Liner dissociation in total hip arthroplasty: a systematic review.

OBJECTIVE: Liner dissociation (LD) is a rare catastrophic mechanical failure of total hip arthroplasty (THA). The study aims at reviewing the available literature regarding liner dissociations to point out their prevalence, describing any possible association and highlighting the surgical management at the time of revision. MATERIALS AND METHODS: A systematic review of the literature was conducted from January 2002, until February 2022, according to the PRISMA guidelines. The main keywords were: "dissociation" AND "liner" OR "hip arthroplasty" OR "THA" and their MeSH terms in any possible combination. Cases of liner dissociation with all levels of evidence of any age published in indexed journals were included. The study quality of all included studies was evaluated using the MINORS criteria. The kappa (k) value was used to assess the consensus between reviewers in the selection of articles and methodological quality assessment. Finally, a sub-analysis was performed specifically concerning the elderly population. RESULTS: Thirty-one manuscripts met the inclusion criteria of the systematic review (21 case reports and 10 case series). 124 LD in 123 patients, (53% females and 47% males) were evaluated. The overall prevalence of LD was 0.15%. The mean age at surgery was of 56.5 years (range 31-75 years). LD occurred in a primary surgery setting in 86% of the cases, at a mean time of presentation of 45.8 months after replacement surgery. 39.5% of the cups and 8.8% of the stems required revision. The mean follow-up after the revision was 18.4 months. Complications after revision occurred in 19.6% of cases, including 3 cases of re-dissociations. Re-revision was required in 13.6% of the revisions. The sub-analysis of the elderly population included 28 cases of LD identified in 10 manuscripts, with an average age of 73.5 years. CONCLUSIONS: LD is a rare but catastrophic mechanical complication of modular THA that requires implant revision. The LD is not related to a specific prosthetic implant, liner material or design, acetabular positioning within the safe zone or age group.

The JAK2 V617F mutation frequently occurs in patients with portal and mesenteric venous thrombosis.

BACKGROUND: Myeloproliferative disorders (MPDs) represent a risk factor for thrombosis in the portal, mesenteric, and hepatic districts. OBJECTIVE: We aimed to assess whether the Janus kinase 2 (JAK2) V617F mutation, an acquired mutation that occurs in MPD patients, is a risk factor for portal and mesenteric venous thrombosis (PMVT) independently of the presence of overt MPDs. PATIENTS AND METHODS: The medical histories of 99 patients presenting with PMVT were obtained. The presence of the JAK2 V617F and VHL 598C > T mutations was determined by polymerase chain reaction followed by restriction enzyme analysis and direct cycle sequence analysis. RESULTS: Over a 10-year period of observation, of the 99 patients presenting with PMVT, the JAK2 V617F mutation was detected in heterozygous state in 17 individuals [17.2%; 95% confidence interval (95% CI) 10.9-25.9]. None of the patients presenting with the JAK2 V617F mutation carried an inherited thrombophilic risk factor. Seven patients with (43.8%; 95% CI 19.8-70.1) and two without (2.4%; 95% CI 0.3-8.4) the JAK2 V617F mutation had a diagnosis of MPD at the occurrence of the venous thrombotic event. After a median follow-up of 41 months (range 3-114 months), three out of the 10 patients carrying the JAK2 V617F mutation were then diagnosed as having idiopathic myelofibrosis (n = 2) or polycythemia vera (n = 1), whereas in seven patients a MPD was not detected. Two of the 83 patients without the JAK2 V617F mutation went on to develop MPDs. CONCLUSIONS: Determination of the JAK2 V617F mutation may contribute to the search for genetic determinants of PMVT and may be useful to recognize patients who should be carefully observed for the subsequent development of overt MPDs.

Association of protein S p.Pro667Pro dimorphism with plasma protein S levels in normal individuals and patients with inherited protein S deficiency.

A dimorphism in PROS1 gene (c.A2,001G, p.Pro667Pro) has been associated with significantly reduced levels of both free and total protein S in carriers of the GG genotype. It is not known how the GG genotype could influence PS levels in normals, whether it could influence the levels of protein S in carriers of mutations in PROS1 gene and whether this genotype acts as an isolated or additive risk factor for venous thrombosis. With this as background, we evaluated the association of p.Pro667Pro dimorphism with free and total protein S centrally measured in a panel of 119 normal controls, 222 individuals with low protein S and 137 individuals with normal PS levels belonging to 76 families with protein S deficiency enrolled in the ProSIT study. Transient expression of recombinant wild type protein S and p.Pro667Pro protein S was performed to evaluate the role of the A to G transition at position 2001 in vitro. The p.Pro667Pro polymorphism was also expressed together with a p.Glu67Ala variant to assess a possible influence on protein S levels in protein S deficient subjects. Free and total protein S levels were significantly lower in normal women. In normal women only was the GG genotype associated with significantly lower free protein S levels in comparison to AA and AG genotypes (P=0.032). No significant influence of GG genotype was observed in patients, either with known mutations or with low protein S levels. These data were confirmed by in vitro transient expression, showing no difference in secretion levels of the p.Pro667Pro variant (even in association with the p.Glu67Ala mutation), compared to the wild type protein S. The genotype in itself was neither a significant risk factor for venous thrombosis nor a risk modifier in patients with known mutations.

Low protein Z levels and risk of occurrence of deep vein thrombosis.

BACKGROUND: Protein Z (PZ) serves as a cofactor for activated factor X inhibition by the PZ-dependent protease inhibitor. In vivo and in vitro studies aimed at investigating the role of PZ levels in venous thombosis have produced conflicting results. OBJECTIVES: We investigated whether reduced PZ levels and PZ gene common variants are associated deep vein thrombosis (DVT). PATIENTS AND METHODS: In 197 patients with DVT and in 197 age-matched and sex-matched controls, PZ plasma levels and gene polymorphisms were evaluated by means of an enzyme-linked immunosorbent assay and direct cycle sequence analysis. RESULTS: Similar PZ levels were found in controls (1.44; SD 0.63 microg mL-1) and in patients (1.44; SD 0.96 microg mL-1). The incidence of PZ levels below the 5.0 (0.52 microg mL-1) or the 2.5 percentile of controls (0.47 microg mL-1) was higher in patients (10.2% and 8.7%, respectively) than in controls {4.1% [odds ratio (OR) 2.7, 95% confidence interval (CI) 1.2-7.3], and 2.0% (OR 4.6, 95% CI 1.5-13.9), respectively}. This relationship was independent of the effect of age, sex, and factor V Leiden and FII A(20210) alleles [OR 2.8 (95% CI 1.1-7.3), and OR 4.9 (95% CI 1.4-17.3)]. PZ levels were associated with the intron C G-42A and the intron F G79A polymorphisms in cases (r2=0.129) and in controls (r2=0.140). However, frequencies of the PZ gene polymorphisms were similar in the two groups and were not associated with very low PZ levels. CONCLUSIONS: The present data suggest an association between very low PZ plasma levels and the occurrence of DVT, with PZ gene polymorphisms contributing little to this relationship.

A randomized clinical trial of high-intensity warfarin vs. conventional antithrombotic therapy for the prevention of recurrent thrombosis in patients with the antiphospholipid syndrome (WAPS).

BACKGROUND: The optimal intensity of oral anticoagulation for the prevention of recurrent thrombosis in patients with antiphospholipid antibody syndrome is uncertain. Retrospective studies show that only high-intensity oral anticoagulation [target international normalized ratio (INR) >3.0] is effective but a recent randomized clinical trial comparing high (INR range 3.0-4.0) vs. moderate (INR 2.0-3.0) intensities of anticoagulation failed to confirm this assumption. METHODS: We conducted a randomized trial in which 109 patients with antiphospholipid syndrome (APS) and previous thrombosis were given either high-intensity warfarin (INR range 3.0-4.5, 54 patients) or standard antithrombotic therapy (warfarin, INR range 2.0-3.0 in 52 patients or aspirin alone, 100 mg day(-1) in three patients) to determine whether intensive anticoagulation is superior to standard treatment in preventing symptomatic thromboembolism without increasing the bleeding risk. RESULTS: The 109 patients enrolled in the trial were followed up for a median time of 3.6 years. Mean INR during follow-up was 3.2 (SD 0.6) in the high-intensity warfarin group and 2.5 (SD 0.3) (P < 0.0001) in the conventional treatment patients given warfarin. Recurrent thrombosis was observed in six of 54 patients (11.1%) assigned to receive high-intensity warfarin and in three of 55 patients (5.5%) assigned to receive conventional treatment [hazard ratio for the high intensity group, 1.97; 95% confidence interval (CI) 0.49-7.89]. Major and minor bleeding occurred in 15 patients (two major) (27.8%) assigned to receive high-intensity warfarin and eight (three major) (14.6%) assigned to receive conventional treatment (hazard ratio 2.18; 95% CI 0.92-5.15). CONCLUSIONS: High-intensity warfarin was not superior to standard treatment in preventing recurrent thrombosis in patients with APS and was associated with an increased rate of minor hemorrhagic complications.

Natural history and risk factors for thrombosis in 360 patients with antiphospholipid antibodies: a four-year prospective study from the Italian Registry.

PURPOSE: To assess the natural history and risk factors for thrombosis in a large cohort of unselected patients with antiphospholipid antibodies. PATIENTS AND METHODS: Three hundred sixty consecutive patients (118 males, 242 females, median age 39 years [range 2 to 78]) fulfilling the currently accepted criteria for diagnosis of lupus anticoagulant (LAC) (n = 326) and/or raised immunoglobulin G anticardiolipin antibodies (IgG ACA) (n = 185) were collected from 16 Italian institutions and prospectively observed for a median of 3.9 years (range 0.5 to 5). Main endpoints were the occurrence of arterial or venous thrombosis, the outcome of pregnancies, and any severe complications leading to hospitalization or death. RESULTS: Thirty-four patients developed a thrombotic complication, with a total incidence of 2.5% patient-years. Multivariate logistic regression analysis identified two independent risk factors for thrombotic events: a previous thrombosis (RR 4.9; 95% CI, 1.76 to 13.7; P < 0.005) and IgG ACA titer above 40 units (RR 3.66; 95% CI, 1.24 to 10.8; P < 0.01). A total of 28 pregnancies were observed in 25 women and 11 (39%) were abortive. Adverse pregnancy outcomes were significantly more frequent in women with a history of miscarriage or vascular occlusion (9/16, 56%) than in asymptomatic women (2/12, 17%) (P = 0.035). Four patients developed non-Hodgkin's lymphoma during the follow-up. Eighteen patients died. Vascular events and hematological malignancies represented the most frequent causes of death (n = 5 for each). CONCLUSIONS: The present study shows that: (a) previous thrombosis and ACA titer > 40 U are independent predictors of thrombosis; (b) history of miscarriage or vascular disease is significantly associated with adverse pregnancy outcome; (c) hematological malignancies can develop during follow-up in patients with antiphospholipid antibodies.

Antiphospholipid antibodies, haemostatic variables and thrombosis--a survey of 144 patients.

Several clotting abnormalities have been put forth to explain the thrombotic tendency of the antiphospholipid syndrome, but a possible role for fibrinogen and von Willebrand factor has been poorly investigated. The present cross-sectional retrospective study evaluated the relationship of IgG anticardiolipin antibodies, lupus anticoagulants, fibrinogen and von Willebrand factor with the occurrence of arterial and venous thromboses in patients with antiphospholipid antibodies. Among the clotting assays for the detection of lupus anticoagulant, dilute Russell's viper venom time correlated with a history of venous thrombosis more strongly than activated partial thromboplastin time (p < 0.0002 vs p < 0.009) and was the only test which correlated with a history of arterial thrombosis (p < 0.01), also at low levels of IgG anticardiolipin antibodies (p = 0.003). By regression analysis, and after correction for confounders, serum levels of IgG anticardiolipin antibodies were found to be positively associated with the number of venous events (p < 0.001). Plasma levels of fibrinogen and von Willebrand factor were associated with each other (p < 0.0001; r: 0.48) and with the occurrence of arterial and venous thromboses (p < 0.001). Moreover, plasma levels of fibrinogen and von Willebrand factor in thrombotic patients with antiphospholipid antibodies were significantly higher than those of a control group of thrombotic patients who suffered thrombosis for other reasons (p < 0.0001 and p = 0.0008 respectively). Titres of IgG anticardiolipin antibodies correlated with plasma levels of von Willebrand factor (p < 0.0001; r: 0.42).(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic modulation of oral anticoagulation with warfarin.

Cytochrome P450 CYP2C9 gene variants have been associated with hyperresponsiveness to small doses of warfarin and a higher bleeding complication rate. The aim of this study was to investigate whether CYP2C9 gene variants affect doses of drug prescribed to acquire the target anticoagulation intensity and the occurence of bleeding complications. In a cohort of 180 patients followed up at one specialized clinic from the start of the anticoagulation with warfarin, we have investigated whether CYP2C9 gene variants have affected doses of drug prescribed to acquire the target anticoagulation intensity and the incidence of bleeding complications. The adjusted dose required of warfarin was higher among patients with the CYP2C9*1 haplotype (5.6 mg) than those of patients carrying the CYP2C9*2 (4.7 mg; p = 0.007, Scheffé's test) or the CYP2C9*3 haplotype (4.0 mg; p <0.001, Scheffé's test). The occurrence of bleeding complications was more frequent among patients with the CYP2C9*2 and/or the CYP2C9*3 haplotype than in carriers of the CYP2C9*1 haplotype (OR: 2.57; 95% CI; 1.16-5.73). An interaction between the presence of local bleeding sources and the CYP2C9*2 and/or the CYP2C9*3 haplotype was observed (p <0.001). Patients with both local sites of potential bleeding and CYP2C9*2 and/or the CYP2C9*3 haplotype had the higher estimated risk of bleeding (OR: 12.81; 95% CI: 2.86-57.26). CYP2C9 gene variants modulate the anticoagulant effect of the dose of warfarin prescribed. The incidence of bleeding complications in CYP2C9*2 and CYP2C9*3 carriers was significantly higher than that in noncarriers and interacted with the presence of local bleeding sources.

Coagulation activation and fibrinolytic imbalance in subjects with idiopathic antiphospholipid antibodies--a crucial role for acquired free protein S deficiency.

To explore the coagulation/fibrinolytic balance and its relation with free protein S (f-PS) in subjects with antiphospholipid antibodies (aPLs) outside the setting of autoimmune inflammatory disorders, we carried out a cross-sectional study on 18 thrombotic patients with primary antiphospholipid syndrome and 18 apparently healthy subjects with persistence of idiopathic aPLs. Prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin complex (TAT) and D-Dimer (D-D) were taken as markers of thrombin generation and fibrin turnover. Mean F1 + 2 levels were higher in thrombotic (p = 0.006) and non-thrombotic subjects (p = 0.0001) than in controls as were those of D-D (p < 0.0001 and p = 0.003 respectively). TAT levels did not differ. Lower mean levels of f-PS were found in thrombotic (p = 0.0006) and non-thrombotic subjects (p = 0.002) than in controls. Within both groups, mean F1 + 2 levels were higher in subjects who had low f-PS levels compared to those with normal f-PS levels (p = 0.01). Gender analysed data revealed blunted tPA release (venous occlusion test) in thrombotic females (from 16.80 +/- 0.79 to 21.3 +/- 3.9 ng/nl, NS) but not in thrombotic males (from 18.2 +/- 2.0 to 33.7 +/- 4.9 ng/ml, p=0.01) nor in asymptomatic subjects of either sex. Also, in both patient groups females had higher mean PAI than males (p < 0.0002) and than control females (p < 0.02). Low free protein S was found in 100% of non-thrombotic and in 90% of thrombotic patients with defective fibrinolysis. These data are consistent with increased thrombin generation, accelerated fibrin turnover and fibrinolysis abnormalities also in asymptomatic carriers of aPLs and highlight a central role for acquired f-PS deficiency in the thrombotic tendency of the antiphospholipid syndrome.

Thrombophilic genotypes in subjects with idiopathic antiphospholipid antibodies--prevalence and significance.

To evaluate the significance of common thrombophilic genotypes in subjects with idiopathic antiphospholipid antibodies (aPL) we determined the methylenetetrahydrofolate reductase C677-->T (MTHFR) and factor V A506-->G (FV Leiden) polymorphisms in 49 subjects with idiopathic aPL (57% of whom suffered spontaneous vein thrombosis), in 70 subjects with a history of spontaneous vein thrombosis and in 193 healthy subjects. The prevalence of MTHFR C677-->T+/+ (homozygotes) was 25%, 18% and 17% respectively amongst aPL thrombotics, non aPL thrombotics and controls and that of MTHFR C677-->T+/- (heterozygotes) was 53%, 59% and 53% respectively in the same groups. The prevalence of FV Leiden was higher in aPL thrombotics (14%) and in non aPL thrombotics (18%) than in controls (4%) (p < or = 0.05). APL thrombotics with MTHFR C677-->T+/+ had a lower mean age at first thrombotic event (22 +/- 6 years) than aPL thrombotics with MTHFR C677-->T+/- and non mutated considered together (38 +/- 14 years, p = 0.0004) and than non aPL thrombotics with MTHFR C677-->T+/+ (38 +/- 14 years, p = 0.003). FV Leiden may contribute to the hypercoagulability of a small, albeit significant proportion of thrombotic aPL subjects, whereas the association between MTHFR C677-->T+/+ and aPL may have an impact on age at first occlusive event and suggests a possible pathogenetic interaction.

Compound heterozygosity (554-589 del, C515-T transition) in the platelet glycoprotein Ib alpha gene in a patient with a severe bleeding tendency.

Giant platelets in the blood smear, absent in vitro platelet agglutination in response to ristocetin, and normal aggregation, ATP secretion and thromboxane B2 formation were found in a young patient with a life-long bleeding tendency. Ristocetin-induced von Willebrand factor binding to her platelets was less than 10% of normal. Flow cytometric analysis with monoclonal antibodies LJ-Ib-1, LJ-Ib-10, and LJ-P3 was consistent with the latter finding. SDS-PAGE analysis of solubilized platelets showed a marked reduction of the platelet glycoprotein (GP) Ibalpha. Genetic characterisation demonstrated that the patient and her father were heterozygous for a deletion of 36 nucleotides (positions 554-589) leading to a mutant GPIalpha (deletion of aminoacids from residue 169 to 180 and a Glu --> Lys substitution at residue 181). In addition, a C --> T transition at nucleotide 515 in the other allele of the GPIbalpha gene was found in the patient and in her mother that results in the substitution of alanine for valine in codon 156 (Bernard-Soulier type Bolzano). These variations occurred within the VI and VII leucine-rich repeats. The novel variant of Bernard-Soulier syndrome identified further suggests that the integrity of leucine-rich repeats is important for normal function of the GP Ib-IX-V receptor complex.

The methylenetetrahydrofolate reductase TT677 genotype is associated with venous thrombosis independently of the coexistence of the FV Leiden and the prothrombin A20210 mutation.

A polymorphism, C-->T677, in the methylenetetrahydrofolate reductase (MTHFR) gene has been identified as a cause of mild hyperhomocysteinemia, a risk factor for venous thrombosis. We have investigated the frequency of the TT genotype in 277 consecutive patients with confirmed deep venous thrombosis and 431 healthy subjects. The TT MTHFR genotype was more frequent in patients than in controls (25.6% vs. 18.1%; p = 0.016). The risk of thrombosis among carriers of this genotype was significantly increased [odds ratio: 1.6 (95% CI: 1.1-2.3)]. The estimated risk associated with the TT genotype was 2.0 (95% CI: 1.3-3.1) in subjects with (n = 122), and 1.3 (95% CI: 0.8-2.0) in those without (n = 155) predisposing (hereditary, acquired or circumstantial) risk factors for venous thrombosis. Factor V Leiden and prothrombin G-->A20210 are known risk factors for venous thrombosis. After stratification for FV Leiden and prothrombin A20210 mutations, a significant association was also observed. After adjustment for sex, FV Leiden and prothrombin A20210 mutation, the estimated risk of venous thrombosis among carriers of the TT MTHFR genotype was 1.7 (95% CI: 1.2-2.6). The TT MTHFR genotype is independently associated with venous thrombosis, mainly among individuals with a high risk profile.

Coexistence of factor V Leiden and Factor II A20210 mutations and recurrent venous thromboembolism.

Patients carrying the FV Leiden or the FII A20210 mutation have a high risk of venous thromboembolism. Among 542 patients with a documented diagnosis of deep venous thrombosis in one leg consecutively referred for a thrombophilic work-up, we have retrospectively assessed the rate of objectively documented previous recurrence in carriers of both FV Leiden and FII A20210 mutations. Eighty-two patients had experienced 115 episodes of recurrent venous thromboembolism. The rate of recurrent venous thromboembolism was 29.2% among subjects with and 14.5% in those without deficiencies of natural anticoagulant proteins (p = 0.055), and 24.6% among patients with and 14.0% in those without antiphospholipid antibodies (p = 0.036). The frequency of having a recurrent thromboembolism was 16.2%, 20.0%, and 36.4% among carriers of FV Leiden, FII A20210 mutation, or both gene defects, respectively, and 12.8% in subjects carrying neither mutation (p for trend = 0.004). When adjusted for age, sex, and thrombophilic risk factors, the rate was higher among patients with than in those without deficiencies of natural anticoagulant proteins (OR: 3.0; 95% CI: 1.2-7.5), aPL 2.5 (95% CI: 1.3-4.9), or both FV Leiden and FII A20210 gene mutations (OR 4.8; 95% CI: 1.9-12.2). The rate of previous recurrent venous thromboembolism was significantly higher in subjects carrying both FV Leiden and FII 20210 mutations and was comparable to that observed in subjects with deficiencies of natural anticoagulant proteins or antiphospholipid antibodies.

Inherited thrombophilic risk factors and venous thromboembolism: distinct role in peripheral deep venous thrombosis and pulmonary embolism.

STUDY OBJECTIVES: To investigate whether the FII A(20210) mutation is associated with isolated pulmonary embolism (PE). DESIGN: Case-control study. SETTING: Five thrombosis centers in southern Italy. PATIENTS: Six hundred forty-seven consecutive referred patients with objectively documented venous thrombosis and 1,329 control subjects. MEASUREMENTS AND RESULTS: Medical histories were collected. The G-to-A transition at nucleotide 1691 within the factor V gene (FV Leiden) and the G-to-A transition at nucleotide position 20210 within the prothrombin gene locus (FII A(20210)), levels of anticoagulant factors, and levels of antiphospholipid antibodies were determined by standard techniques. Patients with deep venous thrombosis (DVT) of the lower extremities (n = 346) or with additional PEs (n = 175) showed similar prevalences of FV Leiden mutation (24.3% and 16.6%, respectively) and FII A(20210) mutation (14.2% and 12.6%, respectively), and similar deficiencies of natural anticoagulants (4.9% and 2.3%, respectively). In both groups, the frequencies of FV Leiden and/or FII A(20210) mutation were higher than those observed among 1,329 apparently healthy control subjects (4.8% and 4.4%, respectively; p < 0.0001). Among patients with isolated PE (n = 126), prevalences of FV Leiden (7.1%) and FII A(20210) mutation (8.7%) were similar to those of control subjects. Inherited thrombophilic abnormalities were less frequent among patients with PE only (15.6%) than among those with DVT only (37.0%; p < 0.001) or whose conditions were complicated by PE (28. 0%; p = 0.020). Adjusting for age and sex, FV Leiden mutation, FII A(20210) mutation, or both mutations were associated with DVT with PE (FV Leiden mutation: odds ratio [OR], 3.0; 95% confidence interval [CI], 1.6 to 5.5; FII A(20210) mutation: OR, 2.6; 95% CI, 1. 3 to 5.2; and both mutations: OR, 82.1; 95% CI, 7.5 to 901.2) or without PE (FV Leiden mutation: OR, 6.1; 95% CI, 4.0 to 9.3; FII A(20210) mutation: OR, 2.8; 95% CI, 1.7 to 4.8; and both mutations: OR, 167.5; 95% CI, 21.6 to 1,297.7), but not with isolated PE (FV Leiden mutation: OR, 1.2; 95% CI, 0.5 to 2.8; FII A(20210) mutation: OR, 1.2; 95% CI, 0.5 to 3.1; and both mutations: OR, 22.1; 95% CI, 1. 3 to 370.2). CONCLUSIONS: FII A(20210) mutation is associated with DVT in the lower extremities alone or when complicated by PE, but it is not associated with isolated PE.

Pyruvate kinase deficiency: characterization of two new genetic variants.

Pyruvate kinase (PK) has been purified from the red blood cells of two sisters who had suffered severe chronic non-spherocytic haemolytic anaemia since infancy, and of one patient who had haemolytic anaemia during pregnancy. The two sisters showed remarkable clinical improvement following splenectomy. The enzyme from their red cells was found to exhibit low activity (about 25% of normal) in crude haemolysates, low affinity for the substrate, phosphoenol pyruvate (PEP), and high sensitivity to fructose-1,6-diphosphate (FDP) activation. This PK differs from previously reported variants and it is provisionally designated PK 'Torre Annunziata'. The enzyme from the other patient had near-normal activity in crude haemolysates, slight changes in kinetics with respect to the substrate, PEP, and with respect to the effects of FDP, ATP and pH, and a markedly reduced thermostability. This PK also differs from previously reported variants and it is provisionally designated PK 'Torre del Greco'. During the course of this study an improved method for purification of PK using Cibacron blue sepharose has been developed.

Improved confirmation of weak lupus anticoagulants by employing sensitive and insensitive reagents to the lupus anticoagulant.

Detection of a lupus anticoagulant (LA) is of major importance to detect a thrombotic tendency. Confirmation of its phospholipid dependency may represent a tricky step in the diagnostic algorithm for LA, as several tests may yield borderline results of little diagnostic help. To improve on this point, we had previously employed a procedure comparing sensitive [rabbit brain kaolin (RBK)] and insensitive [soy bean phosphatides (SBP)] reagents to LA to screen and confirm LA at the same time in activated partial thromboplastin systems (aPTT). Here we compared its performance against a platelet neutralization procedure (PNP). To allow comparisons of our procedures with the PNP, a percentage ratio correction was calculated according to the following formula: [(RBK ratio - SBP ratio) x 100]/ RBK ratio. Similarly for the PNP: percentage ratio correction = [(buffer ratio - platelet phospholipid ratio) x 100]/buffer ratio. On 44 known LA plasmas, the PNP, expressed in seconds, yielded 15 (34%) negative or borderline results. After ratio transformation, the PNP still yielded 10 of 15 (66%) uncertain results, whereas the RBK/SBP procedure did not give any uncertain results (P = 0.0002). The mean percentage ratio correction was far superior for the RBK/SBP procedure than for the PNP (53.24 +/- 15.93 versus 20.28 +/- 12.15%, P < 0.0001). The use of sensitive and insensitive reagents to the lupus anticoagulant increases the confirmatory yield of LA in aPTT systems and may deserve inclusion amongst the confirmatory procedures for its diagnosis.

A rapid screen for lupus anticoagulant with good discrimination from oral anticoagulants, congenital factor deficiency and heparin, is provided by comparing a sensitive and an insensitive APTT reagent.

Lupus anticoagulants (LA) are associated with an increased risk of thrombosis and laboratory detection is of major importance. Various tests are available for LA screening and confirmation, but they differ in sensitivity and specificity, frequently lacking the ability to discriminate between the presence of LA, heparin and oral anticoagulants. We noticed that a patient with LA who had a prolonged activated partial thromboplastin time (APTT) by our routine method, gave a normal result with a different APTT reagent. This latter reagent, which contained soy bean phosphatides (SBP), was compared with a reagent containing rabbit brain phospholipids complexed with kaolin (RBK), for APTT measurement in a variety of patients. There was no significant difference in APTT ratio between the two reagents in plasma samples from healthy normal subjects. In LA samples, SBP gave consistently lower APTT ratios than RBK (mean +/- SEM, 1.04 +/- 0.05 and 2.08 +/- 0.19 for SBP and RBK respectively; P < 0.001). In LA patients receiving oral anticoagulants for antithrombotic prophylaxis or treatment, the APTT ratio was again significantly shorter with SBP (1.60 +/- 0.17 and 3.40 +/- 0.67; P < 0.05). In LA negative patients receiving oral anticoagulants, the relationship was reversed, and a higher APTT ratio was obtained with SBP than RBK (1.61 +/- 0.13 and 1.31 +/- 0.12; P < 0.001). In addition, there were no significant differences in APTT ratios for the two reagents when samples from patients receiving heparin therapy, or patients with acquired factor VIII deficiency or inherited deficiency of factor VIII or IX were studied. The use of the SBP reagent alongside a LA sensitive APTT reagent allows a rapid screening for LA, as well as a confirmation of the phospholipid dependency of the inhibitor.

Impact of plasma homocysteine and prothrombin G20210 A on primary antiphospholipid syndrome.

The prevalence of prothrombin (PT) G20210A and methylenetetrahydrofolate reductase (MTHFR) C677 <-- T was assessed in 40 patients with primary antiphospholipid syndrome (APS) (14 male, 26 female; mean age, 37 +/- 14 years) and in 27 persistent carriers of antiphospholipid antibodies (aPL) (five male, 22 female; mean age, 40 +/- 16 years) without underlying diseases. Non-APS thrombotic patients (n = 100; 47 female, 53 male; mean age, 40 +/- 10 years) and healthy subjects (n = 100; 46 female, 54 male; mean age, 56 +/- 16 years) served as control groups. Plasma homocysteine (HC) (enzyme-linked immunosorbent assay) was measured in all aPL patients and in 51 subjects from the healthy control group (mean age, 38 +/- 16 years). Heterozygous prothrombin PT G20210A was more frequent in the thrombotic group without APS (18%) than in the control (4%), APS (12%) or aPL (11%) groups, whereas homozygous MTHFR C677 <-- T was equally distributed. After genotype sub-grouping, plasma HC was higher in APS patients with homozygous MTHFR C677 <-- T compared with non-homozygous APS patients (22 +/- 5.4 versus 11 +/- 1.3 micromol/l; P < 0.01) and with homozygous MTHFR C677 <-- T controls (22 +/- 5.4 versus 15 +/- 2.0 micromol/l). In the APS group, mean age at first event was lower in homozygous MTHFR C677 <-- T patients than in non-homozygous patients (26 +/- 7.5 versus 36 +/- 13 years; P = 0.008). In the same group, homozygous MTHFR C677 <-- T patients suffered an increased average number of events per person than non-homozygous patients (1.9 versus 1.3; P = 0.04). Heterozygous PT G20210A contributes little to the thrombotic tendency of primary APS whereas plasma HC may influence age at first event and number of events. Measurement of plasma HC in aPL subjects may identify patients at increased thrombotic risk requiring HC lowering.

Minimal trauma knee hemarthrosis.

Four patients who suffered from minimal trauma knee hemarthrosis are presented. In all patients, the cause of the hemarthrosis was not the traumatic event in itself, but an underlying clotting or collagen disorder. The necessity of interaction between the orthopaedic surgeon and a coagulation unit is stressed.