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Copyright of Lijecnicki Vjesnik is the property of Croatian Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Osmangazi Journal of Medicine / Osmangazi Tip Dergisi is the property of Eskisehir Osmangazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Transplant-associated thrombotic microangiopathy (TA-TMA) is a fatal complication of hematopoietic stem cell transplantation and is characterized by severe thrombocytopenia, hemolytic anemia, and organ dysfunction. In response to several possible triggers, dynamic multimetric change in von Willebrand factor (VWF) may contribute to inducing microthrombi in circulation in TA-TMA. Objectives: By performing VWF multimer analysis and measuring VWF-degradation product (DP), we unraveled the relationship between multimeric changes in circulating VWF and the pathogenesis of TA-TMA. Methods: This study analyzed 135 plasma samples from 14 patients who underwent allogeneic hematopoietic stem cell transplantation at a single institute. VWF-associated markers, namely VWF:antigen (VWF:Ag), VWF-DP/VWF:Ag ratio, VWF:ristocetin cofactor activity, VWF:ristocetin cofactor activity/VWF:Ag ratio, and ADAMTS13 activity, were analyzed in these samples collected every 7 days. Results: There were 2 patients with definite thrombotic microangiopathy (TMA) and 6 patients who presented with probable TMA that did not progress to definite TMA. Each plasma sample was classified into 3 groups: definite TMA, probable TMA, and non-TMA. VWF multimer analysis showed the absence of high-molecular-weight VWF multimers in probable TMA, whereas the appearance of unusually large VWF multimers was observed in definite TMA. The median value of the VWF-DP/VWF:Ag ratio in probable TMA was elevated to 4.17, suggesting that excessive cleavage of VWF multimers by VWF cleaving enzyme, ADAMTS13, resulted in the loss of high-molecular-weight VWF multimers. Conclusion: During the transition from probable to definite TMA, drastic VWF multimer changes imply a switch from bleeding to thrombotic tendencies. Extensive VWF-DP and VWF multimer analyses provided novel insights.

Microangiopathic Hemolytic Anemia (MAHA); Congenital Thrombotic thrombocytopenic purpura (TTP), Acquired (Immune) TTP, Shiga toxin associated Endemic hemolytic uremic syndrome (HUS) and Complement-Mediated TMA (CM-TMA), which may present with different clinical findings, Thrombocytopenia is a severe condition that affects multiple organ systems with anemia. In the congenital form, ADAMTS13 (von Willebrand Factor-Cleaving Protease or a metalloprotease that belongs to the "a disintegrin and metalloprotease with a thrombospondin type I motif) is diagnosed by the deficiency of the enzyme and the absence of antibodies. While in autoimmune TTP, the enzyme deficiency is associated with antibodies, endemic HUS associated with Shiga toxin is characterized by decreased ADAMTS13 levels due to endothelial damage. CM-TMA is associated with complement factor H (CFH) inhibitory dysfunction and increased complement levels due to a genetic mutation. On March 27, 2023, the patient with complaints of shortness of breath, headache, dizziness, weakness, and numbness in the hands and arms was admitted to the internal medicine clinic. The patient, presenting with Thrombocytopenia, reduced haptoglobin levels, elevated reticulocyte count, increased LDH, indirect hyperbilirubinemia, and a PLASMIC score of 6 in peripheral blood smear, was hospitalized and treated with the prediagnosis of TTP. Later, ADAMTS13 level was found to be 73% (normal range: 40-130), and the diagnosis of CM-TMA was considered. In addition, we discussed the clinical distinction and treatment of TTP by reviewing the literature. [ABSTRACT FROM AUTHOR]

Background: Hereditary thrombotic thrombocytopenia purpura (hTTP) is an ultra‐rare disorder resulting from an inherited deficiency of ADAMTS13, a von Willebrand factor (VWF)‐cleaving metalloprotease. The plasma‐derived factor VIII/VWF Koate (FVIII/VWFKoate) has been shown to contain ADAMTS13, allowing for its use to treat hTTP at home by the patient/caregiver. Aim: Based on prior demonstration of safe and effective use of FVIII/VWFKoate in eight patients with hTTP, we conducted a retrospective study to gather additional data regarding the use of FVIII/VWFKoate for hTTP. Methods: This was a multicentre, retrospective, noninterventional chart review of patients who had received FVIII/VWFKoate for the management of hTTP. Data collected included demographics, medical history, relevant family history, past use and tolerability of fresh frozen plasma, and details regarding FVIII/VWFKoate therapy. Results: The cohort included 11 patients (seven males, four females) with hTTP, ranging in age at study entry from 2 to 28 years. The average duration of FVIII/VWFKoate therapy was 4.8 years (range, 0.5–6.5 years). Among nine patients using FVIII/VWFKoate as prophylaxis, the normalized annual rate of breakthrough TTP episodes ranged from 0.2 to 1.1 episodes/year. All nine patients who received FVIII/VWFKoate prophylaxis had thrombocytopenia recorded at baseline, while eight (88.9%) did not have thrombocytopenia after using FVIII/VWFKoate. There was one AE (unspecified) attributed to FVIII/VWFKoate. Conclusion: These data suggest that FVIII/VWFKoate is a safe and well‐tolerated source of the missing ADAMTS13 enzyme in patients with hTTP, producing a marked reduction in thrombocytopenia prevalence, low frequency of TTP episodes, and with the added benefit of self‐ or caregiver‐administration. [ABSTRACT FROM AUTHOR]

Objective: To determine and compare plasma thrombomodulin, von Willebrand factor and von Willebrand factor-cleaving protease levels between pre-eclamptic and healthy pregnant females. Method: The cross-sectional, comparative study was conducted at the Department of Haematology, University of Health Sciences, Lahore, Pakistan, from November 2019 to December 2020, and comprised pregnant females who were divided into healthy pregnant group A and pre-eclamptic group B. Plasma thrombomodulin and von Willebrand factor-cleaving protease levels were determined by using commercially available enzyme-linked immunosorbent assay kit, and von Willebrand factor level was determined by using immuno-turbidimetric assay kit. Data was analysed using SPSS 25. Results: Of the 88 participants, there were 44(50%) females with mean age 25.5±6 years in group A and 44(50%) in group B with mean age 26±5 years. Median thrombomodulin level in group B was significantly higher than group A (p=0.003). Median von Willebrand factor-cleaving protease levels were lower in group B compared to group A (p=0.838). A significant difference in von Willebrand factor level was observed between the groups (p=0.038). Conclusion: Females with pre-eclampsia had significantly higher plasma levels of von Willebrand factor and thrombomodulin than healthy pregnant subjects. Key Words: Thrombomodulin, vWF, ADAMTS13 protein, Pre-eclampsia.

Copyright of Acta Medica Colombiana is the property of Acta Medica Colombiana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy (TMA) related to a severe ADAMTS13 deficiency, the specific von Willebrand factor (VWF)-cleaving protease. This deficiency is often immune-mediated (iTTP) and related to the presence of anti-ADAMTS13 autoantibodies that enhance its clearance or inhibit its VWF processing activity. iTTP management may be challenging at extreme ages of life. International cohorts of people with TTP report delayed diagnoses and misdiagnoses in children and elderly people. Child-onset iTTP shares many features with adult-onset iTTP: a female predominance, an idiopathic presentation, and the presence of neurological disorders and therapeutic strategies. Long-term follow-ups and a transition from childhood to adulthood are crucial to preventing iTTP relapses, in order to identify the occurrence of other autoimmune disorders and psychosocial sequelae. In contrast, older iTTP patients have an atypical clinical presentation, with delirium, an atypical neurological presentation, and severe renal and cardiac damages. They also have a poorer response to treatment and prognosis. Long-term sequelae are highly prevalent in older patients. Prediction scores for iTTP diagnoses are not used for children and have a lower sensitivity and specificity in patients over 60 years old. ADAMTS13 remains the unique biological marker that is able to definitely confirm or rule out the diagnosis of iTTP and predict relapses during follow-ups. [ABSTRACT FROM AUTHOR]

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal acquired thrombotic microangiopathy syndrome that frequently develops in the context of infectious diseases or systemic autoimmune conditions including connective tissue diseases. We report the case of a 42-year-old female suffering from severe iTTP associated with anti-Jo-1 positive antisynthetase syndrome, which was successfully treated with combination therapy of intravenous immune globulin, rituximab and plasma exchange. Based on a systematic review of the literature, two additional cases of idiopathic inflammatory myopathy-associated iTTP (secondary iTTP) were identified. In conclusion, iTTP may be a rare complication of IIM that clinicians should consider in cases of marked thrombocytopenia. Further work-up of this finding should include a peripheral blood smear (schistocyte count) and ADAMTS13 activity. The concomitant manifestation of these autoimmune conditions may require intensive immunosuppressive therapy. [ABSTRACT FROM AUTHOR]

Thrombotic thrombocytopenic purpura (TTP) is a fatal disease in which platelet-rich microthrombi cause end-organ ischemia and damage. TTP is caused by markedly reduced ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity. Hereditary or congenital TTP (cTTP) is caused by ADAMTS13 gene mutations. In acquired or immune TTP (iTTP), ADAMTS13 activity is reduced by anti-ADAMTS13 autoantibodies. TTP is characterized by thrombocytopenia, hemolytic anemia, fever, renal dysfunction, and neuropsychiatric symptoms. Therapeutic plasma exchange (TPE) and immunosuppressive therapy are the mainstays of treatment. As untreated TTP has a high mortality rate, immediate initiation of TPE is recommended when TTP is suspected. Conventionally, corticosteroids have been used for immunosuppressive therapy. Current drug therapies include rituximab, an anti-CD20 antibody that is effective in newly diagnosed cases and refractory cases, as well as for relapse prevention, and caplacizumab, an anti- von Willebrand factor (VWF) nanobody that inhibits the binding of platelets to VWF and prevents microthrombi formation. Recombinant human ADAMTS13 is a promising treatment for cTTP. Although these therapeutic advances have improved the outcomes of TTP, early diagnosis and prompt initiation of appropriate therapy are necessary to achieve these outcomes. [ABSTRACT FROM AUTHOR]

Background: Thrombotic thrombocytopenic purpura (TTP) considers a rare cause of ischemic stroke (IS). We reported a case of a newly diagnosed patient with acquired immune-mediated TTP (iTTP), in whom two IS events developed during 48 h. Case presentation: A 59-year-old diabetic male was presented to the hospital 24 h after symptoms onset, including left hemiparesis, dysarthria, and decreased consciousness. A brain CT scan was performed with the suspicion of acute IS, indicating infarct lesions in the right middle cerebral artery (MCA) territory. The patient was not eligible for thrombolytic therapy due to admission delay. Over the next 24 h, the patient's neurological condition deteriorated, and the second brain CT scan showed new ischemic lesions in the left MCA territory. Initial laboratory evaluation indicated thrombocytopenia without evidence of anemia. However, in the following days, thrombocytopenia progressed, and microangiopathic hemolytic anemia (MAHA) developed. The ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity and inhibitors assay confirmed the diagnosis of iTTP. The patient underwent plasma exchange activity and inhibitors assay confirmed the diagnosis of iTTP. The patient underwent and pulse IV methylprednisolone. Rituximab was also added due to the refractory course of the disease. After a prolonged hospital course, he had considerable neurologic recovery and was discharged. Conclusions: Clinicians should consider two points. First, TTP should be considered in any patient presenting with IS and having thrombocytopenia or anemia without other symptoms of TTP. Second, worsening the patient's condition during hospitalization may indicate a new stroke and should be investigated immediately. [ABSTRACT FROM AUTHOR]

Upshaw‐Schulman syndrome (USS)—rare autosomal recessive disease that affects <1/1 000 000 individuals. It is characterized by the massive formation of platelet thrombi in the microcirculation accompanied by haemolytic anaemia, thrombocytopenia and clinical and laboratory signs of renal and neurological failure. USS is caused by mutations in the ADAMTS13 gene. Mutations in the ADAM metallopeptidasewith thrombospondin type 1 motif 13 (ADAMTS13) gene can lead to disruption of secretion of this enzyme, or to decrease of enzyme proteinase activity without effect on ADAMTS13 secretion. The aim of this work is to describe a clinical case of USS caused by a new missense mutation in the ADAMTS13 gene. The diagnosis of thrombotic thrombocytopenic purpura was based on clinical signs and confirmed if plasma ADAMTS13 activity was <10%. ADAMTS13 gene sequencing was performed by the Sanger method using oligonucleotide primers of our own design. We found a new, undescribed mutation p.Trp387Ser in a TrpXXTrp motif. Previously, a pathogenic variation disrupting the 387TrpSerSerTrp390 motif of the ADAMTS13 protein was detected only once. Clinical picture of a patient with the combination of the p.Trp387Ser and p.Arg1060Trp variations is quite similar to that of the homozygous state of p.Arg1060Trp variant. [ABSTRACT FROM AUTHOR]

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy (TMA) related to a severe ADAMTS13 deficiency, the specific von Willebrand factor (VWF)-cleaving protease. This deficiency is often immune-mediated (iTTP) and related to the presence of anti-ADAMTS13 autoantibodies that enhance its clearance or inhibit its VWF processing activity. iTTP management may be challenging at extreme ages of life. International cohorts of people with TTP report delayed diagnoses and misdiagnoses in children and elderly people. Child-onset iTTP shares many features with adult-onset iTTP: a female predominance, an idiopathic presentation, and the presence of neurological disorders and therapeutic strategies. Long-term follow-ups and a transition from childhood to adulthood are crucial to preventing iTTP relapses, in order to identify the occurrence of other autoimmune disorders and psychosocial sequelae. In contrast, older iTTP patients have an atypical clinical presentation, with delirium, an atypical neurological presentation, and severe renal and cardiac damages. They also have a poorer response to treatment and prognosis. Long-term sequelae are highly prevalent in older patients. Prediction scores for iTTP diagnoses are not used for children and have a lower sensitivity and specificity in patients over 60 years old. ADAMTS13 remains the unique biological marker that is able to definitely confirm or rule out the diagnosis of iTTP and predict relapses during follow-ups.

Abstract Background Thrombotic thrombocytopenic purpura (TTP) is a life‐threatening thrombotic microangiopathy (TMA) caused by a severe functional deficiency in ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type I repeats‐13), the specific von Willebrand factor (VWF) cleaving protease. ADAMTS13 activity is essential to diagnose TTP but remains challenging to assess, as reference ADAMTS13 activity assays are manual and time consuming. Current techniques also lack robustness in low detectable ADAMTS13 activity range, which could prove problematic for therapy‐driven monitoring. Objectives The HemosIL AcuStar ADAMTS13 activity assay is a fast, automated chemiluminescent assay, the performance of which remains to be evaluated prospectively on very large cohorts of patients with TMA and in real‐life conditions. Patients and Methods Our study was conducted over two successive sequences: a retrospective evaluation followed by a “real‐life” prospective evaluation. Overall, we evaluated the HemosIL AcuStar ADAMTS13 activity assay on 539 citrated plasma samples. We extensively studied linearity, limit of detection, contamination, intra‐assay and interassay precisions with a specific focus on levels

Objective To explore the levels and their possible effects of serum von Willebrand factor (vWF) and vWF lyase (ADAMTS13) in patients with diabetic nephropathy (DN). Methods Fifty cases of healthy physical examination (the normal control group) and 144 patients with type 2 diabetes (the T2DM group) were selected in this study. According to the ratio of urine microalbumin to urine creatinine (ACR), the diabetic T2DM patients were divided into the simple diabetes group (n=42, ACR＜30 mg/g), the microalbuminuria group (n=56, 30 mg/g≤ACR˂300 mg/g), and the macroalbuminuria group (n=46, ACR≥300 mg/g). The immunoturbidimetric method was used to detect vWF levels. The double antibody sandwich method was used to detect ADAMTS13 level, creatinine (sCr), urea nitrogen (BUN) and glycosylated hemoglobin (HbA1c). The glomerular filtration rate (eGFR), D-Dimer and fibrinogen (Fib) were estimated. Results HbA1c, Fib, D-dimer and vWF increased successively in the normal control group, the T2DM group, the microalbuminuria group and the macroalbuminuria group, while ADAMTS13 decreased in turn (P＜0.05). Multiple linear regression analysis showed that albumin and D-dimer were the main factors affecting serum vWF, and D-dimer was the main factor affecting ADAMTS13 levels. ROC curve analysis showed that vWF was more sensitive in diagnosing DN renal damage, while D-dimer had more balanced sensitivity and specificity in the diagnosis of DN renal damage, and specificity was more advantage. Conclusion Serum vWF and ADAMTS13 may play an important role in the occurrence and development of DN, and their levels can be used as clinical indicators for the early diagnosis and prediction of DN. [ABSTRACT FROM AUTHOR]

Abstract Thrombotic microangiopathies are disorders characterized by nonimmune microangiopathic hemolytic anemia, thrombocytopenia, and multi-systemic failure. They are classified as thrombotic thrombocytopenic purpura, atypical hemolytic-uremic syndrome, and typical hemolytic uremic syndrome. The latter is associated with intestinal infections by Shiga toxin-producing bacteria. Typical hemolytic uremic syndrome in adults is an extremely rare condition, characterized by high morbidity and mortality. It has been seldom described in solid organ transplant recipients. Here is presented the case of a kidney transplant recipient who had typical hemolytic uremic syndrome with multisystem commitment, refractory to management and with a fatal outcome.

Abstract Background Thrombotic thrombocytopenic purpura (TTP) is associated with more deleterious outcomes in patients with systemic lupus erythematosus (SLE). However, ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) levels and ADAMTS13 inhibitor were not routinely assayed in most previous studies. The objective of this study is to compare the characteristics and outcomes of immune-mediated TTP (iTTP) in patients with and without SLE. Methods The medical data of 28 patients with iTTP from Peking Union Medical College Hospital were analysed. ADAMTS13 activity and ADAMTS13 inhibitor were measured in all patients. Results All 28 patients had ADAMTS13 inhibitor and severe ADAMTS13 deficiency. iTTP was considered SLE-related (SLE-TTP) in 10 patients and primary (primary iTTP) in 18 patients. Renal involvement on presentation was more severe in patients with primary iTTP as determined by higher serum creatinine (162.7 ± 110.6 vs 73.3 ± 13.4 μmol/L, p

Abstract Background In immune‐mediated thrombotic thrombocytopenic purpura (iTTP), patients develop an immune response against the multidomain enzyme ADAMTS13. ADAMTS13 consists of a metalloprotease (M) and disintegrin‐like (D) domain, 8 thrombospondin type 1 repeats (T1‐T8), a cysteine‐rich (C), a spacer (S), and 2 CUB domains (CUB1‐2). Previous epitope mapping studies have used relatively large overlapping ADAMTS13 fragments. Objectives We aimed at developing small nonoverlapping ADAMTS13 fragments to fine map anti‐ADAMTS13 autoantibodies in iTTP patients. Methods A library of 16 ADAMTS13 fragments, comprising several small (M, DT, C, S, T2‐T5, T6‐T8, CUB1, CUB2), and some larger fragments with overlapping domains (MDT, MDTC, DTC, CS, T2‐T8, CUB1‐2, MDTCS, T2‐C2), were generated. All fragments, and ADAMTS13, were expressed as a fusion protein with albumin domain 1, and purified. The folding of the fragments was tested using 17 anti‐ADAMTS13 monoclonal antibodies with known epitopes. An epitope mapping assay using small ADAMTS13 fragments was set up, and validated by analyzing 18 iTTP patient samples. Results Validation with the monoclonal antibodies demonstrated that single S and CUB1 were not correctly folded, and therefore CS and CUB1‐2 fragments were selected instead of single C, S, CUB1, and CUB2 fragments. Epitope mapping of antibodies of patients with iTTP confirmed that 6 nonoverlapping ADAMTS13 fragments M, DT, CS, T2‐T5, T6‐T8, and CUB1‐2 were sufficient to accurately determine the antibody‐binding sites. Conclusion We have developed a tool to profile patients with iTTP according to their anti‐ADAMTS13 antibodies for a better insight in their immune response.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy (TMA) that requires prompt plasma exchange. Clinical prediction tools may facilitate decision-making in institutions with delayed turnaround time or limited access to ADAMTS13 assays. The PLASMIC score and Bentley score have been shown to predict severe ADAMTS13 deficiency with excellent sensitivity and specificity. To validate the PLASMIC score using a population of suspected TTP, and evaluate its discriminatory power in predicting severe ADAMTS13 deficiency in comparison with Bentley score and clinical gestalt. Adults presenting with suspected TTP in Alberta, Canada between 2008 and 2018 with available ADAMTS13 results were included. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for PLASMIC score, Bentley score and clinical gestalt. Receiver operator characteristics analysis assessed the performance of the scoring systems. Among 163 individuals with suspected TTP, ADAMTS13 activity was available in 117 (72%). Severe ADAMTS13 deficiency <10% was present in 62 (53%). High-risk PLASMIC score (≥6) predicted severe ADAMTS13 deficiency with a sensitivity of 81.7%, specificity 71.4%, PPV 75.4% and NPV 78.4% (c-statistic 0.80). Intermediate-high risk Bentley score (≥20) had a lower sensitivity (59.5%) and higher specificity (93.9%) with similar c-statistic (0.77). Clinical gestalt had similar sensitivity as PLASMIC score but very low specificity (16.1%). Both PLASMIC and Bentley scores had good discriminatory power in identifying severe ADAMTS13 deficiency in a Canadian TMA population compared to clinical gestalt. Integration into institutional clinical pathways may help supplement clinical judgment and reduce costs. • Validation of the PLASMIC score in detecting TTP in a Canadian population • Compared predictive power between PLASMIC and Bentley scores vs clinical gestalt • PLASMIC score predicted TTP (c-statistic 0.80), superior to clinical gestalt. [ABSTRACT FROM AUTHOR]

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA) with significant morbidity and mortality. Guidelines recommend initiating plasma exchange within 4–8 h of suspected diagnosis. It is unclear what are real-world practice patterns and whether delays >8 h increases mortality. To determine if delayed initiation of plasma exchange is associated with increased risk of death and complications. In this retrospective cohort study, we evaluated the time from suspected diagnosis to plasma exchange in all adults presenting with suspected TTP to apheresis centres in Alberta, Canada (2008–2018). Among patients with acquired TTP, the association between delayed plasma exchange and risk of death was evaluated using Cox regression. Overall 190 episodes of suspected TTP were included among 163 individuals. Acquired TTP was confirmed in 61 patients. Inappropriate Emergency Department triage occurred in 59%. The median time from suspected diagnosis to first plasma exchange was 10.7 h; 59% had delayed plasma exchange >8 h, among whom plasma infusion was administered in only 45%. 36% of suspected TTP and 13% of confirmed TTP patients died. Delayed plasma exchange between 8 and 24 h was not associated with a significantly higher risk of death (adjusted hazards ratio; aHR 0.63, 95% CI 0.08–4.83) in confirmed TTP. On the other hand, the risks of death (aHR 1.40, 95% CI 0.20–9.79) and major thrombotic events (aHR 2.9, 95% CI 0.6–12.8) were markedly increased with >24 h delay. Our study demonstrated that TTP care in a real-world setting is discordant with expert guidelines due to multiple barriers. There is a gradient of increased mortality risk and thrombotic complications with longer treatment delays, although the study is likely underpowered. • It is unclear if treatment delay affects mortality in TTP. • 10-year retrospective cohort study of all suspected TTP in Alberta, Canada • Over half of suspected TTP cases had delayed plasma exchange >8 h. • Delays >24 h adversely impact survival and thrombotic sequelae. [ABSTRACT FROM AUTHOR]

Mian Zeng, Qingui Chen, Wenjie Liang, Wanmei He, Haichong Zheng, Chunrong Huang Department of Medical Intensive Care Unit, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China Background: Impaired renal function is often neglected in COPD patients. Considering that COPD patients usually have an ongoing prothrombotic state and systemic inflammation status, we investigated the association among them and explored the predictive value of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS-13), on concealed chronic renal failure (CRF) in COPD patients.Methods: COPD patients were recruited from the First Affiliated Hospital of Sun Yat-Sen University between January 2015 and December 2016. Control was selected from contemporaneous hospitalized patients without COPD and matched by age and gender at a ratio of 1:1. Estimated glomerular filtration rate (eGFR) was calculated by using the Chronic Kidney Disease Epidemiology Collaboration formula, and all subjects were categorized as having normal renal function (eGFR ≥60 mL min–1 1.73 m–2) and having concealed CRF (normal serum creatinine while eGFR

Thrombotic thrombocytopenic purpura is a disease belongs to thrombotic microangiopathies caused by the deficiency or dysfunction of ADAMTS13 protein. It has three possible presentations: chronic, idiopathic or autoimmune, being the last one the most common. Clinical manifestations are variable depending on its time of evolution, it can cause fever, fatigue, arthralgia, abdominal and lumbar pain, as well as myocardial infarction, neurological alterations, renal failure, ischemic stroke and arterial and venous thrombosis. Given the complexity and diversity of the manifestations and complications related to this disease, early and effective diagnosis and treatment are still a little bit difficult; however, now there is a first line treatment which is mainly based on plasma replacement therapy. [ABSTRACT FROM AUTHOR]

A diagnosis of thrombotic thrombocytopenic purpura (TTP) is confirmed by a severe deficiency (

Thrombotic thrombocytopenic purpura (TTP) is caused by inactivation of a von Willebrand factor (VWF)-cleaving enzyme, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), which leads to platelet-rich thrombi comprising unusually large VWF multimers. We have found that ADAMTS13 can bind to the inactivated form of plasmin. In addition, plasmin cleaves purified ADAMTS13 into several fragments and inactivates it. Hence, we hypothesized that activation of plasminogen to plasmin becomes a new-onset factor for TTP due to ADAMTS13 inactivation. Plasmin was added exogenously or activated from plasminogen by streprokinase addition in human plasma (HP). ADAMTS13 digestion and effects of the digestion on ADAMTS13 activity were evaluated. Exogenous plasmin cleaved ADAMTS13 into several fragments, but a portion of ADAMTS13 remained in full-length form. Digestion profile of ADAMTS13 with streprokinase added exogenously in HP was similar to that of ADAMTS13 with exogenous plasmin. ADAMTS13 activity measured using FRETS-VWF73 decreased to ∼40% compared with that for normal plasma. Endogenous VWF multimer-cleaving activity was attenuated more severely (∼10%). These data suggest that endogenous plasmin cleaves ADAMTS13 into fragments and reduces its activity to ∼10%. We suggest that endogenous plasmin activation alone is not sufficient to cause TTP, but plasmin activation with ADAMTS13 deficiency might increase the risk of TTP onset. [ABSTRACT FROM AUTHOR]

Background: Platelet adhesion is mediated by von Willebrand factor (vWF), and disintegrin-like and metalloprotease domain with thrombospondin type-1 motif, number 13 (ADAMTS13) is a protease that cleaves vWF. A change in the balance between vWF and ADAMTS13 in favor of thrombosis might occur shortly before ischemic cardiovascular (CV) events. Objective: To determine whether vWF, ADAMTS13, and the ratio of vWF and ADAMTS13 change during the months preceding an acute CV event. Design: Prospective longitudinal observational study. Setting: Outpatient. Patients: A total of 595 participants with peripheral artery disease (PAD). Measurements: Blood samples were obtained every 2 months for up to 3 years and hemostatic factors examined at intervals preceding events. Results: Sixty-one participants (cases) experienced events and were matched to 122 PAD controls. During the 2-month interval prior to an event, cases (n = 48) had higher levels of the vWF and ADAMTS13 than controls (n = 95; P = .05), but significance was lost after adjusting for the baseline differences in myocardial infarction, unstable angina, and stroke. During the 10 months prior to an event, median values for vWF and the ratio of vWF and ADAMTS13 were higher in cases than in controls, but the differences were not statistically significant. However, in a subset of 20 patients with complete bimonthly data, there was a trend toward an increase in the ratio in the 10 months prior to a CV event (P = .04). Conclusion: In patients with PAD experiencing an ischemic CV event, a significant increase in the ratio of vWF to ADAMTS13 prior to the event could not be confirmed, although there was a weak trend in this direction. [ABSTRACT FROM AUTHOR]

Background Acquired thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy due to the development of autoantibodies against the VWF-cleaving protease ADAMTS13. ADAMTS13-specific circulating immune complexes (CICs) have been described in patients with acquired TTP, but their clinical relevance remained to be established. The aim of this study was to assess the association between ADAMTS13-specific CICs and ADAMTS13-related measurements, clinical and laboratory markers of disease severity, and occurrence of TTP relapse, in autoimmune TTP patients. Material and methods We measured ADAMTS13-specific CICs in 51 patients with severe ADAMTS13 deficiency and anti-ADAMTS13 autoantibodies, at the first episode of acquired TTP. The associations between ADAMTS13-specific CICs and the variables of interest were assessed by linear, logistic and Cox proportional hazard regression models, where appropriate. Results The prevalence of ADAMTS13-specific CICs in patients experiencing the first TTP episode was 39% (95% confidence intervals [CI]: 26–52%). ADAMTS13-specific CICs were not associated neither with laboratory markers of disease severity, nor with patterns of clinical presentation. Conversely, among 45 survivors, a positive association was found between the presence of ADAMTS13-specific CICs and the risk of recurrence within 2 years after the first TTP episode (adjusted hazard ratio, 3.4 [95% CI: 0.9 to 13.5]). Conclusions ADAMTS13-specific CICs seem to be able to predict the recurrence of acute TTP episodes in the first 2 years after disease onset. Therefore, their measurement might be used as a tool to stratify the risk of disease relapse, with potential influence on surveillance and therapeutic choices during remission phase. [ABSTRACT FROM AUTHOR]

Recent successive reports on acute pancreatitis-induced thrombotic thrombocytopenic purpura (TTP) have revealed that TTP-related microvascular damage is an aggravating factor of acute pancreatitis. Here, we report the case of a 26-year-old man diagnosed with acute pancreatitis due to high alcohol consumption. The patient was unconscious as he had taken an overdose of medication, and presented with fever and renal failure due to acute pancreatitis on admission. Although the pancreatitis subsequently improved, the symptoms were still observed; on the next day, he exhibited hemoglobinuria, anemia, and thrombocytopenia. Moreover, general blood examinations indicated the presence of schistocytes and reduced activity of ADAMTS13 (a disintegrin-like metalloproteinase with thrombospondin type 1 motif 13) to 47 %. Thus, the patient was diagnosed with TTP, and plasma exchange was performed. After the development of TTP, the acute pancreatitis recurred, but a severe pathogenesis was prevented by plasma exchange. Thus, ADAMTS13 activity may be useful for predicting a severe pathogenesis of acute pancreatitis. In ADAMTS13-deficient cases, plasma exchange may be an effective technique for preventing aggravation of acute pancreatitis. [ABSTRACT FROM AUTHOR]

Introduction: The prognosis of thrombotic thrombocytopenic purpura (TTP) has considerably improved since the introduction of plasma exchange (PEX) therapy. However, unresponsive thrombotic thrombocytopenic purpura (Un-TTP) still carries high morbidity and mortality rates, indicating a need for early specific treatments. Patients and Methods: In a retrospective study including consecutive adults with TTP admitted between January 1997 and January 2011 in a teaching hospital intensive care unit (ICU), our objective here is to identify early clinical and laboratory features predicting Un-TTP. Patients who responded to plasma exchange and steroids ( N = 49) were compared with patients with unresponsive TTP defined as requirement for other treatments, protracted course, or death ( N = 37, 43 %). Results: Hospital mortality was 24.3 % in the Un-TTP group. Variables associated with Un-TTP on univariate logistic regression were older age, cardiac involvement, neurological involvement, higher anti-a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS13) immunoglobulin G (IgG) titer, lower platelet counts starting on day 2, higher Sequential Organ Failure Assessment (SOFA) scores starting on day 3, need for higher plasma volumes to obtain remission, and greater use of adjuvant treatments and life-sustaining interventions. Multivariate logistic regression identified four factors independently associated with Un-TTP: age over 60 years [odds ratio (OR) 7.90; 95 % confidence interval (95 % CI) 1.06-78.34], cardiac (OR 5.17; 95 % CI 1.63-16.39) or neurological (OR 8.04; 95 % CI 1.27-51.03) manifestations at diagnosis, and day 2 platelet count less than 15 G/l (OR 3.88; 95 % CI 1.30-11.62). Conclusion: Therapeutic intensification starting on day 3 or even earlier in patients with the independent risk factors for unresponsive TTP identified in our study deserves evaluation in a multicenter prospective study. [ABSTRACT FROM AUTHOR]

We prospectively studied the correlations between plasma levels of von Willebrand factor and its cleaving protease- disintegrin and metalloproteinase with thrombo spondin type I motif, member 13 (ADAMTS13)-in 126 patients who did or did not develop no-reflow phenomenon after primary percutaneous intervention for acute ST-segment-elevation myocardial infarction. Quantitative plasma levels of von Willebrand factor and ADAMTS13 were measured by immunoturbidometric assay. Angiographic no-reflow was observed in 46 (37%) of the 126 patients. At admission, plasma levels of von Willebrand factor were significantly higher in the no-reflow group (P <0.001), but levels of ADAMTS13 at admission were similar in the 2 groups (P=0.143). At logistic regression, after adjustment for serum creatinine, left ventricular ejection frac- tion, high-sensitivity C-reactive protein, and N-terminal pro B-type natriuretic peptide, plas- ma von Willebrand factor level at admission (=5,531 mU/mL) was still the predictive factor for the no-reflow phenomenon. The area under the receiver operating characteristics curve was 0.785. Our results suggest that high von Willebrand factor level is related to the no-reflow phenomenon in such a way that it might be a predictor of the phenomenon. [ABSTRACT FROM AUTHOR]