PubMed Health⌕ Search

Biomedical subjects

G Reber

Publications and source records attributed to G Reber.

At least 73 records · Page 4Linked to original sources
PubMed1992

Value of liquid crystal contact thermography and plasma level of D-dimer for screening of deep venous thrombosis following general abdominal surgery.

Because the use of radioactive fibrinogen uptake test (FUT) has become questionable both for ethical (risk of virus transmission) and technical (lack of sensitivity) reasons, we investigated the potential value of two alternative methods for screening of asymptomatic deep venous thrombosis following elective digestive surgery: liquid crystal contact thermography (LCCT) and measurement of plasma concentration of D-dimer (DD), as compared with bilateral ascending phlebography. Out of 194 patients, 185 underwent phlebography on the 8th (0-19, median and range) postoperative day. Despite prophylaxis with low-molecular-weight heparin and elastic stockings, DVT was detected on phlebography in 58 legs of 45 patients. Sensitivity of LCCT with respect to the presence of DVT was 55% (n = 184 patients) or 28% (n = 368 legs) with a specificity of 67% and 82%, respectively. These poor performances were obtained despite a good interobserver agreement for the LCCT assessments (overall kappa coefficient of 0.66 between three experts). The most accurate cut-off of DD for discriminating patients with or without DVT was 3,000 micrograms/l, as determined by ROC curve analysis. Sensitivity of a DD level of more than 3,000 micrograms/l for the presence of phlebographically documented DVT on the 8th postoperative day was 89% for a specificity of 48%. Thus, LCCT cannot be used for screening of postoperative, mainly asymptomatic DVT following general surgery. On the other hand, measurement of plasma DD may be useful for initial screening, a negative result (level less than 3,000 micrograms/l) allowing to exclude DVT (negative predictive value of 93%) and a positive result (positive predictive value of 35%) requiring confirmation by phlebography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Procoagulant activity in bronchoalveolar fluids: no relationship with tissue factor pathway inhibitor activity.

Abnormalities in local coagulation may explain alveolar fibrin deposition which often accompanies human lung injuries. The purpose of this study was to investigate the generation of procoagulant activity (PCA) and tissue factor pathway inhibitor (TFPI) in selected bronchoalveolar lavage fluids (BAL) from controls (n = 7) and from patients with interstitial lung diseases (n = 9), Pneumocystis carinii (PCP) pneumonia (n = 11) and bacterial pneumonia (n = 8). As compared with controls a significant increase of PCA was observed in the three groups with lung diseases. PCA in BAL from patients with untreated interstitial lung diseases (PC Units mean of 162 +/- 48) was significantly higher than PCA of treated patients (PC Units 36 +/- 10; p less than 0.05). Increases of PCA paralleled protein levels in BAL and the protein/albumin ratios were comparable in the four groups. TFPI was significantly increased in PCP (p less than 0.02) and bacterial pneumonia (p less than 0.03), but only marginally increased in interstitial lung diseases when compared with controls. No correlation was found between TFPI and PCA in any of the four groups. These data indicate that increased procoagulant activity observed in various lung diseases is not counterbalanced by TFPI.

Adult↗
PubMed1992

Effects of exercise test on plasma markers of an activation of coagulation and/or fibrinolysis in patients with symptomatic or silent myocardial ischemia.

It has been suggested that unstable angina at rest, like acute myocardial infarction, might be associated with a thrombotic process. In order to study the hypothesis that myocardial ischemia during exercise could also be associated with an activation of blood coagulation and/or fibrinolysis, we investigated the presence of plasma markers of a prethrombotic or thrombotic state (thrombin-antithrombin III complexes TAT, prothrombin fragment F1 + 2, and D-dimers DD) in 100 consecutive patients with confirmed or suspected coronary artery disease during ergometric test with myocardial thallium-201 scintigraphy. Symptoms and scintigrams allowed to define three groups of patients: those showing no ischemia (n = 79) and those with symptomatic (n = 8) or silent myocardial ischemia (n = 13). Before exercise, DD and TAT levels were not significantly different among the three groups. On the other hand, the F1 + 2 levels were slightly albeit significantly higher in the patients without ischemia than in the patients with symptomatic or silent ischemia. After exercise, no significant difference was found between the three groups. Exercise induced a significant and parallel increase in both the TAT and the F1 + 2 levels (but not of the DD levels) in the three groups. Thus, our study does not support the hypothesis that myocardial ischemia, silent or symptomatic, is associated with an activation of plasma coagulation and fibrinolysis that can be distinguished from the exercise-induced thrombin generation.

Adult↗
PubMed1992

Procoagulant and fibrinolytic activities in bronchoalveolar fluid of HIV-positive and HIV-negative patients.

Imbalance between intra-alveolar procoagulant activity (PCA) and fibrinolytic activity may lead to fibrin deposition, as described in several pneumopathies, and may eventually contribute to fibrotic changes as observed in Pneumocystis carinii pneumonia (PCP). The aim of our study was to compare these activities in bronchoalveolar lavages of human immunodeficiency virus (HIV)-positive and HIV-negative patients. The material comprised: a) controls (n = 7); b) HIV-positive patients subdivided into PCP (n = 11), bacterial pneumonia (n = 8) and other pneumopathies (n = 22); and c) HIV-negative patients with bacterial pneumonia (n = 8). PCA was significantly increased (p less than 0.05) in all patient groups compared to controls. The urokinase-type plasminogen activator (u-PA) antigen levels were highest during bacterial pneumonia. Regardless of the HIV status, in bacterial pneumonia there was a marked elevation of plasminogen activator inhibitor antigens with little residual fibrinolytic activity. In contrast, the fibrinolytic activity was not decreased in PCP. D-dimer were elevated during PCP compared to controls; the highest levels were found in HIV-negative bacterial pneumonia. These data indicate that transient fibrotic changes seen in PCP may be favoured by increased PCA, but not by a depressed fibrinolytic activity. In bacterial pneumonia PCA is increased and fibrinolysis decreased independently of the HIV status.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Hemostatic disturbances induced by two hollow-fiber hemodialysis membranes.

The effects on hemostasis of two high-flux membranes in hollow-fiber configuration, polyamide (PAM) and polyacrylonitrile (AN69), were analyzed in a cross-over study involving ten chronic hemodialyzed patients. Blood samples were obtained at arterial and venous sites of the extracorporeal circuit before dialysis and at 15, 30 and 180 min. Primary hemostasis: PAM induced an early significant drop in platelet counts, but at 180 min there was no longer any difference between membranes. Beta-thromboglobulin release by PAM was significantly higher at all time points. Coagulation: thrombin-antithrombin III complexes (TAT) and fibrinopeptide A increased significantly, the highest values being found with AN69. With both membranes the arterio-venous differences in TAT levels were negative throughout the sessions. Fibrinolysis: no significant differences were observed. In conclusion, both membranes induced hemostatic changes. Although these two hollow-fiber dialyzers look relatively similar, the changes observed were different, polyamide acting mainly on primary hemostasis and polyacrylonitrile on coagulation.

Acrylic Resins↗
PubMed1991

Laboratory and clinical features in systemic lupus erythematosus patients with or without anticardiolipin antibodies.

The purpose of this study was to investigate whether the presence of anticardiolipin antibodies (aCL) in systemic lupus erythematosus (SLE) patients was associated with particular laboratory or clinical features. Anticardiolipin antibodies were determined in 63 unselected SLE patients: 32 (50.8%) were found to be aCL positive and this positivity was significantly associated with the presence of lupus anticoagulant (p less than 0.003) and false positive VDRL reaction (p less than 0.001), but not with other haematological or biological markers. Thrombin-antithrombin III (TAT) complexes were found to be increased with disease activity, but no relationship was found between TAT complexes and the presence or absence of aCL. In this study a statistically significant association was found between aCL positivity and arterial thromboembolic events, but not with venous thrombotic complications. In summary half of SLE patients had aCL and the presence of these antibodies was associated with other antiphospholipid antibodies and with arterial thromboembolic events.

Adolescent↗
PubMed1991

Measurement of D-dimer in plasma as diagnostic aid in suspected pulmonary embolism.

The potential of plasma measurement of D-dimer (DD), a specific derivative of crosslinked fibrin, for diagnosis or exclusion of pulmonary embolism was investigated in a prospective series of 171 consecutive patients who attended an emergency department with suspected pulmonary embolism. The diagnosis was made or excluded by means of a clinical decision-making process which included clinical evaluation, ventilation-perfusion (VQ) lung scan, and, as indicated, pulmonary angiography, venography, or non-invasive examination of the leg veins. Pulmonary embolism was diagnosed by this process in 55 (32%) of 170 patients with sufficient data. All but 1 of these 55 patients had a DD concentration of 500 micrograms/l or above. The sensitivity and specificity of this cutoff concentration for the presence of pulmonary embolism were 98% and 39%, respectively, which give positive and negative predictive values of 44% and 98%. Among the 115 patients (68%) who had inconclusive VQ scans, 31 were diagnosed as having pulmonary embolism. 29 of the remaining 84 patients without pulmonary embolism had DD concentrations below 500 micrograms/l, which means that further diagnostic procedures could have been avoided in a quarter of the patients with inconclusive VQ scans. The sensitivity of the plasma measurement of DD remained high even 3 and 7 days after presentation (96% and 93%). Plasma measurement of DD therefore has a definite place in the diagnostic procedure for suspected acute pulmonary embolism in attenders at emergency departments: a concentration below 500 micrograms/l rules out the diagnosis.

Adolescent↗
PubMed1991

[Value of the plasma measurement of D-dimers in the diagnosis of venous thromboembolism].

Plasma measurement of D-dimers (DD), which are fibrin-specific degradation products, progressively replaces the cumbersome dosage of fibrinogen degradation products (FDP's) in serum for diagnosis and follow-up of consumption coagulopathies, for diagnosis of prethrombotic states and, potentially, for the control of the efficacy of antithrombotic therapies. Moreover, when the ELISA technique is used, this measurement may be very useful in the diagnosis approach of venous thromboembolic disease. In the present review, data are presented which strongly support the view that a low level of plasma D-dimers (less than 500 micrograms/L when using the ELISA from Stago) allows to exclude the diagnosis of deep venous thrombosis or pulmonary embolism with predictive values of 94 % and 100 % respectively. It is suggested that such a diagnostic potential might be very useful in the group of patients with inconclusive perfusion-ventilation scintigraphy (low or indeterminate probability of pulmonary embolism) which represent about 50 % of the patients with suspected pulmonary embolism.

Enzyme-Linked Immunosorbent Assay↗
PubMed1990

Anticardiolipin antibodies and thrombosis: buffer's influence on the detection and quantitation of anticardiolipin antibody measured by ELISA.

The influence of adult bovine serum (ABS) and fetal calf serum (FCS) on IgG anticardiolipin antibodies (ACA) levels measured by ELISA has been investigated. In control subjects the frequency of the optical density (O.D.) distribution was found to be non-gaussian. The O.D. of the 97th percentile was similar with both buffers, although the distribution of O.D. was statistically different (P less than 0.004). The slope of the dilution curves of two house standards as well as the curves obtained with reference standards were found to be very different depending on the buffer. In 55 consecutive patients with thrombotic events, recurrent fetal loss or auto-immune disorders, ACA positivity was also dependent on the way to express the data and the choice of the buffer: when O.D. values were read with their respective standard curves, IgG ACA positivity was 98% with FCS and 20% with ABS (P less than 0.001), but when the 97th percentile O.D. was considered, 40% were positive with FCS and 51% with ABS (n.s.). Furthermore 10 patients were found to be negative with FCS and positive with ABS and 4 others showed the inverse picture. Levels of positivity were also dependent on the buffer. These differences arise from the solution used to dilute the sera and not of that to block the plates. These methodological problems may explain some conflicting data found in the literature about the prevalence of ACA positivity.

Antibodies↗
PubMed1990

Biological true and false serological tests for syphilis: their relationship with anticardiolipin antibodies.

Anticardiolipin antibodies (ACA) were determined by an ELISA assay in 142 VDRL-positive patients who were classified in two groups: group I consisted of 77 patients with syphilis and group II of 65 patients with biological false-positive reaction in the standard test for syphilis. In group I 10% had ACA versus 52% in group II (p less than 0.0001). Isotype distribution in group II showed a predominance of IgG. These results suggest that antiphospholipid antibodies in VDRL and ACA tests have different specificities.

Adult↗
PubMed1990

Plasma D-dimer in suspected pulmonary embolism: a comparison with pulmonary angiography and ventilation--perfusion scintigraphy.

The diagnosis of pulmonary embolism remains a difficult issue. In a previous study of patients submitted to ventilation--perfusion (V-P) scintigraphy we suggested that measurement of D-dimer might be of value for ruling out the diagnosis of pulmonary embolism if the plasma level was less than 500 micrograms/l (ELISA). In the present paper, this cut-off was validated in a consecutive series of 21 patients who were submitted to pulmonary angiography. Sensitivity and specificity were 100% and 36%, respectively. When these data were pooled with the results obtained following V-P scintigraphy (total number of patients = 67), sensitivity, specificity, and positive and negative predictive values were 100%, 70%, 59% and 100%, respectively. It is therefore worthwhile to further evaluate the value of the plasma measurement of D-dimers, especially in patients with inconclusive lung scintigraphy.

Angiography, Digital Subtraction↗
PubMed1990

Comparison of two hemodialysis membranes, polyacrylonitrile and cellulose acetate, on complement and coagulation systems.

Two hemodialysis membranes, polyacrilonitrile (AN 69) and cellulose acetate (CA), were compared for their effects on complement and hemostasis. Two groups of 5 patients, in dialysis for more than 5 years, were successively dialysed for 4 weeks periods with each type of membrane. We measured C3a (complement activation), platelets and beta-thromboglobulin (platelet activation), thrombin-antithrombin III complexes and fibrinopeptide A (coagulation activation), using C-Reactive Protein as a control for dilution effects. As previously shown, activation of complement was more important with CA than with AN 69 (p less than 0.01). In contrast, activation of coagulation (increase in fibrinopeptide A and thrombin-antithrombin III complexes) was more pronounced with AN 69 than with CA. This study emphasizes the need to consider different biological systems when the bioincompatibility of a hemodialysis membrane is evaluated.

Acrylic Resins↗
PubMed1990

Determination of anti-cardiolipin and other antibodies in HIV-1-infected patients.

Anti-cardiolipin antibodies (ACA) were determined by an ELISA assay in 116 HIV-1-infected patients. A positive test was found in 27 patients (23.3%) with a predominance of IgG ACA isotype. No significant difference in ACA positivity was observed between homosexuals (22.2%) and intravenous drug users (25.8%). The presence of different immunological markers was compared in ACA-positive and ACA-negative patients: ACA-positive patients had higher IgG levels (p less than 0.05) and a tendency to higher frequencies of anti-ss DNA, anti-ds DNA, anti-i antibodies, as well as circulating immune complexes. When patients were classified according to CDC criteria, no significant difference was observed for the prevalence of ACA in class II (21.2%), in class III (25%), and in class IV (21%). Our results indicate that ACA antibodies occur with other immunological alterations in HIV-1-infected patients, but do not confirm that ACA is a useful prognostic marker for development of AIDS.

Adult↗
PubMed1989

Laboratory diagnosis of pulmonary embolism: value of increased levels of plasma D-dimer and thrombin--antithrombin III complexes.

Plasma D-dimer (DD) and thrombin--antithrombin III complex (TAT) were measured with ELISAs in 99 patients investigated by 102 ventilation--perfusion lung scintigraphy because of suspected pulmonary embolism. High-probability lung scan was associated with increased DD (more than 500 ng/ml) and TAT (more than 4.1 ng/ml) levels (sensitivity of 100 and 70%, respectively). The corresponding figures of specificity were 81 and 42%. In the 56 patients with low-probability or indeterminate probability scans, 31 (55%) had DD concentrations of less than 500 ng/ml. These preliminary data suggest that a plasma DD concentration of less than 500 ng/ml might rule out the diagnosis of pulmonary embolism in suspected patients with an inconclusive lung scanning.

Adult↗
PubMed1989

Measurement of plasma D-dimer for diagnosis of deep venous thrombosis.

Venography was performed on fifty-six patients suspected of having deep venous thrombosis (DVT) of the legs. The accuracy of the D-dimer measurement in plasma using two latex tests and an enzyme-linked immunosorbent assay (ELISA) was compared with that of usual determination of total fibrin(ogen) degradation products (FDPs) in serum with respect to the presence of DVT. The three D-dimer tests were clearly superior to the FDP assay, but only the ELISA could accurately rule out the diagnosis of DVT with a predictive value of 100% when plasma D-dimer level was less than 200 micrograms/L. However, this test cannot be used for positive diagnosis (false positive rate of 69%). Thus, plasma D-dimer measurement with ELISA allows identification of patients in whom further investigation by means of more specific tests (venography or plethysmography) is indicated in order to establish the diagnosis of DVT. In contrast to this, sensitivity of the two latex tests studied was low (60 and 76%, respectively), which makes them unsuitable for emergency screening. In addition, the potential of D-dimer dosage for diagnosis of DVT in hospitalized patients is hampered by the presence of associated conditions that are responsible for elevated plasma levels in most cases.

Adult↗
PubMed1989

Anticoagulation by ancrod for carbon dioxide removal by extracorporeal membrane lung in the dog.

Ten dogs were subjected to defibrinogenation with an intravenous perfusion of ancrod (1 unit/kg) (Arvin, Knoll AG, Ludwigshafen, Federal Republic of Germany) over a 2 1/2 hour period. Six of them were subjected to extracorporeal elimination of carbon dioxide with a polypropylene membrane lung by means of veno-venous bypass. The remaining four dogs did not undergo extracorporeal circulation and served as control subjects. In both groups, ancrod administration itself resulted in a marked drop in alpha 2-antiplasmin (33% and 67%, respectively, of the baseline values) and in slight but significant decreases in factor II and plasminogen activities of 25% and 20%, respectively (p less than 0.05), in the group subjected to carbon dioxide removal. There were no significant changes in platelet number or factor V and antithrombin III activities. During the 6-hour bypass period, platelet count and antithrombin III and factor II and V levels decreased significantly. No bleeding was observed. Histologic examination of lung biopsy tissue showed no pathologic features. Analysis of the membrane of the artificial lungs revealed no fibrin deposits. In the control group, except for a drop in alpha 2-antiplasmin levels (54%), no significant changes in hemostatic parameters occurred during the corresponding 6 hours. We conclude that, despite the drop in coagulation factors and in alpha 2-antiplasmin activity during bypass, ancrod can be considered as a valuable alternative anticoagulant for extracorporeal carbon dioxide removal.

Ancrod↗