Biomedical subjects

A Haeberli

Publications and source records attributed to A Haeberli.

At least 37 records · Page 2Linked to original sources

PubMed1995

The suppression of the coagulation of nonanticoagulated whole blood in vitro by human umbilical endothelial cells cultivated on microcarriers is not dependent on protein C activation.

Human umbilical vein endothelial cells (HUVEC) were cultivated on globular microcarriers in order to improve the endothelial cell surface to blood-volume ratio over the conventional flat bed cultures. HUVEC-beads were tested for their modulation of blood coagulation using a combination of two steps: HUVEC-beads were added into the syringe used for the venipuncture, in order to achieve immediate contact between cells and blood, and no anticoagulant was used during the incubation time of HUVEC-beads with whole blood. The coagulation initiation produced by venipuncture was almost completely suppressed as judged by thrombin measurements over a period of 60 min. The activated partial thromboplastin time showed a prolongation by a factor > 3. Direct measurements of activated protein C (APC) were negative. Moreover, inhibition of APC-generation with a monoclonal anti-human protein C antibody did not affect the anticoagulant properties of endothelial cells. Therefore the anticoagulant properties exerted by HUVEC-beads are not dependent on APC.

Blood Coagulation↗

PubMed1994

pH-dependent formation of ethylenediaminetetraacetic acid supramolecular aggregates.

Pure ethylenediaminetetraacetic acid tetrasodium salt (EDTA.Na4) in water showed a pH-dependent change of optical density detected in the ultraviolet region. The most important change was found between pH 4 and 8, corresponding to the deprotonation of the third ionizable group having a pK of 6.2. The absorbance change was reversible and depended on the addition/removal of only 1 proton equivalent. The presence of supramolecular aggregates was suggested by size-exclusion chromatography, dialysis and cryo-electronmicroscopy. The molecular weight of EDTA supramolecular aggregates was 10-15,000 and 8-14,000, as determined by gel chromatography and dialysis, respectively. Cryo-electronmicroscopy revealed structures of 2-4 nm in diameter.

Chromatography, Gel↗

PubMed1994

Fibrin formation and degradation in patients with arteriosclerotic disease.

BACKGROUND: The blood coagulation cascade was reported to be activated in patients with arteriosclerotic disease of the lower limbs (peripheral arterial disease, PAD). There is more thrombin and fibrin formation compared with healthy control subjects. In many studies, however, the presence of arteriosclerotic disease had not been thoroughly ruled out in the control group. Therefore, markers of the activation of the blood coagulation cascade were measured in patients with PAD and in a carefully defined control group, both groups being subjected to an exercise test. METHODS AND RESULTS: Twenty-two patients with angiographically documented PAD of grade II (Fontaine classification) and 13 control subjects in whom the presence of arteriosclerotic lesions was ruled out by noninvasive means in the carotid arteries, abdominal aorta, leg arteries, and coronary arteries took part in the study. Before and immediately after a treadmill stress test, the concentrations of prothrombin fragment F1 + 2 (F1 + 2), thrombin-antithrombin III complexes (TAT), fibrinopeptide A (FPA; this peptide was measured in spot urine also), and D-dimers were measured. Before exercise, the concentrations of F1 + 2 (1.0 +/- 0.6 versus 0.7 +/- 0.3 nmol/L), TAT (2.9 +/- 2.1 versus 1.9 +/- 0.8 micrograms/L), and D-dimers (318.2 +/- 270.1 versus 150.0 +/- 91.4 micrograms/L) were significantly higher in the patients with PAD compared with the healthy control subjects. FPA concentrations in plasma (1.9 +/- 1.0 versus 1.4 +/- 0.6 micrograms/L) and spot urine were not different, however. F1 + 2, FPA, and D-dimer concentrations correlated with the severity of the PAD as assessed by the ankle systolic blood pressure index (ABPI). The symptom-limited stress test did not lead to further activation of the blood coagulation cascade. However, concentrations of F1 + 2 (P < .001) and TAT (P < .01) after exercise correlated with the presence of ischemic changes in the stress-test ECG. CONCLUSIONS: There is evidence of enhanced thrombin formation in patients with PAD compared with an age- and sex-matched control group without clinical and sonographic evidence of arteriosclerosis. The thrombin formed, however, appears to be almost completely neutralized by antithrombin III. No direct evidence of fibrin formation was obtained, since the FPA concentrations were not different. In the patients with PAD, the higher concentrations of D-dimers are indicative of in vivo fibrinolysis. Thus, some fibrin formation must be postulated to occur in patients with arteriosclerosis.

Aged↗

PubMed1994

Human endothelial cells suppress prothrombin activation in nonanticoagulated whole blood in vitro.

Human endothelial cells cultivated on polystyrene microcarrier beads were used to study endothelial anticoagulant activity in vitro. Spontaneous whole blood coagulation was inhibited by endothelial cells on microcarriers at a surface to volume ratio of 16 cm2/ml blood. Thrombin activity generated in nonanticoagulated whole blood during 1 hour and assessed by its fibrinogen clotting effect was reduced by 87% in the presence of endothelial cells. Consistent with this observation, prothrombin fragment1+2, fibrinopeptide A, and thrombin-antithrombin III-complex release during the same period of time were inhibited by 81%, 47%, and 88%, respectively. Immunoblotting analysis of cell-free supernatants derived from the same samples demonstrated that prothrombin activation was strongly suppressed in the presence of endothelial cells. Furthermore, the incubation of nonanticoagulated whole blood with endothelialized beads for only 5 minutes after venipuncture was sufficient to prevent subsequent prothrombin activation in the cell-free supernatants of the same whole blood sample after centrifugation. These findings suggest that interruption of the coagulation cascade is probably one major mechanism of endothelial anticoagulant activity in vivo.

Antithrombin III↗

PubMed1994

Whole blood clot lysis: enhanced by exposure to autologous but not to homologous plasma.

A new phenomenon is described: Whole blood clots lyse faster in the plasma of the same donor than in another donor's plasma. We have confirmed this finding in 68 healthy volunteers by a standardized, pair-wise analysis and have found a mean difference in clot weights of 8.8 +/- 0.99% (SEM, p < 0.0001) after 6 h of urokinase-induced (200 U/ml) clot lysis. No difference was found in a group of 7 pairs of identical twins. Further analysis revealed that increasing concentrations of platelets in the plasma reduced the difference significantly but did not abolish it. A 1:1 mixture of autologous with homologous plasma reduced the autologous advantage by almost 50%, thus making an inhibitor unlikely. The absence of cellular components in clots of platelet-poor plasma resulted in the loss of the advantage after 2 h of lysis, but not in the early phase. We conclude that there is a clear advantage of autologous over homologous clot lysis. Potential mechanisms are discussed and include an increased affinity of enzymes for their substrates in a given individual.

Adolescent↗

PubMed1994

Prothrombin fragment 1 + 2, thrombin-antithrombin III-complexes and fibrinopeptide A in spontaneously clotting whole blood in vitro. Effects of heparin addition and antithrombin III deficiency.

Previous in vitro studies using spontaneously clotting whole blood revealed thrombin formation and high fibrinopeptide A (FPA) concentrations measured during incubation time. This occurred in spite of normal concentrations of thrombin antagonists present in the blood of the healthy subjects examined. However, there are several reports showing that in vivo increased thrombin-antithrombin III-complex (TAT) concentrations and relatively low FPA concentrations may occur e.g. in patients with (pre)thrombotic disorders. These in vivo findings indicate more effective thrombin inhibition by antithrombin III, with almost no fibrin formation. To find an explanation for the differences observed in vitro and in vivo, we extended the in vitro studies by measuring concentrations of prothrombin fragment 1 + 2 (F1 + 2), TAT and FPA at several time points until 30 min. Our goal was to test whether thrombin at least initially is neutralized by antithrombin III, resulting in a lack of fibrin formation, either in the absence or in the presence of heparin (0.2 and 0.5 U/ml whole blood, respectively). In the absence of heparin a simultaneous increase in the concentrations of F1 + 2, TAT and FPA was observed. Thrombin was only partially neutralized by antithrombin III and large amounts of fibrin were formed. The addition of heparin virtually suppressed thrombin formation since the F1 + 2 concentration remained low. Moreover, the small amounts of thrombin formed were neutralized by antithrombin III to a greater extent than in the absence of heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Fibronectin is more active than fibrin or fibrinogen in promoting Staphylococcus aureus adherence to inserted intravascular catheters.

To further define the role of fibrin(ogen) and fibronectin in Staphylococcus aureus adherence to central venous catheters, the amount, chemical integrity, and biologic activity of these proteins adsorbed on lines inserted in hospitalized patients were prospectively studied. Polyurethane cannulas promoted a significantly lower adherence of S. aureus than polyvinyl chloride (P < .01) or Hickman (P < .001) cannulas and contained the lowest amount of immunologically assayed fibronectin but not of fibrin(ogen). Fibrinogen showed an extensive loss of adherence-promoting activity on inserted cannulas, which was related to its proteolytic breakdown, as detected by SDS-PAGE and immunoblots with antifibrinogen antibodies and confirmed by in vitro studies with purified protein fragments. In contrast, either intact or fragmented fibronectin, although present in much lower amounts than fibrin(ogen), could actively promote S. aureus adherence onto intravenous catheters.

Anticoagulants↗

PubMed1993

Influence of endothelial surface on flow velocity in vitro.

The influence of the endothelial surface and its interaction with various plasma components on flow velocity was investigated in vitro. The falling velocity of microcarrier beads with and without cultured porcine aortic endothelial cells in a vertical tube containing different media was recorded with a video system attached to a light microscope. The falling velocity of the beads was in agreement with values predicted from Stokes's law. Endothelium did not affect the falling velocity in various media, except in plasma, where it was slower than expected. Fibrinogen was found to have a strong surface tension effect, disturbing viscosity measurements, and to bind to endothelial cells and collagen-coated surfaces. We conclude that the endothelial surface may interact with plasma and plasma constituents such as fibrinogen in a way that affects blood flow.

Animals↗

PubMed1993

Fibrinopeptide A in liver cirrhosis: evidence against a major contribution of disseminated intravascular coagulation to coagulopathy of chronic liver disease.

To test the hypothesis that disseminated intravascular coagulation contributes to hemostatic failure in liver cirrhosis, fibrinopeptide A and fibrin(ogen) degradation fragment E were measured in 69 patients with stable liver cirrhosis and compared with fibrinopeptide A and fibrin(ogen) degradation fragment E in 32 healthy subjects, 33 patients with thromboembolism, and 10 patients with hypofibrinogenemic disseminated intravascular coagulation. Mean fibrinopeptide A in cirrhosis was slightly increased compared with healthy subjects (2.4 vs. 1.8 ng/ml, p < 0.005), but fourfold lower than in thromboembolism (mean fibrinopeptide A 9.7 ng/ml; p < 0.0001), and tenfold lower than in disseminated intravascular coagulation (mean FPA 24.3 ng/ml; p < 0.0001). Single fibrinopeptide A levels in cirrhosis were within the normal range in 75% of the patients, marginally increased in 9%, and definitely increased in 16%. A definite increase in both fibrinopeptide A and fibrin(ogen) degradation fragment E, which characterized the groups of patients with thromboembolism and disseminated intravascular coagulation, was found in 10% of the cirrhotic patients. Among 17 patients with cirrhosis and hypofibrinogenemia, mean fibrinopeptide A (2.7 ng/ml) was tenfold lower compared with mean fibrinopeptide A in patients with hypofibrinogenemic disseminated intravascular coagulation (p < 0.0001), whereas the frequency of increased single fibrinopeptide A levels (29%) was not significantly different compared with the 52 cirrhotic patients without hypofibrinogenemia (single levels elevated in 23% of the cases). Moreover, the frequency of hypofibrinogenemia, thrombocytopenia, or abnormal clotting times was not significantly different in cirrhotic patients with normal fibrinopeptide A level when compared with cirrhotic patients with increased fibrinopeptide A. These findings do not support an important contribution of disseminated intravascular coagulation to coagulopathy of liver cirrhosis.

Adult↗

PubMed1992

Increased thrombin-antithrombin III complexes after 1 h of physical exercise.

Concentrations of thrombin-antithrombin III (TAT) complexes in plasma were previously reported to be increased after a 100-km run, while fibrinopeptide A (FPA) concentration remained unchanged. Thus, antithrombin III appears to neutralize thrombin generated during running and prevents fibrin formation. To determine the clinical relevance of these findings, we compared the effects of exhaustive running (1 h, n = 10) on the plasma concentrations of prothrombin fragments F1 and F2, TAT, FPA, and beta-thromboglobulin with the effects of recreational jogging (1 h, n = 10) and exhaustive bicycling on an ergometer (1 h, n = 8). Prothrombin fragments F1 and F2 and TAT concentrations increased significantly in each group. The most significant increase in TAT concentration was measured in the running group (from 1.72 +/- 0.49 to 3.61 +/- 1.03 ng/ml, P < 0.001). The best correlation was found between the postexercise TAT and lactate concentrations (r = 0.62, n = 28, P < 0.001). Mean FPA concentrations after exercise did not exceed normal values in any of the three groups analyzed. An increase in beta-thromboglobulin concentration was measured in the running and in the cycling group. Thus, thrombin is formed, in particular, when associated with anaerobic metabolism, and platelets are activated during high-intensity exercise.

Adult↗

PubMed1991

Effects of low and high dose oral contraceptives on blood coagulation and thrombogenesis induced by vascular subendothelium exposed to flowing human blood.

We investigated the effect of oral contraceptives with low and high estrogen concentration on blood coagulation and thrombogenesis, induced by vascular subendothelium of rabbit aorta exposed to flowing human blood. Twenty healthy women intending to take oral contraceptives were studied [1] before drug ingestion (control), and subsequently during the intake of oral contraceptives with [2] low estrogen content (20 micrograms ethinyl estradiol and 150 micrograms desogestrel per day) and [3] high estrogen content (50 micrograms ethinyl estradiol and 125 micrograms desogestrel per day). All experiments were performed between day 17 and 21 of the menstrual cycle and drug effects were studied during the third tablet cycle. Deposition of fibrin, platelets and platelet thrombi on vascular subendothelium was tested at a defined blood flow and wall shear rate (10 ml/min, 650 s-1) and was quantified by morphometrical techniques. Treatment with the low and high dose contraceptive increased the plasma levels of ethinyl estradiol (728 +/- 139 and 1438 +/- 212 vs. 0 fmol/l [low and high dose vs. control], means +/- SEM, P less than 0.001) and fibrinogen (2.3 +/- 0.1 and 2.6 +/- 0.1 vs. 2.0 +/- 0.1 g/l, P less than 0.05); and decreased antithrombin III activity (95 +/- 3 and 92 +/- 3 vs. 101 +/- 3 %, P less than 0.05). Fibrin deposition on vascular subendothelium was enhanced by the high dose contraceptive only (47 +/- 4 vs. 35 +/- 4 % coverage of the subendothelial surface with fibrin, high dose vs. control, P less than 0.05). The subendothelial deposition of platelets and platelet thrombi was not changed by contraceptive treatment. These results indicate that treatment with high dose contraceptives leads to an increase of fibrin-subendothelial interactions, whereas low dose contraceptives do not significantly alter the blood-subendothelium interactions. observed in this ex vivo model of thrombogenesis.

Adolescent↗

PubMed1991

Effects of the oral anticoagulant phenprocoumon on blood coagulation and thrombogenesis induced by rabbit aorta subendothelium exposed to flowing human blood: role of dose and shear rate.

We investigated the effect of oral anticoagulation on thrombogenesis induced by the subendothelium of rabbit aorta. Eighteen healthy volunteers underwent a 2-week treatment with the oral coumarin preparation phenprocoumon to a target international normalized ratio (INR) of 5. By using an ex-vivo perfusion chamber system, the interaction between flowing blood and exposed subendothelium was measured at low (50 sec-1) and high (650 sec-1) wall shear rates. The low shear rate simulated blood flow in venous vessels and the high shear rate simulated blood flow in arterial vessels. Deposition of fibrin, platelets, and platelet thrombi on subendothelium was quantified by morphometric and immunologic techniques. Fibrin deposition prevailed at the low shear rate (183 +/- 57 ng/mm2 vs 46 +/- 16 ng/mm2, low vs high shear rate; mean +/- SEM; p less than 0.01). In contrast, the interaction of platelets with subendothelium was more intense at high shear rates when compared with low shear rates, as indicated by higher platelet adhesion (44% +/- 2% vs 9% +/- 1% coverage of subendothelium with platelets, p less than 0.001) and platelet thrombus volumes (3.6 +/- 0.4 microns 3/microns 2 vs 1.3 +/- 0.3 microns 3/microns 2, p less than 0.001). Fibrin deposition on subendothelium was substantially reduced even at a low intensity of anticoagulation (reduction by 60% at INR 2.1 and by 75% at INR 3.7) and was abolished after high coumarin doses (INR 5.2). In contrast, a significant inhibition of platelet thrombus formation could be achieved only by high doses of phenprocoumon (INR 5.2). Our data indicate that relatively low doses of oral anticoagulants (INR between 2 and 3.5) substantially inhibit the fibrin formation on subendothelium prevailing at venous shear conditions, whereas a high intensity of anticoagulation (INR 4 to 5) is necessary to inhibit the formation of platelet-rich thrombi prevailing at arterial shear conditions.

Administration, Oral↗

PubMed1990

Blood coagulation after long distance running: antithrombin III prevents fibrin formation.

Physical exercise causes shortening of activated partial thromboplastin time (aPTT) and euglobulin clot lysis time. To investigate whether this activation of coagulation and fibrinolysis leads to in vivo thrombin or plasmin action after long distance running, 19 well trained male runners (36-65 years) were examined 5 to 53 min after termination of a 100 km race and 5 days later after at least 1 day without physical exercise. Compared to the control examination aPTT was decreased (30.2 +/- 2.8 vs 35.3 +/- 3.0 sec) and the following parameters were increased after the race: beta thromboglobulin (40 +/- 16 vs 23 +/- 7 ng/ml), thrombin-antithrombin III (TAT) complexes (5.5 +/- 3.4 vs 2.3 +/- 0.7 microgram/l), the fibrin(ogen) degradation products fragment E (57 +/- 15 vs 35 +/- 7 ng/ml) and B beta 15-42 (8.5 +/- 2.5 vs 6.5 +/- 2.5 ng/ml) (all p values less than 0.001). Platelet count, platelet factor 4, fibrinoepetide A (FPA) and haematocrit did not change significantly. Increased TAT complexes and unchanged FPA suggest that the generated thrombin was fully inactivated by antithrombin III (AT III) and did therefore not give rise to fibrin formation. The small increase of fibrin(ogen) degradation products indicates a minor in vivo activity of the fibrinolytic system. This investigation demonstrates the importance of AT III in the regulation of haemostasis in activated blood coagulation.

Adult↗

PubMed1990

Isolation of human fibrinogen and its derivatives by affinity chromatography on Gly-Pro-Arg-Pro-Lys-Fractogel.

With an immobilized synthetic pentapeptide GlyProArgProLys comprising the N-terminal sequence GlyProArg of the alpha-chain of fibrin, a new affinity method for the quantitative isolation of fibrinogen out of anticoagulated plasma was developed. The method proved to be superior to all known isolation methods in respect to ease of use and yield, since fibrinogen could be isolated in one step out of plasma with a recovery of more than 95% when compared to the immunologically measurable amounts of fibrinogen. Moreover the amounts of contaminating proteins such as fibronectin, factor XIII or plasminogen were negligible and the purity of the isolated fibrinogen was higher than 95% as measured by polyacrylamide gel electrophoresis. The clottability was 90% and more. Another advantage of this affinity purification method is the possibility to isolate fibrinogen quantitatively out of small plasma samples (less than 5 ml). Further, abnormal fibrinogen molecules, provided their complementary binding site for GlyProArg is preserved, may also be quantitatively isolated independent of any solubility differences as compared to normal fibrinogen. In addition fibrin(ogen) fragments originating from plasmic digestion can be separated on the basis of their affinity to GlyProArg. The described affinity gel can be used more than 50 times without any loss of capacity.

Amino Acid Sequence↗

PubMed1990

A new concept of fibrin formation based upon the linear growth of interlacing and branching polymers and molecular alignment into interlocked single-stranded segments.

In a previous electron microscopic study of early fibrin polymers processed by freeze drying and rotatory shadowing, a large proportion of loosely constructed, frequently branching linear molecular chains was observed; their structural organization was inconsistent with a half-staggered double-stranded model for fibrin polymerization. These conflicting results prompted us to investigate the structure of early fibrin polymers prepared according to a large variety of methods currently used for electron microscopy of macromolecules. By use of a systematic random sampling procedure, fibrin polymers were photographically recorded. They were classified according to their morphological form, and the frequency of occurrence of each configuration was determined. Half-staggered double-stranded forms accounted for less than 1% of all types encountered. Interpretation of the structural organization manifested in the diverse polymer forms observed necessitated the construction of a new interlocked single-strand model for fibrin polymerization. The fibrin polymerization process combines simultaneous propagation of linear growth, branching, and lateral interlocking (leading to lateral association), resulting in the rapid formation of a fibrin network. The structural pattern developing during growth of fibrin polymers appears to be determined principally by the enzymatic mechanism and not solely by the intrinsic molecular structure of fibrinogen. The validity of the interlocked single-strand model was tested by selective fibrinopeptide-B-releasing experiments. Under such activation conditions, the polymer forms predicted according to this and the half-staggered double-strand models should differ; the structures observed were indeed consistent with the interlocked single-strand hypothesis. The compatibility of existing data with this model is discussed.

Fibrin↗

PubMed1990

Influence of blood withdrawal and anticoagulant on clotting activity, hematologic data, and certain rheologic measurements.

The influence of blood withdrawal (vacuum or slow aspiration) and anticoagulants (ethylenediaminetetraacetic acid [EDTA]; heparin; citrate; a mixture of citrate, theophylline, adenosine, and dipyridamole [CTAD]; and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone [PPACK]) on clotting activity, hematologic data, and rheologic measurements (whole blood and plasma viscosity, red cell filtration in one study) were investigated. No difference was found between the two blood withdrawal techniques on the basis of the affected measurements. EDTA appeared to be the best anticoagulant with regard to blood cell preservation and showed the lowest whole blood viscosity over a wide range of shear rates (0.1 to 87.0 sec-1). PPACK was the most potent inhibitor of clotting activity as monitored by fibrinopeptide A concentration. The results suggest that EDTA is probably a reasonable choice for rheologic studies of whole blood and should be combined with PPACK when plasma properties are studied.

Adenosine↗

PubMed1990

Gel filtration: a new method to analyze and separate red blood cells with different deformabilities.

Filtration of red blood cells through agarose gels (Sephadex, Sepharose, and Superose) was used to assess red cell deformability and simultaneously obtain fractions of red cells with different properties. The hemoglobin concentration in each fraction was used to define a filtration profile of red cells. It was found that gel filtration was a reproducible process. A gel filtration index (GFI) was derived from the height and the width of the filtration curve at half the maximum height. Osmotically treated red cells, red cells partially hardened with increasing glutaraldehyde concentrations, and mixtures of normal and hardened red cells were used to test the method. Changes in red cell deformability were sensitively detected by the GFI. The first fractions eluted from the column contained red cells with normal deformability, whereas the later fractions contained primarily less deformable cells with an increased membrane elastic modulus. By repeated filtration of late fractions it was possible to enrich the suspensions with less deformable cells. Patients with chronic renal failure had a decreased filterability; their GFI was 1.04 +/- 0.27 (n = 15) compared with 1.18 +/- 0.17 in controls (n = 20, p less than 0.05). We conclude that gel filtration is useful to detect and isolate abnormal red cell subpopulations. It could be a valuable tool for the investigation of disorders such as sickle cell anemia.

Chromatography, Gel↗

PubMed1989

Host factors selectively increase staphylococcal adherence on inserted catheters: a role for fibronectin and fibrinogen or fibrin.

Intravascular catheters are prone to staphylococcal infections. To study the role in staphylococcal adherence played by fibrinogen or fibrin and fibronectin deposited on inserted catheters, 187 peripheral or central cannulae were prospectively removed from hospitalized patients. Compared with uninserted catheters, which allowed only minimal adherence, previously inserted catheters promoted significant adherence of staphylococcal isolates from patients with intravenous device infection. Adhesion-promoting properties were studied with laboratory strains having well-defined affinities for either fibronectin or fibrinogen: adherence of Staphylococcus aureus Cowan I, which has the highest affinity for both adhesins, was more strongly promoted (10- to 50-fold) on inserted cannulae than was that of S. aureus Wood 46 (4- to 10-fold) or Staphylococcus epidermidis Rp 12 (2.2-fold), which has no affinity for fibrinogen but does for fibronectin. Although all types of cannulae contained significant amounts of fibrin, which may promote adherence of coagulase-positive staphylococci, results obtained with coagulase-negative isolates suggested that in vivo-deposited fibronectin is also a critical determinant in this process.

Bacterial Adhesion↗