Introduction of a high sensitivity troponin reduces ED length of stay.

BACKGROUND: High sensitivity cardiac troponins (hs-cTn) allow earlier identification and exclusion of acute myocardial infarction. We determined if transitioning from contemporary to high sensitivity troponin T (hs-cTnT) would reduce ED length of stay in chest pain (CP) patients. METHODS: We conducted a pragmatic, prospective, before and after study of implementing a hs-cTnT by reviewing the electronic health records in all adult ED patients presenting to a large, suburban academic medical center during the 3 months before and after transitioning from a 4th generation troponin to a 5th generation hs-cTnT (Elecsys® Troponin T-high sensitive, Roche Diagnostics, Indianapolis, IN). RESULTS: There were 1431 and 1437 CP patients before and after the intervention. Mean (SD) age was 51.5 (18) yrs. and 54.3% were female. The median (IQR) ED LOS for chest pain patients directly discharged to home was 6.2 (4.7-8.4) and 5.3 (4.0-7.2) hours before and after introducing hs-cTn respectively; difference 47 min (95%CI, 35-59); P < 0.001. The median (IQR) ED LOS for chest pain patients admitted to the hospital was 9.5 (6.6-13.8) and 8.1 (5.7-11.2) hours before and after introducing hs-cTn respectively; difference 77 min (95%CI, 35-121); P < 0.001. Overall admission rates (22 vs 21% both before and after) did not change during the study. The rates of computed tomography coronary angiography before and after the intervention were 21 and 20.4% respectively. The rates of invasive coronary angiography before and after the intervention were 5.8 and 5.6% respectively. CONCLUSIONS: Transitioning to a hs-cTnT is associated with a clinically relevant and statistically significant reduction in ED LOS for both discharged and admitted patients with and without CP with no increase in admission or coronary angiography rates.

Novel characteristics of soluble fibrin: hypercoagulability and acceleration of blood sedimentation rate mediated by its generation of erythrocyte-linked fibers.

Soluble fibrin (SF) in blood consists of monomers lacking both fibrinopeptides A with a minor population in multimeric clusters. It is a substantial component of isolated fibrinogen (fg), which spontaneously self-assembles into protofibrils progressing to fibers at sub-physiologic temperatures, a process enhanced by adsorption to hydrophobic and some metal surfaces. Comparisons of SF-rich (FR) and SF-depleted (FD) fg isolates disclosed distinct molecular imprints of each via an adsorption/desorption procedure using gold surfaced silica microplates. Accelerated plasminogen activator-induced lysis and decreased stiffness (G') of thrombin-induced FR fg clots were revealed by thomboelastography. Erythrocyte sedimentation (ESR) in afibrinogenemic plasma (Hematocrit 25-33%) was accelerated by FR fg nearly threefold that of FD fg. Stained smears disclosed frequent rouleaux formations and fibers linking stacked erythrocytes in contrast to no rouleaux by FD fg. Rouleaux formations were more pronounced at 4 °C than at ambient temperatures and at fiber-membrane contacts displayed irregular, knobby membrane contours. One of several FR fg isolates also displayed incomplete fiber networks in cell-free areas. What is more, pre-mixing FR fg with each of three monoclonal IgG anti-fg antibodies at 1.5 mol/mol fg, that inhibited fibrin polymerization, prevented rouleaux formation save occasional 2-4 erythrocyte aggregates. We conclude that spontaneously generated SF fibers bound to erythrocytes forming intercellular links culminating in rouleaux formation and ensuing ESR acceleration which in clinical settings reflects hypercoagulability. Also, the results can explain the reported fg binding to erythrocytes via ligands such as CD47, stable in vivo RBC aggregates in capillaries, and red areas of pathologic thrombi.

Thrombin Generation in Cardiac Versus Noncardiac Surgical Cohorts.

BACKGROUND: Bleeding can be a significant problem after cardiac surgery. As a result, venous thromboembolism (VTE) or anticoagulation or both following mechanical valve implantation are often delayed in these patients. The calibrated automated thrombin (CAT) generation assay has become the gold standard to evaluate thrombin generation, a critical step in clot formation independent of other hemostatic processes (eg, platelet activation, fibrin cross-linking, and fibrinolysis), and is increasingly used to examine thrombotic and hemorrhagic outcomes. No study has currently used this assay to compare the thrombin generation profiles of cardiac surgical patients to noncardiac surgical patients. We hypothesize that noncardiac patients may be less prone to postoperative changes in thrombin generation. METHODS: A prospective, observational, cohort study was undertaken using blood samples from 50 cardiac and 50 noncardiac surgical patients preoperatively, immediately postoperatively, and on postoperative days 1 to 4. Platelet-poor plasma samples were obtained from patients preoperatively, on arrival to the postanesthesia care unit (PACU) or intensive care unit (ICU), and daily on postoperative days 1 to 4 if patients remained inpatient. Samples were evaluated for CAT measurements. Patient and surgical procedure characteristics were obtained from the electronic medical record. RESULTS: The primary outcome variable, median endogenous thrombin potential (ETP), measured in nanomolar × minutes (nM × min), was decreased 100% in cardiac surgical versus 2% in noncardiac patients (P < .001). All parameters of thrombin generation were similarly depressed. Cardiac (versus noncardiac) surgical type was associated with -76.5% difference of percent change in ETP on multivariable regression analysis (95% confidence interval [CI], -87.4 to -65.5; P value <.001). CONCLUSIONS: Cardiac surgical patients exhibit a profound decrease in thrombin generation postoperatively compared with noncardiac surgical patients evaluated by this study. Hemodilution and coagulation factor depletion likely contribute to this decreased thrombin generation after cardiac surgery.

The Acute Effect of Chamomile Intake on Blood Coagulation Tests in Healthy Volunteers: A Randomized Trial.

BACKGROUND: Chamomile administration may have desirable effects in the perioperative setting. Current practice, however, discourages perioperative chamomile use due to a theoretical increase in bleeding. Therefore, we evaluated if chamomile acutely (within 4 h of ingestion) prolongs coagulation assays. METHODS: Eight healthy volunteers were randomized to receive 2 interventions in a crossover design: (a) single dose of chamomile extract capsule (500 mg) and (b) single dose of chamomile tea (3 g in 150 mL water). Interventions were separated at least 3 days apart from each other. Blood was sampled pre-ingestion, 2 h post-ingestion, and 4 h post-ingestion for each intervention. The primary outcome was the maximal change in prothrombin time (PT) before vs after each intervention. Secondary outcomes included changes in international normalized ratio, activated partial thromboplastin time, thrombin time, reptilase time, and fibrinogen levels. RESULTS: All 8 subjects completed the study. The average pre-ingestion PT values for tea and capsules were 11.9 (1.1) s and 12.0 (0.9) s, respectively. Tea significantly increased the average maximum PT by 0.7 (0.2) s (P = 0.0078). Extract capsules increased the maximum PT by 0.3 (0.2) s (P = 0.06). Neither PT prolongation met the predefined 10% threshold for clinical significance. No significant changes in secondary outcomes were observed. CONCLUSIONS: Chamomile tea ingestion prolongs PT. However, the clinical significance of this is unclear at this time and warrants further investigation. ClinicalTrials.gov Registration Number: NCT05272475.

SALL4 is a robust stimulator for the expansion of hematopoietic stem cells.

HSCs are rare cells that have the unique ability to self-renew and differentiate into cells of all hematopoietic lineages. The lack of donors and current inability to rapidly and efficiently expand HSCs are roadblocks in the development of successful cell therapies. Thus, the challenge of ex vivo human HSC expansion remains a fertile and critically important area of investigation. Here, we show that either SALL4A- or SALL4B-transduced human HSCs obtained from the mobilized peripheral blood are capable of rapid and efficient expansion ex vivo by >10 000-fold for both CD34(+)/CD38(-) and CD34(+)/CD38(+) cells in the presence of appropriate cytokines. We found that these cells retained hematopoietic precursor cell immunophenotypes and morphology as well as normal in vitro or vivo potential for differentiation. The SALL4-mediated expansion was associated with enhanced stem cell engraftment and long-term repopulation capacity in vivo. Also, we demonstrated that constitutive expression of SALL4 inhibited granulocytic differentiation and permitted expansion of undifferentiated cells in 32D myeloid progenitors. Furthermore, a TAT-SALL4B fusion rapidly expanded CD34(+) cells, and it is thus feasible to translate this study into the clinical setting. Our findings provide a new avenue for investigating mechanisms of stem cell self-renewal and achieving clinically significant expansion of human HSCs.

Effect of chamomile intake on blood coagulation tests in healthy volunteers: a randomized, placebo-controlled, crossover trial.

BACKGROUND: Chamomile is consumed worldwide for enjoyment and its potentially desirable properties. Widespread patient resource websites, however, discourage preoperative chamomile intake, lest bleeding could worsen. This precaution, though, stems largely from indirect evidence in one case report. To evaluate if chamomile ingestion impacts coagulation assays via coumarin-like substances, we designed a randomized, placebo-controlled, crossover study. MATERIALS AND METHODS: Healthy volunteers were randomized to three interventions in a cross-over-design spanning 5 weeks per subject. Interventions included 7-day consumption of chamomile tea (3 tea bags × 3 times daily = 9 tea bags daily), a chamomile extract capsule (3 times daily), or a placebo capsule (3 times daily). A 7-day washout period elapsed between intervention periods. The primary outcome was the change in prothrombin time (PT) before vs. after each intervention. Secondary outcomes included changes in the international normalized ratio (INR), activated partial thromboplastin time (aPTT), thrombin time (TT), reptilase time (RT), and fibrinogen (FG) surrounding each intervention. RESULTS: All 12 enrolled subjects were randomized and completed the study. The primary outcome of PT change (mean ± SD) was similar across interventions (chamomile tea = - 0.2 ± 0.4 s, extract capsule = - 0.2 ± 0.4 s, and placebo capsule = 0.1 ± 0.5 s; p = 0.34). INR change was 0 s (p = 0.07) for each intervention. The aPTT, TT, RT, and FG, did not change significantly across interventions (p = 0.8, p = 0.08, p = 0.8, and p = 0.2 respectively). CONCLUSIONS: Chamomile intake by tea or capsule does not prolong PT. These findings challenge the notion to avoid perioperative chamomile intake in patients not taking warfarin. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05006378; Principal Investigator: Jonathon Schwartz, M.D.; Registered August 16, 2021.

Thrombotic thrombocytopenic purpura and its look-alikes: a single institution experience.

At presentation, variant or "look-alike" conditions can resemble TTP. We reviewed charts of 26 consecutive patients treated for presumed TTP. Of 15 classic TTP patients, 11 were tested for ADAMTS13; all showed severe deficiency, and inhibitor levels correlated with probability of relapse. The variant TMA group consisted of 8 patients who had active clinical disorders which overlapped with TTP. Variant TMA patients had higher creatinine and worse prognosis than classic TTP patients. "Look-alike" disorders included ITP with intravascular hemolysis following administration of WinRho™, and human granulocytic anaplasmosis. These conditions had not been previously described as TTP look-alikes.

The role of therapeutic apheresis in the treatment of acute antibody-mediated kidney rejection.

Approximately 10% of renal transplant recipients experience acute antibody-mediated rejection (AMR) due to alloimmunization against human leukocyte antigen (HLA) molecules and other antigens. While therapeutic apheresis is included in most treatment protocols for acute kidney allograft rejection, these protocols have been derived mainly from single center experience rather than controlled trials. This concise review focuses on the role of therapeutic apheresis in AMR treatment. Two groups have recently reported treating acute AMR using drug-only strategies without therapeutic apheresis in particular situations, namely in clinically less severe cases or in resource-limited situations without testing for donor specific antibodies. A randomized controlled trial, designed to test the efficacy of immunoadsorption apheresis in AMR treatment, was terminated early and suggested a benefit of apheresis. An observational study suggested efficacy of plasmapheresis in acute AMR treatment, but all patients who received plasmapheresis also received rituximab. As new therapeutic modalities are becoming available, therapeutic apheresis continues to play a role in the treatment of acute kidney allograft rejection.

Clinical pathology resident education during the COVID-19 pandemic.

COVID-19 arrived at our medical centre in March 2020 with substantial force. Clinical pathology concepts began to have a new, direct relevance to our residents' lives. As we wondered 'Have I been exposed? Do I need to self-isolate? Are the tests reliable? Am I protecting myself adequately while handling specimens?', these questions drew new interest in laboratory methods, test interpretation and limitations, supply chain issues, safety and quality. By incorporating SARS-CoV-2 teaching points into laboratory medicine lectures, we enlivened concepts of sensitivity, specificity, predictive value and methodologic issues in serologic, molecular and antigen testing for pathology residents. We drew from the emerging literature on SARS-CoV-2 to create lectures and added details from our own institutional experience with COVID-19. When the pandemic fades from memory, clinical pathology education can still benefit from mnemonics, analogies, anecdotes and creative efforts that capture the attention of the audience.

The platelet proteome.

PURPOSE OF REVIEW: The proteome is the pool of proteins expressed at a given time and circumstance. The word 'proteomics' summarizes several technologies for visualization, quantitation and identification of these proteins. Recent advances in these techniques are helping to elucidate platelet processes which are relevant to bleeding and clotting disorders, transfusion medicine and regulation of angiogenesis. RECENT FINDINGS: Over 1100 platelet proteins have been identified using proteomic techniques. Various subproteomes have been characterized, including platelet releasates (the 'secretome'), alpha and dense granules, membrane and cytoskeletal proteins, platelet-derived microparticles, and the platelet 'phosphoproteome'. Proteomic data about platelets have become increasingly available in integrated databases. SUMMARY: Proteomic experiments in resting and activated platelets have identified novel signaling pathways and secreted proteins which may represent therapeutic targets, as well as potential cancer biomarkers.

Targeting Two Antigens Associated with B-ALL with CD19-CD123 Compound Car T Cell Therapy.

The recent FDA approval of the first CAR immunotherapy marks a watershed moment in the advancement toward a cure for cancer. CD19 CAR treatment for B cell acute lymphocytic leukemia has achieved unprecedented remission rates. However, despite success in treating previously relapsed and refractory patients, CD19 CAR faces similar challenges as traditional chemotherapy, in that malignancy can adapt and overcome treatment. The emergence of both antigen positive and negative blasts after CAR treatment represents a need to bolster current CAR approaches. Here, we report on the anti-tumor activity of a CAR T cell possessing 2 discrete scFv domains against the leukemic antigens CD19 and CD123. We determined that the resulting compound CAR (cCAR) T cell possesses consistent, potent, and directed cytotoxicity against each target antigen population both in vitro and in vivo. Our findings indicate that targeting CD19 and CD123 on B-ALL cells may be an effective strategy for augmenting the response against leukemic blasts and reducing rates of relapse.

Laboratory Monitoring of Platelet P2Y12 Receptor Inhibitors and Reversal of Antiplatelet Agents.

OBJECTIVES: To review the use of laboratory tests for antiplatelet agents to determine escalation of antiplatelet therapy and for emergent reversal of P2Y12 inhibitors. METHODS: A case scenario and review of cardiovascular and neurointerventional literature are described. RESULTS: In cardiovascular disease patients, large randomized trials failed to demonstrate superiority of tailored antiplatelet regimens using the VerifyNow P2Y12 assay, where earlier studies had shown promise. Platelet transfusions restored platelet function measured by vasodilator-stimulated phosphoprotein, light transmission aggregometry, or thromboelastography but not VerifyNow P2Y12, with the most restoration for clopidogrel and the least for ticagrelor. CONCLUSIONS: Current evidence does not support changing antiplatelet therapy based on the results of platelet function monitoring tests. For emergent reversal of P2Y12 inhibitors, test method can affect platelet dosing recommendations, as different methods may give different results.

Genomic and proteomic applications in diagnosis of platelet disorders and classification.

The transcriptome is the mRNA pool found within a cell. Transcriptomic discovery approaches include microarray-based technologies as well as sequencing-based technologies. Transcriptomic experiments provide dynamic information about gene expression at the tissue level. The proteome is the pool of proteins expressed at a given time and circumstance. The word PROTEOMICS summarizes several technologies for visualization, quantitation, and identification of these proteins. Protein separation can be accomplished by two-dimensional electrophoresis, use of protein chips with an affinity matrix, or by a variety of advanced chromatographic methods. Mass spectrometry is used to identify the proteins in conjunction with protein sequence databases. Recent proteomic experiments in resting and activated platelets have identified novel signaling pathways and secreted proteins. Platelet transcriptomic studies in essential thrombocythemia, atherosclerotic disease, sickle cell disease, and an inherited platelet defect are reviewed. Transcript profiling has the potential to distinguish molecular signatures in normal and diseased platelets and to classify prothrombotic patient phenotypes to tailor their therapy.

Negative Heparin-Induced Thrombocytopenia Test Result After Massive Transfusion: Believe It or Not?

OBJECTIVES: Diagnosis of heparin-induced thrombocytopenia (HIT) is complicated by a high false-positive rate for the screening enzyme immunoassay (EIA) and limited availability of confirmatory platelet activation assays such as serotonin release assay (SRA). We evaluate the impact of a massive transfusion on EIA and SRA testing and emphasize that the timing of the confirmatory sample is important. METHODS: We present a case in which separate samples for HIT testing were collected before and after a major bleed requiring massive transfusion. We also discuss a recent study in which HIT serum samples were diluted in vitro and in vivo. RESULTS: The EIA was strongly positive, but SRA was negative, leading to suspicion of a false-positive EIA result. However, SRA performed on the initial EIA specimen was strongly positive. A second EIA, drawn after a massive transfusion, was negative. CONCLUSIONS: Replacement of several blood volumes diluted the HIT antibodies below the limit of detection. Confirmatory testing for HIT antibodies should be done on the specimen that initially tested positive.