Assessing the Assessment-Developing and Deploying a Novel Tool for Evaluating Clinical Notes' Diagnostic Assessment Quality.

BACKGROUND: Ambulatory diagnostic errors are increasingly being recognized as an important quality and safety issue, and while measures of diagnostic quality have been sought, tools to evaluate diagnostic assessments in the medical record are lacking. OBJECTIVE: To develop and test a tool to measure diagnostic assessment note quality in primary care urgent encounters and identify common elements and areas for improvement in diagnostic assessment. DESIGN: Retrospective chart review of urgent care encounters at an urban academic setting. PARTICIPANTS: Primary care physicians. MAIN MEASURES: The Assessing the Assessment (ATA) instrument was evaluated for inter-rater reliability, internal consistency, and findings from its application to EHR notes. KEY RESULTS: ATA had reasonable performance characteristics (kappa 0.63, overall Cronbach's alpha 0.76). Variability in diagnostic assessment was seen in several domains. Two components of situational awareness tended to be well-documented ("Don't miss diagnoses" present in 84% of charts, red flag symptoms in 87%), while Psychosocial context was present only 18% of the time. CONCLUSIONS: The ATA tool is a promising framework for assessing and identifying areas for improvement in diagnostic assessments documented in clinical encounters.

Features of diffuse gliomas that are misdiagnosed on initial neuroimaging: a case control study.

PURPOSE: The neuroimaging diagnosis of diffuse gliomas can be challenging owing to their variable clinical and radiologic presentation. The purpose of this study was to identify factors that are associated with imaging errors in the diagnosis of diffuse gliomas. METHODS: A retrospective case-control analysis was undertaken. 18 misdiagnosed diffuse gliomas on initial neuroimaging (cases) and 108 accurately diagnosed diffuse gliomas on initial neuroimaging (controls) were collected. Clinical, pathological, and imaging metrics were tabulated for each patient. The tabulated metrics were compared between cases and controls to determine factors associated with misdiagnosis. RESULTS: Cases of misdiagnosed diffuse glioma (vs controls) were more likely to undergo initial triage as a stroke workup [OR 14.429 (95% CI 4.345, 47.915), p < 0.0001], were less likely to enhance [OR 0.283 (95% CI 0.098, 0.812), p = 0.02], were smaller (mean diameter 4.4 vs 6.0 cm, p = 0.0008), produced less midline shift (median midline shift 0.0 vs 2.0 mm, p = 0.003), were less likely to demonstrate necrosis [OR 0.156 (95% CI 0.034-0.713), p = 0.008], and were less likely to have IV contrast administered on the initial MRI [OR 0.100 (95% CI 0.020, 0.494), p = 0.008]. CONCLUSION: Several clinical and radiologic metrics are associated with diffuse gliomas that are missed or misdiagnosed on the initial neuroimaging study. Knowledge of these associations may aid in avoiding misinterpretation and accurately diagnosing such cases in clinical practice.

Primary CNS posttransplant lymphoproliferative disease (PTLD): an international report of 84 cases in the modern era.

We performed a multicenter, International analysis of solid organ transplant (SOT)-related primary central nervous system (PCNS) posttransplant lymphoproliferative disease (PTLD). Among 84 PCNS PTLD patients, median time of SOT-to-PTLD was 54 months, 79% had kidney SOT, histology was monomorphic in 83% and tumor was EBV+ in 94%. Further, 33% had deep brain involvement, 10% had CSF involvement, while none had ocular disease. Immunosuppression was reduced in 93%; additional first-line therapy included high-dose methotrexate (48%), high-dose cytarabine (33%), brain radiation (24%) and/or rituximab (44%). The overall response rate was 60%, while treatment-related mortality was 13%. With 42-month median follow-up, three-year progression-free survival (PFS) and overall survival (OS) were 32% and 43%, respectively. There was a trend on univariable analysis for improved PFS for patients who received rituximab and/or high-dose cytarabine. On multivariable Cox regression, poor performance status predicted inferior PFS (HR 2.61, 95% CI 1.32-5.17, p = 0.006), while increased LDH portended inferior OS (HR 4.16, 95% CI 1.29-13.46, p = 0.02). Moreover, lack of response to first-line therapy was the most dominant prognostic factor on multivariable analysis (HR 8.70, 95% CI 2.56-29.57, p = 0.0005). Altogether, PCNS PTLD appears to represent a distinct clinicopathologic entity within the PTLD spectrum that is associated with renal SOT, occurs late, is monomorphic and retains EBV positivity.

Phase I study of panobinostat in combination with bevacizumab for recurrent high-grade glioma.

Bevacizumab is frequently used to treat patients with recurrent high-grade glioma (HGG), but responses are generally not durable. Panobinostat is a histone deacetylase inhibitor with anti-neoplastic and anti-angiogenic effects and may work synergistically with VEGF inhibitors. We performed a phase I study to evaluate the safety and tolerability of the combination of orally administered panobinostat with bevacizumab in patients with recurrent HGG. Patients with recurrent HGG were treated on a 3 + 3 trial design. Patients received bevacizumab 10 mg/kg every other week in combination with oral panobinostat. The starting dose of panobinostat was 20 mg three times per week, weekly (cohort 1). Due to concerns for thrombocytopenia with the weekly dosing regimen, the protocol was amended to examine an every other week regimen. Cohort 2 received panobinostat 20 mg three times per week, every other week, and cohort 3 received 30 mg three times per week, every other week. Dose-limiting toxicity during the first 30 days was used to determine the maximum-tolerated dose. Twelve patients (median age 50, median KPS 90) with recurrent HGG were enrolled. One dose-limiting toxicity (DLT) (Grade 3 thrombocytopenia) was observed in cohort 1. No DLTs were observed in cohorts 2 and 3. The following grade 3 toxicities were seen in one patient each: thrombocytopenia, hypophosphatemia, esophageal hemorrhage, and deep venous thrombosis. There were no grade 4 or 5 toxicities. There were three patients with partial responses and seven with stable disease. The recommended doses for further study are oral panobinostat 30 mg three times per week, every other week, in combination with bevacizumab 10 mg/kg every other week. A phase II clinical trial in recurrent HGG is underway.

Response assessment in neuro-oncology (a report of the RANO group): assessment of outcome in trials of diffuse low-grade gliomas.

Although low-grade gliomas (LGG) have a less aggressive course than do high-grade gliomas, the outcome of these tumours is ultimately fatal in most patients. Both the tumour and its treatment can cause disabling morbidity, particularly of cognitive functions. Because many patients present with seizures only, with no other signs and symptoms, maintenance of quality of life and function constitutes a particular challenge in LGG. The slow growth pattern of most LGG, and the rare radiological true responses despite a favourable clinical response to treatment, interferes with the use of progression-free survival as the primary endpoint in trials. Overall survival as an endpoint brings logistical challenges, and is sensitive to other non-investigational salvage therapies. Clinical trials for LGG need to consider other measures of patient benefit such as cognition, symptom burden, and seizure activity, to establish whether improved survival is reflected in prolonged wellbeing. This Review investigates clinical and imaging endpoints in trials of LGG, and provides response assessment in neuro-oncology (RANO) criteria for non-enhancing tumours. Additionally, other measures for patients with brain tumours that assess outcome are described. Similar considerations are relevant for trials of high-grade gliomas, although for these tumours survival is shorter and survival endpoints generally have more value than they do for LGG.

Prognostic Value of Preoperative MRI Metrics for Diffuse Lower-Grade Glioma Molecular Subtypes.

BACKGROUND AND PURPOSE: Despite the improved prognostic relevance of the 2016 WHO molecular-based classification of lower-grade gliomas, variability in clinical outcome persists within existing molecular subtypes. Our aim was to determine prognostically significant metrics on preoperative MR imaging for lower-grade gliomas within currently defined molecular categories. MATERIALS AND METHODS: We undertook a retrospective analysis of 306 patients with lower-grade gliomas accrued from an institutional data base and The Cancer Genome Atlas. Two neuroradiologists in consensus analyzed preoperative MRIs of each lower-grade glioma to determine the following: tumor size, tumor location, number of involved lobes, corpus callosum involvement, hydrocephalus, midline shift, eloquent cortex involvement, ependymal extension, margins, contrast enhancement, and necrosis. Adjusted hazard ratios determined the association between MR imaging metrics and overall survival per molecular subtype, after adjustment for patient age, patient sex, World Health Organization grade, and surgical resection status. RESULTS: For isocitrate dehydrogenase (IDH) wild-type lower-grade gliomas, tumor size (hazard ratio, 3.82; 95% CI, 1.94-7.75; P < .001), number of involved lobes (hazard ratio, 1.70; 95% CI, 1.28-2.27; P < .001), hydrocephalus (hazard ratio, 4.43; 95% CI, 1.12-17.54; P = .034), midline shift (hazard ratio, 1.16; 95% CI, 1.03-1.30; P = .013), margins (P = .031), and contrast enhancement (hazard ratio, 0.34; 95% CI, 0.13-0.90; P = .030) were associated with overall survival. For IDH-mutant 1p/19q-codeleted lower-grade gliomas, tumor size (hazard ratio, 2.85; 95% CI, 1.06-7.70; P = .039) and ependymal extension (hazard ratio, 6.34; 95% CI, 1.07-37.59; P = .042) were associated with overall survival. CONCLUSIONS: MR imaging metrics offers prognostic information for patients with lower-grade gliomas within molecularly defined classes, with the greatest prognostic value for IDH wild-type lower-grade gliomas.

Enhanced distress vocalization through selective reinforcement.

Eighteen Peking ducklings were imprinted and tested for their tendency to emit distress calls during the presentation and withdrawal of the imprinted stimulus. A subsequent arrangement in which each distress vocalization led to a 5-second presentation of the imprinted stimulus resulted in an enhanced tendency to emit distress calls.

Molecular Subtype Classification in Lower-Grade Glioma with Accelerated DTI.

BACKGROUND AND PURPOSE: Image-based classification of lower-grade glioma molecular subtypes has substantial prognostic value. Diffusion tensor imaging has shown promise in lower-grade glioma subtyping but currently requires lengthy, nonstandard acquisitions. Our goal was to investigate lower-grade glioma classification using a machine learning technique that estimates fractional anisotropy from accelerated diffusion MR imaging scans containing only 3 diffusion-encoding directions. MATERIALS AND METHODS: Patients with lower-grade gliomas (n = 41) (World Health Organization grades II and III) with known isocitrate dehydrogenase (IDH) mutation and 1p/19q codeletion status were imaged preoperatively with DTI. Whole-tumor volumes were autodelineated using conventional anatomic MR imaging sequences. In addition to conventional ADC and fractional anisotropy reconstructions, fractional anisotropy estimates were computed from 3-direction DTI subsets using DiffNet, a neural network that directly computes fractional anisotropy from raw DTI data. Differences in whole-tumor ADC, fractional anisotropy, and estimated fractional anisotropy were assessed between IDH-wild-type and IDH-mutant lower-grade gliomas with and without 1p/19q codeletion. Multivariate classification models were developed using whole-tumor histogram and texture features from ADC, ADC + fractional anisotropy, and ADC + estimated fractional anisotropy to identify the added value provided by fractional anisotropy and estimated fractional anisotropy. RESULTS: ADC (P = .008), fractional anisotropy (P < .001), and estimated fractional anisotropy (P < .001) significantly differed between IDH-wild-type and IDH-mutant lower-grade gliomas. ADC (P < .001) significantly differed between IDH-mutant gliomas with and without codeletion. ADC-only multivariate classification predicted IDH mutation status with an area under the curve of 0.81 and codeletion status with an area under the curve of 0.83. Performance improved to area under the curve = 0.90/0.94 for the ADC + fractional anisotropy classification and to area under the curve = 0.89/0.89 for the ADC + estimated fractional anisotropy classification. CONCLUSIONS: Fractional anisotropy estimates made from accelerated 3-direction DTI scans add value in classifying lower-grade glioma molecular status.

Correction to: Multiple receptor tyrosine kinases converge on microRNA-134 to control KRAS, STAT5B, and glioblastoma.

Following publication of the article, the author named as "B Dey", wished to point out that his full name is "Bijan K. Dey". This was not reflected in the typesetting of the article, and as a consequence the article is not visible on Pub Med when a search is conducted on his full name.

Neuroimaging-Based Classification Algorithm for Predicting 1p/19q-Codeletion Status in IDH-Mutant Lower Grade Gliomas.

BACKGROUND AND PURPOSE: Isocitrate dehydrogenase (IDH)-mutant lower grade gliomas are classified as oligodendrogliomas or diffuse astrocytomas based on 1p/19q-codeletion status. We aimed to test and validate neuroradiologists' performances in predicting the codeletion status of IDH-mutant lower grade gliomas based on simple neuroimaging metrics. MATERIALS AND METHODS: One hundred two IDH-mutant lower grade gliomas with preoperative MR imaging and known 1p/19q status from The Cancer Genome Atlas composed a training dataset. Two neuroradiologists in consensus analyzed the training dataset for various imaging features: tumor texture, margins, cortical infiltration, T2-FLAIR mismatch, tumor cyst, T2* susceptibility, hydrocephalus, midline shift, maximum dimension, primary lobe, necrosis, enhancement, edema, and gliomatosis. Statistical analysis of the training data produced a multivariate classification model for codeletion prediction based on a subset of MR imaging features and patient age. To validate the classification model, 2 different independent neuroradiologists analyzed a separate cohort of 106 institutional IDH-mutant lower grade gliomas. RESULTS: Training dataset analysis produced a 2-step classification algorithm with 86.3% codeletion prediction accuracy, based on the following: 1) the presence of the T2-FLAIR mismatch sign, which was 100% predictive of noncodeleted lower grade gliomas, (n = 21); and 2) a logistic regression model based on texture, patient age, T2* susceptibility, primary lobe, and hydrocephalus. Independent validation of the classification algorithm rendered codeletion prediction accuracies of 81.1% and 79.2% in 2 independent readers. The metrics used in the algorithm were associated with moderate-substantial interreader agreement (κ = 0.56-0.79). CONCLUSIONS: We have validated a classification algorithm based on simple, reproducible neuroimaging metrics and patient age that demonstrates a moderate prediction accuracy of 1p/19q-codeletion status among IDH-mutant lower grade gliomas.

Extent of Surgical Resection in Lower-Grade Gliomas: Differential Impact Based on Molecular Subtype.

BACKGROUND AND PURPOSE: Diffuse lower-grade gliomas are classified into prognostically meaningful molecular subtypes. We aimed to determine the impact of surgical resection on overall survival in lower-grade glioma molecular subtypes. MATERIALS AND METHODS: For 172 patients with lower-grade gliomas (World Health Organization grade II or III), pre- and postsurgical glioma volumes were determined using a semiautomated segmentation software based on FLAIR or T2-weighted MR imaging sequences. The association of pre- and postsurgical glioma volume and the percentage of glioma resection with overall survival was determined for the entire cohort and separately for lower-grade glioma molecular subtypes based on isocitrate dehydrogenase (IDH) and 1p/19q status, after adjustment for age, sex, World Health Organization grade, chemotherapy administration, and radiation therapy administration. RESULTS: For the entire cohort, postsurgical glioma volume (hazard ratio, 1.80; 95% CI, 1.18-2.75; P = .006) and the percentage of resection (hazard ratio, 3.22; 95% CI, 1.79-5.82; P < .001) were associated with overall survival. For IDH-mutant 1p/19q-codeleted oligodendrogliomas, the percentage of resection (hazard ratio, 6.69; 95% CI, 1.57-28.46; P = .01) was associated with overall survival. For IDH-mutant 1p/19q-noncodeleted astrocytomas, presurgical glioma volume (hazard ratio, 3.20; 95% CI, 1.22-8.39; P = .018), postsurgical glioma volume (hazard ratio, 2.33; 95% CI, 1.32-4.12; P = .004), and percentage of resection (hazard ratio, 4.34; 95% CI, 1.74-10.81; P = .002) were associated with overall survival. For IDH-wild-type lower-grade gliomas, pre-/postsurgical glioma volume and percentage of resection were not associated with overall survival. CONCLUSIONS: The extent of surgical resection has a differential survival impact in patients with lower-grade gliomas based on their molecular subtype. IDH-mutant lower-grade gliomas benefit from a greater extent of surgical resection, with the strongest impact observed for IDH-mutant 1p/19q-noncodeleted astrocytomas.

Farnesylthiosalicylic acid induces caspase activation and apoptosis in glioblastoma cells.

Primary glioblastomas (GBMs) commonly overexpress the oncogene epidermal growth factor receptor (EGFR), which leads to increased Ras activity. FTA, a novel Ras inhibitor, produced both time- and dose-dependent caspase-mediated apoptosis in GBM cell lines. EGFR-mediated increase in 3H-thymidine uptake was inhibited by FTA. FACS analysis was performed to determine the percent of apoptotic cells. The sub-Go population of GBM cells was increased from 4.5 to 13.8% (control) to over 45-53.6% in FTA-treated cells within 24 h. Furthermore, FTA also increased the activities of both caspase-3 and -9, and PARP cleavage. Treatment of GBMs with FTA before or after EGF addition to the cultures blocked phosphorylation of Akt and mitogen-activated protein kinases (MAPK). FTA also significantly reduced the amount of EGF-induced Ras-GTP as reflected by a decrease in the level of Ras bound to Raf-RBD-GST. This study demonstrates that inhibition of Ras methylation may provide a therapeutic target for the treatment of GBMs overexpressing EGFR.

Primary intraocular lymphoma: an International Primary Central Nervous System Lymphoma Collaborative Group Report.

BACKGROUND: Primary intraocular lymphoma (PIOL) is an uncommon subset of primary central nervous system lymphoma. Because it is rare and difficult to diagnose, the natural history and optimal management are unknown. PATIENTS AND METHODS: A retrospective study of 83 HIV negative, immunocompetent PIOL patients was assembled from 16 centers in seven countries. RESULTS: Median age at diagnosis was 65. Median ECOG performance status was 0. Presenting symptoms included blurred vision, decreased visual acuity, and floaters. Median time to diagnosis was 6 months. Diagnosis was made by vitrectomy (74), choroidal/retinal biopsy (6) and ophthalmic exam (3). Eleven percent had positive CSF cytology. Initial treatment was categorized as focal in 23 (intra-ocular methotrexate, ocular radiotherapy) or extensive in 53 (systemic chemotherapy, whole brain radiotherapy). Six received none; details are unknown in one. Forty-seven relapsed: brain 47%, eyes 30%, brain and eyes 15%, and systemic 8%. Median time to relapse was 19 months. Focal therapy alone did not increase risk of brain relapse. Median progression free (PFS) and overall survival (OS) were 29.6 and 58 months, respectively, and unaffected by treatment type. CONCLUSION: Treatment type did not affect relapse pattern, median PFS or OS. Focal therapy may minimize treatment toxicity without compromising disease control.

Management of neuro-oncologic emergencies.

Patients with brain tumors and systemic malignancies are subject to diverse neurologic complications that require urgent evaluation and treatment. These neurologic conditions are commonly due to the tumor's direct effects on the nervous system, such as cerebral edema, increased intracranial pressure, seizures, spinal cord compression, and leptomeningeal metastases. In addition, neurologic complications can develop as a result of thrombocytopenia, coagulopathy, hyperviscosity syndromes, infection, immune-related disorders, and adverse effects of treatment. Patients may present with typical disease syndromes. However, it is not uncommon for patients to have more subtle, nonlocalizing manifestations, such as alteration of mental status, that could be attributed to other systemic, nonneurologic complications. Furthermore, neurologic complications are at times the initial manifestations of an undiagnosed malignancy. Therefore a high index of suspicion is essential for rapid assessment and management. Timely intervention may prolong survival and improve quality of life. In this chapter, we will discuss the common neuro-oncologic emergencies, including epidemiology, pathophysiology, clinical presentation, diagnosis, and treatment.

Bilirubin-neural cell interaction: characterization of initial cell surface binding leading to toxicity in the neuroblastoma cell line N-115.

The toxicity of bilirubin to the nervous system might be due to its effect on several key enzyme reactions occurring in the intracellular compartment as suggested by in vitro studies. The question of how bilirubin, a molecule with poor solubility in water and organic solvents, interacts with the plasma membrane and reaches intracellular targets is unclear. In an attempt to get some insight into this problem, we have measured the uptake of bilirubin from bilirubin-albumin solutions by the murine neuroblastoma cell line N-115. At a constant total concentration of bilirubin, the initial rate, as well as the extent of uptake, increases with increasing bilirubin to albumin molar ratio (B/A). The binding is reversible, at least partially, as indicated by the ability of albumin to extract cell-bound bilirubin. The cellular uptake of bilirubin was found to depend also on the concentration of bilirubin, on temperature and on pH. The results are not consistent with either a carrier-mediated transport or passive diffusion across the plasma membrane. The data, however, seem to fit a multistep binding of bilirubin to the plasma membrane proposed for the interaction of bilirubin with synaptosomal plasma membrane vesicles, erythrocyte ghosts and lipid vesicles. These studies, thus, reveal the complexity of the binding interaction at the level of the plasma membrane and leave open the question of transport across the membrane.

Bilirubin diffusion through lipid membranes.

The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.

Phase II study of phenylacetate in patients with recurrent malignant glioma: a North American Brain Tumor Consortium report.

PURPOSE: To determine the response rate, time to treatment failure, and toxicity of phenylacetate in patients with recurrent malignant glioma and to identify plasma concentrations achieved during repeated continuous infusion of this agent. PATIENTS AND METHODS: Adult patients with recurrent malignant glioma were treated with phenylacetate. The schedule consisted of a 2-week continuous, intravenous infusion followed by a 2-week rest period (14 days on, 14 days off). A starting dose of 400 mg/kg total body weight per day of phenylacetate was initially used and subsequently changed to 400 mg/kg/d based on ideal body weight. Intrapatient dose escalations were allowed to a maximum of 450 mg/kg ideal body weight/d. Tumor response was assessed every 8 weeks. The National Cancer Institute common toxicity criteria were used to assess toxicity. Plasma concentrations achieved during the patients' first two 14-day infusions were assessed. RESULTS: Forty-three patients were enrolled between December 1994 and December 1996. Of these, 40 patients were assessable for toxicity and response to therapy. Reversible symptoms of fatigue and somnolence were the primary toxicities, with only mild hematologic toxicity. Thirty (75%) of the 40 patients failed treatment within 2 months, seven (17.5%) had stable disease, and three (7.5%) had a response defined as more than 50% reduction in the tumor. Median time to treatment failure was 2 months. Thirty-five patients have died, with a median survival of 8 months. Pharmacokinetic data for this dose schedule showed no difference in the mean plasma concentrations of phenylacetate between weeks 1 and 2 or between weeks 5 and 6. CONCLUSION: Phenylacetate has little activity at this dose schedule in patients with recurrent malignant glioma. Further studies with this drug would necessitate an evaluation of a different dose schedule.

Preponderance of thiopurine S-methyltransferase deficiency and heterozygosity among patients intolerant to mercaptopurine or azathioprine.

PURPOSE: To assess thiopurine S-methyltransferase (TPMT) phenotype and genotype in patients who were intolerant to treatment with mercaptopurine (MP) or azathioprine (AZA), and to evaluate their clinical management. PATIENTS AND METHODS: TPMT phenotype and thiopurine metabolism were assessed in all patients referred between 1994 and 1999 for evaluation of excessive toxicity while receiving MP or AZA. TPMT activity was measured by radiochemical analysis, TPMT genotype was determined by mutation-specific polymerase chain reaction restriction fragment length polymorphism analyses for the TPMT*2, *3A, *3B, and *3C alleles, and thiopurine metabolites were measured by high-performance liquid chromatography. RESULTS: Of 23 patients evaluated, six had TPMT deficiency (activity < 5 U/mL of packed RBCs [pRBCs]; homozygous mutant), nine had intermediate TPMT activity (5 to 13 U/mL of pRBCs; heterozygotes), and eight had high TPMT activity (> 13.5 U/mL of pRBCs; homozygous wildtype). The 65.2% frequency of TPMT-deficient and heterozygous individuals among these toxic patients is significantly greater than the expected 10% frequency in the general population (P <.001, chi(2)). TPMT phenotype and genotype were concordant in all TPMT-deficient and all homozygous-wildtype patients, whereas five patients with heterozygous phenotypes did not have a TPMT mutation detected. Before thiopurine dosage adjustments, TPMT-deficient patients experienced more frequent hospitalization, more platelet transfusions, and more missed doses of chemotherapy. Hematologic toxicity occurred in more than 90% of patients, whereas hepatotoxicity occurred in six patients (26%). Both patients who presented with only hepatic toxicity had a homozygous-wildtype TPMT phenotype. After adjustment of thiopurine dosages, the TPMT-deficient and heterozygous patients tolerated therapy without acute toxicity. CONCLUSION: There is a significant (> six-fold) overrepresentation of TPMT deficiency or heterozygosity among patients developing dose-limiting hematopoietic toxicity from therapy containing thiopurines. However, with appropriate dosage adjustments, TPMT-deficient and heterozygous patients can be treated with thiopurines, without acute dose-limiting toxicity.

Phagocytosis of gram-negative bacteria by a unique CD14-dependent mechanism.

THP-1-derived cell lines were stably transfected with constructs encoding glycophosphatidylinositol (GPI)-anchored or transmembrane forms of human CD14. CD14 expression was associated with enhanced phagocytosis of serum (heat-inactivated)-opsonized Escherichia coli (opEc). Both the GPI-anchored and transmembrane forms of CD14 supported phagocytosis of opEc equally well. Lipopolysaccharide-binding protein (LBP) played a role in CD14-dependent phagocytosis as evidenced by inhibition of CD14-dependent phagocytosis of opEc with anti-LBP monoclonal antibody (mAb) and by enhanced phagocytosis of E. coli opsonized with purified LBP. CD14-dependent phagocytosis was inhibited by a phosphatidylinositol (PI) 3-kinase inhibitor (wortmannin) and a protein tyrosine kinase inhibitor (tyrphostin 23) but not a protein kinase C inhibitor (bisindolyl-maleimide) or a divalent cation chelator (ethylenediaminetetraacetate). Anti-LBP mAb 18G4 and anti-CD14 mAb 18E12 were used to differentiate between the pathways involved in CD14-dependent phagocytosis and CD14-dependent cell activation. F(ab')2 fragments of 18G4, a mAb to LBP that does not block cell activation, inhibited ingestion of opEc by THP1-wtCD14 cells. 18E12 (an anti-CD14 mAb that does not block LPS binding to CD14 but does inhibit CD14-dependent cell activation) did not inhibit phagocytosis of LBP-opEc by THP1-wtCD14 cells. Furthermore, CD14-dependent phagocytosis was not inhibited by anti-CD18 (CR3 and CR4 beta-chain) or anti-Fcgamma receptor mAb.