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SummaryVery-high-purity Factor VIII concentrates produced by monoclonal or recombinant technology have been postulated to be more antigenic resulting in an increased risk of inhibitor development in hemophilia A patients. However, previous reports, mainly based on prevalence figures, may have understimated the “true” risk of this complication in patients treated with less pure Factor VIII concentrates. The present study, started in 1975, has been designed to calculate the risk of inhibitor development in patients with severe or moderate hemophilia A, followed since their first exposure to intermediate or high-purity Factor VIII concentrates, produced by conventional technologies. Sixty-four hemophiliacs fulfilled the enrollment criteria. Inhibitors developed in 20.3% (13/64) of all patients and in 23% (11/48) of those with severe Factor VIII deficiency. Eleven patients manifested a strong anamnestic response after exposure to Factor VIII (high responders) and 2 had low inhibitor concenlialions despite repeated Factor Vlll infusions (low responders). The incidence of inhibitor development was 24.6 per 1000 patient yeuis of observalion. The, cumulative! risk of inhibitor formation was 19,9% at age of 6 years, and 20.3% at 5 years after the first exposure. The risk was 19.3% at 70 days of exposure to Factor VIII concentrates, and 17.2% after a total of 50,000 units of Factor VIII given.Further stuides are needed to confirm the above risk of acquiring an inhibitor, which indicates and under-estimations by previous studies. In addition, more data is needed to demonstrate whether very high purity Factor VIII concentrates may be more antigenie than conventional preparations.

In the cases presented herein, the TIA episode occurred in the setting of a long history of migraine. Our findings suggest that in a sample of Southern Italy population, aPL are independently associated with the risk for TIA episode.

We investigated the activated partial thromboplastin time prolongation after addition to citrated plasma of a heparin-antithrombin mixture, expressed as the ratio of the APTT carried out in the presence of the heparin mixture divided by the baseline APTT of the same plasma mixture. Thrombophilia defects are recognized in about one third of the patients presenting with a venous thromboembolic event.

Bechet's disease may be considered an immune-mediated vasculitis involving vessels of all size. We would like to suggest that Bechet's disease should be considered as a prethrombotic state. Howerer, we feel that the hypercoagulable/prethrombotic state of the Bechet's disease remains to be elucidaded.

Haemostatic system compounds not routinely studied, have been evaluated to define the individual risk of VTE (venous thromboembolism) and to influence the prognosis using selective drugs. Significantly high values of fibrinogen, free-TFPI, F1 + 2 fragments and TAT complexes on coagulation side and PAI-1 and TAFI on fibrinolysis side have been detected. Thrombin seems to have a role in the inhibition of TAFI dependent fibrinolysis not inhibited by heparin.

Inhibitor antibodies to transfused factor VIII pose significant challenges in the management of haemophilia A patients. The main concern is the inefficacy of replacement therapy in patients with high-titre antibodies, who have a shorter life-span and a greater morbidity compared to subjects without inhibitors. The ultimate goal in treating these patients is to eliminate the inhibitor antibody entirely, allowing the recommencement of specific replacement therapy. The results of an immune tolerance regimen based on pharmacokinetic parameters are reported here. In 12 high-responder haemophilia A patients immune tolerance induction (ITI) was attempted with daily administration of factor VIII concentrates of very high purity, either plasma-derived or produced by recombinant-DNA technology. Patients were given 100 IU kg(-1) day(-1) until the inhibitor was shown to be absent by at least two negative assays 1 month apart, with normal recovery of infused factor VIII and normal half-life (> 6 h), as assessed after a 3-day washout period. After the patient was judged to be inhibitor-free, immune tolerance treatment was continued with unmodified factor VIII doses for 2 months. Doses were thereafter gradually reduced and finally, regular prophylaxis by administration of 25 IU kg(-1) three times weekly was instituted. Immune tolerance was achieved in 10 of the 12 patients (including six of seven with long-standing inhibitors) within a median time of 8 months. Outcome of immune tolerance was not influenced by age at start of ITI nor by the interval between inhibitor development and ITI. The success rate and the inhibitor disappearance time of our immune tolerance regimen, utilizing high-purity factor VIII, agrees with those reported by other investigators.

A total gastrectomy with omentectomy and resection of the distal oesophagus in a 69-year-old haemophilia A patient with high inhibitor of 128 Bethesda units is described. Surgery was successfully performed after infusion of 112 microg kg-1 bw of recombinant FVIIa. Ninety-two microg kg-1 were given thereafter at time intervals of 2 h until 12 h, then every 3 h until 24 h, and every 4 h until 48 h after surgery. Doses were gradually reduced in the following days and finally discontinued on day 28 after surgery. The complete treatment schedule required the administration of a total of 708 mg of recombinant FVIIa. Using this approach, we observed normal haemostasis, and there were no signs of excessive postoperative bleeding or wound haematoma. No clinical side-effects or evidence of systemic activation of coagulation occurred during the treatment. As judged from the clinical course of this major surgery, recombinant FVIIa appears to be highly efficacious and safe and should be used as first line treatment in high titre inhibitor patients with cross-reactivity to porcine factor VIII, undergoing surgery.

Recent findings have indicated the association between APC-resistance and cerebrovascular disease. These reports prompted us to investigate whether resistance to APC could be found in patients suffering from stroke.Therefore, we studied APC-resistance in 50 young adults (or =45 yrs) with a history of ischemic stroke. Eleven out of fifty cerebrovascular subjects showed APC-resistance, while 2 had PC deficiency and 3 PS deficiency. No deficiencies in the anticoagulant protein AT III and in fibrinolytic proteins were found. The family history demonstrated a distribution of APC-resistance compatible with dominant autosomal inheritance. The plasma concentration of prothrombin fragment 1+2 (F1+2), which is a marker of hypercoagulable states, was also measured in patients and family members of resistant subjects (n = 38).DNA analysis showed factor V R506Q mutation (Leiden mutation) in 11 patients and their relatives with poor response to activated protein C detected by APTT tests. Of 11 investigated subjects with APC-resistance, 9 were heterozygotes and 2, with the lowest APC-ratio values, were homozygotes for factor V mutation. Among 38 relatives, 22 showed a poor response to APC and according to the APC-ratio values, 18 were heterozygotes and 4 homozygotes for FV Leiden mutation. The mutation, in heterozygous form, was also found in 2% of our normal population (n = 100). The plasma concentration of F1+2 was significantly higher both in 11 individuals carrying the FV:Q506 mutation and in 39 patients without APC-resistance compared to that found in the control group. However, the patients with FV:Q506 mutation showed the highest values in F1+2. In the studied family members F1+2 plasma levels were within normal values.Our findings indicate a possible involvement of APC-resistance in the pathogenesis of cerebral thrombosis in young adults and agree with the hypothesis that individuals with APC-resistance have an imbalance between pro-and anti-coagulant forces leading to increased thrombin generation and a hypercoagulable state.

Recent findings have indicated the association between activated protein C (APC)-resistance and cerebrovascular disease. These reports prompted us to investigate whether resistance to APC could be found in patients suffering from transient ischaemic attacks or stroke. Therefore, we studied APC-resistance in 14 young adults belonging to three different families with a history of transient ischemic attacks (TIAs) and stroke. Nine out of fourteen subjects showed APC-resistance but no deficiencies in the anticoagulant proteins AT III, PC and PS. The family history demonstrated a distribution of APC-resistance compatible with dominant autosomal inheritance. A rapid screening method to detect factor V R506Q (Leiden) mutation without sequencing or restriction enzyme digestion has been set-up after biochemical analyses. DNA analysis showed a guanine to adenine transition at nucleotide 1,691 in patients and their relatives with poor response to activated protein C detected by APTT tests. Of 14 investigated subjects and their family members, 5 were normals, 6 were heterozygotes and 3 were homozygotes for factor V mutation. The mutation, in heterozygous form, was also found in 1.3% of our normal population (n = 75). Our findings indicate a possible involvement of APC-resistance in the pathogenesis of arterial thrombosis in young adults.

The aim of this study was to investigate the role of natural cascade inhibitors in Juvenile Transient Ischemic Attacks. Fifty patients with anterior or posterior brain attacks were studied. One hundred healthy subjects matched for sex and age were randomly assigned to a control group. All had a physical examination and radiologic work-up. Computerized tomography showed no ischaemia either with or without contrast medium. Digital angiography of epiaortic and intracerebral vessels was unremarkable patients non controls ever had war-farin therapy. Antithrombin III, protein C and plasminogen were determined by functional methods. Protein S was assayed by a functional clotting method based on prolonged PT. The activated protein C resistance test was performed and a poor response to activated protein C was verified in patients. Our findings show protein S, protein C and antithrombin III type I deficiency with a functional activity70% compared to controls. Eight of fifty patients (16%) had low protein S levels, 5 (10%) had low protein C, 2 (4%) had low antithrombin III and 1 (2%) plasminogen deficiency. A significant (p0.01) difference in activated protein C ratio was seen for controls and patients. These results suggest that screening for natural anticoagulants in young people suffering from transient ischemic attacks could be beneficial and should be encouraged.

Fibrin and fibrinogen degradation products in the cerebrospinal fluid (CSF-FDP) were first studied in a group of 29 patients observed during the first and the second week after subarachnoid hemorrhage (SAH), then in a second group of 26 patients for a total of 55 patients. In the latter group only the first FDP value obtained as soon as possible after SAH was taken in consideration. In the whole series of 55 patients several noteworthy factors were found: 1) FDP determination should be performed as soon as possible after SAH; 2) CSF-FDP at or above 40, 80 micrograms/ml was found both in the patients with severe neurological deficits and in those with cerebral ischemia (statistically significant); 3) the significance of CSF-FDP in patients who rebled was also evaluated. In conclusion CSF-FDP could be considered useful in predicting cerebral ischemia.

Very-high-purity Factor VIII concentrates produced by monoclonal or recombinant technology have been postulated to be more antigenic resulting in an increased risk of inhibitor development in hemophilia A patients. However, previous reports, mainly based on prevalence figures, may have underestimated the "true" risk of this complication in patients treated with less pure Factor VIII concentrates. The present study, started in 1975, has been designed to calculate the risk of inhibitor development in patients with severe or moderate hemophilia A, followed since their first exposure to intermediate or high-purity Factor VIII concentrates, produced by conventional technologies. Sixty-four hemophiliacs fulfilled the enrollment criteria. Inhibitors developed in 20.3% (13/64) of all patients and in 23% (11/48) of those with severe Factor VIII deficiency. Eleven patients manifested a strong anamnestic response after exposure to Factor VIII (high responders) and 2 had low inhibitor concentrations despite repeated Factor VIII infusions (low responders). The incidence of inhibitor development was 24.6 per 1000 patient-years of observation. The cumulative risk of inhibitor formation was 19.9% at age of 6 years, and 20.3% at 5 years after the first exposure. The risk was 19.3% at 70 days of exposure to Factor VIII concentrates, and 17.2% after a total of 50,000 units of Factor VIII given. Further studies are needed to confirm the above risk of acquiring an inhibitor, which indicates an under-estimation by previous studies. In addition, more data is needed to demonstrate whether very-high-purity Factor VIII concentrates may be more antigenic than conventional preparations.

Previous studies of the inheritance of the two molecular subunits of fibrin stabilizing factor (factor XIII) refer to isolated cases. The present work investigates the hereditary mode of transmission of subunits A and S, measured by the Laurell technique, in seven homozygotes and in 29 heterozygotes belonging to four families with factor XIII deficiency. The results indicate that the homozygotes were devoid of immunologically identifiable A subunit, whereas the heterozygotes could be identified by measuring this protein. The subunit S has been found to be decreased both in homozygous and in heterozygous patients, so that it seems that the two subunits, even if their synthesis is controlled by different genes, are genetically related. The mode of transmission of this disorder, supported by quantitative determinations of plasma subunit A, is autosomal recessive.