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Abstract Background Factor V (FV) in its activated form, FVa, is a critical regulator of thrombin generation during fibrin clot formation. There is a need of a simple, fast, and inexpensive microplate-based coagulation assay to measure the functional activity of FV in human plasma. The objective of this study was to develop a microplate-based assay that measures FV coagulation activity during clot formation in human plasma, which is currently not available. Methods The FV assay requires a kinetic microplate reader to measure the change in absorbance at 405nm during fibrin formation in human plasma. The FV assay accurately measures the time, initial rate, and extent of fibrin clot formation in human plasma. Results The FV microplate assay is simple, fast, economical, sensitive to approx 24-80pM, and multiple samples may be analyzed simultaneously. All the required materials are commercially available. Standard curves of time or initial rate of fibrin clot formation vs FV activity in the 1-stage assay (Without activation by thrombin) may be used to measure FV activity in samples of human plasma. The assay was used to demonstrate that in nine patients with disseminated intravascular coagulation (DIC), the FV 1-stage, 2-stage (With activation by thrombin), and total (2-stage activity - 1-stage activity) activities were decreased, on average, by approximately 54%, 44%, and 42%, respectively, from prolonged clot times when compared to normal pooled human reference plasma (NHP). The results indicate that the FV in the DIC patient plasmas supported both a delayed and slower rate of fibrin clot formation compared with NHP; however, the extent of fibrin clot formation in the DIC patients remained largely unchanged from that observed with NHP. Conclusions The FV microplate assay may be easily adapted to measure the activity of any coagulation factor using the appropriate factor-deficient plasma and clot initiating reagent. The microplate assay will find use in both research and clinical laboratories to provide measurement of the functional coagulation activity of FV in human plasma.

Purpose: The most common indications for total thyroidectomy (TT) in children are malignancy and thyrotoxicosis due to Graves' disease (GD). However, the incidence of patients with GD among patients undergoing TT is unknown. This study aims to examine trends in pediatric TT., Materials and Methods: The US Agency for Health Research and Quality Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID) was queried to identify patients who underwent TT between 1997 and 2019. Weighted national estimates were obtained. Statistical analysis was completed using univariate logistic regression and one-sided Mann-Kendall Test., Results: An estimated 4803 pediatric patients underwent TT within the study years. GD was the indication in 25 % of cases. Mann-Kendall testing showed a trend toward an increasing proportion of TT for GD without reaching statistical significance (z = 1.3609, S = 12, p = 0.0688). Statistically significant univariate associations were found among those who underwent thyroidectomy for GD compared to other indications, as they were more likely to be female (β = 0.286, 95 % CI [0.058, 0.514], p = 0.014), Black, or Hispanic (β = 1.392 [1.064, 1.721], p < 0.001; and β = 0.562 [0.311, 0.814], p < 0.001, respectively). Additionally, they were less likely to have private insurance (β = -0.308 [-1.076, -0.753], p = 0.002) and more likely to live in a ZIP code associated with a median household income below the 50th percentile (β = 0.190 [0.012, 0.369], p = 0.036). The associations with the female sex, Black race, and Hispanic race persisted in multivariate analysis., Conclusion: GD appears to be an increasingly prevalent indication for TT. Patient characteristics differ from those who undergo TT for other diagnoses., Competing Interests: Declaration of competing interest The authors have no disclosures or conflicts of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The efficacy and safety of nilotinib in pediatric patients with imatinib/dasatinib resistant/intolerant (R/I) or newly diagnosed (ND) Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP) was demonstrated in the phase 2, open-label DIALOG study. In this final analysis, long-term efficacy and safety are presented for patients who completed 66 cycles (of 28 days) of treatment with nilotinib (230 mg/m2 twice daily) or discontinued early. Overall, 59 patients were enrolled and 58 were treated (R/I, n = 33; ND, n = 25; median time on treatment: 60.5 and 51.9 months, respectively). In the R/I cohort, the cumulative major molecular response (MMR; BCR::ABL1 international scale [IS] ≤ 0.1%) rate was 60.6%, and no patients had a confirmed loss of MMR. Among ND patients, the best overall MMR rate was 76.0%; 3 patients had a confirmed loss of MMR. The cumulative molecular response MR4 (BCR::ABL1IS ≤ 0.01%) and MR4.5 (BCR::ABL1IS ≤ 0.0032%) rates by 66 cycles were 27.3% and 12.1% in the R/I cohort, and 56.0% and 44.0% in the ND cohort, respectively. The safety profile of nilotinib was consistent with those of earlier reports. No on-treatment deaths occurred. These long-term (up to ∼5 years) data support the efficacy and safety of nilotinib in pediatric patients with Ph+ CML-CP. This trial was registered at www.clinicaltrials.gov.uk as #NCT01844765., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Reproductive late effects after hematopoietic stem cell transplant can have a significant impact on cancer survivors' quality of life. Potential late effects include gonadal insufficiency, genital graft-versus-host disease, uterine injury, psychosexual dysfunction, and an increased risk of breast and cervical cancer in patients treated with total body irradiation. Despite guidelines, screening and treatment are not standardized among at-risk patients. Provider barriers include lack of knowledge of at-risk therapies and evidenced-based guidelines. Patient barriers include a reluctance to report symptoms and lack of awareness of treatment options. System barriers include inefficient implementation of screening tools and poor dissemination of guidelines to providers who serve as the medical home for survivors. This review guides the clinician in identifying and managing reproductive late effects after hematopoietic stem cell transplant to improve outcomes., (© 2023 Wiley Periodicals LLC.)

Objective: To identify variables that are associated with poor compliance to thyroid hormone replacement therapy in children after total thyroidectomy., Method: A retrospective cohort study of children who underwent total thyroidectomy by high-volume pediatric otolaryngologists between 1/2014 and 9/2021. Postoperative poor compliance was characterized by at least three separate measurements of high TSH levels not associated with radioactive iodine treatment., Results: There were 100 patients, ages 3-20 years old who met inclusion criteria; 44 patients underwent thyroidectomy for cancer diagnosis, and 56 for Graves' disease. The mean follow-up time was 36.5 months (range 3.0-95.6 months). Overall, 42 patients (42%) were found to have at least three measurements of high TSH during follow-up, and 29 patients (29%) were diagnosed with clinical hypothyroidism. Sex, race, income, insurance type, and benign versus malignant etiology for thyroidectomy were not associated with adherence to therapy. Multivariate regression analysis identified patients with Graves' disease and hyperthyroidism at the time of surgery and Hispanic ethnicity to be associated with postoperative clinical hypothyroidism (OR 9.38, 95% CI 2.16-49.2, p = 0.004 and OR 6.15, 95% CI 1.21-36.0, p = 0.033, respectively)., Conclusions: Preoperative hyperthyroidism in patients with Graves' disease and Hispanic ethnicity were predictors of postoperative TSH abnormalities. Preoperative counseling for patients and their families on the implications of total thyroidectomy and the need for life-long medications postoperatively is necessary. Efforts should be made to evaluate and improve adherence to therapy pre-and postoperatively in patients with Graves' disease., Level of Evidence: 4 Laryngoscope, 133:2402-2406, 2023., (© 2022 The American Laryngological, Rhinological and Otological Society, Inc.)

Fontan palliation has improved survival in single ventricle patients. However, Fontan patients are subject to long-term morbidity. A few previous studies suggest Fontan patients have an increased risk of abnormal glucose metabolism without a clear mechanism. We aim to evaluate the prevalence and severity of abnormal hemoglobin A1c (HbA1c) values in Fontan patients and identify associated factors. Single-center retrospective cross-sectional cohort study including Fontan patients and documented HbA1c testing. Univariate demographic, anthropometric, and laboratory variable comparisons were completed and a stepwise selection multivariate regression model was attempted. The study included 414 Fontan patients, median age of 19 years (range 3-59 years). Of these, 190 patients (60.5% male) had at least one HbA1c. Abnormal HbA1c (> 5.6%) was found in 36% (n = 70) and diabetic-range HbA1c (≥ 6.5%) in 4.7% (n = 9). Factors associated with abnormal HbA1c included non-white race (63% vs 45%, p = 0.018), female sex (49% vs 34%, p = 0.050), elevated adult BMI [29.6 (± 8.4) vs 24.8 (± 4.8), p =  < 0.0001], elevated blood glucose [108.7 (± 47.3) vs 91.1 (± 17.9), p =  < 0.0001], and elevated triglycerides [101.5 (± 52.9) vs 84.1 (± 50.9), p = 0.029]. There were no significant differences found between the two HbA1c groups regarding cardiac diagnoses or surgical factors including type of stage 1 procedure, type of stage 3 procedure, or fenestration of Fontan. Patient age at time of initial Fontan procedure and time since initial Fontan showed no association with abnormal glucose metabolism. Obesity (BMI z-score ≥ 1.6 in children and BMI ≥ 30 in adults) was correlated with abnormal HbA1c (p = 0.008, 95%CI 0.069-0.45). There is a high prevalence of elevated HbA1c values in Fontan patients with modifiable associated factors, such as obesity and hypertriglyceridemia. Further investigation is needed to identify additional associated factors for abnormal glucose metabolism and determine its clinical significance. Lastly, we propose a new management protocol to screen for abnormal glucose metabolism., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Hashimoto's thyroiditis (HT) affects 1-2 % of the pediatric population. In adults with HT, thyroidectomy is considered challenging and prone to postoperative complications due to the chronic inflammatory process. However, the complications of thyroidectomy among children with HT have not been established. The objective of our study was to evaluate whether children with HT undergoing total thyroidectomy for presumed thyroid cancer have higher complication rates than children without HT., Methods: A retrospective cohort study of children who underwent total thyroidectomy by high-volume pediatric otolaryngologists between 2014 and 2021., Results: 111 patients met inclusion criteria, 15 of these were diagnosed with HT preoperatively. Operative time and length of admission were similar among the groups. Postoperatively, patients with HT were more likely to have low levels of parathyroid hormone (60 % vs 26 %, p = 0.014) and transient hypocalcemia compared to non-HT patients, present with symptomatic hypocalcemia (67 % vs 27 %, p = 0.006), demonstrate EKG changes (20 % vs 6.3 %, p = 0.035) within 24 h of surgery, and to require both oral and intravenous calcium supplements (80 % vs 35 %, p = 0.001 and 60 % vs 22 % p = 0.004 respectively). Persistent hypocalcemia at 6 months follow-up, and recurrent laryngeal nerve paralysis rates were similar between groups. Parathyroid tissue was found in the thyroid specimen of 9 (60 %) HT patients vs 34 (35 %) non-HT patients (p = 0.069)., Conclusions: The risk of permanent complications among children with HT following thyroidectomy is low. However, patients with HT are more likely to develop symptomatic transient hypocalcemia and to require oral and intravenous calcium supplements in the immediate post-operative period compared to non-HT patients. Tailoring a perioperative treatment protocol to optimize calcium levels may be considered for children with HT., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest and that this study did not receive financial support. All authors have seen and approved the manuscript., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Graves' disease (GD) is the most common cause of childhood hyperthyroidism. Surgery is often chosen as a treatment modality given the high relapse rates and side effects of antithyroid drugs and has shown to be safe and efficacious. The goal of our study was to evaluate whether hyperthyroidism at time of thyroidectomy is associated with higher intra and postoperative complication rates., Methods: A retrospective cohort study of children who underwent thyroidectomy for GD by high-volume pediatric otolaryngologists between 2014 and 2021., Results: 64 patients met inclusion criteria. Patients with hyperthyroidism (defined as free T4≥1.63 ng/dL) were more likely to be treated with beta-blocker preoperatively compared to the euthyroid group (20/24 patients (83%) vs 23/40 patients (58%) respectively, p = 0.035). Twenty (83%) patients with hyperthyroidism and 39 euthyroid patients (98%) were treated with methimazole prior to surgery. Intraoperative tachycardia was noted in 5% of euthyroid patients and 20.8% of patients with hyperthyroidism. The mean peak heart rate intra-operatively and the number of patients with heart rate ≥120bmp were significantly higher for patients with hyperthyroidism (96.5 ± 16.2 vs 87.6 ± 22.1bpm, p = 0.02). Two patients required administration of esmolol during surgery for heart rate control, both with hyperthyroidism. Intra-operative peak systolic blood pressure, operative time, estimated blood loss, persistent hypocalcemia, length of admission and recurrent laryngeal nerve paralysis rates were similar among groups., Conclusions: Hyperthyroidism at surgery is associated with increased heart rate intraoperatively, with no increased risk for other complications. While optimizing thyroid hormone levels before surgery should be pursued in all children, our data suggest that hyperthyroidism should not delay the surgery., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Introduction: The topics of sub-specialization and regionalization of care have garnered increased attention among pediatric surgeons. Thyroid surgeries are one such sub-specialty and are commonly concentrated within practices. A national survey was conducted examining current surgeon practices and beliefs surrounding pediatric thyroid surgery., Methods: Non-resident members of the American Pediatric Surgical Association (APSA) were surveyed in October 2020. Respondents were stratified based on self-reported thyroid surgical experience. Those who performed thyroid surgery were asked about surgical technique and operative practices; those who did not were asked about referral patterns. All respondents were asked about perceptions surrounding the volume-outcome relationship for pediatric thyroid surgery., Results: Among 1015 APSA members, 405 (40%) responded, with 79% (317/400) practicing at academic hospitals, 58% (232/401) practicing in major metropolitan area, and 41% (161/392) with over 10 years of attending pediatric surgery experience. Most respondents (88%, n = 356) agreed that thyroid surgery volume affects outcome, though wide variation was reported in the annual case threshold for "high volume" surgery. Eighty-four respondents (21%) reported performing ≥ 1 pediatric thyroid surgery in the past year. Of these, 82% routinely use recurrent laryngeal nerve monitoring, 32% routinely send hemithyroidectomy patients home the same day, and there was little consensus surrounding postoperative hypocalcemia management. The majority of respondents endorse performing thyroid procedures with a colleague., Conclusions: Pediatric thyroid surgery appears to be performed by a subset of active pediatric surgeons, most of whom endorse the use of a dual operating team. More evidence is needed to build consensus around additional perioperative practices., (Copyright © 2022. Published by Elsevier Inc.)

The phase 2, open-label study (DIALOG) of nilotinib in pediatric patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) met its coprimary end points, showing sustained nilotinib efficacy in patients with newly diagnosed (ND) or imatinib/dasatinib resistant/intolerant (R/I) CML. This update assessed growth and safety profiles in patients who had completed ≥48, 28-day treatment cycles of nilotinib 230 mg/m2 twice daily, or previously discontinued the study. Height was assessed regularly and reported using standard deviation scores (SDSs) based on World Health Organization growth charts. All data were summarized descriptively (cutoff, 6 March 2019). Overall, 33 patients in the R/I cohort and 25 patients in the ND cohort received nilotinib. Each cohort showed a negative slope in height SDS over the course of the study, indicating attenuated growth rates during nilotinib treatment: overall median change from baseline in height SDS after 48 cycles was -0.54 SDS (range, - 1.6 to 0.4) and -0.91 SDS (-1.4 to -0.1) in R/I and ND cohorts, respectively. Patients in the R/I cohort were shorter at baseline than those in the ND cohort, and remained so throughout the study. The most common all-cause adverse events were increased blood bilirubin (53.4%), headache (46.6%), pyrexia (37.9%), and increased alanine transferase (36.2%). Apart from the impact on growth, the safety profile of nilotinib was generally consistent with previous reports. This study was registered on www.clinicaltrials.gov at #NCT01844765., (© 2021 by The American Society of Hematology.)

Purpose: Craniopharyngiomas are benign tumors of the sellar or parasellar regions. They arise from the remnants of Rathke's pouch and are considered a "developmental disease." microRNAs are short non-coding RNAs that play a key regulatory role in the control of expression of entire gene networks. We performed an extensive analysis of miRNAs in craniopharyngiomas aiming to identify a miRNA expression signature that might aid in the prognosis of disease progression and outcome., Methods: Thirty-seven craniopharyngioma samples from twenty-three patients, ten age-matched controls from autopsy, and ten infant controls from the developing pituitary from autopsy were evaluated for the expression of 754 miRNAs using TaqMan® Low Density Arrays (TLDAs) v2.0 (Applied Biosystems, Foster City, CA)., Results: Among the most differentially expressed miRNAs, downregulation of miR-132 appears to be a marker of aggressiveness and also plays a role in epithelial-mesenchymal transition., Conclusions: This is the first time that an extensive study of miRNA expression has been performed in craniopharyngiomas. Further research needs to be performed to investigate the potential role of miR-132 in the development and progression of craniopharyngiomas, and its value as a prognostic marker of aggressiveness.

Side effects of tyrosine kinase inhibitor (TKI) treatment vary in children and adults with chronic myelogenous leukemia (CML). As children have a much longer life expectancy than adults, TKI therapy may continue for decades and with long-term consequences that differ from adults. Children may develop endocrinopathies related to "off-target" effects of TKIs, such as delayed growth, changes in bone metabolism, thyroid abnormalities, and effects on puberty and fertility. These endocrinopathies present additional challenges for pediatric patients with CML. This review critically evaluates the literature on long-term endocrine side effects of TKIs in the pediatric CML population and provides suggested recommendations., (© 2016 Wiley Periodicals, Inc.)

The 'biphasic transmittance waveform' (BTW) refers to a decrease in light transmittance that often occurs prior to clotting in coagulation assays of critically ill patient plasmas. It correlates with disseminated intravascular coagulation and mortality. The present work shows that the BTW is due to the rapid formation of a precipitate and a coincident change in turbidity in re-calcified plasma. The precipitate was isolated from patient plasma and contained lipids typical of very low density lipoprotein (VLDL), plus the proteins apolipoprotein B-100 and C-reactive protein (CRP). Precipitation also occurred in normal plasma supplemented with CRP. In addition, CRP precipitated with VLDL and intermediate density lipoprotein, but not low density lipoprotein or high density lipoprotein. The Kd value for the CRP/VLDL interaction is 340 nM. The IC50 value of Ca2+ for complex formation is 5.0 mM, and epsilon-aminocaproic acid inhibits the process. In 15 plasmas with the BTW from critically ill patients, CRP was highly elevated (77-398 microg/mL) and VLDL cholesterol ranged from 0.082 to 1.32 mM. The magnitude of the turbidity change on re-calcification correlated well with the calculated level of the CRP/VLDL complex. Thus, the Ca2+-dependent formation of a complex between CRP and VLDL accounts for the BTW.

A decrease in light transmittance before clot formation, manifesting as a biphasic waveform (BPW) pattern in coagulation assays, was previously correlated with the onset of disseminated intravascular coagulation (DIC). In this study of 1187 consecutive admissions to the intensive care unit, the degree of this change on admission predicts DIC better than D-dimer measurements. Additionally, the BPW preceded the time of DIC diagnosis by 18 hours, on average, in 56% (203 of 362) of DIC patients. The BPW is due to the rapid formation of a precipitate and coincident turbidity change on recalcification of plasma. The isolated precipitate contains very-low-density lipoprotein (VLDL) and C-reactive protein (CRP). The addition of CRP and Ca(++) to normal plasma also causes the precipitation of VLDL and IDL, but not LDL or HDL. The K(d) of the CRP/VLDL interaction is 340 nM, and the IC(50) for Ca(++) is 5.0 mM. In 15 plasmas with the BPW, CRP was highly elevated (77-398 microg/mL), and the concentration of isolated VLDL ranged from 0.082 to 1.32 mM (cholesterol). The turbidity change on recalcification correlates well with the calculated level of the CRP-VLDL complex. Clinically, the BPW better predicts for DIC than either CRP or triglyceride alone. The complex may have pathophysiological implications because CRP can be detected in the VLDL fraction from sera of patients with the BPW, and the VLDL fraction has enhanced prothrombinase surface activity. The complex has been designated lipoprotein complexed C-reactive protein.

We have investigated the influence of the type of factor VIII deficient plasma used on the assay results of the Nijmegen modification of the Bethesda method for factor VIII inhibitors. Immuno depleted factor VIII deficient plasmas, lacking besides factor VIII also von Willebrand factor, gave decreased inhibitor titres compared to assay results with factor VIII deficient plasmas containing von Willebrand factor suggesting the need of the latter in the test system for the stability of factor VIII:C. Moreover the performance of the assay with immuno depleted plasma was contaminated in a certain type of this plasma by the presence of a factor VIII:C inhibitor. Chemically depleted factor VIII deficient plasma appeared to give falsely elevated titres when used in combination with other types of deficient plasmas as substrate plasma in the factor VIII:C assay due to the presence of activated factor Va in the preparation. Suggestions are described with respect to the observed limitations in order to obtain reliable results.

Conservative Trp-to-Phe mutations were individually created in human thrombin at positions 60d, 96, 148, 207, and 215. Fluorescence intensities for these residues varied by a factor of 6. Residues 60d, 96, 148, and 215 transferred energy to the thrombin inhibitor 5-dimethylaminonaphthalene-1-sulfonylarginine-N-(3-ethyl-1,5- pentanediyl)amide efficiently, but residue 207 did not. Intensities correlated inversely with exposure to solvent, and measured and theoretical energy transfer efficiencies agreed well. Function was measured with respect to fibrinogen clotting, platelet and factor V activation, inhibition by antithrombin, and the thrombomodulin-dependent activation of protein C and thrombin-activable fibrinolysis inhibitor (TAFI). All activities of W96F and W207F ranged from 74 to 154% of the wild-type activity. This was also true for W148F, except for inhibition by antithrombin, where it showed 60% activity. W60dF was deficient by 30, 57, and 43% with fibrinogen clotting, platelet activation, and factor V cleavage (Arg(1006)), respectively. W215F was deficient by 90, 55, and 56% with fibrinogen clotting, platelet activation, and factor V cleavage (Arg(1536)). With protein C and TAFI, W96F, W148F, and W207F were normal. W60dF, however, was 76 and 23% of normal levels with protein C and TAFI, respectively. In contrast, W215F was 25 and 124% of normal levels in these reactions. Thus, many activities of thrombin are retained upon substitution of Trp with Phe at positions 96, 148, and 207. Trp(60d), however, appears to be very important for TAFI activation, and Trp(215) appears to very important for clotting and protein C activation.

Previous studies have shown that thrombin generation in vivo caused a 92% decrease in factor IX (F.IX) activity and the appearance of a cleavage product after immunoblotting that comigrated with activated F.IX (F.IXa). Under these conditions, the fibrinolytic system was clearly activated, suggesting plasmin may have altered F.IX. Thus, the effect(s) of plasmin on human F.IX was determined in vitro. Plasmin (50 nM) decreased the 1-stage clotting activity of F.IX (4 microM) by 80% and the activity of F.IXa (4 microM) by 50% after 30 minutes at 37 degrees C. Plasmin hydrolysis of F.IX yields products of 45, 30, 20, and 14 kd on reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 2 products of 52 and 14 kd under nonreducing conditions. Plasmin-treated F.IX did not bind the active site probe, p-aminobenzamidine, or form an SDS-stable complex with antithrombin. It only marginally activated human factor X in the presence of phospholipid and activated factor VIII. Although dansyl-Glu-Gly-Arg-chloromethyl ketone inactivated-F. IXa inhibited the clotting activity of F.IXa, plasmin-treated F.IX did not. Plasmin cleaves F.IX after Lys43, Arg145, Arg180, Lys316, and Arg318, but F.IXa is not appreciably generated despite cleavage at the 2 normal activation sites (Arg145 and Arg180). Tissue plasminogen activator-catalyzed lysis of fibrin formed in human plasma results in generation of the 45- and 30-kd fragments of F.IX and decreased F.IX clotting activity. Collectively, the results suggest that plasmin is able to down-regulate coagulation by inactivating F.IX.

In preliminary studies, the generation of thrombin in vivo was found to induce a 92% loss of functional activity of factor IX (F.IX) despite the detection by Western blotting of a product resembling activated F.IX (F.IXa) and a 25% increase in F.IX antigen levels (Hoogendoorn et al, Thromb Haemost 69:1127, 1993 [abstr]). These changes were associated with evidence of increased elastase availability. To study the possibility that these two observations were related, a detailed physical and functional characterization of the hydrolysis of purified human F.IX by human neutrophil elastase (HNE) was performed in vitro. An activated partial thromboplastin time (aPTT) clotting assay demonstrated that, although HNE eliminated the potential of F.IX to be activated, it only marginally reduced the F.IXa activity. Reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that HNE treatment of F.IX generated cleavage products of 30 and 20 kD that could not be distinguished from the respective heavy and light chain peptides that were identified in parallel studies when F.IX was activated by activated bovine F.XI (F.XIa), one of its physiological activators. In addition, nonreducing SDS-PAGE demonstrated that HNE-treated F.IX formed no complexes with antithrombin III (ATIII) in the presence of heparin. Furthermore, HNE-treated F.IX was unable to (1) bind the active site probe p-aminobenzamidine; (2) hydrolyze the synthetic peptide substrate CH3SO2-Leu-Gly-Arg-p-nitroanilide; and (3) activate human factor X (F.X). In contrast to dansyl-Glu-Gly-Arg-chloromethyl ketone (dEGR)-inactivated F.IXa, HNE-treated F.IX (0.01 to 10,000 pmol/L) failed to inhibit the clotting activity of F.IXa (10 pmol/L) in the aPTT. NH2-terminal sequencing indicated that HNE cleaved human F.IX at Thr140, Thr144, Ile164, Thr172, and Val181. The cleavages at Thr140/Thr144 and at Thr172/Val181 are both very close to the normal F.XIa alpha-(Arg145) and beta-(Arg180) cleavage sites, respectively. In summary, the results suggest that the activatability of F.IX is eliminated after cleavage by HNE and that the inability of HNE-treated F.IX to support F.IXa-like coagulant function is a consequence of improper active site formation. These in vitro observations support the possibility that increased HNE cleavage of F.IX in vivo may contribute to the disregulation of hemostasis that occurs in conditions such as disseminated intravascular coagulation (DIC)., (Copyright 1998 by The American Society of Hematology.)

The effect of human neutrophil elastase (HNE) on human factor V (F.V) or alpha-thrombin-activated human factor V (F.Va) was studied in vitro by prothrombinase assays, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and NH2-terminal sequence analysis. Incubation of F.V (600 nmol/L) with HNE (2 nmol/L) in the presence of Ca2+ resulted in a time-dependent increase in its cofactor activity. In contrast, treatment of F.Va (600 nmol/L) with HNE (60 nmol/L) in the presence of Ca2+ resulted only in a time-dependent decrease in its cofactor activity. Under the conditions of these experiments, the maximum extent of F.V activation accomplished by incubation with HNE was approximately 65% to 70% of that observed with alpha-thrombin in presence of Ca2+. The extent of both the HNE-dependent enhancement in F.V cofactor activity and the HNE-dependent decrease in F.Va cofactor activity was not influenced by the addition of phosphatidylcholine/phosphatidylserine (PCPS) vesicles (50 micromol/L). The HNE-derived cleavage products of F.V, which correlated with increased cofactor activity, as demonstrated by SDS-PAGE under reducing conditions, were different from those generated using alpha-thrombin. Treatment of F.V (600 nmol/L) with HNE (2 nmol/L) in the presence of Ca2+ resulted in the production of three closely spaced doublets of: 99/97, 89/87, and 76/74 kD whose appearance over time correlated well with the increased cofactor activity as judged by densitometry. Treatment of F.Va (600 nmol/L) with HNE (60 nmol/L) in the presence of Ca2+ resulted in the cleavage of both the 96 kD heavy chain and the 74/72 kD light chain into products of: 56, 53, 35, 28, 22, and 12 kD. Although densitometry indicated that both the heavy and light chains of F.Va were hydrolyzed by HNE, cleavage of the 96 kD heavy chain was more extensive during the time period (10 to 30 minutes) of the greatest loss of F.Va cofactor activity. NH2-terminal sequence analysis of F.V treated with HNE indicated cleavage at Ile819 and Ile1484 under conditions during which the procofactor expressed enhanced cofactor activity in the prothrombinase complex. NH2-terminal sequence analysis of F.Va treated with HNE indicated cleavage at Ala341, Ile508, and Thr1767 under conditions, which the cofactor became inactivated, as measured by prothrombinase activity. The activation and inactivation cleavage sites are close to those cleaved by the physiological activator and inactivator of F.V and F.Va, namely alpha-thrombin (Arg709 and Arg1545) and Activated Protein C (APC) (Arg306 and Arg506), respectively. These results indicate that HNE can generate proteolytic products of F.V, which initially express significantly enhanced procoagulant cofactor activity similar to that observed following activation with alpha-thrombin. In contrast, HNE treatment of F.Va resulted only in the loss of its cofactor activity, but again, this is similar to that observed following inactivation by APC.

The complete cDNA of 3.2 kb for rat calpain II large subunit has been constructed from library- and polymerase chain reaction-derived fragments, and sequenced. The cDNA encodes a protein of 700 amino acids having 93% sequence identity with human calpain II, and 61% identity with human calpain I. The gene possesses 21 exons, of which exons 3-21 have been mapped over 33 kb of the rat genome. A new phagemid expression vector was created from pT7-7 by insertion of the f1 origin and mutation of an NdeI to an NcoI site. Rat calpain II cDNA ligated into this vector expressed in Escherichia coli an 80 kDa protein identical in size to highly purified rat calpain II; this protein was specifically recognized on immunoblots by an affinity-purified anti-rat calpain II antibody. This is the second mammalian calpain II large subunit to be fully sequenced, and the first to be artificially expressed.

With a view to understanding the function of calpain I (EC 3.4.22.17) in vivo, the localization of the enzyme was studied by immunoelectron microscopy in human erythrocytes. Thin sections of the cells embedded in Spurr's resin were exposed to solutions of monoclonal anti-calpain I or control antibodies, biotin antimouse IgG antibodies, and streptavidin-gold. Most of the calpain I (93%) was found to be distributed throughout the cytoplasm, and only 7% of the gold particles were associated with the erythrocyte membrane. Erythrocytes were Ca2+-loaded by means of the calcium ionophore A23187, and the rise in intracellular [Ca2+] was demonstrated both by crenation of the cells, and by activation of calpain which was detected by immunoblotting. The proportions of cytosolic and membrane-bound gold labelling were, however, not altered by Ca2+-loading. These results are not consistent with the hypothesis that activation of calpain requires membrane-binding.