUND: Hemorrhage is a major complication experienced in 10% to 35% of neonates treated with extracorporeal life support (ECLS). The increased bleeding tendency is partly due to an ECLS-induced thrombocytopenia and impaired platelet function. In the present study, we evaluated the effect of nitric oxide on the ECLS-induced platelet consumption and activation. METHODS: Two identical in vitro ECLS circuits were primed with fresh, heparin-treated human blood and circulated for 24 hours. Nitric oxide (15, 40, or 77 ppm) was added to one of the oxygenators in each pair. Eight paired experiments were performed. Platelet count, plasma beta-thromboglobulin, platelet serotonin content, plasma nitrate, plasma cyclic guanosine monophosphate, and platelet membrane glycoprotein Ib were assayed before the start and at 0.5, 1, 3, 12, and 24 hours of perfusion. RESULTS: Plasma nitrate and plasma cyclic guanosine monophosphate levels were significantly higher in the nitric oxide circuits than in the control circuits (p < 0.01). Higher platelet counts (p < 0.01) and lower beta-thromboglobulin levels (p < 0.01) were observed in the nitric oxide circuits compared with the control circuits. However, no significant differences in platelet serotonin content or platelet membrane glycoprotein Ib density were noted between the circuits. CONCLUSIONS: Nitric oxide probably reduces platelet consumption and platelet activation during ECLS.

Analysis of Variance↗
PubMed1996

Platelet activation and degradation in an experimental extracorporeal system. A comparison between a silicone membrane and a hollow-fibre oxygenator.

Blood platelets are rapidly activated in contact with biomaterials and, therefore, can be used as markers of the biocompatibility of various components in an extracorporeal system. In the present work two different oxygenators, one membrane oxygenator (Avecor) and one hollow-fibre oxygenator ("Lilliput', Dideco) were compared. Complete in vitro extracorporeal membrane oxygenation circuits were perfused with fresh, heparinized human blood for 24 h. Eight experiments were performed with the hollow-fibre oxygenator and five experiments with the membrane oxygenator. Blood gases, electrolytes, glucose and haematocrit were kept within physiological limits. Platelet count, plasma concentration of beta-thromboglobulin, platelet serotonin content, platelet membrane glycoprotein lb and its degradation product glycocalicin, as well as plasma haemoglobin concentration were assayed. As regards most of these variables, significant differences in favour of the hollow-fibre oxygenator were observed.

Extracorporeal Membrane Oxygenation↗
PubMed1995

Improved control of invasive cervical cancer in Sweden over six decades by earlier clinical detection and better treatment.

PURPOSE: Cancer of the cervix uteri can be controlled by cytologic screening for the detection of precursor lesions, but such intervention remains unrealistic in many countries in which this cancer is common. The possibility of reducing mortality by earlier clinical detection, followed by basic therapy, has never been properly assessed. PATIENTS AND METHODS: We compiled records of incident cases of invasive cancer of the cervix diagnosed in a defined area of Sweden from 1930 through 1990. In a cohort of 6,044 women, we analyzed temporal trends in incidence and survival by clinical stage and age at diagnosis. Generalized proportional hazards models were used to study several factors simultaneously and quantify the overall reduction in mortality. RESULTS: For each successive stage at diagnosis, the overall risk of dying increased 2.5-fold (95% confidence interval [CI], 2.4 to 2.7). From 1930, a marked improvement in stage distribution was accompanied by increasing survival rates in stages I and II disease. These changes largely took place before the introduction of screening and external-beam radiation. The 10-year relative survival rate increased from 33% in the 1930s to approximately 55% in the 1950s and thereafter. CONCLUSION: Improvements in public and professional awareness of cervical cancer resulted in diagnoses at earlier clinical stages. The rate of cure in early stages improved when basic local treatment was introduced, but only little of the progress was attributable to the introduction of more advanced treatment technologies. These findings offer considerable hope for a substantial reduction in the mortality of cervical cancer without cytologic screening, even in countries with limited resources.

Adult↗
PubMed1995

Carboplatin in combination with epirubicin and cyclophosphamide in patients with advanced ovarian cancer. A phase II study.

Seventy-one patients with epithelial ovarian cancer stage III (n = 56) or IV (n = 15) were treated with carboplatin 300 mg/m2, epirubicin 50 mg/m2 and cyclophosphamide 400 mg/m2 every fourth week. Patients clinically free of tumour after six courses (n = 58) underwent a second-look laparotomy. Seventeen patients were microscopically tumour-free (24% of all) and an additional 10 (14%) had only microscopic cancer. Median time to progression was 19 months. The median survival was 33 months and the estimated 5-year survival 27%. The toxicity was mainly haematological, with leukopenia WHO grade 3-4 seen in 88% and thrombocytopenia grade 3-4 in 42% of the patients. The gastrointestinal toxicity was mild and no renal toxicity was seen. This chemotherapy regimen was effective with acceptable toxicity and could be given on an out-patient basis. The possibility of increasing the efficacy and decreasing the toxicity was discussed.

Adult↗
PubMed1995

Blood platelet activation and membrane glycoprotein changes during extracorporeal life support (ECLS). In vitro studies.

The aim of this study was to evaluate an in vitro model for investigation of platelet function parameters in an extracorporeal system. Two different perfusion pumps were compared, a roller pump (Polystan) and a centrifugal pump (Biomedicus). A continuous increase in glycoprotein (GP)1b-negative platelets was observed in both circuits. A marked increase of plasma beta-thromboglobulin thromboglobulin concentration and a decrease of the intracellular pool of serotonin was observed, indicating a marked release of alpha as well as of dense granules. The plasma concentration of glycocalicin increased in parallel with a reduced platelet surface expression of GP1b, suggesting that the loss of GP1b is caused by proteolysis rather than by a downregulation of this receptor protein. It is concluded that ECLS results in a pronounced platelet degranulation and causes changes of important membrane receptors which might explain some of the bleeding problems observed in patients treated with ECLS. No significant difference was noted between the roller pump and the centrifugal pump. Trial of strategies, e.g., protease inhibitors and nitric oxide to revert this untoward effect of ECLS are highly warranted.

Artificial Organs↗
PubMed1994

Survival trend after invasive cervical cancer diagnosis in Sweden before and after cytologic screening. 1960-1984.

BACKGROUND: Cytologic screening can reduce mortality from cervical cancer by detection and removal of premalignant lesions. Conceivably, mortality is further reduced because more women with invasive disease are diagnosed at an earlier, curable stage. This hypothesis can be assessed in Sweden, where population-based screening programs were introduced successively over about a decade starting in 1964. METHODS: Record linkages permitted complete follow-up through 1986 of all 17,377 patients with invasive cervical cancer diagnosed in Sweden from 1960 through 1984. We analyzed relative survival rates that describe the survival of patients after elimination of the effects of causes of death other than cancer of the cervix. RESULTS: Prognosis improved substantially in patients younger than age 50 years at diagnosis; from 1960-1964 to 1980-1984, the 5-year relative survival rate increased from 69.8% to 88.8% at age 20-29 years, from 71.7% to 85.5% at age 30-39 years, and from 68.6% to 77.9% at age 40-49 years. The excess mortality was thus reduced by more than half in patients diagnosed when younger than 40 years. In contrast, only slight or no improvement was noted in those diagnosed at older ages when screening was less extensive. In all time periods, a strong association was found between older age at diagnosis and poorer prognosis. CONCLUSION: Although alternative explanations for our findings must be seriously considered, the most obvious interpretation is that cytologic screening reduces mortality from cervical cancer by earlier diagnosis of invasive disease.

Adult↗
PubMed1994

Prognostic value of DNA ploidy and S-phase fraction in endometrial cancer stage I and II: a prospective 5-year survival study.

Knowledge of reliable prognostic factors is essential in cancer treatment. Especially when intensified treatment is to be considered to improve the overall result, it is desirable to identify well-defined high-risk groups. In a prospective study DNA ploidy and S-phase fraction were measured in 88 patients with endometrial cancer stage I and II. Fresh tumor samples were analyzed using flow cytometry prior to treatment. Diploid tumors represented 84% of the cases, and aneuploid represented 16%. The mean S-phase fraction in diploid tumors was 10%, as compared with 22% in aneuploid tumors. The follow-up time was 5 years in all cases. The survival rate for patients with diploid tumors was 92% and for aneuploid tumors 36%. In the surviving patients, the mean S-phase fraction was 10.4%, a significant difference from 19.9% in the nonsurviving patients (P < 0.001). The highest mortality was found when aneuploidy was combined with an S-phase fraction over 20%, with only 11% survival for 5 years. In diploid tumors with an S-phase fraction below 20%, the survival rate was 92%. In a stepwise regression analysis, S-phase fraction was found to be of the most important prognostic value, followed by myometrial invasion and stage of the tumor and ploidy. Grade was not found to be of any important significance.

Adult↗
PubMed1994

The effect of prolonged perfusion with a membrane oxygenator (PPMO) on white blood cells.

Preserving the rheological properties of whole blood cells is vital for their smooth passage in the capillaries without causing blockage and disturbances in the microcirculation. To evaluate the effect of mechanical trauma on the rheology of white blood cells during prolonged perfusion with membrane oxygenation (PPMO), 16 in vitro experiments were conducted for 72 hours. The St George Carrimed Filtrometer was used to estimate the plasma white cell filtration rates (P-WFR). Also an in vitro estimation of the ability of individual cells to pass through capillaries, the white blood cell clogging rate (WBC-CR), the number of clogging particles (WBC-CP), the total white blood cell count (T-WBC) and two in vitro estimations to assess the effect of aggregates and stiff cells in blocking the microcirculation were performed. The traumatized white cells reduced their mean P-WFR by 37% +/- 9, 72% +/- 2 and 76% +/- 2 at 24, 48 and 72 hours respectively (p < 0.001). The mean WBC-CR was increased to 15.2 +/- 1.5, 32.6 +/- 2.2 and 40.3 +/- 8.3 x 10(2)%/ml at 24, 48 and 72 hours respectively (p < 0.001). The mean WBC-CP was increased to 6.6 +/- 1.5, 9.7 +/- 1.2 and 13.9 +/- 2.1 x 10(6)/ml at 24 hours (p < 0.05), 48 and 72 hours respectively (p < 0.001). The T-WBC was decreased to 55% +/- 0.3, 23% +/- 0.2 and 14% +/- 0.1 and 14% +/- 0.1 at 24, 48 and 72 hours respectively (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal Membrane Oxygenation↗
PubMed1994

Resection+carotid flap plasty. A new surgical technique for newborn children with coarctation of the aorta and critical hypoplasia of the aortic arch.

Coarctation of the aorta with critical hypoplasia of the aortic arch is a ductus dependent malformation-complex often combined with severe intracardiac malformations with a common denominator: there is a predominance of the pulmonary circulation and a flow restriction through the ascending aorta. Coarctation of the aorta with critical hypoplasia of the aortic arch may be looked upon as a malformation bordering on hypoplastic left heart syndrome. The degree of aortic arch hypoplasia seems to mirror the severity of the intracardiac malformation. The first objective in reconstructing these hearts is to create an unobstructed flow through the aortic arch. Resection of the coarcted segment combined with carotid flap plasty is a surgical alternative which fulfils this objective. We have used the technique in premature-born and severely ill neonates where one-step total correction was considered contraindicated. Thirteen neonates were operated upon, there were no cerebral consequences referable to the carotid artery ligation and no recoarctations.

Anastomosis, Surgical↗