Evaluation of the Effectiveness of Functional Chewing Training Compared with Standard Treatment in a Population of Children with Cerebral Palsy: A Systematic Review of Randomized Controlled Trials.

BACKGROUND: Functional Chewing Training (FuCT) was designed as a holistic approach to improve chewing function by providing postural alignment, sensory and motor training, and food and environmental adjustments. The aim of this systematic review was to evaluate the effectiveness of FuCT in improving chewing function and the severity of tongue thrust and drooling in children with cerebral palsy as compared with standard treatment. METHODS: We conducted a systematic review of randomized controlled trials. The search was performed between October 2021 and January 2022 using the following databases: PubMed, Scopus, Web of Science, and CINAHL. The review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: The initial search yielded 56 articles. After reading the studies in full, 3 articles were chosen based on the inclusion criteria. Included participants were people with PCI; the studies reported a sample size ranging from 40-80 individuals, one study was on a pediatric population, while the others on adults. The selected studies were then evaluated using Jadad and PEDro scales. CONCLUSION: Our study confirmed the value of FuCT in improving chewing function and the severity of tongue thrust and drooling. Our results may be useful in optimizing appropriate therapeutic management.

The adjusted global antiphospholipid syndrome score (aGAPSS) and the risk of recurrent thrombosis: Results from the APS ACTION cohort.

OBJECTIVES: To assess whether patients with antiphospholipid syndrome (APS) and history of recurrent thrombosis have higher levels of adjusted Global AntiphosPholipid Syndrome Score (aGAPSS) when compared to patients without recurrent thrombosis. METHODS: In this cross-sectional study of antiphospholipid antibody (aPL)-positive patients, we identified APS patients with a history of documented thrombosis from the AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking (APS ACTION) Clinical Database and Repository ("Registry"). Data on aPL-related medical history and cardiovascular risk factors were retrospectively collected. The aGAPSS was calculated at Registry entry by adding the points corresponding to the risk factors: three for hyperlipidemia, one for arterial hypertension, five for positive anticardiolipin antibodies, four for positive anti-ß2 glycoprotein-I antibodies and four for positive lupus anticoagulant test. RESULTS: The analysis included 379 APS patients who presented with arterial and/or venous thrombosis. Overall, significantly higher aGAPSS were seen in patients with recurrent thrombosis (arterial or venous) compared to those without recurrence (7.8 ±â€¯3.3 vs. 6 ±â€¯3.9, p<0.05). When analyzed based on the site of the recurrence, patients with recurrent arterial, but not venous, thrombosis had higher aGAPSS (8.1 ± SD 2.9 vs. 6 ±â€¯3.9; p<0.05). CONCLUSIONS: Based on analysis of our international large-scale Registry of aPL-positive patients, the aGAPSS might help risk stratifying patients based on the likelihood of developing recurrent thrombosis in APS.

The comparison of real world and core laboratory antiphospholipid antibody ELISA results from antiphospholipid syndrome alliance for clinical trials & international networking (APS ACTION) clinical database and repository analysis.

BACKGROUND: The APS ACTION International Clinical Database and Repository includes a secure web-based data capture system storing patient information including demographics, antiphospholipid antibodies (aPL)-related medical history, and aPL tests. Despite efforts at harmonization, inter-assay variability remains a problem in aPL testing. As a clinical repository open to researchers, ensuring comparability between assays and consistency in results between APS ACTION laboratories is essential to the validity of studies emerging from this network. OBJECTIVE: To assess the level of agreement between an aPL-registry inclusion and core laboratory (core lab) anticardiolipin antibody (aCL) and anti-ß2-glycoprotein-I antibody (aß2GPI) ELISA testing results. METHODS: Patients are recruited from 25 international centers based on positive aPL tests at inclusion. All samples are retested at the corresponding national APS ACTION core lab to confirm aPL positivity based on standard validated protocols. We analysed the categorical agreement, degree of linear association, and correlation between inclusion (local laboratory) and core lab aPL tests. Samples were included in this study only if results of aPL testing with ELISA at baseline were available. RESULTS: 497 registry samples underwent confirmatory aPL tests. Categorical agreement between the inclusion and core lab values, as expressed by Cohen's kappa coefficients, ranged between 0.61 and 0.80 (as substantial agreement). The correlation between quantitative results in the aCL and aß2GPI was better for IgM and IgA compared to IgG (Spearman rho 0.789 and 0.666 vs. 0.600 for aCL and rho 0.892 and 0.744 vs. 0.432 for aß2GPI). CONCLUSIONS: The results of inclusion for aCL and aß2GPI tests used for recruitment into the registry were in agreement to the results obtained by the APS ACTION core laboratories; aCL and aß2GPI results showed very good categorical agreement. This agreement increased when considering high titer (>40 units) samples. APS ACTION is a reliable and useful research resource for APS.

The Impact of Systemic Lupus Erythematosus on the Clinical Phenotype of Antiphospholipid Antibody-Positive Patients: Results From the AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Clinical Database and Repository.

OBJECTIVE: Although systemic lupus erythematosus (SLE) is the most common autoimmune disease associated with antiphospholipid antibodies (aPL), limited data exist regarding the impact of SLE on the clinical phenotype of aPL-positive patients. The primary objective of this study was to compare the clinical, laboratory, and treatment characteristics of aPL-positive patients with SLE with those of aPL-positive patients without SLE. METHODS: A secure web-based data capture system was used to store patient demographic characteristics and aPL-related clinical and laboratory characteristics. Inclusion criteria included positive aPL according to the updated Sapporo classification criteria. Antiphospholipid antibody-positive patients fulfilling the American College of Rheumatology criteria for the classification of SLE ("aPL with SLE") and those with no other autoimmune diseases ("aPL only") were included in the analysis. RESULTS: Six hundred seventy-two aPL-positive patients were recruited from 24 international centers; 426 of these patients did not have other autoimmune disease, and 197 had SLE. The frequency of thrombocytopenia, hemolytic anemia, low complement levels, and IgA anti-ß2 -glycoprotein I (anti-ß2 GPI) antibodies was higher in the aPL-positive patients with SLE, whereas the frequency of cognitive dysfunction and IgG anti-ß2 GPI antibodies was higher in the aPL-only group. The frequency of arterial and venous thromboses (including recurrent) as well as pregnancy morbidity was similar in the 2 groups. The prevalence of cardiovascular disease risk factors at the time of entry into the registry entry did not differ between the 2 groups, with the exception of current smoking, which was more frequent in aPL-positive patients with SLE. CONCLUSION: Although the frequencies of thrombosis and pregnancy morbidity are similar in aPL-positive patients with and those without SLE, the diagnosis of SLE in patients with persistently positive aPL is associated with an increased frequency of thrombocytopenia, hemolytic anemia, low complement levels, and positive IgA anti-ß2 GPI antibodies.

Rivaroxaban vs warfarin in high-risk patients with antiphospholipid syndrome.

Rivaroxaban is an effective and safe alternative to warfarin in patients with atrial fibrillation and venous thromboembolism. We tested the efficacy and safety of rivaroxaban compared with warfarin in high-risk patients with thrombotic antiphospholipid syndrome. This is a randomized open-label multicenter noninferiority study with blinded end point adjudication. Rivaroxaban, 20 mg once daily (15 mg once daily based on kidney function) was compared with warfarin (international normalized ratio target 2.5) for the prevention of thromboembolic events, major bleeding, and vascular death in patients with antiphospholipid syndrome. Only high-risk patients triple positive for lupus anticoagulant, anti-cardiolipin, and anti-ß2-glycoprotein I antibodies of the same isotype (triple positivity) were included in the study. The trial was terminated prematurely after the enrollment of 120 patients (59 randomized to rivaroxaban and 61 to warfarin) because of an excess of events among patients in the rivaroxaban arm. Mean follow-up was 569 days. There were 11 (19%) events in the rivaroxaban group, and 2 (3%) events in the warfarin group. Thromboembolic events occurred in 7 (12%) patients randomized to rivaroxaban (4 ischemic stroke and 3 myocardial infarction), whereas no event was recorded in those randomized to warfarin. Major bleeding occurred in 6 patients: 4 (7%) in the rivaroxaban group and 2 (3%) in the warfarin group. No death was reported. The use of rivaroxaban in high-risk patients with antiphospholipid syndrome was associated with an increased rate of events compared with warfarin, thus showing no benefit and excess risk. This trial was registered at www.clinicaltrials.gov as #NCT02157272.

Laboratory Diagnostics of Antiphospholipid Syndrome.

Diagnosis of antiphospholipid syndrome (APS) lies in the recognition of antiphospholipid antibodies (aPL). As standardization of tests for the detection of aPL is far from being optimal and reference material is not available, inappropriate diagnoses of APS are not unusual. In the last few years, the concept of triple test positivity has emerged as a useful tool to identify patients with APS. Clinical studies on patients and carriers of triple positivity clearly show that these individuals are at high risk of thromboembolic events and pregnancy loss. Moreover, triple positivity arises from a single (probably pathogenic) antibody directed to domain 1 of ß2-glycoprotein I, a protein whose function is still unknown. Studies on homogenous group of patients with single or double positivity are scant, and uncertainties arise on their association with clinical events. Promising but undetermined results come also from the determination of antibodies directed to phosphatidylserine/prothrombin complex. Interpretation of laboratory profile in APS is challenging, and the collaboration between clinical pathologists and clinicians is highly desirable.

Lupus Anticoagulant Testing: Diluted Russell Viper Venom Time (dRVVT).

Diluted Russell Viper Venom Time (dRVVT) has become the most popular test to detect Lupus Anticoagulant (LA). dRVVT is more sensitive than other global tests employed to detect LA and is not affected by inhibitors of factor VIII or IX. The test is most successfully implemented if you observe three steps in its execution: screening, mixing, and confirmatory studies. Interference due to the presence of heparin in tested plasma must be excluded by means of thrombin time (TT). The prior use of Vitamin K Antagonists (VKAs) or Non-vitamin K Oral Anticoagulants (NOACs) must also be evaluated by means of International Normalized Ratio, or specific tests, respectively.

Detection of lupus anticoagulant in the era of direct oral anticoagulants.

Lupus anticoagulant (LAC) is an in vitro phenomenon determining a phospholipid-dependent elongation of clotting times. The presence of LAC associated with anticardiolipin (aCL) and anti-ß2 glycoprotein I (anti-ß2GPI) antibodies is strongly associated with thrombosis and pregnancy morbidity. Direct oral anticoagulants (DOACs) targeting thrombin and factor Xa are currently widely use to prevent and treat venous and arterial thromboembolism. Some concern has, however, been expressed about the possibility of false laboratory results during LAC assessment in patients taking these drugs. Several in vitro studies, spiking DOACs into normal plasma as well as ex vivo at peak levels in treated patients, led in false-positive LAC. The dilute Russell Viper Venom time is the assay that is most influenced by rivaroxaban, edoxaban, dabigatran and less by apixaban. Both screening and confirmatory tests have resulted equally prolonged for activated partial thromboplastin time and have not led to false-positive results, but this may depend on the type of reagent used for the test. Taipan/Ecarin snake venoms ratios, has been recommend by some investigators as they do not seem to be affected by rivaroxaban or edoxaban, but these tests are neither standardized nor generally available in clinical practice. In conclusion, for the time being it does not seem advisable to carry out LAC testing during anti-factor Xa and anti-factor IIa treatment because of the risk of false-positive results. Whenever needed in deciding the suspension of DOACs or in case of recurrent thrombosis, LAC determination should be carried out at trough better if DOAC concentration is known.

Additional Treatments for High-Risk Obstetric Antiphospholipid Syndrome: a Comprehensive Review.

Most investigators currently advocate prophylactic-dose heparin plus low-dose aspirin as the preferred treatment of otherwise healthy women with obstetric antiphospholipid syndrome, whilst women with a history of vascular thrombosis alone or associated with pregnancy morbidity are usually treated with therapeutic heparin doses in association with low-dose aspirin in an attempt to prevent both thrombosis and pregnancy morbidity. However, the protocols outlined above fail in about 20 % of pregnant women with antiphospholipid syndrome. Identifying risk factors associated with pregnancy failure when conventional therapies are utilized is an important step in establishing guidelines to manage these high-risk patients. Some clinical and laboratory risk factors have been found to be related to maternal-foetal complications in pregnant women on conventional therapy. However, the most efficacious treatments to administer to high-risk antiphospholipid syndrome women in addition to conventional therapy in order to avoid pregnancy complications are as yet unestablished. This is a comprehensive review on this topic and an invitation to participate in a multicentre study in order to identify the best additional treatments to be used in this subset of antiphospholipid syndrome patients.

The challenges of lupus anticoagulants.

The term "lupus anticoagulant" (LA) refers to a heterogeneous group of immunoglobulins behaving as acquired in vitro inhibitors of coagulation. These antibodies, namely anti-ß2GPI and anti-prothrombin antibodies, induce the in vitro elongation of clotting time interfering with phospholipid-dependent coagulation cofactors. Positive LA is associated with thrombosis and pregnancy complications, providing one of the three laboratory criteria for the classification of the anti-phospholipid syndrome. LA is the strongest predictor of clinical events, especially when associated with other anti-phospholipid antibodies. Much more controversial is the risk conveyed by isolated and weak LA. LA detection is technically laborious, envisaging screening, mixing and confirming tests. Hopefully critical issues in LA detection, such as the interference of anticoagulants, will be overcome, in the next future.

Diagnosis and therapy of antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is a clinical condition that has not been well defined yet. Although the clinical component is well established, the laboratory part is a mood issue. According to current guidelines, 3 tests (lupus anticoagulant, anticardiolipin, and anti ß2-glycoprotein I antibodies) are officially recommended to assess the presence of antiphospholipid antibodies. According to test positivity, patients are classified into categories in clinical studies. However, it is now clear that classification categories have a different impact on the clinical course of APS. Indeed, patients and healthy carriers with a full positive antibody profile (triple positivity) are those at the highest risk of events. Patients with a single test positivity are those at a lower risk. In this review, on the basis of a laboratory profile, we grade the diagnosis of APS into definite, probable/possible, and uncertain. We also discuss secondary prevention of thrombotic APS, prevention of pregnancy morbidity, and treatment of catastrophic APS. Finally, new tools in laboratory diagnosis and treatment are highlighted.

Incidence of a first thromboembolic event in carriers of isolated lupus anticoagulant.

Among the so called antiphospholipid (aPL) antibodies Lupus Anticoagulant (LAC) is considered the strongest risk factor for thromboembolic events. In individuals without a previous thromboembolic event (carriers), LAC is a risk factor when associated with the presence of anticardiolipin (aCL) and aß2-Glycoprotein I (aß2GPI) antibodies. On the other hand, data on carriers of isolated LAC positivity are sparse and inconclusive. The aim of this study was to prospectively determine the incidence of thrombosis in a cohort of carriers of isolated LAC positivity. One-hundred seventy-nine carriers of LAC confirmed twelve weeks apart and in a reference laboratory were studied. During a total follow up of 552 person-years, there were seven thromboembolic events (1.3% person-y). All the seven patients had at least one adjunctive major risk factor for thrombosis. The cumulative incidence of thromboembolic events was 3.1% (95% CI 0.6-5.6) after 2years, and 5.9% (95% CI 1.2-10.6) after 5 and 10years. On a multivariate regression analysis considering age, sex, autoimmune disease, risk factors for arterial and venous thrombosis, use of aspirin, only age was found to be an independent predictor of thromboembolic events (HR=1.1, 95% CI 1.0-1.2, p=0.02). These data might be relevant in clinical practice and underline the importance of differentiating LAC carriers in terms of isolated positivity or positivity associated with the presence of antibodies to aCL and ß2-glycoprotein I.

The paradox of the lupus anticoagulant: history and perspectives.

A unique coagulation inhibitor prolonging whole-blood clotting time was described more than 50 years ago in two patients with systemic lupus erythematosus (SLE). The immunoglobulin nature of the inhibitor and its interaction with antiphospholipid antibodies was later demonstrated and the term "lupus anticoagulant (LA)" was coined to describe this laboratory finding. It soon became apparent that LA was a misnomer as it is often found in plasma from patients with clinical conditions other than SLE and is associated with thromboembolic events that may occur in otherwise healthy individuals. Individuals with LA have circulating autoantibodies that inhibits blood coagulation. These are mostly of IgG or IgM class and mainly directed against a phospholipid (PL)-binding plasma protein, ß2-glycoprotein I (ß2GPI). The presence of ß2GPI-dependent LA represents a well-recognized risk factor for venous and arterial thromboembolism, as well as pregnancy loss and morbidity. ß2GPI-dependent LA in the presence of documented previous thromboembolism, or history of pregnancy loss/morbidity, identifies definite anti-PL syndrome. Laboratory diagnosis of LA is thus of particular importance, as it may assign patients with a common event (thrombosis) to a group with a high risk for recurrence, which is a prerequisite for long-term oral antithrombotic treatment.

Clinical relevance of ß2-glycoprotein-I plasma levels in antiphospholipid syndrome (APS).

Antiphospholipid syndrome (APS) is characterized by the presence of antiphospholipid (aPL) antibodies associated with thrombosis or pregnancy morbidity. The antibodies mainly involved in this disorder are directed against ß2-glycoprotein I (ß2-GPI). ß2-GPI plasma level is usually not reported in studies on APS, because it is not regarded as relevant to the diagnosis and prognosis of APS. Nevertheless its measurement may be important for understanding the pathophysiology of the syndrome. This review summarizes available data from the literature on plasma concentrations of ß2-GPI in patients with different antibody profiles.

Estimated frequency of antiphospholipid antibodies in patients with pregnancy morbidity, stroke, myocardial infarction, and deep vein thrombosis: a critical review of the literature.

OBJECTIVE: Antiphospholipid Syndrome Alliance For Clinical Trials and International Networking (APS ACTION) is an international research network devoted to conducting well-designed clinical trials in persistently antiphospholipid antibody (aPL)­positive patients. One of the first needs of APS ACTION was to know the true aPL frequency in patients with pregnancy morbidity (PM), stroke (ST), myocardial infarction (MI), and deep venous thrombosis (DVT). METHODS: The search for "aPL" and multiple keywords regarding the outcomes of interest was completed in PubMed. The median frequency for positive aPL tests (lupus anticoagulant, antibody against cardiolipin [aCL], and antibody against ß(2)-glycoprotein I [anti-ß(2)GPI]) was calculated for each outcome and was used to estimate the overall aPL frequency. RESULTS: Based on the analysis of 120 full-text papers, the overall aPL frequency was estimated as 6% for PM, 13.5% for ST, 11% for MI, and 9.5% for DVT. Limitations of the literature were that 60% of the papers were published before 2000, all 3 criteria aPL tests were performed in only 11% of the papers, 36% of papers used a low-titer aCL cutoff, anti-ß(2)GPI cutoff was quite heterogeneous, aPL confirmation was performed in only one-fifth of papers, and the study design was retrospective in nearly half of the papers. CONCLUSION: It is difficult to determine the frequency of a "clinically significant aPL profile" in patients with aPL-related clinical outcomes due to the lack of robust data. Our best estimates of the incidence of aPL-associated events should be confirmed with appropriately designed population studies.

Paclitaxel-hyaluronan hydrosoluble bioconjugate: mechanism of action in human bladder cancer cell lines.

OBJECTIVES: A previously described hydrosoluble paclitaxel-hyaluronan bioconjugate appears particularly well suited for treatment of superficial bladder cancer because of its in vitro cytotoxic profile against urothelial carcinoma (UC) cell lines and in vivo biocompatibility. The aim of this work was to assess the mechanism of action of the bioconjugate in UC cells. MATERIALS AND METHODS: Expression of CD44 and RHAMM hyaluronan-binding receptors in RT-4 and RT-112/84 UC cell lines, interaction of fluorochrome-labeled bioconjugate with tumor cells, CD44 modulation upon incubation with the compound or free hyaluronan, and caspase activation were assessed by flow cytometry. Cytotoxicity was studied by the MTT assay. Analysis of bioconjugate intracellular localization and effects on ß-tubulin organization was carried out by confocal microscopy. RESULTS: The paclitaxel-hyaluronan bioconjugate bound to UC tumor cells entered intracellular compartments through a saturable and energy-dependent mechanism that involved CD44, as assessed by blocking with specific antibody. Upon internalization, the bioconjugate accumulated into lysosomes where the esteric bond between paclitaxel and the hyaluronan moiety was cleaved, leading to cytoplasmic diffusion of the free drug, caspase activation, and disruption of the ß-tubulin microtubular mesh with subsequent cell death. CONCLUSIONS: Conjugation of paclitaxel to hyaluronan results in a new chemical entity, characterized by selective targeting to polymer receptors on plasma membrane and cell entry through receptor-mediated endocytosis, followed by lysosomal accumulation. Ultimately, the active molecule is released, fully preserving the cytotoxic potential and profile of clinically used free paclitaxel.

What have we learned about antiphospholipid syndrome from patients and antiphospholipid carrier cohorts?

Venous or arterial thrombosis or pregnancy morbidity in the presence of circulating antiphospholipid antibodies (aPL) define the antiphospholipid syndrome (APS). In terms of accepted APS criteria, aPL are detected by one coagulation test (lupus anticoagulant; LAC) and two immunoassays (anticardiolipin antibodies and anti-ß2-glycoptrotein I antibodies). In patients with APS, a single positive test carries a much lower risk of thrombosis recurrence or new pregnancy loss than does multiple (or triple) positivity. The same holds true for aPL carriers, namely subjects with laboratory tests but without clinical criteria for APS. Thus, very different risk categories exist among patients with APS as well as in carriers of aPL. Triple positivity apparently identifies the pathogenic autoantibody (antidomain I-II of ß2-glycoptrotein I); it is in this category of patients that trials on new therapeutic strategies should focus.

Incidence of a first thromboembolic event in asymptomatic carriers of high-risk antiphospholipid antibody profile: a multicenter prospective study.

Persistent antiphospholipid (aPL) antibodies are occasionally found in subjects without prior history of thromboembolic events (TEs), raising the dilemma of whether to initiate or not a primary thromboprophylaxis. A first TE is considered rare in aPL carriers, but previous studies did not consider the aPL profile nor was the test positivity confirmed in a reference laboratory. In this study, 104 subjects with high-risk aPL profile (positive lupus anticoagulant, anticardiolipin, and anti-ß(2)-glycoprotein I antibodies, triple positivity) confirmed in a reference laboratory, were followed up for a mean of 4.5 years. There were 25 first TEs (5.3% per year): the cumulative incidence after 10 years was 37.1% (95% confidence interval [CI], 19.9%-54.3%). On multivariate analysis, male sex (hazard ratio = 4.4; 95% CI, 1.5-13.1, P = .007) and risk factors for venous thromboembolism (hazard ratio = 3.3; 95% CI, 1.3-8.5, P = .01) were independent predictors for TEs. Aspirin did not significantly affect the incidence of TE. In conclusion, the occurrence of a first TE in carriers of high-risk aPL profile is considerable; it is more frequent among male subjects and in the presence of additional risk factors for venous TE. These data can help in the decision to initiate primary thromboprophylaxis in these subjects.

Standardization of lupus anticoagulant. Feasibility study of a calibration model to minimize between-method variability.

BACKGROUND: Results for lupus anticoagulant (LA) are currently expressed as ratio of patient-to-normal clotting times (LA-ratio). Yet, numerical results do vary according to the method used for testing, thus making difficult the between-method comparison of results. We hypothesized that the standardization model currently used for the INR for patients on oral-anticoagulants (OAT) would be of value also for LA standardization. PATIENTS AND METHODS: To test this hypothesis we determined a sensitivity index valid for LA (called LASI) for six LA-detection methods against a common-standard using two sets of calibration-plasmas: (i)normal-plasmas spiked with IgG derived from patients strongly-positive for LA or (ii)plasmas from LA-positive patients. The LASI was then used to convert the LA-ratio into the standardized-LA-ratio (SLA-ratio) according to the equation: SLA-ratio = (LA-ratio)(LASI). RESULTS: We demonstrate that (i)the model is feasible because calibration plots of log-transformed clotting times obtained for the LA-detection methods-vs.-the common-standard gave acceptable LASI values; (ii)the model is effective because between-method variability expressed as coefficient of variation, which was 42.8% with results expressed as LA-ratio, decreased to 7.8% with results expressed as SLA-ratio; (iii)the LASI value calculated with the LA-positive plasmas is more effective in minimizing between-method variability than the LASI value calculated with IgG-spiked plasmas. CONCLUSIONS: A model of LA calibration similar to the INR for patients on OAT is feasible by using plasmas from LA-positive patients instead of patients on OAT. Potential application of the model are:(i)to compare the relative responsiveness of different LA-detection methods,(ii)to minimize differences between their results and (iii)to quantify LA potency.

Chemical synthesis and characterization of wild-type and biotinylated N-terminal domain 1-64 of beta2-glycoprotein I.

The antiphospholipid syndrome (APS) is a severe autoimmune disease associated with recurrent thrombosis and fetal loss and characterized by the presence of circulating autoantibodies (aAbs) mainly recognizing the N-terminal domain (DmI) of beta2-glycoprotein I (beta2GpI). To possibly block anti-beta2GpI Abs activity, we synthesized the entire DmI comprising residues 1-64 of beta2GpI by chemical methods. Oxidative disulfide renaturation of DmI was achieved in the presence of reduced and oxidized glutathione. The folded DmI (N-DmI) was purified by RP-HPLC, and its chemical identity and correct disulfide pairing (Cys4-Cys47 and Cys32-Cys60) were established by enzymatic peptide mass fingerprint analysis. The results of the conformational characterization, conducted by far- and near-UV CD and fluorescence spectroscopy, provided strong evidence for the native-like structure of DmI, which is also quite resistant to both Gdn-HCl and thermal denaturation. However, the thermodynamic stability of N-DmI at 37 degrees C was remarkably low, in agreement with the unfolding energetics of small proteins. Of note, aAbs failed to bind to plates coated with N-DmI in direct binding experiments. From ELISA competition experiments with plate-immobilized beta2GpI, a mean IC(50) value of 8.8 microM could be estimated for N-DmI, similar to that of the full-length protein, IC(50)(beta2GpI) = 6.4 microM, whereas the cysteine-reduced and carboxamidomethylated DmI, RC-DmI, failed to bind to anti-beta2GpI Abs. The versatility of chemical synthesis was also exploited to produce an N-terminally biotin-(PEG)(2)-derivative of N-DmI (Biotin-N-DmI) to be possibly used as a new tool in APS diagnosis. Strikingly, Biotin-N-DmI loaded onto a streptavidin-coated plate selectively recognized aAbs from APS patients.