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.

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.

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.

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.

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.

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.

[Acquired hemophilia. Apropos of a case report with a fatal course]

We report the case of an 86-year-old female with an unremarkable past history who suddenly developed severe and generalized bleeding. Laboratory work-up revealed prolonged aPTT, a factor VIII level of 7% and the presence of a factor VIII inhibitor. In spite of whole blood, factor VIII concentrates and immunoglobulin administration, the patient died of multiple hemorrhages on the third day after admission. At autopsy no causal or associated pathology could be found. Chromatographic separation of plasma immunoglobulins showed that the anti-factor VIII activity was associated with the patient's IgG. This inhibition was partially corrected in vitro by injectable immunoglobulin preparation. The case report stresses the discrepancy between the measured levels of inhibitor and the severity of the bleeding; our in vitro results may shed light on the mode of action of intravenous immunoglobulins.

Acute effects of retinoids on fibrinolysis before and after venous occlusion in healthy humans

The effects of acitretin and etretinate on the fibrinolytic system have been investigated in a double-blind, placebo-controlled cross-over study in twelve healthy volunteers. Euglobulin fibrinolytic activity, euglobulin clot lysis time, tissue-type plasminogen activator (t-PA) activity and antigen concentration in plasma were measured before and after 10 min of venous occlusion (VO), three hours after ingestion of the compounds. The plasminogen activator inhibitor (PAI) activity was also measured in each session before fibrinolysis stimulation. None of the parameters studied was significantly affected by the two retinoids in comparison with placebo. Our study demonstrates that a single oral dose of 100 mg of etretinate or acitretin, investigated 3 hours after drug administration does not significantly influence the fibrinolytic system in vivo in humans. This observation does not exclude an effect of retinoids after prolonged intake.

Comparison between a low molecular weight and standard heparin for anticoagulation during extracorporeal CO2 removal in the dog

Anticoagulant properties towards an artificial surface of a chemically depolymerized low molecular weight heparin (LMWH) have been compared to those of a standard heparin (SH). The experimental model consisted in a seven hours extracorporeal veno-venous bypass for CO2 removal (EC-CO2R) using a membrane lung. Four animals received 150 anti-FXa U/kg followed by 40 anti-FXa U/kg/h of LMWH or 300 IU/kg followed by 100 IU/kg/h of SH. Mean Factor Xa inhibition was 49% in LMWH group and 28.5% in SH group. Mean Factor IIa inhibition was 31% and 49% respectively. After three hours of bypass fibrin deposition occurred in the reservoir in three out of four dogs receiving LMWH while none was observed under SH. No statistically significant difference between the two groups was found for any of the coagulation parameters tested (fibrinogen, factor V, antithrombin III, plasminogen, alpha 2-antiplasmin, platelet counts). At the end of bypass 5000 U protamine abolished both anti-FXa and anti-FIIa activities in the SH group but failed to neutralize more than half of the anti-FXa activity in the LMWH group. These results suggest that high anti-FIIa activities are required to prevent fibrin formation induced by artificial surfaces and that equivalent amounts of anti-FXa activities are ineffective for this purpose. In addition the use of LMWH may raise problems when emergency neutralization procedures are required.

Spacelab-2 Plasma Depletion Experiments for Ionospheric and Radio Astronomical Studies

The Spacelab-2 Plasma Depletion Experiments were a series of studies to examine shuttle-induced perturbations in the ionosphere and their application to ground-based radio astronomy. The space shuttle Challenger fired its orbital maneuvering subsystem engines on 30 July and 5 August 1985, releasing large amounts of exhaust molecules (water, hydrogen, and carbon dioxide) that caused the electrons and ions in Earth's upper atmosphere to chemically recombine, thereby creating so-called "ionospheric holes." Two burns conducted over New England produced ionospheric peak depletions ranging from 25 to 50 percent, affected the ionosphere over a 200-kilometer altitude range, and covered 1 degrees to 2 degrees of latitude. Optical emissions associated with the hole spanned an area of several hundred thousand square kilometers. A third burn was conducted over a low-frequency radio observatory in Hobart, Australia, to create an "artificial window" for ground-based observations at frequencies normally below the natural ionospheric cutoff (penetration) frequency. The Hobart experiment succeeded in making high-resolution observations at 1.7 megahertz through the induced ionospheric hole.

Antithrombin III Geneva: a hereditary abnormal AT III with defective heparin cofactor activity

A 43-year-old man presented a pulmonary embolism. The unusual circumstances of apparition, the age and the increased heparin requirements suggested an antithrombin III (AT III) deficiency. AT III activity was low in the propositus and seven other members of his family (mean 55%), but immunologic levels were normal (mean 110%). Crossed immunoelectrophoresis in absence of heparin showed a normal pattern, but in presence of heparin showed an abnormal peak as compared with controls. Kinetics experiments showed a normal inhibition of thrombin and Xa in absence of heparin, but abnormal in presence of heparin. Affinity chromatography on heparin-Sepharose revealed two populations of AT III, one of which was devoid of heparin cofactor activity. The toponym AT III Geneva is proposed for this new familial abnormal AT III with defective heparin cofactor activity.

Acute influence of cigarette smoke in platelets, catecholamines and neurophysins in the normal conditions of daily life

Cigarette smoking is firmly linked to the occurrence of acute coronary events. In twenty-two healthy volunteers in normal conditions of daily life we studied the acute influence of smoking on the following parameters: beta-thromboglobulin, thromboxane B2, epinephrine, norepinephrine, estrogen-stimulated neurophysin, and nicotine-stimulated-neurophysin. Our results show that in our population and following our protocol, smoking did not induce platelet activation, thromboxane formation, catecholamine release or estrogen-stimulated-neurophysin secretion. However, smoking did provoke a significant increase of nicotine-stimulated-neurophysin (p less than 0.05) which reflects vasopressin increase and which might explain the high incidence of ischaemic accidents in cigarette smoking via the vasoactive properties of vasopressin.

[Platelet function and coronary disease: demonstration of a so-called unstable platelet syndrome]

Radio-immunological assay of specific platelet substances in the serum allows assessment of in vivo platelet function at a given moment. Plasma levels of beta thromboglobulin (beta TG) platelet factor 4 (PF4) and thromboxane B2 (TXB2) were measured at rest and during exercise stress testing in 39 patients with known coronary artery disease with stable effort angina. The patients were divided into two groups according to the results of exercise ECG and thallium 201 myocardial scintigraphy: ischaemic (n = 28) and non-ischaemic (n = 11). Resting and exercise levels of the three platelet substances were compared with a group of normal controls (n = 14). The average control values at rest and on exercise were, respectively: PF4: 8.5 +/- 5 and 22 +/- 14 ng/ml; beta TG: 36 +/- 17 and 68 +/- 36 ng/ml and TXB2: 112 +/- 41 and 201 +/- 81 pg/ml. The average values of the non-ischaemic patients did not differ significantly, either at rest or during exercise. The variation of pathological values was higher in the ischaemic group. This seems to reflect the absence of univocal platelet behaviour and does not allow statistical comparison of mean values. Our results suggest the existence of an "unstable platelet syndrome", which seems to be associated with poor effort tolerance especially when present under resting conditions. There would seem to be a causal relationship between platelet instability and myocardial ischaemia, which would justify anti-platelet aggregation therapy in primary and secondary prophylaxis of myocardial infarction.

Anticoagulant properties of three mucopolysaccharides used in rheumatology

Three mucopolysaccharides (MPS) used in the treatment of degenerative joint disease were compared to heparin to establish their relative potencies on 3 coagulation tests, the aPTT, the antifactor Xa activity and the dilute thrombin time. One of the compounds, Arteparon, was one fourth as potent as heparin on the aPTT, but had little or no influence on the 2 other tests. Further in vitro studies suggested that Arteparon acted at a higher level than factor Xa generation in the intrinsic amplification system and that its effect was independent of antithrombin III. In vivo administration of Arteparon confirmed its anticoagulant properties, which raises the question of the clinical use of this MPS.

Pregnancy-associated plasma protein-A (PAPP-A) inhibits thrombin-induced coagulation of plasma

Concentrations of immunoreactive PAPP-A have been found significantly lower in the serum as compared to heparin or EDTA plasma from the same patients. After coagulation significant amounts of PAPP-A remain associated with the clot. Purified PAPP-A inhibits thrombin induced coagulation of plasma. This inhibition cannot be attributed to a direct effect of PAPP-A on thrombin. It is exerted via an activation of endogenous antithrombin III since the inhibitory effect of PAPP-A on thrombin induced coagulation in a euglobulin system can be observed only if antithrombin III is added. The fact that protamine sulphate is capable of neutralizing the inhibitory effects of PAPP-A made us postulate that PAPP-A, like heparin, possesses strongly acidic residues which bind to protamine.

Anticoagulant Properties of Three Mucopolysaccharides Used in Rheumatology

Three mucopolysaccharides (MPS) used in the treatment of degenerative joint disease were compared to heparin to establish their relative potencies on 3 coagulation tests, the aPTT, the antifactor X a activity and the dilute thrombin time. One of the compounds, Arteparon®, was one fourth as potent as heparin on the aPTT, but had little or no influence on the 2 other tests. Further in vitro studies suggested that Arteparon® acted at a higher level than factor Xa generation in the intrinsic amplification system and that its effect was independent of antithrombin III. In vivo administration of Arteparon® confirmed its anticoagulant properties, which raises the question of the clinical use of this MPS.

Energetics of myo-inositol transport in Pseudomonas putida

The effects of specific inhibitors on the high-affinity transport system of cyclitols and on the respiration of Pseudomonas putida shows that the transport activity is dependent on high energy phosphate bond.

Labelling of the cyclitol permease in Klebsiella aerogenes

The protein component(s) of the cyclitol-transport system in Klebsiella aerogenes has been labelled by using three different procedures. One method is based on differential alkylation with N-ethylmaleimide, and another on incorporation of amino acids during the induction process. A protein of mol.wt. 34 000 was labelled by both procedures; by alkylation with N-ethylmaleimide two other proteins of mol.wts. 55 000 and 67 000 were also labelled. The third uses diazotized [35S]sulphanilic acid after protection by substrate and the comparison of labelling of induced cells with non-induced cells; the label was also concentrated in a mol.wt.-33 000 peak. The labelled protein is, from the evidence, the cyclitol carrier.

Assymetry of the myo-inositol transport system in Klebsiella aerogenes. Energy is necessary to create the assymetry of the transport system

1. In Klebsiella aerogenes the influx of myo-inositol proceeds during the steady state at a rate equal to that of efflux. 2. The kinetic parameters of influx during the steady state are similar to those observed at the initial time of uptake. 3. Efflux and influx processes share the same transport system. 4. The ability of other cyclitols to chase the accumulated scyllo-inositol is dependent on their affinity for the transport system. 5. A counter transport can be observed in preloaded cells only in poisoned cells and under anaerobiosis. 6. The efflux process is not temperature-dependent. 7. The KT of influx in poisoned cells is larger than that in normal cells. 8. Although no saturation kinetics of efflux could be observed, it can be inferred that the KT of efflux is at least 50-fold larger than the KT of influx; 9. The results suggest that in the transport of myo-inositol by K. aerogenes energy coupling enhances the affinity of the carrier for the substrate at the outer side of the cytolplasmic membrane by lowering the KT.

Transport of cyclitols by a proton symport in Klebsiella aerogenes

The respiration and the ATP content of Klebsiella aerogenes in the presence of various inhibitors were compared to the transport of scyllo-inositol. The ATPase was found to be inhibited by dicyclohexyl carbodiimide. The transport has been tested in anaerobiosis and aerobiosis. From the results obtained it is concluded that either ATP or respiration can sustain the transport activity in independent manner. 2. The energy derived from the respiratory chain reactions or the ATP hydrolysis results in electrogenic extrusion of protons. The electrochemical potential created drives the accumulation of scyllo-inositol, as shown by an increase of pH of the medium on addition of the substrate to cells in anaerobiosis. With non-induced cells no change in pH occurs, which demonstrates that proton flow is really linked to the transport. No H+/Na+ or K+ exchange is observed and the proton conductor carbonylcyanide m-chlorophenylhydrazone abolishes the pH shift caused by substrate addition. The stoichiometry of the symport H+/cyclitol is 1 and the half-maximum value of the pH variation as a function of the amount of scyllo-inositol added corresponds to a concentration of scyllo-inositol very close to the KT of influx.