A machine learning approach to predict mortality due to immune-mediated thrombotic thrombocytopenic purpura

Background

Mortality due to immune-mediated thrombotic thrombocytopenic purpura (iTTP) remains significant. Predicting mortality risk may potentially help individualize treatment. The French Thrombotic Microangiopathy (TMA) Reference Score has not been externally validated in the United States. Recent advances in machine learning technology can help analyze large numbers of variables with complex interactions for the development of prediction models.

Objectives

To validate the French TMA Reference Score in the United States Thrombotic Microangiopathy (USTMA) iTTP database and subsequently develop a novel mortality prediction tool, the USTMA TTP Mortality Index.

Methods

We analyzed variables available at the time of initial presentation, including demographics, symptoms, and laboratory findings. We developed our model using gradient boosting machine, a machine learning ensemble method based on classification trees, implemented in the R package gbm.

Results

In our cohort (n = 419), the French score predicted mortality with an area under the receiver operating characteristic curve of 0.63 (95% CI: 0.50-0.77), sensitivity of 0.35, and specificity of 0.84. Our gradient boosting machine model selected 8 variables to predict acute mortality with a cross-validated area under the receiver operating characteristic curve of 0.77 (95% CI: 0.71-0.82). The 2 cutoffs corresponded to sensitivities of 0.64 and 0.50 and specificities of 0.76 and 0.87, respectively.

Conclusion

The USTMA Mortality Index was acceptable for predicting mortality due to acute iTTP in the USTMA registry, but not sensitive enough to rule out death. Identifying patients at high risk of iTTP-related mortality may help individualize care and ultimately improve iTTP survival outcomes. Further studies are needed to provide external validation. Our model is one of many recent examples where machine learning models may show promise in clinical prediction tools in healthcare.

Race, rituximab, and relapse in TTP

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is characterized by recurring episodes of thrombotic microangiopathy, causing ischemic organ impairment. Black patients are overrepresented in iTTP cohorts in the United States, but racial disparities in iTTP outcome and response to therapy have not been studied. Using the United States Thrombotic Microangiopathies Consortium iTTP Registry, we evaluated the impact of race on mortality and relapse-free survival (RFS) in confirmed iTTP in the United States from 1995 to 2020. We separately examined the impact of rituximab therapy and presentation with newly diagnosed (de novo) or relapsed iTTP on RFS by race. A total of 645 participants with 1308 iTTP episodes were available for analysis. Acute iTTP mortality did not differ by race. When all episodes of iTTP were included, Black race was associated with shorter RFS (hazard ratio [HR], 1.60; 95% CI, 1.16-2.21); the addition of rituximab to corticosteroids improved RFS in White (HR, 0.37; 95% CI, 0.18-0.73) but not Black patients (HR, 0.96; 95% CI, 0.71-1.31). In de novo iTTP, rituximab delayed relapse, but Black patients had shorter RFS than White patients, regardless of treatment. In relapsed iTTP, rituximab significantly improved RFS in White but not Black patients. Race affects overall relapse risk and response to rituximab in iTTP. Black patients may require closer monitoring, earlier retreatment, and alternative immunosuppression after rituximab treatment. How race, racism, and social determinants of health contribute to the disparity in relapse risk in iTTP deserves further study.

Sipuleucel-T associated inflammatory cardiomyopathy: a case report and observations from a large pharmacovigilance database

Aims

The major cardiovascular (CV) adverse effects observed with sipuleucel‐T from large multi‐institutional clinical trials included thromboembolic events, myocardial infarction, and congestive heart failure in up to 0.3% of patients with CV risk factors. The incidence, outcomes, and mechanisms in real‐world clinical settings of these CV adverse effects to date have not been fully elucidated. Our study identified a patient with sipuleucel‐T‐induced inflammatory cardiomyopathy, which led to the identification of CV adverse effects associated with sipuleucel‐T from a large pharmacovigilance database and elucidation of its potential mechanisms.

Methods and results

Using the MedDRA term ‘cardiac disorders’ (System Organ Class level), CV adverse events associated with sipuleucel‐T versus all other drugs were reviewed from VigiBase, a large pharmacovigilance database. Disproportionality analysis was calculated by the information component (IC), a Bayesian disproportionality indicator. A positive IC₀₂₅ (IC 95% lower end credibility interval) value (>0) is the traditional threshold used in statistical signal detection at the Uppsala Monitoring Centre. From VigiBase, the total number of CV adverse drug reaction reported with sipuleucel‐T was 306 out of a total of 22 980 104 adverse drug reactions in VigiBase on 10/25/2020. MedDRA preferred terms levels were grouped into major CV adverse drug reaction categories where we observed significant reports of myocardial ischaemia, supraventricular tachycardia (particularly atrial fibrillation/atrial flutter), congestive heart failure, and valvular disorders. Myocardial ischemia included acute myocardial infarction (IC₀₂₅ 2.3) with n = 4/26 (15%) of these individual case safety reports considered fatal. Among patients with ‘cardiac failure congestive’ (IC₀₂₅ 1.5), 11 of these 43 cases (26%) were fatal with 42 (98%) of these cases considered to be solely due to sipuleucel‐T.

Conclusions

Patients with CV risk factors who are receiving sipuleucel‐T may be at higher risk for congestive heart failure, myocardial ischemia, and supraventricular tachycardia. Electrocardiograms during weekly sipuleucel‐T infusions and left ventricular function monitoring with echocardiogram should be considered in these patients. Our findings are suggestive of another rare presentation of T‐cell‐mediated CV toxicity with cancer immunotherapy.

Concomitant use of renin-angiotensin-aldosterone system inhibitors prevent trastuzumab-induced cardiotoxicity in HER2+ breast cancer patients: an institutional retrospective study

Background

Cardiotoxicity is an adverse effect of trastuzumab (TRA) in the treatment of human epidermal growth factor 2 positive (HER2+) breast cancer. Current literature on the cardioprotective effects of agents targeted against the renin-angiotensin-aldosterone system (RAAS) and beta-blockers (BB) in TRA-treated HER2+ breast cancer patients is conflicting. We hypothesized that concurrent use of RAAS inhibitors would prevent TRA-induced cardiotoxicity (TIC).

Methods and materials

Surveillance ejection fraction (EF) at 3-month intervals up to 36 months obtained from echocardiogram or multigated acquisition (MUGA) scans were retrospectively compared to baseline EF in TRA-treated HER2+ breast cancer patients between 2011 to 2016 at a tertiary cancer center. TIC was defined as a decrease of EF by more than 15 EF percentage points from baseline on surveillance imaging. Cardiac medications and comorbidities were compared between patients with reduced EF secondary to TIC (rEF) and patients who did not experience TIC (pEF). A published clinical risk score (CRS) was applied to the patient population with calculated sensitivity analyses to determine if the CRS could predict TIC.

Results

Of 127 patients with TRA-treated HER2+ breast cancer, 11% developed cardiotoxicity resulting in discontinuation of TRA. Cardiotoxicity with reduced EF was seen as early as 3 months and at subsequent 3-month follow up intervals up to the 15-month follow-up. Co-existing arrhythmia, coronary artery disease (CAD), hypertension (HTN) and diabetes mellitus (DM) tended to infer an increased risk for cardiotoxicity. Patients with pEF were found to be concurrently on a RAAS inhibitor more than the rEF group (OR of 0.24, 95% CI 0.05-1.11, p 0.06). The CRS high-risk cut-off had a sensitivity of 0.17 (95% CI 0.03-0.49), specificity of 0.89 (95% CI 0.82-0.94), positive predictive value of 0.14 (95% CI 0.03-0.44) and negative predictive value of 0.91 (95% CI 0.84-0.95).

Conclusion

Our data suggest that the concurrent use of a RAAS inhibitors during TRA treatment may provide a protective effect against TIC and warrants further investigation. The low sensitivity and positive predictive value demonstrated that the CRS has minimal utility as a screening tool for prediction of patients at high risk for TIC. Therefore, closer surveillance of patients receiving TRA is warranted for early detection of TIC.

Metastatic pattern and tumor sidedness in colorectal cancer

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Background: Tumor side has emerged as an important prognostic and predictive factor in metastatic colon cancer. We sought to study its impact on the metastatic pattern of colorectal cancer. Methods: The SEER database (version 8.3.5) was reviewed for patients with Stage IV colorectal cancer diagnosed between 2004-2015. We only included patients with labeled primary site, and excluded appendiceal, unlabeled and autopsy alone cases. Variables included in the analysis were: age, race, gender, grade, primary tumor side and sites of metastasis at diagnosis. Primary outcome analyzed was overall survival and disease specific survival.Cox proportional hazard regression model was employed to test the association between survival and side of cancer/ site of metastasis. Results: A total of 74,768 cases were identified who met the eligibility criteria. The mean age was 68.5 yrs. for right colon cancer (RCC),64.0 yrs. for left colon cancer (LCC). and 62.9 yrs. for rectal cancer. White race was predominant group for RCC, LCC and rectum. More females were vs men in RCC (52% vs 48%), LCC (44% vs 56%) and rectum (60% vs 40%). (The cox regression model suggested inferior outcome for black race HR 1.05(1.03-1.07) (<0.001), high grade HR 1.32(1.30-1.35) p<.0001, right side tumors HR 1.23(1.21-1.250, p <.0001 (table). Conclusions: Over last few years tumor sidedness has emerged as an important prognostic and predictive factor in colon cancer. Our study also highlights the impact of sidedness on survival irrespective of distant metastatic pattern. This analysis contributes to the ongoing discussion that right and left colon cancer are two distinct disease entities. Impact of primary tumor side and metastatic site on survival in colorectal cancer. [Table: see text]

Effect of crizanlizumab on pain crises in subgroups of patients with sickle cell disease: A SUSTAIN study analysis

The cell adhesion molecule P-selectin plays a key role in the pathogenesis of a vaso-occlusive crisis (VOC) in patients with sickle cell disease (SCD). In the double-blind, placebo-controlled phase 2 SUSTAIN study, crizanlizumab (humanized, anti-P-selectin monoclonal antibody) 5 mg/kg significantly lowered the rate of VOC in patients with SCD by 45% vs placebo. In SUSTAIN, patients with SCD were randomized to crizanlizumab 2.5 mg/kg, crizanlizumab 5 mg/kg, or placebo intravenously 14 times over 52 weeks. The primary endpoint was the annual rate of VOC with crizanlizumab vs placebo. This post hoc descriptive analysis evaluated the proportion of patients who did not experience a VOC during the study in the following subgroups: VOCs in the year prior to study entry (2-4/5-10), SCD genotype (HbSS/non-HbSS), and concomitant hydroxyurea use (yes/no). More patients were VOC event-free in the crizanlizumab 5 mg/kg arm than in the placebo arm, including those with more frequent prior VOCs (ie, 5-10; 28.0% vs 4.2%), the HbSS genotype (31.9% vs 17.0%) and/or using concomitant hydroxyurea (33.3% vs 17.5%). Further analyses of secondary endpoints demonstrated that crizanlizumab treatment significantly increased time-to-first VOC vs placebo in these subgroups. The rates of treatment-emergent adverse events were similar between treatment arms across all subgroups. This post hoc analysis of SUSTAIN shows that in patients with a high number of prior VOCs, on concomitant hydroxyurea and/or with the HbSS genotype, crizanlizumab treatment increases the likelihood of patients being VOC event-free and delays time-to-first VOC.

Unusual disease characteristics of multiple myeloma in eastern North Carolina

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Background:Multiple Myeloma (MM) is a relatively common malignancy in Eastern NC, especially in African American population. There have been several advances in treatment of MM but it is unclear how well current therapies are being utilized and what barriers prevent this. Our goal was to identify any unique clinical and epidemiological features of this disease in our patient population as this may help us to improve outcomes. Methods: Demographics, clinical features, FISH/ Cytogenetic features, clinical outcomes of the patients enrolled on MMRF CoMMpass study at our institution were reviewed and analyzed to identify any unusual features in our dataset. Results:The median age at diagnosis of MM is 69 years. There was a higher proportion of younger patients in our dataset, 40% of our patients were < 60 years and 11% of patients were < 40 years which may point to environmental and genetic factors in this population and needs to be studied further. About 20% of patients with MM are reported to have Light Chain Myeloma (LCM) while 30% patients had LCM in our dataset. More patients had a higher stage of disease, ISS stage III at diagnosis, 72%.The benefits of Autologous Stem Cell Transplant (ASCT) in management of Multiple Myeloma is well established but only 22% of the patients had ASCT as part of their management. This appears to be secondary to multiple factors including comorbidities, socioeconomic factors such as financial concerns, difficulty with access to treatment and availability of care givers Conclusions:There is a disproportionately high proportion of younger patients with Multiple Myeloma in Eastern NC, especially with LCM. The environmental and genetic factors responsible for this need to be studied further. Many patients have a high tumor burden at diagnosis. Improvement in access to care, enhancement of provider education, collaboration with regional oncologists and study of novel drug combinations to achieve deeper and more durable responses may help improve outcomes for this treatable malignancy. "These data were generated as part of the Multiple Myeloma Research Foundation Personalized Medicine Initiatives (https://research.themmrf.org and www.themmrf.org)”.

Clinical outcomes in very early breast cancer (≤ 1cm): A national population based analysis

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Background: The utilization of screening mammogram has resulted in increased diagnosis of very small breast cancers including T1a (≤5 mm), T1b ( > 0.5 but ≤1 cm). These small tumors have excellent prognosis with cancer-specific survival rates as high as 90% to 95%.This study evaluates outcomes in very early breast cancer in a national database. Methods: Patients with stage I breast cancer, tumor ≤ 1cm (T1aN0, T1bN0) diagnosed between 2006 and 2011 were selected from the SEER database. We excluded patients with missing biomarker information. Treatment outcome and prognostic factors for disease-specific survival (DSS) and overall survival (OS) were evaluated. Results: We identified 70,543 cases and included 54,796 patients with stageT1aN0M0 and T1bN0M0 in the final analysis.The mean age was 62.09 yrs(CI 95% 62.2-61.99),84% are white,7% black and 7% Other.89% were ER positive,11% ER negative and 3% had Her 2 positive tumors.71% of patients had T1b. ≤ 1cm breast cancer cases increased from 15% in 2006 to 18% in 2011.The 5-year disease specific survival (DSS) and overall survival (OS) for patients with stage T1aN0T1b N0 was 98.7% and 93.7%, respectively. Estrogen receptor(ER) positive tumors were associated with improved 5-yr DSS 99% vs 96% in ER negative (p < 0.0001) and OS in ER positive 94% vs 92%( p < 0.0001).Among white patients 5-yr DSS was 98.8% and OS was 93.7% while 5yr-DSS was 94%,OS 91.5% among black vs 5-yr DSS 99% and OS 96.3% in others( Asian or Pacific Islanders,AI), (p < 0.0001).Tumor subtype was not associated with significant difference in outcome but T1a tumor was associated with OS 94.5% vs 93.4% with T1b tumors(p < 0.0001) On cox model analysis factors which correlated with prolonged DSS and OS are race (p < 0.0001),older age (p < 0.0001), ER positivity (p < 0.0001) and tumor less than 5mm (p = 0.0006). Conclusions: Very early breast cancer is associated with excellent outcome but has some heterogeneity. Nonwhite/Non Black race was associated with better survival compared to white and black patients.ER positive tumors, older age were also associated with better outcome. This data while reassuring also brings into question of overtreatment of this disease subset.

Vitamin D Deficiency in Adult Sickle Cell Patients

INTRODUCTION

Vitamin D levels in adult black Americans with sickle cell disease (SCD) are comparatively lower than those found in the general population of black Americans. The objectives of this study were to examine the prevalence of Vitamin D deficiency (VDD) in adults with various subtypes of sickle cell disease and identify risk factors for vitamin D deficiency.

METHODS

In a retrospective study serum Vitamin D25(OH)D and/or VitaminD1,25(OH)2D levels were obtained in 120 subjects with sickle cell disease. Baseline studies also included LFTs, total protein, albumin, total bilirubin, and creatinine levels. In a portion of subjects that were treated with oral ergocalciferol vitamin D levels and chemistries were obtained within 6 months of treatment. Data was statistically analyzed with Welch two sample t-tests and individual simple linear regressions (including logarithmic values) for each variable.

RESULTS

Vitamin D25(OH)D levels were found to be significantly lower in a group of subjects with Hgb SS disease, than in a group with other subtypes of sickle cell disease. In both groups combined, significant (p = 0.05) and clinically suggestive negative correlations with Vitamin D25(OH)D were seen for total bilirubin and total protein, respectively. When total bilirubin and total protein levels were compared between the Hgb SS and HgbS/other groups, t-test revealed these levels were significantly higher in the Hgb SS group levels at p < 0.001 and p = 0.005, respectively.

IMPLICATIONS

Low total Vitamin D25(OH)D levels in adults with sickle cell disease may be a reflection of chronic inflammation and overall disease severity.

Vascular Localization of the Heparin-binding Serpins Antithrombin, Heparin Cofactor II, and Protein C Inhibitor

Heparin is one of the most widely used drugs in the world, acting as an anticoagulant by stimulating the reaction between heparin-binding serpins and the serine proteases of the coagulation cascade. To determine whether the heparin-binding serpins antithrombin (AT), heparin cofactor II (HCII), and protein C inhibitor (PCI) were bound to glycosaminoglycans on the endothelial wall, a bolus of heparin (100 U/kg body weight) was in jected into human volunteers, and serpin concentrations and activities were measured in both pre- and postheparin plasma. No increase in circulating concentrations of AT, HCII, or PCI were observed in postheparin plasma. Sim ilarly, AT and HCII activities did not increase in posthe parin plasma. In contrast, the concentration of another heparin-binding protein, lactoferrin (LF), increased six- fold after heparin injection. Immunohistochemistry of hu man artery was performed using polyclonal antisera to AT, HCII, PCI, LF, and tissue factor pathway inhibitor (TFPI), another heparin-binding protein released by hep arin injection. AT, HCII, and PCI were present in the intima, whereas LF, TFPI, and traces of AT were found on the surface of the vessel wall. The distribution of the proteins in the vessel wall supports the results of the hep arin-injection studies and may give valuable clues to the role of each protein in vascular homeostasis.

Edmonton Symptom Assessment System for outpatient symptom monitoring of sickle cell disease

OBJECTIVES

Although the extension of palliative care methodology to sickle cell disease (SCD) care has been proposed, there is no current standard for symptom assessment. Our goal was to assess the feasibility of integrating the Edmonton Symptom Assessment System (ESAS) into the outpatient management of SCD.

METHODS

Seventy-five adult patients presenting for outpatient visits at a comprehensive SCD center were enrolled. Patients completed the ESAS (self-report of 10 symptoms during the last 24 hours) and a survey regarding their opinion of the ESAS at enrollment and follow-up.

RESULTS

Pain (P = 0.0272) was the only symptom score that changed significantly between the initial and follow-up visits. In patients with a self-reported pain crisis, pain (P < 0.0001), fatigue (P = 0.0025), depression (P = 0.0458), nausea (P = 0.0384), and symptom distress scores (P = 0.0019) were significantly higher than for patients without a pain crisis. On the initial visit, 92% of all patients agreed or strongly agreed that the ESAS was easy to complete; 83% were satisfied or very satisfied with the ESAS as a way to report symptoms.

CONCLUSIONS

Our data suggest that the ESAS is well received and can be successfully included as part of the longitudinal symptom management strategy for SCD.

Continuous infusion interleukin-2 and famotidine in metastatic kidney cancer

Infusional interleukin-2 (IL-2) is able to elicit lymphokine-activated killer cell (LAK) cytotoxicity against kidney cancer in vitro and in vivo. Famotidine may be able to augment LAK cytotoxicity against neoplastic cells. Fifteen (15) patients were treated with continuous-infusion IL-2 (9-18 MIU/m2/24 hours) for 72 hours and famotidine 20 mg intravenously twice per day. Cycles were repeated every 3 weeks. These patients had a median age of 60 years (range, 29-72), had a median performance status of 1 (range, 0-1), and had metastatic sites, including lung, bone, lymph node, and liver. The most common toxicities of this regimen were hypophosphatemia, fever, nausea/emesis, rigors, elevated creatinine, and hypomagnesemia. One (1) complete and 6 partial responses have been seen (47% response rate). The median duration of response is 9 months. The median survival for all patients is 20 months. Five (5) patients are alive at a median of 36+ months. This combination of infusional IL-2 with famotidine is active in metastatic kidney cancer.

Continuous infusion interleukin-2 and intravenous famotidine in metastatic melanoma

Lymphokine-activated killer cell (LAK) cytotoxicity against tumor cells is induced by the use of high-dose infusional interleukin-2 (IL-2). LAK cytotoxicity against neoplastic cells may be augmented by famotidine. Twelve (12) patients have been treated with continuous infusion IL-2 (18 MIU/m2/24 hours) for 72 hours and famotidine 20 mg IVPB twice per day. Cycles were repeated every 3 weeks. These patients were of median age--67 years (range, 25-79), had a median performance status of 1 (range, 0-1), and had metastatic sites, including lung, lymph node, subcutaneous/soft tissue, and liver. The most common toxicities of this regimen were fever, rigors, nausea/emesis, hypophosphatemia, and hypomagnesemia. Three (3) partial responses have been seen (25% response rate). One (1) of these responders has undergone complete surgical resection and is disease-free at 15+ months. Four (4) patients are alive at a median of > 25 months. The median survival for all patients is 13 months. This combination of infusional IL-2 with famotidine is active in metastatic melanoma.

Activity of Continuous Infusion Plus Pulse Interleukin-2 with Famotidine in Patients with Metastatic Kidney Cancer or Melanoma Previously Treated with Interleukin-2

Lymphokine-activated killer (LAK) cells generated by high-dose continuous infusion interleukin-2 (IL-2) are able to nonspecifically lyse melanoma and kidney cancer cells. In vitro famotidine enhances cytotoxicity of LAK against tumor cells, possibly by increasing IL-2 uptake at the IL-2 receptor on lymphocytes. Outpatient IL-2 regimens typically have response rates of 15% or less, with most patients eventually experiencing progressive disease. Second-line therapy is, therefore, needed. We treated 11 patients (6 with metastatic melanoma; 5 having metastatic kidney cancer) who had previously experienced progressive disease on prior IL-2 regimens, with a combination of famotidine 20 mg intravenously (i.v.) twice per day and continuous-infusion IL-2 18 MIU/M2/24 hours x 72 hours, followed 24 hours later by a pulse IL-2 dose (18 MIU/M2 over 15 minutes). Cycles were repeated every 3 weeks. Patient characteristics were: 9 males, median age 63 years (range, 57-75), median Eastern Cooperative Oncology Group (ECOG) performance status: 1; most common metastatic sites: lungs, lymph nodes, and soft tissue/subcutaneous (s.c.); median number of cycles received: 4; most common toxicities were fever, nausea/emesis, hypophosphatemia, and hypomagnesemia. Five (5) patients (3 with melanoma, 2 with kidney cancer) have had partial responses. Two (2) patients with kidney cancer have been converted to complete responders with resection of residual disease, remaining without relapse at 5+ and 20+ months. Responding sites are lungs, lymph nodes, abdominal mass, and s.c. Median duration of response was 9.5 months. Median survival was 12 months. This combination has activity in patients with metastatic kidney cancer or melanoma who have received prior IL-2.

An Unusual Cause of New-onset Atrial Flutter: Primary Cardiac Lymphoma

Primary cardiac lymphoma is a rare disease with a high mortality rate due to the advanced stage of myocardial involvement at presentation. The diagnosis is extremely difficult to make because of the rarity of the disease, variability of clinical manifestations, limited noninvasive diagnostic techniques available, and difficulties and/or delays in the use of invasive measures. The incidence of the disease is increasing, especially among immunocompromised patients, with those suffering from acquired immunodeficiency syndrome accounting for the greatest increase. We report the case of an immunocompetent 76-year-old black woman who presented with near-syncopal episodes. Transthoracic echocardiogram revealed a right atrial mass. Surgical resection was performed, and a diagnosis of large B-cell non-Hodgkin's lymphoma was made. Primary cardiac lymphoma should be considered in any patient with a cardiac mass. Prompt diagnosis and treatment of primary cardiac lymphoma is imperative for survival.

Mammalian recombinant coagulation proteins: structure and function

Recombinant DNA technology has permitted the production of synthetic proteins which are potentially free of human infectious agents. Despite production in foreign cells, these proteins are structurally and functionally comparable to the native proteins. Recombinant clotting factors VIII, IX, VIIa, and von Willebrand factor have the same primary sequence as their plasma counterparts. The secondary and tertiary structures are similar, Post-translational modifications, including proteolytic processing, disulfide bonding, addition and processing of N- and O-linked glycans, gamma-carboxylation of glutamic acid residues, beta-hydroxylation of aspartic acid residues, sulfation of tyrosine residues, and phosphorylation of serine residues, are similar but not always identical, In some instances. these differences may cause significant functional differences. For example, reduced tyrosine sulfation and serine phosphorylation of recombinant factor IX have been correlated with reduced recovery following intravenous infusion. The specific clotting activity of the recombinant factors, an indication of their coagulant function, is equivalent to that of the plasma factors. Finally, these proteins have been used clinically and shown to correct clinical deficiencies of these proteins in a manner that is similar to replacement with plasma factors. All in all, the promise of recombinant DNA technology for coagulation and other disorders remains bright.

Successful treatment of transient acquired factor X deficiency by plasmapheresis with concomitant intravenous immunoglobulin and steroid therapy

Two patients with no history of previous bleeding diatheses presented with active bleeding from multiple body sites, declining hemoglobin levels, and markedly prolonged prothrombin times (PT) and activated partial thromboplastin times (aPTT) with incomplete correction on PT mix assays. Both patients demonstrated a severe deficiency of factor X (F.X) (<1%; reference range 60-150%). F.X levels and bleeding were refractory to multiple transfusions of fresh frozen plasma (FFP) in both patients. In contrast, daily therapeutic plasma exchange (PLEX) with concomitant administration of intravenous immunoglobulin (IV IgG) and steroids produced a rapid increase in F.X levels with cessation of bleeding, followed by stabilization and normalization of F.X levels and progressive correction of coagulation times. Neither patient has demonstrated a recurrence of the bleeding tendency following discontinuation of steroid therapy. These patients had transient acquired F.X deficiency, a rare coagulopathy, which can result in a lethal bleeding diathesis. An IgG inhibitor that selectively inhibited F.X activation in Russell's viper venom or tissue factor/F.VIIa assays was demonstrated in one patient's pretreatment plasma. Previous treatment of hemorrhage in transient acquired F.X deficiency has been prothrombin complex and/or activated clotting concentrates, which can be associated with transient hypercoagulable states. This is the first reported use of PLEX in transient acquired F.X deficiency. PLEX is safe, efficacious, and rapidly restores hemostasis in this rare acquired bleeding disorder.

Cloning, expression, and characterization of mouse tissue factor pathway inhibitor (TFPI)

Tissue factor pathway inhibitor (TFPI) acts to regulate the initiation of coagulation by first inhibiting factor Xa. The complex of factor Xa/TFPI then inhibits the factor VIIa/tissue factor complex. The cDNA sequences of TFPI from several different species have been previously reported. A high level of similarity is present among TFPIs at the molecular level (DNA and protein sequences) as well as in biochemical function (inhibition of factor Xa, VIIa/tissue factor). In this report, we used a PCR-based screening method to clone cDNA for full length TFPI from a mouse macrophage cDNA library. Both cDNA and predicted protein sequences show significant homology to the other reported TFPI sequences, especially to that of rat. Mouse TFPI has a signal peptide of 28 amino acid residues followed by the mature protein (in which the signal peptide is removed) which has 278 amino acid residues. Mouse TFPI, like that of other species, consists of three tandem Kunitz type domains. Recombinant mouse TFPI was expressed in the human kidney cell line 293 and purified for functional assays. When using human clotting factors to investigate the inhibition spectrum of mouse TFPI, it was shown that, in addition to human factor Xa, mouse TFPI inhibits human factors VIIa, IXa, as well as factor XIa. Cloning and expression of the mouse TFPI gene will offer useful information and material for coagulation studies performed in a mouse model system.

Needle aspiration for diagnosis of cellulitis

Diagnosing the causative agent of bacterial cellulitis is difficult. Blood culturing and needle aspiration have been used: the former has an extremely low sensitivity, the yield of the latter ranges from 4 to 42 percent. A retrospective study was conducted to determine the diagnostic success of needle aspiration and culture of the leading edge of cellulitis with a 21 to 22 gauge syringe and conventional bacteriologic culture of blood in determining the agent that causes acute cellulitis. This agent was determined in 33 percent of patients by needle aspiration and in 4 percent using blood cultures.