POS0822 NEW FACES OF POLYARTERITIS NODOSA: 18F-FLUORODEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHY FINDINGS IN A SERIES OF 10 PATIENTS

Background:

18F-fluorodeoxyglucose positron emission tomography with computed tomography (FDG-PET/CT) is widely used in patients with large-vessel vasculitis (1). The benefits of FDG-PET/CT in polyarteritis nodosa (PAN) has only been assessed in a few case reports (2-3).

Objectives:

Our aim was to describe FDG-PET/CT findings in 10 patients with newly diagnosed PAN.

Methods:

This was a retrospective study of patients with PAN who underwent FDG-PET/CT at the time of diagnosis, between 2017 and 2020. The FDG-PET/CT data were analysed retrospectively and compared with clinical, biological, histological and conventional imaging data.

Results:

Ten patients were included: 9 men and 1 woman, median age of 67 (43–78) years. PAN was diagnosed according to ACR criteria (6) in 9 patients, and histologically in the remaining patient. The clinical manifestations were: systemic (n=10), muscular (n=6), joint (n=3), skin (n=3), peripheral nervous system (n=3), and gastrointestinal (n=2). All patients had high C-reactive protein levels (median, 223 mg/L). One patient had incomplete FDG-PET exploration. Three patients had begun corticosteroid therapy before their FDG-PET/CT scan. The main FDG-PET/CT abnormality was increased tracer uptake in the muscles, particularly in the connective tissue (perimysium, epimysium) (n=7), in linear (n=5) or focal (n=2) patterns. Increased FDG uptake in large-diameter vessels was observed in 4 patients, in the humeral (n=4), femoral (n=1) and the common interosseous (n=1) arteries. Nine patients had bone-marrow FDG uptake, six had splenic FDG uptake. Three patients had synovitis. Three had lymph-node uptake. One patient had subcutaneous FDG uptake, with a “leopard skin” appearance.

Conclusion:

FDG-PET/CT seems to be a useful non-invasive imaging technique for diagnosing PAN, particularly in patients with non-specific systemic features. Tracer uptake in muscular connective tissue seems to be a recurrent sign in patients with PAN.

References:

[1]Prieto-González S, Depetris M, García-Martínez A, Espígol-Frigolé G, Tavera-Bahillo I, Corbera-Bellata M et al. Positron emission tomography assessment of large vessel inflammation in patients with newly diagnosed, biopsy-proven giant cell arteritis: a prospective, case-control study. Ann Rheum Dis. 2014;73(7):1388-92.

[2]Mino N, Yamashita H, Takahashi Y, Kaneko H. Polyarteritis Nodosa With Reversible FDG Accumulation in Vessels and Kidneys. Clin Nucl Med. 2019;44(11):889-891.

[3]Schollhammer R, Schwartz P, Jullie ML, Pham-Ledard A, Mercie P, Fernandez P et al. 18F-FDG PET/CT Imaging of Popliteal Vasculitis Associated With Polyarteritis Nodosa. Clin Nucl Med. 2017;42(8):e385-e387.

[4]Lightfoot RW Jr, Michel BA, Bloch DA, Hunder GG, Zvaifler NJ, McShane DJ et al. The American College of Rheumatology 1990 criteria for the classification of polyarteritis nodosa. Arthritis Rheum. 1990;33(8):1088-93.

Disclosure of Interests:

None declared

Immunological Alterations in Haemophiliacs Treated with Lyophilized Factor VIII Cryoprecipitate from Volunteer Donors

We studied immune function in Belgian haemophiliacs treated with Factor VIII from volunteer donors. No patient had clinical evidence of immune deficiency. We found a decrease in T-helper cells (p <0.0005), in the ratio of T-helper over T-cytotoxic/ suppressor cells (1.72 ± 0.47 versus 2.24 ± 0.82 in controls, p <0.005) and in lymphocyte responsiveness to mitogens (p <0.05).

These findings could not be linked to the amount of F VIII received over the last year, the time since last F VIII administration, circulating immune complexes (54% positive patients, 7% positive controls, p <0.005), increased ALT levels, antibodies to cytomegalo-virus (85% of the patients, 45% of the controls, p <0.005), antibodies to Epstein-Barr virus, nor to the presence of HLA-DR 5 which was found in 56% of the haemophiliacs (20% of the overall Belgian population, p <0.005).

Either F VIII induces long lasting immunological alterations unrelated to AIDS, or haemophilia is itself associated with such changes.

Biological and Thrombolytic Properties of Proenzyme and Active Forms of Human Urokinase – III. Thrombolytic Properties of Natural and Recombinant Urokinase in Rabbits with Experimental Jugular Vein Thrombosis

The thrombolytic properties of recombinant pro-urokinase (Rec-pro-UK), recombinant active urokinase (Rec-UK) and natural urinary urokinase (Nat-UK) were compared with those of tissue-type plasminogen activator (t-PA) in rabbits with a radiolabeled thrombus in the jugular vein. The thrombolytic agents were infused intravenously over a time period of 4 hr and the extent of thrombolysis measured two hours later.

In control animals the extent of thrombolysis was 11 ± 2% (n=8) after 6 hr. Nat-UK and Rec-UK had very similar thrombolytic properties. Significant thrombolysis was only obtained with infusion of 240,000 IU per kg (41 ± 2%, n=4 for Nat-UK and 37 ± 4%, n=4 for Rec-UK) and this was associated with a marked systemic activation of the fibrinolytic system, as evidenced by consumption of plasminogen and α2-antiplasmin and fibrinogen breakdown.

Infusion of Rec-pro-UK induced thrombolysis at a dose of 60,000 IU per kg (44 ± 8%, n=3) but without associated systemic activation of the fibrinolytic system. In this respect the properties of Rec-pro-UK were similar to those of t-PA, which, however, had a 2- to 4-fold higher specific thrombolytic activity (30,000 IU/ kg yielding 48 ± 1% lysis, n=4).

It is concluded that Rec-UK has very similar thrombolytic properties as Nat-UK and that Rec-pro-UK has a beter thrombus- selectivity and less systemic side effects than the active enzymes.

Heparin-Induced Thrombocytopenia Platelet Aggregation Studies in the Presence of Heparin Fractions or Semi-Synthetic Analogues of Various Molecular Weights and Anticoagulant Activities

One case of heparin-induced thrombocytopenia is reported. Aggregation was observed in the platelet-rich plasma of this patient in the presence of two commercial standard heparin preparations (from a final concentration of 0.025 IU/ml upwards), of two semi-synthetic heparin analogues (0.1 APTT U/ml) and of three low-molecular weight heparin (LMWH) fractions (0.1 anti-Xa U/ml) but not in the presence of five other LMWH fractions.

The patient’s isolated platelets no longer aggregated in the presence of heparin but the phenomenon recurred after addition of the patient’s platelet poor plasma (PPP).

Furthermore, addition of patient’s PPP to control platelets led to heparin-induced aggregation.

The phenomenon was associated with thromboxane generation and could be blocked by in vitro addition of aspirin, PGI2, and PGD2 whereas the lag phase was dose-dependently prolonged by adenosine.

It is concluded that platelet aggregation may be induced in some patients by standard heparin and by certain LMWH fractions or semi-synthetic analogues, independently of their molecular weight and anticoagulant activity.

Platelet Survival in Patients with Angiographically Diseased and Normal Coronary Arteries

Platelets may contribute to the pathogenesis of atherosclerosis and to the complications of coronary artery disease. Therefore, platelet kinetics were studied in 69 patients with angiographically documented coronary artery disease and in 16 patients with a normal coronary angiogram. Platelet survival time was calculated from the decay of radioactivity after injection of 51Cr-labeled autologous platelets. None of the mathematical models used was able to discriminate between the two patients groups. No correlation existed between survival time and extent of the arterial disease. Patients with a high serum cholesterol did not exhibit an enhanced platelet consumption. Thus, these studies do not support the idea that platelet turnover is enhanced in patients with coronary artery disease as compared to those with normal coronary arteries.

Blood Changes and Enhanced Thromboxane and 6-Keto Prostaglandin F1α Production in Experimental Acute Plasmodium Bergei Infection in Hamsters

Golden hamsters inoculated intraperitoneally with Plasmodium bergei infected mouse blood regularly developed P. bergei parasitaemia. This was associated with progressive thrombocytopenia and leucocytosis as the degree of parasitaemia increased with time. When infected whole blood was stimulated with collagen, significantly enhanced thromboxane B2 (TXB2) production per platelet was seen. 6-keto prostaglandin (PG) F1α formation in the same system increased from the sixth infection day onwards and correlated with the relative leukocytosis. The production of 6-keto PGF1α by aorta rings was significantly higher during the 4-7th days postinoculation. The increase in thromboxane production however was much more important than that of 6-keto PGF1α and it therefore is concluded that P. bergei parasitaemia in hamsters tilts the haemostatic balance towards the platelet hyperaggregability that has also been described in P. falciparum infection in man.

Questions and Answers on Prothrombin Time Standardisation in Oral Anticoagulant Control

One of the reasons why oral anticoagulants fell into disrepute is the absence of internationally accepted standardised procedures for controlling the level of anticoagulatiori. This deplorable situation resulted in over- and under-coagulation and uncertainty in the therapeutic range. International conformity can now be obtained by using an International Normalised Ratio (INR) which is derived from the individual result obtained in a given plasma sample and the International Sensitivity Index (ISI) of the tissue thromboplastin reagent used. Any thromboplastin reagent can be calibrated against an international primary or secondary W.H.O. reference preparation, so as to obtain its International Sensitivity Index. The new system of reporting the level of anticoagulation was designed and can only safely be applied in patients taking oral anticoagulants.

Dipyridamole Inhibits Platelet Aggregation in Whole Blood

Dipyridamole possesses antithrombotic properties in the animal and in man but it does not inhibit platelet aggregation in plasma. We evaluated the effect of dipyridamole ex vivo and in vitro on platelet aggregation induced by collagen and adenosine- 5’-diphosphate (ADP) in human whole blood with an impedance aggregometer. Two hundred mg dipyridamole induced a significant inhibition of both ADP- and collagen-induced aggregation in human blood samples taken 2 hr after oral drug intake. Administration of the drug for four days, 400 mg/day, further increased the antiplatelet effect. A significant negative correlation was found between collagen-induced platelet aggregation in whole blood and dipyridamole levels in plasma (p <0.001). A statistically significant inhibition of both collagen (p <0.0025) and ADP-induced (p <0.005) platelet aggregation was also obtained by incubating whole blood in vitro for 2 min at 37° C with dipyridamole (3.9 μM). No such effects were seen in platelet-rich plasma, even after enrichment with leukocytes. Low-dose adenosine enhanced in vitro inhibition in whole blood.

Our results demonstrate that dipyridamole impedes platelet aggregation in whole blood by an interaction with red blood cells, probably involving adenosine.

Pharmacokinetics and Effects on Fibrinolytic and Coagulation Parameters of Two Doses of Recombinant Tissue-Type Plasminogen Activator in Healthy Volunteers

Pharmacokinetics and pharmacological effects of two intravenous doses of recombinant tissue-type plasminogen activator (rt-PA) (40 and 60 mg over 90 min) were determined in healthy volunteers. Mean maximum plasma concentrations were 1080 and 1560 ng/ml respectively. The steady state level during subsequent maintenance infusion of 30 mg over 6 h was 250 ng/ml. The pharmacokinetics of rt-PA showed a bi-exponential disappearance from plasma consistent with a 2-compartment model of t½α = 5.7 min, a t½β = 1.3 h and a total clearance of 380 ml/min.

Mean fibrinogen levels at the end of the infusions of 40 mg or 60 mg rt-PA over 90 min, measured in thawed plasma samples collected on citrate/aprotinin, decreased to 74% and 57% of the preinfusion values respectively. Plasminogen fell to 55% and 48%, and α2-antiplasmin to 28% and 18% of initial values. No further decrease of these parameters was observed during the infusion of 30 mg rt-PA over 6 h. Only 2% of the preinfusion fibrinogen levels could be recovered as fibrinogen-fibrin degradation products. This moderate extent of systemic fibrinogenolysis is much less than that reported for therapeutic i.v. infusions of streptokinase.

Biochemical Changes Noted during Intermittent Administration of Streptokinase

An intermittent dosage scheme of streptokinase (standard initial dose 600,000 units SK infused over 30 min and repeated injections of 250,000 units SK at 24 hr intervals) was applied during 4 days in 9 patients with chronic obliterative arterial disease and in 8 patients with venous occlusion.

Each dose of streptokinase produced an immediate fall in plasminogen to 17 % (SEM 5.1) of the initial value, the level then rose to 50 % (SEM 5.4) within 24 hr. Lowered levels of antiplasmin and fibrinogen (both less than 40% of the initial values) were maintained. This safe level of fibrinogen was maintained despite brief but high peaks of plasmin activity after each injection of SK. A parallel increase of the thrombin time and the fibrin(ogen) degradation products was obtained following each infusion. No bleeding was observed. The relative therapeutic effect of intermittent infusions of streptokinase has still to be compared with the continuous administration of streptokinase in controlled clinical trials.

Sodium Acetate Buffer

Sodium acetate buffer, 0.12 M, pH 7.4 as a diluent in the low temperature technique of dilute clot lysis time, is more effective in accelerating the velocity of lysis than phosphate buffer of similar pH and molarity. A uniform shape of the clot is maintained throughout the digestion in sodium acetate buffer and the end point of lysis is characteristically marked by an abrupt and sharply defined disintegration. Sodium acetate buffer can be employed advantageously in this technique not only to improve the observation but also to shorten the lysis times.

Inhibition of Clot Retraction by Previous In Vitro Platelet Aggregation

Clot retraction was not observed in plasma when coagulation was preceded by in vitro platelet aggregation; this inhibition was proportional to the degree of platelet aggregation.

In the absence of continuous stirring, the coagulation of citrated-platelet rich plasma by CaCl2 was not preceded by measurable aggregation of platelets and was followed by normal retraction of the clot. In presence of a continuous stirring of platelet-rich plasma, the addition of CaCl2 led to platelet clumping and coagulation but not to clot retraction.

Platelet-rich plasma containing ADP-unresponsive platelets, retracted normally.

Using different inhibitors of platelet aggregation, clot retraction was shown to be inhibited by antimycin A and by 2-deoxy-D-glucose together, but was normal in presence of adenosine or acetylsalieylic acid.

Which pool of ATP provides energy for clot retraction has been discussed.

Suggestions were presented that the appearance of platelet factor 3 activity during clotting is not invariably linked to platelet aggregation.

Comparison between the Changes in the Plasma Fibrinogen and Plasminogen Levels Induced by a Moderate or High Initial Dose of Streptokinase

Patients with thrombo-embolic diseases received a maintenance infusion of 0.1 × 106 u streptokinase (SK) h for at least 24 h; the infusion was started either with an initial dose of 0.25 × 106 u SK or an initial dose of 1.2 × 106 u SK.

Before the infusion no significant differences were found betv/een the groups studied here in regard to the plasma fibrinogen and plasminogen levels.

The fibrinogen and plasminogen levels were significantly more depressed immediately after the high initial dose than immediately after the moderate initial dose.

However, 24 h later, as a maintenance dose of 0.1 × 108 u SK was given in both groups, the number of patients with a plasma plasminogen level below 5% was not significantly (P more than 0.1) different. The subsequent evolution of the plasminogen level in the patients treated for 72 h was independent of the initial dose used. After 24 h infusion, the fibrinogen level was already raised in the patients receiving a high initial dose, while it was further decreased in the patients with a moderate initial dose. The subsequent evolution of the fibrinogen level, followed in the patients treated for 72 h, showed that at 48 h the fibrinogen level was not significantly higher in the group receiving 1.2 × 108 u SK as initial dose than in the other group. At 72 h the fibrinogen level was nearly identical for both groups.

A Double Blind Study of the Effect of Tranexamic Acid in Essential Menorrhagia

Oral administration of tranexamic acid, in a dosage of 3 g daily from the first day of menstruation onwards, significantly decreases menstrual haemoglobin loss in women with so-called essential menorrhagia.

The frequency of side-effects reported did not differ between “active” and “placebo” periods.

Acute and Chronic “Defibrination” in Obstetrical Practice

In case thromboplastic material (amniotic fluid, tissue fragments, activated coagulation factors or certain bacterial products) enters the maternal circulation, excessive and diffuse intravascular coagulation often with secondary fibrinolysis will occur in a sufficient degree to decrease the fibrinogen concentration in the blood below the hemostatic level. If this disseminated coagulation is precipitous, blockade of the microcirculation and quick defibrination will result with shock and a definitive bleeding syndrome (amniotic fluid embolism, premature separation of placenta, septic abortion). In subacute and chronic situations (foeto-maternal blood passage in hetero-specific pregnancy, retention of death foetus, hydatiform mole) external bleeding is not necessarily overt and the correct diagnosis often remains undiscovered.

The laboratory diagnosis is difficult and more so as the clinical situation requires urgent therapy. The finding of reduced levels of some coagulation factors (factors IV, VIII) a low platelet count and the detection of products of fibrinolysis (fibrin split products) in the serum indicate the occurrence of disseminated intravascular coagulation.

Treatment will be different in chronic and acute cases but aims in both to eliminate rapidly the source of thromboplastin release. In acute cases of premature separation of the placenta, fibrinogen under cover of heparin can be administered and shock combated with agents increasing cardiac output and causing peripheral vasodilatation. In septic abortion immediate administration of antibiotics and hysterectomy are probably the best advice.

Usefulness of and a Simple Method for Serial Successive Fibrinogen Determinations in Human Pathology

Serial, successive determinations of the fibrinogen content are valuable tools in the management of hypofibrinogenemia syndromes. A detailed description is given of the FPT-test, which has been demonstrated to be a simple and accurate method for serial quantitation of the normally-reactive fibrinogen.

The Streptokinase Reactivity Test. I. Standardization

1. An attempt was made to standardize a method which determines the reactivity of a given blood sample with streptokinase (SKRT).

2. The nature of the thrombin and streptokinase used can greatly influence the test.

3. The 20 minutes value is less influenced by a number of parameters than other points on the streptokinase versus lysis time plot.

Enhancing the Fibrinolytic Activity in Human Blood by Occlusion of Blood Vessels

The lytic activity was measured in blood obtained from a superficial elbow vein when a cuff with a known pressure was attached above the elbow and compared with the activity in the blood taken at the same moment from the control arm without any pressure.

1. Using a pressure 20 mm above the systolic pressure, no enhancement could be obtained in the first 10 minutes.

2. Using a diastolic or systolic pressure during 3 minutes, the fibrinolytic activity was about 2.8 times the activity in the control sample.

3. Using a pressure halfway the diastolic and systolic, the fibrinolytic activity after 3 minutes was about 3.5 times, and after 10 minutes about 11 times the activity in the control sample.

Disappearance of Factor V Activity after Incubation of Plasma with Heparin and Heparinoids

1. Heparin and heparinoids, added to oxalated or citrated plasma produce in this plasma an inactivation of factor V; this inactivation is progressive and directly related to the length of incubation.

The rate of inactivation of factor V is directly proportional to the quantity of anticoagulant added.

2. When quantities with identical anticoagulant activity in the thromboplastin-calcium clotting time are compared, heparin proves to have a stronger effect than heparinoids.

3. The inactvation of factor V in plasma by heparin or heparinoïds is an irreversible process, which cannot be nullified by addition of protamine sulphate.

Propriétés coagulantes d’hémolysats erythrocytaires

1. L’hémolysat érythrocytaire possède une activité coagulante, démontrée dans les tests globaux de la coagulation.

2. Cette activité ne peut pas être expliquée par une contamination plaquet-taire des préparations d’hémolysat.

3. L’hémolysat ne contient pas de thrombine, de prothrombine, facteur VII, facteur anti-hémophilique, ni de facteur IX. Il est par contre légèrement contaminé par le facteur V, probablement d’origine plasmatique.

4. L’activité de l’hémolysat est située surtout dans la première phase de la coagulation sanguine, c. à d. la formation de la thromboplastine. Son rôle est à peu près identique à celui du facteur thromboplastique des thrombocytes.

5. L’hémolysat préparé à partir du sang du cordon ombilical montre une activité très prononcée, qui n’est pas retrouvée dans le test de la formation de la thromboplastine.

6. Les hémolysats préparés du sang de différents animaux sont les plus actifs sur les plasmas de la même espèce.

7. Les hémolysats préparés du sang d’hémophiles du type A ou B, de malades atteints d’anémies hémolytiques, et de malades traités aux dérivés coumariniques ont une activité coagulante normale.

Comparison of Quantification Methods of111In-Labelled Platelet Deposition in Peripheral Bypass Grafts

The action of antithrombotic drugs can be evaluated by measuring the deposition of111In-labelled platelets on peripheral bypass grafts several days after injection. This evaluation can be performed qualitatively (visual interpretation on the daily images) or quantitatively. Four different methods which calculate the ratio of platelet uptake with a reference region are compared: two methods use a gamma camera and two a detector. A blood sample or the region under the sternal angle are used as reference. The daily ratio of the counts, recorded by a gamma camera in a region of interest covering the graft, and the blood radioactivity interpolated from a platelet survival curve appears to be the most reliable method. The information of all the ratios can be combined in a single thrombogenicity index which reflects the daily rise of a linear or exponential regression versus time.