Proteomic profiling for biomarker discovery in heparin-induced thrombocytopenia.

New analytical techniques can assess hundreds of proteins simultaneously with high sensitivity, facilitating the observation of their complex interplay and role in disease mechanisms. We hypothesized that proteomic profiling targeting proteins involved in thrombus formation, inflammation, and the immune response would identify potentially new biomarkers for heparin-induced thrombocytopenia (HIT). Four existing panels of the Olink proximity extension assay covering 356 proteins involved in thrombus formation, inflammation, and immune response were applied to randomly selected patients with suspected HIT (confirmed HIT, n=32; HIT ruled-out, n=38; positive heparin/PF4 [H/PF4] antibodies, n=28). The relative difference in protein concentration was analyzed using a linear regression model adjusted for sex and age. To confirm the test results, soluble P-selectin was determined using ELISA in above mentioned patients and an additional second dataset (n=49). HIT was defined as a positive heparin-induced platelet aggregation test (HIPA; washed platelet assay). Among 98 patients of the primary dataset, the median 4Ts score was 5 in patients with HIT, 4 in patients with positive heparin/PF4 antibodies, and 3 in patients without HIT. The median OD of a polyspecific heparin/PF4 ELISA was 3.0, 0.9, and 0.3, respectively. Soluble P-selectin remained statistically significant after multiple test adjustments. The area under the receiver-operating-characteristics-curve was 0.81 for Olink and 0.8 for ELISA. Future studies shall assess the diagnostic and prognostic value of soluble P-selectin in the management of HIT.

Accuracy of Diagnosing Heparin-Induced Thrombocytopenia.

Importance: Heparin-induced thrombocytopenia (HIT) is a life-threatening condition that requires urgent diagnostic clarification. However, knowledge of the diagnostic utility of the recommended diagnostic tests is limited in clinical practice. Objective: To evaluate the current diagnostic practice for managing the suspicion of HIT. Design, Setting, and Participants: This prospective diagnostic study was conducted from January 2018 to May 2021 among consecutive patients with suspected HIT from 11 study centers in Switzerland, Germany, and the United States. Detailed clinical data and laboratory information were recorded. Platelet factor 4/heparin antibodies were quantified using an automated chemiluminescent immunoassay (CLIA). A washed-platelet heparin-induced platelet activation (HIPA) test was used as a reference standard to define HIT. Exposures: Suspicion of HIT. Main Outcomes and Measures: The primary outcome was the diagnostic accuracy of the 4Ts score, the CLIA, and the recommended algorithm serially combining both tests. Results: Of 1448 patients included between 2018 and 2021, 1318 were available for the current analysis (median [IQR] age, 67 [57-75] years; 849 [64.6%] male). HIPA was positive in 111 patients (prevalence, 8.4%). The most frequent setting was intensive care unit (487 [37.0%]) or cardiovascular surgery (434 [33.0%]). The 4Ts score was low risk in 625 patients (46.8%). By 2 × 2 table, the numbers of patients with false-negative results were 10 (9.0%; 4Ts score), 5 (4.5%; CLIA), and 15 (13.5%; recommended diagnostic algorithm). The numbers of patients with false-positive results were 592 (49.0%; 4Ts score), 73 (6.0%; CLIA), and 50 (4.1%; recommended diagnostic algorithm), respectively. Conclusions and Relevance: In this diagnostic study of patients suspected of having HIT, when the recommended diagnostic algorithm was used in clinical practice, antibody testing was required in half the patients. A substantial number of patients were, however, still misclassified, which could lead to delayed diagnosis or overtreatment. Development of improved diagnostic algorithms for HIT diagnosis should be pursued.

Tranexamic Acid for Intracerebral Hemorrhage in Patients on Non-Vitamin K Antagonist Oral Anticoagulants (TICH-NOAC): A Multicenter, Randomized, Placebo-Controlled, Phase 2 Trial.

BACKGROUND: Evidence-based hemostatic treatment for intracerebral hemorrhage (ICH) associated with non-vitamin K antagonist oral anticoagulants (NOACs) is lacking. Tranexamic acid (TXA) is an antifibrinolytic drug potentially limiting hematoma expansion. We aimed to assess the efficacy and safety of TXA in NOAC-ICH. METHODS: We performed a double-blind, randomized, placebo-controlled trial at 6 Swiss stroke centers. Patients with NOAC-ICH within 12 hours of symptom onset and 48 hours of last NOAC intake were randomized (1:1) to receive either intravenous TXA (1 g over 10 minutes followed by 1 g over 8 hours) or matching placebo in addition to standard medical care via a centralized Web-based procedure with minimization on key prognostic factors. All participants and investigators were masked to treatment allocation. Primary outcome was hematoma expansion, defined as ≥33% relative or ≥6 mL absolute volume increase at 24 hours and analyzed using logistic regression adjusted for baseline hematoma volume on an intention-to-treat basis. RESULTS: Between December 12, 2016, and September 30, 2021, we randomized 63 patients (median age, 82 years [interquartile range, 76-86]; 40% women; median hematoma volume, 11.5 [4.8-27.4] mL) of the 109 intended sample size before premature trial discontinuation due to exhausted funding. The primary outcome did not differ between TXA (n=32) and placebo (n=31) arms (12 [38%] versus 14 [45%]; adjusted odds ratio, 0.63 [95% CI, 0.22-1.82]; P=0.40). There was a signal for interaction with onset-to-treatment time (Pinteraction=0.024), favoring TXA when administered within 6 hours of symptom onset. Between the TXA and placebo arms, the proportion of participants who died (15 [47%] versus 13 [42%]; adjusted odds ratio, 1.07 [0.37-3.04]; P=0.91) or had major thromboembolic complications within 90 days (4 [13%] versus 2 [6%]; odds ratio, 1.86 [0.37-9.50]; P=0.45) did not differ. All thromboembolic events occurred at least 2 weeks after study treatment, exclusively in participants not restarted on oral anticoagulation. CONCLUSIONS: In a smaller-than-intended NOAC-ICH patient sample, we found no evidence that TXA prevents hematoma expansion, but there were no major safety concerns. Larger trials on hemostatic treatments targeting an early treatment window are needed for NOAC-ICH. REGISTRATION: URL: https://clinicaltrials.gov; Unique identifier: NCT02866838.

[Folie à deux - Thrombosis and Infections]. / Folie à deux ­ Thrombose und Infektionen.

Folie à deux - Thrombosis and Infections Abstract: Although infections are not represented in the Revised Geneva or Wells score, they increase the risk of venous thromboembolism (VTE) similarly to the known risk factors (immobilization, major surgery, active neoplasia). This increased risk of VTE can persist for six to twelve months after infection; moreover, the more severe the infection, the higher the risk of VTE may be. In addition to VTEs, infections can promote arterial thromboembolism. For example, 20% of pneumonias are accompanied by an acute cardiovascular event (acute coronary syndrome, heart failure, atrial fibrillation). In the case of infection-associated atrial fibrillation, the CHA2DS2 VASc score remains an appropriate guide for the indication of anticoagulation.

Limited concordance of heparin/platelet factor 4 antibody assays for the diagnosis of heparin-induced thrombocytopenia: an analysis of the TORADI-HIT study.

BACKGROUND: Anecdotal reports suggest that the correlation between heparin/platelet factor 4 (PF4) antibody assays for the diagnosis of heparin-induced thrombocytopenia (HIT) is limited. OBJECTIVES: To investigate the correlation between widely used assays and examine possible factors contributing to variability. METHODS: This is a large, prospective cohort study with 10 participating tertiary care hospitals including 1393 patients with suspected HIT in clinical practice. HIT was defined by a positive heparin-induced platelet activation (HIPA) assay (washed platelet reference standard test). Three different immunoassays were used to measure heparin/PF4 antibodies: chemiluminescent immunoassay, enzyme-linked immunosorbent assay, and particle gel immunoassay. Various factors that could influence the assays were examined: sex (male or female), age (<65 years or ≥65 years), unfractionated heparin exposure, presence of thrombosis, cardiovascular surgery, and intensive care unit. Spearman's correlation coefficients were calculated. Z-scores and diagnostic odds ratios were determined in the aforementioned subgroups of patients. RESULTS: Among 1393 patients, 119 were classified as HIT-positive (prevalence, 8.5%). The median 4Ts score was 5 (IQR, 4-6) in patients with HIT compared with 3 (IQR, 2-4) in patients without HIT. Correlations (rs) between immunoassays were weak (0.53-0.65). Inconsistencies between immunoassays could not be explained by further analyses of z-scored test results and diagnostic odds ratios in subgroups of patients. CONCLUSION: The correlation between widely used heparin/PF4 antibody assays was weak, and key factors could not explain this variability. Standardization of immunoassays is requested to improve comparability.

Enhancement of the haemostatic effect of platelets in the presence of high normal concentrations of von Willebrand factor for critically ill patients needing platelet transfusion-a protocol for the will-plate randomised controlled trial.

INTRODUCTION: von Willebrand Factor (vWF) is a key protein mediating platelet adhesion on the surface of damaged endothelia. To the best of our knowledge, no trial exists that investigated the effect of platelet transfusion in combination with the administration of balanced vWF in severe blood loss, despite being widely used in clinical practice. The Basel Will-Plate study will investigate the impact of the timely administration of balanced vWF (1:1 vWF and FVIII) in addition to platelet transfusion on the need for blood and coagulation factor transfusion in patients admitted to the intensive care unit (ICU) who suffer from severe bleeding. The study hypothesis is based on the assumption that adding balanced vWF to platelets will reduce the overall need for transfusion of blood products compared to the transfusion of platelets alone. METHODS AND ANALYSIS: The Will-Plate study is an investigator-initiated, single-centre, double-blinded randomised controlled clinical trial in 120 critically ill patients needing platelet transfusion. The primary outcome measure will be the number of fresh frozen plasma (FFP) and red blood cell (RBC) transfusions according to groups. Secondary outcome measures include the number of platelet concentrates transfused within the first 48 h after treatment of study medication, quantity of blood loss in the first 48 h after treatment with the study medication, length of stay in ICU and hospital, number of revision surgeries for haemorrhage control, ICU mortality, hospital mortality, 30-day mortality and 1-year mortality. Patients will be followed after 30 days and 1 year for activities of daily living and mortality assessment. The sample size was calculated to detect a 50% reduction in the number of blood products subsequently transfused within 2 days in patients with Wilate® compared to placebo. ETHICS AND DISSEMINATION: This study has been approved by the Ethics Committee of Northwestern and Central Switzerland and will be conducted in compliance with the protocol, the current version of the Declaration of Helsinki, the ICH-GCP or ISO EN 14155 (as far as applicable) and all national legal and regulatory requirements. The study results will be presented at international conferences and published in a peer-reviewed journal. TRIALS REGISTRATION: ClinicalTrials.gov NCT04555785. PROTOCOL VERSION: Clinical Study Protocol Version 2, 01.11.2020. Registered on Sept. 21, 2020.

A machine-learning model for reducing misdiagnosis in heparin-induced thrombocytopenia: A prospective, multicenter, observational study.

Background: Diagnosing heparin-induced thrombocytopenia (HIT) at the bedside remains challenging, exposing a significant number of patients at risk of delayed diagnosis or overtreatment. We hypothesized that machine-learning algorithms could be utilized to develop a more accurate and user-friendly diagnostic tool that integrates diverse clinical and laboratory information and accounts for complex interactions. Methods: We conducted a prospective cohort study including 1393 patients with suspected HIT between 2018 and 2021 from 10 study centers. Detailed clinical information and laboratory data were collected, and various immunoassays were conducted. The washed platelet heparin-induced platelet activation assay (HIPA) served as the reference standard. Findings: HIPA diagnosed HIT in 119 patients (prevalence 8.5%). The feature selection process in the training dataset (75% of patients) yielded the following predictor variables: (1) immunoassay test result, (2) platelet nadir, (3) unfractionated heparin use, (4) CRP, (5) timing of thrombocytopenia, and (6) other causes of thrombocytopenia. The best performing models were a support vector machine in case of the chemiluminescent immunoassay (CLIA) and the ELISA, as well as a gradient boosting machine in particle-gel immunoassay (PaGIA). In the validation dataset (25% of patients), the AUROC of all models was 0.99 (95% CI: 0.97, 1.00). Compared to the currently recommended diagnostic algorithm (4Ts score, immunoassay), the numbers of false-negative patients were reduced from 12 to 6 (-50.0%; ELISA), 9 to 3 (-66.7%, PaGIA) and 14 to 5 (-64.3%; CLIA). The numbers of false-positive individuals were reduced from 87 to 61 (-29.8%; ELISA), 200 to 63 (-68.5%; PaGIA) and increased from 50 to 63 (+29.0%) for the CLIA. Interpretation: Our user-friendly machine-learning algorithm for the diagnosis of HIT (https://toradi-hit.org) was substantially more accurate than the currently recommended diagnostic algorithm. It has the potential to reduce delayed diagnosis and overtreatment in clinical practice. Future studies shall validate this model in wider settings. Funding: Swiss National Science Foundation (SNSF), and International Society on Thrombosis and Haemostasis (ISTH).

[Harvest of Stem Cells from Umbilical Cord Blood: Relevance of Perinatal Factors for the Quality of Umbilical Cord Transplant Units]. / Gewinnung von Stammzellen aus Nabelschnurblut: Relevanz peripartaler Faktoren für die Qualität von Transplantaten.

INTRODUCTION: Umbilical cord blood (UCB) contains hematopoietic stem cells with therapeutic potential and unique cellular properties. Due to the limited number of stem cells in the UCB (surrogate marker total nucleated cells, TNC), only one in five donations is suitable for transplantation. The aim of this study was to investigate whether predictive factors exist for a TNC count above the 99th percentile. MATERIAL AND METHODS: Retrospective data analysis of the 100 largest donations from 2,299 registered UCB units. Differences between maternal, fetal, and obstetric factors were analyzed and compared with a standardized cohort of 731 registered UCB units. RESULTS: maternal age and BMI in the Top100 cohort were higher compared with the comparative cohort (32 vs. 31 years, p=0.007; 30 kg/m2 vs. 29 kg/m2, p=0.024). There were significantly more P1 (76.0 vs. 62.8%, p=0.013) and women with gestational diabetes (5.00 vs. 1.65%, p=0.044). The gestational week, birth weight, the proportion of vaginal-operative deliveries and secondary caesarean sections were higher in the Top100 cohort (40+4 vs. 40+1 wks, p=0.002), (3700 vs. 3450 g, p<0.001), (53.0 vs. 22.7%, p<0.001) (10 vs. 6.2%, p=0.014). CONCLUSION: For a successful transplant, the amount of TNC in the UCB unit is crucial. Vaginal-operative deliveries, secondary caesarean sections, and a birth weight above 3700 g are favorable with regard to stem cell content. In cases with a complicated course of delivery, collection should not be neglected once the mother and child are safely cared for.

Identification of Patients with Cobalamin Deficiency Crucially Depends on the Diagnostic Strategy.

BACKGROUND: Our goal was to determine vitamin B12 (cobalamin) deficiency with different diagnostic strategies, to propose the best possible laboratory strategy, and to synthesize the relevance of biomarkers in the diagnosis of a cobalamin deficiency. METHODS: We performed a secondary data analysis. The testing strategies were (i) vitamin B12 solely, (ii) holotranscobolamin solely, (iii) vitamin B12 and holotranscobolamin, and (iv) reflex testing of holotranscobalamin in samples with vitamin B12 < 300 pmol. A set of 3,044 laboratory samples with vitamin B12 and holotranscobalamin serum values from unselected in- and outpatients from a secondary care hospital. A sample was classified as cobalamin deficient when low values of vitamin B12 < 137 pmol/L or holotranscobalamin ≤ 37 pmol/L were measured. RESULTS: Low cobalamin values were identified in 591 (19.4%) samples either according to low vitamin B12 values (305; 10.0%) or low holotranscobalamin values (436; 14.3%). For 2,404 values with vitamin B12 < 300 pmol/L, the additional measurement of holotranscobalamin (reflex-testing) enabled the detection of an additional 278 (9.1%) deficiencies. When the grey zone was decreased to 138 - 219 pmol/L, the reflex testing of an additional 1,240 samples identified a total of 511 (16.8%) samples as cobalamin deficient. CONCLUSIONS: The identification of cobalamin deficiency or sufficiency highly depends on the diagnostic strategy. A reflex testing with a grey zone for vitamin B12 < 220 pmol/L identifies cobalamin deficiency cost efficiently in 86.5% cases (511 out of 591). Physicians should apply a uniform strategy on how to address the diagnosis of cobalamin deficiency and indication for treatment. In-hospital guidelines, which describe methodology and sensitivity of the locally used assays for vitamin B12 and holotranscobalamin could guide them.

Blast counts are lower in the aspirate as compared to trephine biopsy in acute myeloid leukemia and myelodysplastic syndrome expressing CD56.

INTRODUCTION: CD56 is aberrantly expressed in myeloid neoplasms including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Considering the adhesion effects of CD56, blast quantification in bone marrow might depend on the technique used to obtain respective diagnostic specimens. Therefore, the objective of our study was to investigate the impact of CD56-expression on blast counts in myeloid neoplasms comparing bone marrow aspirates to biopsies. METHODS: We retrospectively analyzed 75 patients diagnosed with MDS and AML. We compared patients with (n = 36) and without (n = 39) CD56-expression by flow cytometry with respect to their blast quantities assessed on bone marrow aspirates versus biopsies. RESULTS: The frequency of CD56-expression on blasts correlated with higher blast counts on biopsies vs. aspirate smears (rs  = 0.52; P = .001). This difference in blast counts was only significant in the CD56 high expressing subgroup (median 68%, 5.5%-95% in biopsy compared to median 32.5%, 1.5%-90% in aspirate; P < .01). The percentage of CD56-positive blasts among the total blast population was lower in the peripheral blood compared to bone marrow (median 31%, 6%-88% vs. 55%, 14%-98%; P = .016). The discrepancy in the blast count between the aspirate and trephine biopsy would have led to misclassification of four cases as MDS instead of AML, if diagnosis had based on the bone marrow aspirate blast count alone. CONCLUSION: Counting blasts in bone marrow aspirates of CD56-positive AML and MDS may be linked to underestimation, potentially leading to misclassification of these myeloid neoplasms, and should therefore be adjusted considering the results obtained on trephine biopsies for reliable diagnosis.

Acquired haemophilia A in the postpartum and risk of relapse in subsequent pregnancies: A systematic literature review.

BACKGROUND: About 1%-5% of acquired haemophilia A cases affect mothers in the postpartum setting. AIMS: This study delineates the characteristics of this disease, specific to the postpartum setting, notably relapse in subsequent pregnancies. METHODS: Report of two cases and literature study (1946-2019), yielding 73 articles describing 174 cases (total 176 cases). RESULTS: Patients were aged 29.9 years (17-41) and 69% primigravidae. Diagnosis was made at a median of 60 days after delivery (range 0-308). Bleeding types were obstetrical (43.4%), cutaneous (41.3%), and muscular (36.7%). In >90% of the cases, FVIII at diagnosis was <1% (range 0%-8%). FVIII inhibitor was documented in 75.4% cases (median titre of 20 BU/ml, range 1-621). Haemostatic treatment was necessary in 57.1% using fresh frozen plasma (16%), factor concentrate (27.6%) and/or bypassing agents (37.4%). Immunosuppressive treatment was administered in 90.8%, mostly steroids (85.3%), alone or combined with immunosuppressants (27%). Rituximab was used mostly as a second line treatment. Only 24 patients (13.6%) had documented subsequent pregnancies and 6 (22.2%) suffered haemophilia recurrence during pregnancy. CONCLUSION: This study allows better definition of: (1) clinical and laboratory characteristics of postpartum acquired haemophilia, (2) response to therapy, and (3) the risk of relapse for subsequent pregnancies.

Haemophagocytic lymphohistiocytosis and liver failure-induced massive hyperferritinaemia in a male COVID-19 patient.

The authors present the case of a 58-year-old man with the unique combination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and, later on, haemophagocytic lymphohistiocytosis admitted to the intensive care unit. During his ICU stay the patient developed a variety of complications including acute respiratory distress syndrome, pulmonary embolism, right heart failure and suspected HLH leading to multiorgan failure and death. Despite the proven diagnosis of haemophagocytic lymphohistiocytosis, the excessively high ferritin levels of the patient did not seem fully explained by this diagnosis. Therefore, the authors want to highlight different causes of hyperferritinaemia in critically ill patients and underline the importance of differential diagnoses when interpreting continuously rising ferritin levels.

Cellular immunotherapy with multiple infusions of in vitro-expanded haploidentical natural killer cells after autologous transplantation for patients with plasma cell myeloma.

BACKGROUND AIMS: To investigate the feasibility and safety of haploidentical natural killer (NK) cell infusions as consolidation immunotherapy after autologous stem cell transplant (ASCT) in patients with plasma cell myeloma. METHODS: Ten patients (median age, 59 years) received induction treatment followed by high-dose melphalan (200 mg/m2) at day -1, ASCT at day 0 and increasing NK cell doses (1.5 × 106, 1.5 × 107 and multiple doses of 1.0 × 108 cells/kg body weight) from day +1 to day +30 after ASCT. NK cells were harvested and purified from peripheral blood of haploidentical donors and expanded for 19 days with interleukin (IL)-2 and IL-15 under Good Manufacturing Practice conditions. RESULTS: NK cell numbers increased 56.0-fold (37.4- to 75.5-fold). Patients received a median of 3.8 × 108 (0.9-5.7 × 108) NK cells/kg body weight in six (three to eight) infusions. Multiparametric mass cytometry analysis demonstrated an altered surface receptor repertoire of expanded NK cells with increased degranulation and cytokine production activities but diminished expression of perforin. Donor NK cells were detectable in the peripheral blood, peaking 1 h after each dose (up to 90% donor NK cells). The treatment was safe and well tolerated, without evidence of graft-versus-host disease. Comparison with a control patient population receiving ASCT without NK cell infusions showed no significant difference in relapse, progression-free survival and overall survival. CONCLUSIONS: This study demonstrates reliable manufacturing of high numbers of activated NK cells for multiple-dose infusions and safe administration of these cellular products. The trial was registered at ClinicalTrials.gov (identifier no. NCT01040026).

Management of bleeding events and invasive procedures in patients with haemophilia A without inhibitors treated with emicizumab.

INTRODUCTION: Emicizumab (Hemlibra®, Hoffmann-La Roche, Switzerland) is now available for haemophilia A patients with or without factor VIII inhibitors. Management of bleeding events and replacement therapy for invasive procedures have to be adapted. OBJECTIVE: To provide a practical guidance for the management of breakthrough bleeding events and elective or urgent surgery in adult and paediatric patients with haemophilia A without inhibitors treated with emicizumab. METHODS: Based on the available literature and the experiences collected from adult and paediatric patients treated in Switzerland, the Working Party on Haemostasis of the Swiss Society of Haematology and the Swiss Haemophilia Network worked together to reach a consensus on the management of bleeding events and invasive procedures. RESULTS AND CONCLUSION: Minor bleeding events and invasive procedures associated with low bleeding risk can be treated without factor replacement therapy in most cases, whereas major bleeding events and high-risk surgery require additional factor VIII replacement at usual doses, at least for the first days. Emicizumab treatment should be continued throughout the procedure and during the postoperative period. Elective major surgery should be planned according to emicizumab dosing for patients with a once-a-month posology. Of note, so far only few data are available on the management of major bleeds and surgery in patients with haemophilia A treated with emicizumab and this practical guidance will have to be regularly updated with growing experience.  .

Incidence of CMV Replication and the Role of Letermovir Primary/Secondary Prophylaxis in the Early Phase After Allogeneic Hematopoietic Stem Cell Transplantation - A Single Centre Study.

BACKGROUND/AIM: Cytomegalovirus (CMV) replication may cause life-threatening complications after allogeneic haematopoietic stem cell transplantation (allo-HSCT). The aim of the study was to characterize CMV events, and the outcome of letermovir (LTV) CMV prophylaxis. PATIENTS AND METHODS: In this retrospective analysis of patients treated with an allo-HSCT between 2010 and 2020, we determined plasma CMV events, as well as associated risk factors. RESULTS: We identified 423 patients who had undergone allo-HSCT between 2010 and 2020. CMV DNAemia was found in 130/423 (30.7%) of patients. CMV reactivation rate was significantly higher in patients with acute graft-versus-host disease, HLA mismatch, and CMV IgG seropositivity of donors and recipients. Among 42 patients receiving LTV prophylaxis those, 5 (11.9%) showed CMV DNAemia under LTV versus 87/353 (24.6%) in a control group. CONCLUSION: Despite the development of better approaches with weekly monitoring and early treatment initiation, CMV reactivations play an important role after allo-HSCT.

Complement C1q Enhances Primary Hemostasis.

The cross-talk between the inflammatory complement system and hemostasis is becoming increasingly recognized. The interaction between complement C1q, initiation molecule of the classical pathway, and von Willebrand factor (vWF), initiator molecule of primary hemostasis, has been shown to induce platelet rolling and adhesion in vitro. As vWF disorders result in prolonged bleeding, a lack of C1q as binding partner for vWF might also lead to an impaired hemostasis. Therefore, this study aimed to investigate the in vivo relevance of C1q-dependent binding of vWF in hemostasis. For this purpose, we analyzed parameters of primary and secondary hemostasis and performed bleeding experiments in wild type (WT) and C1q-deficient (C1qa-/-) mice, with reconstitution experiments of C1q in the latter. Bleeding tendency was examined by quantification of bleeding time and blood loss. First, we found that complete blood counts and plasma vWF levels do not differ between C1qa-/- mice and WT mice. Moreover, platelet aggregation tests indicated that the platelets of both strains of mice are functional. Second, while the prothrombin time was comparable between both groups, the activated partial thromboplastin time was shorter in C1qa-/- mice. In contrast, tail bleeding times of C1qa-/- mice were prolonged accompanied by an increased blood loss. Upon reconstitution of C1qa-/- mice with C1q, parameters of increased bleeding could be reversed. In conclusion, our data indicate that C1q, a molecule of the first-line of immune defense, actively participates in primary hemostasis by promoting arrest of bleeding. This observation might be of relevance for the understanding of thromboembolic complications in inflammatory disorders, where excess of C1q deposition is observed.

Bite by a juvenile Bothrops venezuelensis (Venezuelan lancehead) resulting in severe envenomation: A case report.

Bothrops venezuelensis is a venomous snake of the Viperidae family. It is associated with a high snakebite-related morbidity and mortality in Venezuela, although clinical case descriptions are scarce. Bites by other Bothrops sp. can result in coagulopathy and acute kidney injury. We describe a bite by a captive juvenile B. venezuelensis that caused local swelling, severe pain, endothelial damage, excessive fibrinolysis (INR >12, aPTT 136s, fibrinogen 0.3g/l) and incoagulable blood within 1.5 hours after the bite. The patient was treated with prothrombin complex factors concentrate, fibrinogen and antivenom (Antivipmyn®, Instituto Bioclon, Mexico) 4.5 h after the bite, which improved coagulation parameters progressively. Subsequently signs of compensated disseminated intravascular coagulation manifested and the patient received fresh frozen plasma and erythrocyte concentrate. The patient developed acute kidney injury with macroscopic hematuria. Fluid overload resulted in pulmonary edema requiring intermittent ventilation and diuretic treatment with furosemide. He was discharged with moderately elevated creatinine 16 days after hospitalization. Creatinine level normalized within another week. This case displays the life-threatening toxicity even after juvenile B. venezuelensis bites and the comparability to bites by other Bothrops sp.

Recommendations on the use of anticoagulants for the treatment of patients with heparin-induced thrombocytopenia in Switzerland.

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug effect that occurs in 0.1–5% of heparin treated patients. Management of acute HIT currently involves (1) cessation of heparin exposure, and (2) inhibition of coagulation with an anticoagulant other than heparin. Several anticoagulants can be considered for the treatment of HIT. Anticoagulant monitoring, management of drug-induced adverse events including bleeding, and therapeutic dosing schedules in selected clinical settings represent challenges to the clinician treating HIT patients. Moreover, the fact that not all registered anticoagulants are approved for HIT in Switzerland further complicates the management of HIT. The present recommendations on the anticoagulant treatment of HIT in Switzerland have been elaborated by a panel of Swiss experts belonging to the Working Party Hemostasis (WPH) of the Swiss Society of Hematology (SGH-SSH). They are intended to support clinicians in their decision making when treating HIT patients.