Differential RNA editing landscapes in host cell versus the SARS-CoV-2 genome.

The SARS-CoV-2 pandemic was defined by the emergence of new variants formed through virus mutation originating from random errors not corrected by viral proofreading and/or the host antiviral response introducing mutations into the viral genome. While sequencing information hints at cellular RNA editing pathways playing a role in viral evolution, here, we use an in vitro human cell infection model to assess RNA mutation types in two SARS-CoV-2 strains representing the original and the alpha variants. The variants showed both different cellular responses and mutation patterns with alpha showing higher mutation frequency with most substitutions observed being C-U, indicating an important role for apolipoprotein B mRNA editing catalytic polypeptide-like editing. Knockdown of select APOBEC3s through RNAi increased virus production in the original virus, but not in alpha. Overall, these data suggest a deaminase-independent anti-viral function of APOBECs in SARS-CoV-2 while the C-U editing itself might function to enhance genetic diversity enabling evolutionary adaptation.

Stem cell-derived porcine macrophages as a new platform for studying host-pathogen interactions.

BACKGROUND: Infectious diseases of farmed and wild animals pose a recurrent threat to food security and human health. The macrophage, a key component of the innate immune system, is the first line of defence against many infectious agents and plays a major role in shaping the adaptive immune response. However, this phagocyte is a target and host for many pathogens. Understanding the molecular basis of interactions between macrophages and pathogens is therefore crucial for the development of effective strategies to combat important infectious diseases. RESULTS: We explored how porcine pluripotent stem cells (PSCs) can provide a limitless in vitro supply of genetically and experimentally tractable macrophages. Porcine PSC-derived macrophages (PSCdMs) exhibited molecular and functional characteristics of ex vivo primary macrophages and were productively infected by pig pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV) and African swine fever virus (ASFV), two of the most economically important and devastating viruses in pig farming. Moreover, porcine PSCdMs were readily amenable to genetic modification by CRISPR/Cas9 gene editing applied either in parental stem cells or directly in the macrophages by lentiviral vector transduction. CONCLUSIONS: We show that porcine PSCdMs exhibit key macrophage characteristics, including infection by a range of commercially relevant pig pathogens. In addition, genetic engineering of PSCs and PSCdMs affords new opportunities for functional analysis of macrophage biology in an important livestock species. PSCs and differentiated derivatives should therefore represent a useful and ethical experimental platform to investigate the genetic and molecular basis of host-pathogen interactions in pigs, and also have wider applications in livestock.

Volume at First Leak Is Associated With Sling Failure Among Women With Stress Urinary Incontinence.

INTRODUCTION: Stress urinary incontinence at a low bladder volume is a clinically observed phenomenon that is not well studied with regard to treatment outcomes. The primary aim of our study was to determine if the volume at first leak is associated with sling outcome. METHODS: This is a retrospective cohort study evaluating whether urodynamic stress urinary incontinence observed at low volumes is associated with sling failure using the Synthetic Derivative database. Sling failure was defined as (1) undergoing a subsequent surgery for stress incontinence (eg, urethral bulking agent, repeat sling) or (2) leakage that was subjectively worse or unchanged from baseline. Sling success was defined as subjective improvement in incontinence or being dry. Intrinsic sphincter deficiency was defined as maximum urethral closure pressure 20 cm H20 or less or abdominal leak point pressure less than 60 cm H20. RESULTS: Outcome data were available for 168 of 206 women who underwent a sling after urodynamic testing from 2006 to 2014. Of the 168 women, 80 were transobturator, 79 were retropubic, 8 lacked data regarding the approach to the midurethral sling, and 1 was an autologous pubovaginal sling. Similar failure rates were seen for transobturator (10%) and retropubic slings (7.6%). Preoperative urodynamic parameters, such as cystometric capacity and intrinsic sphincter deficiency, were similar among failed and successful slings. For every additional 50 mL in bladder volume at first leak (SUIvol), there was a 1.6 increased odds of having a successful sling (odds ratio, 1.576; 95% confidence interval, 1.014-2.450; P = 0.04). There was no statistically significant association between maximum urethral closure pressure, abdominal leak point pressure, body mass index, age, sling type, or whether a prior anti-incontinence procedure had been performed and sling success. CONCLUSIONS: Bladder volume at first leak is a strong predictor of sling failure.

Schlafen 14 (SLFN14) is a novel antiviral factor involved in the control of viral replication.

Schlafen (SLFN) proteins have been suggested to play important functions in cell proliferation and immune cell development. In this study, we determined the antiviral activities of putative RNA-helicase domain-containing SLFN14. Murine SLFN14 expression was specifically induced by TLR3-mediated pathways and type I interferon (IFN) in RAW264.7 mouse macrophages. To examine the role of SLFN during viral infection, cells were infected with either wild-type PR8 or delNS1/PR8 virus. SLFN14 expression was specifically induced following influenza virus infection. Overexpression of SLFN14 in A549 cells reduced viral replication, whereas knockdown of SLFN14 in RAW264.7 cells enhanced viral titers. Furthermore, SLFN14 promoted the delay in viral NP translocation from cytoplasm to nucleus and enhanced RIG-I-mediated IFN-ß signaling. In addition, SLFN14 overexpression promoted antiviral activity against varicella zoster virus (VZV), a DNA virus. In conclusion, our data suggest that SLFN14 is a novel antiviral factor for both DNA and RNA viruses.

Variables affecting maximum urethral closure pressure (MUCP) and abdominal leak point pressure (ALPP) measurements.

INTRODUCTION AND HYPOTHESIS: The relationship between pelvic floor muscles and measurements of urethral function is not well studied. It is not known whether adjusting for clinical, demographic and urodynamic parameters would improve the association between MUCP and ALPP. Our hypothesis was that pelvic floor muscle strength (PFMS) influences the relationship between MUCP and ALPP. METHODS: This was a retrospective study of women who underwent a complex urodynamic study with evaluation of MUCP and ALPP using ICD-9 codes with documentation of PFMS. RESULTS: Urodynamic stress incontinence was confirmed in 478 patients, of whom 323 had MUCP recorded and 263 had both MUCP and ALPP recorded. Women with higher PFMS had a higher MUCP. In regression analysis ALPP at 150 mL and MUCP were weakly associated (coefficient 0.43, 95% CI 0.08-0.78; p = 0.02), whereas ALPP at capacity and MUCP were moderately associated (coefficient 0.60, 95% CI 0.25-0.95; p < 0.001). CONCLUSIONS: This study showed that MUCP and ALPP at 150 mL were weakly associated and that this improved to a moderate association for ALPP at capacity. MUCP increased with increasing PFMS among women with stress urinary incontinence and decreased with increasing age. There was no evidence that ALPP was associated with PFMS or age. The relationship between MUCP and ALPP was unchanged when accounting for covariates of PFMS (age, parity, BMI, prior procedure, urethral mobility, bladder capacity, stage of cystocele, or stage of uterine or apical prolapse).

Increased vitamin D and calcium intake associated with reduced mammographic breast density among premenopausal women.

Vitamin D has been identified as a weak protective factor for postmenopausal breast cancer (relative risk, ~0.9), whereas high breast density has been identified as a strong risk factor (relative risk, ~4-6). To test the hypothesis that there is an association between vitamin D intake, but not circulating vitamin D levels, and mammographic breast density among women in our study, we conducted a cross-sectional study of 165 screening mammography patients at Nashville General Hospital's Breast Health Center, a public facility serving medically indigent and underserved women. Dietary and total (dietary plus supplements) vitamin D and calcium intakes were estimated by the Harvard African American Food Frequency Questionnaire, and blood samples were analyzed for 25-hydroxyvitamin D. Average percent breast density for the left and right breasts combined was estimated from digitized films using an interactive thresholding method available through Cumulus software. After statistical adjustment for age, race, and body mass index, the results revealed that there were significant trends of decreasing breast density with increasing vitamin D and calcium intake among premenopausal but not among postmenopausal women. There was no association between serum vitamin D and breast density in premenopausal or postmenopausal women. Confirmation of our findings in larger studies may assist in clarifying the role of vitamin D in breast density.

The impact of chronic endurance and resistance training upon the right ventricular phenotype in male athletes.

OBJECTIVES: The traditional view of differential left ventricular adaptation to training type has been questioned. Right ventricular (RV) data in athletes are emerging but whether training type mediates this is not clear. The primary aim of this study was to evaluate the RV phenotype in endurance- vs. resistance-trained male athletes. Secondary aims included comparison of RV function in all groups using myocardial speckle tracking, and the impact of allometric scaling on RV data interpretation. METHODS: A prospective cross-sectional design assessed RV structure and function in 19 endurance-trained (ET), 21 resistance-trained (RT) and 21 sedentary control subjects (CT). Standard 2D tissue Doppler imaging and speckle tracking echocardiography assessed RV structure and function. Indexing of RV structural parameters to body surface area (BSA) was undertaken using allometric scaling. RESULTS: A higher absolute RV diastolic area was observed in ET (mean ± SD: 27 ± 4 cm(2)) compared to CT (22 ± 4 cm(2); P < 0.05) that was maintained after scaling. Whilst absolute RV longitudinal dimension was greater in ET (88 ± 9 mm) than CT (81 ± 10 mm; P < 0.05), this difference was removed after scaling. Wall thickness was not different between ET and RT and there were no between group differences in global or regional RV function. CONCLUSION: We present some evidence of RV adaptation to chronic ET in male athletes but limited structural characteristics of an athletic heart were observed in RT. Global and regional RV functions were comparable between groups. Allometric scaling altered data interpretation in some variables.

Cost-effectiveness of initial diagnostic strategies for pulmonary nodules presenting to thoracic surgeons.

BACKGROUND: Patients presenting to thoracic surgeons with pulmonary nodules suggestive of lung cancer have varied diagnostic options including navigation bronchoscopy (NB), computed tomography-guided fine-needle aspiration (CT-FNA), (18)F-fluoro-deoxyglucose positron emission tomography (FDG-PET) and video-assisted thoracoscopic surgery (VATS). We studied the relative cost-effective initial diagnostic strategy for a 1.5- to 2-cm nodule suggestive of cancer. METHODS: A decision analysis model was developed to assess the costs and outcomes of four initial diagnostic strategies for diagnosis of a 1.5- to 2-cm nodule with either a 50% or 65% pretest probability of cancer. Medicare reimbursement rates were used for costs. Quality-adjusted life years were estimated using patient survival based on pathologic staging and utilities derived from the literature. RESULTS: When cancer prevalence was 65%, tissue acquisition strategies of NB and CT-FNA had higher quality-adjusted life years compared with either FDG-PET or VATS, and VATS was the most costly strategy. In sensitivity analyses, NB and CT-FNA were more cost-effective than FDG-PET when FDG-PET specificity was less than 72%. When cancer prevalence was 50%, NB, CT-FNA, and FDG-PET had similar cost-effectiveness. CONCLUSIONS: Both NB and CT-FNA diagnostic strategies are more cost-effective than either VATS biopsy or FDG-PET scan to diagnose lung cancer in moderate- to high-risk nodules and resulted in fewer nontherapeutic operations when FDG-PET specificity was less than 72%. An FDG-PET scan for diagnosis of lung cancer may not be cost-effective in regions of the country where specificity is low.

Predicting lung cancer prior to surgical resection in patients with lung nodules.

BACKGROUND: Existing predictive models for lung cancer focus on improving screening or referral for biopsy in general medical populations. A predictive model calibrated for use during preoperative evaluation of suspicious lung lesions is needed to reduce unnecessary operations for a benign disease. A clinical prediction model (Thoracic Research Evaluation And Treatment [TREAT]) is proposed for this purpose. METHODS: We developed and internally validated a clinical prediction model for lung cancer in a prospective cohort evaluated at our institution. Best statistical practices were used to construct, evaluate, and validate the logistic regression model in the presence of missing covariate data using bootstrap and optimism corrected techniques. The TREAT model was externally validated in a retrospectively collected Veteran Affairs population. The discrimination and calibration of the model was estimated and compared with the Mayo Clinic model in both the populations. RESULTS: The TREAT model was developed in 492 patients from Vanderbilt whose lung cancer prevalence was 72% and validated among 226 Veteran Affairs patients with a lung cancer prevalence of 93%. In the development cohort, the area under the receiver operating curve (AUC) and Brier score were 0.87 (95% confidence interval [CI], 0.83-0.92) and 0.12, respectively compared with the AUC 0.89 (95% CI, 0.79-0.98) and Brier score 0.13 in the validation dataset. The TREAT model had significantly higher accuracy (p < 0.001) and better calibration than the Mayo Clinic model (AUC = 0.80; 95% CI, 75-85; Brier score = 0.17). CONCLUSION: The validated TREAT model had better diagnostic accuracy than the Mayo Clinic model in preoperative assessment of suspicious lung lesions in a population being evaluated for lung resection.

The fellowship effect: how the establishment of a fellowship in female pelvic medicine and reconstructive surgery affected resident vaginal hysterectomy training.

OBJECTIVE: We report on trends in resident-performed vaginal hysterectomies before and after the establishment of a female pelvic medicine and reconstructive surgery fellowship at Vanderbilt University Medical Center. STUDY DESIGN: We examined medical records and resident self-reports concerning all hysterectomies at our institution in an 8-year period: 4 years before fellowship and 4 years after. Route of hysterectomy, resident and fellow involvement, and division of attending surgeon were recorded from the electronic medical record. Resident Accreditation Council for Graduate Medical Education (ACGME) case log data were used to estimate the number of hysterectomies where residents reported themselves as the primary surgeon. RESULTS: During the 8-year period of this study, 3317 hysterectomies were performed at our institution, 41% (1371) before and 59% (1946) after fellowship. Prior to fellowship, 29% (393) were vaginal, 56% (766) were abdominal, and 15% (212) were laparoscopic/robotic. After addition of fellowship, 23% (449) were vaginal, 31% (597) were abdominal, and 46% (900) were laparoscopic/robotic. Of the total vaginal hysterectomies (TVH), there was resident involvement in 98.0% (385) cases before fellowship and 98.2% (441) cases after fellowship. From the ACGME case log data, the resident identified himself/herself as the primary surgeon in 388 cases before and 393 cases after fellowship. During this time period, medical records indicate a fellow was involved in 42% (189) of TVH, with resident involvement in all but 5 of these procedures. CONCLUSION: Frequency of resident involvement in TVH cases, either as primary surgeon or team member, remained constant after the addition of the female pelvic medicine and reconstructive surgery fellowship.

USP17 is required for clathrin mediated endocytosis of epidermal growth factor receptor.

Previously we have shown that expression of the deubiquitinating enzyme USP17 is required for cell proliferation and motility. More recently we reported that USP17 deubiquitinates RCE1 isoform 2 and thus regulates the processing of 'CaaX' motif proteins. Here we now show that USP17 expression is induced by epidermal growth factor and that USP17 expression is required for clathrin mediated endocytosis of epidermal growth factor receptor. In addition, we show that USP17 is required for the endocytosis of transferrin, an archetypal substrate for clathrin mediated endocytosis, and that USP17 depletion impedes plasma membrane recruitment of the machinery required for clathrin mediated endocytosis. Thus, our data reveal that USP17 is necessary for epidermal growth factor receptor and transferrin endocytosis via clathrin coated pits, indicate this is mediated via the regulation of the recruitment of the components of the endocytosis machinery and suggest USP17 may play a general role in receptor endocytosis.

TR3 modulates platinum resistance in ovarian cancer.

In metastatic ovarian cancer, resistance to platinum chemotherapy is common. Although the orphan nuclear receptor TR3 (nur77/NR4A1) is implicated in mediating chemotherapy-induced apoptosis in cancer cells, its role in ovarian cancer has not been determined. In an ovarian cancer tissue microarray, TR3 protein expression was elevated in stage I tumors, but downregulated in a significant subset of metastatic tumors. Moreover, TR3 expression was significantly lower in platinum-resistant tumors in patients with metastatic disease, and low TR3 staining was associated with poorer overall and progression-free survival. We have identified a direct role for TR3 in cisplatin-induced apoptosis in ovarian cancer cells. Nucleus-to-cytoplasm translocation of TR3 was observed in cisplatin-sensitive (OVCAR8, OVCAR3, and A2780PAR) but not cisplatin-resistant (NCI/ADR-RES and A2780CP20) ovarian cancer cells. Immunofluorescent analyses showed clear overlap between TR3 and mitochondrial Hsp60 in cisplatin-treated cells, which was associated with cytochrome c release. Ovarian cancer cells with stable shRNA- or transient siRNA-mediated TR3 downregulation displayed substantial reduction in cisplatin effects on apoptotic markers and cell growth in vitro and in vivo. Mechanistic studies showed that the cisplatin-induced cytoplasmic TR3 translocation required for apoptosis induction was regulated by JNK activation and inhibition of Akt. Finally, cisplatin resistance was partially overcome by ectopic TR3 overexpression and by treatment with the JNK activator anisomycin and Akt pathway inhibitor, wortmannin. Our results suggest that disruption of TR3 activity, via downregulation or nuclear sequestration, likely contributes to platinum resistance in ovarian cancer. Moreover, we have described a treatment strategy aimed at overcoming platinum resistance by targeting TR3.

Nonrenal indications for continuous renal replacement therapy: A report from the Prospective Pediatric Continuous Renal Replacement Therapy Registry Group.

OBJECTIVE: Continuous renal replacement therapy is the most often implemented dialysis modality in the pediatric intensive care unit setting for patients with acute kidney injury. However, it also has a role in the management of patients with nonrenal indications such as clearance of drugs and intermediates of disordered cellular metabolism. MEASUREMENTS AND METHODS: Using data from the multicenter Prospective Pediatric Continuous Renal Replacement Therapy Registry, we report a cohort of pediatric patients receiving continuous renal replacement therapy for nonrenal indications. Nonrenal indications were obtained from the combination of "other" category for continuous renal replacement therapy initiation and patient diagnosis (both primary and secondary). This cohort was further divided into three subgroups: inborn errors of metabolism, drug toxicity, and tumor lysis syndrome. RESULTS: From 2000 to 2005, a total of 50 continuous renal replacement therapy events with nonrenal indications for therapy were included in the Prospective Pediatric Continuous Renal Replacement Therapy Registry. Indication-specific survival of the subgroups was 62% (inborn errors of metabolism), 82% (tumor lysis syndrome), and 95% (drug toxicity). The median small solute dose delivered among the subgroups ranged from 2125 to 8213 mL/1.73 m/hr, with 54%-59% receiving solely diffusion-based clearance as continuous venovenous hemodialysis. No association was established between survival and dose delivered, modality of continuous renal replacement therapy, or use of intermittent hemodialysis prior to continuous renal replacement therapy. CONCLUSIONS: Pediatric patients requiring continuous renal replacement therapy for nonrenal indications are a distinct cohort within the population receiving renal replacement therapy with little published experience of outcomes for this group. Survival within this cohort varies by indication for continuous renal replacement therapy and is not associated with continuous renal replacement therapy modality. Additionally, survival is not associated with small solute doses delivered within a cohort receiving >2000 mL/1.73 m/hr. Our data suggest metabolic control is established rapidly in pediatric patients and that acute detoxification may be provided with continuous renal replacement therapy for both the initial and maintenance phases of treatment using either convection or diffusion at appropriate doses.

n-3 and n-6 polyunsaturated fatty acids differentially regulate adipose angiotensinogen and other inflammatory adipokines in part via NF-κB-dependent mechanisms.

Excessive secretion of proinflammatory adipokines has been linked to metabolic disorders. We have previously documented anti-inflammatory effects of n-3 polyunsaturated fatty acids (n-3 PUFAs) in adipose tissue; however, the mechanisms by which these fatty acids regulate adipokine secretion remain unclear. Here, we determined differential effects of eicosapentaenoic acid (EPA, n-3 PUFA) vs. arachidonic acid (AA, n-6 PUFA) on expression and secretion of angiotensinogen (Agt), interleukin 6 (IL-6) and monocyte chemotactic protein (MCP-1) in 3T3-L1 adipocytes. While both PUFAs increased intracellular Agt protein and mRNA expression, Agt secretion into culture media was increased only by AA treatment, which in turn was prevented by co-treatment with EPA. At various AA/EPA ratios, increasing AA concentrations significantly increased secretion of the above three adipokines, whereas increasing EPA dose-dependently, while lowering AA, decreased their secretion. Moreover, IL-6 and MCP-1 were more significantly reduced by EPA treatment compared to Agt (IL-6>MCP>Agt). Next, we tested whether nuclear factor-κB (NF-κB), a major proinflammatory transcription factor, was involved in regulation of these adipokines by PUFAs. EPA significantly inhibited NF-κB activation compared to control or AA treatments. Moreover, EPA attenuated tumor necrosis factor-α-induced MCP-1 and further reduced its secretion in the presence of an NF-κB inhibitor. Taken together, we reported here novel beneficial effects of EPA in adipocytes. We demonstrated direct anti-inflammatory effects of EPA, which are at least in part due to the inhibitory effects of this n-3 PUFA on the NF-κB pathway in adipocytes. In conclusion, these studies further support beneficial effects of n-3 PUFAs in adipocyte inflammation and metabolic disorders.

Hepatitis C virus induces CD81 and claudin-1 endocytosis.

Hepatitis C virus (HCV) leads to progressive liver disease and hepatocellular carcinoma. Current treatments are only partially effective, and new therapies targeting viral and host pathways are required. Virus entry into a host cell provides a conserved target for therapeutic intervention. Tetraspanin CD81, scavenger receptor class B member I, and the tight-junction proteins claudin-1 and occludin have been identified as essential entry receptors. Limited information is available on the role of receptor trafficking in HCV entry. We demonstrate here that anti-CD81 antibodies inhibit HCV infection at late times after virus internalization, suggesting a role for intracellular CD81 in HCV infection. Several tetraspanins have been reported to internalize via motifs in their C-terminal cytoplasmic domains; however, CD81 lacks such motifs, leading several laboratories to suggest a limited role for CD81 endocytosis in HCV entry. We demonstrate CD81 internalization via a clathrin- and dynamin-dependent process, independent of its cytoplasmic domain, suggesting a role for associated partner proteins in regulating CD81 trafficking. Live cell imaging demonstrates CD81 and claudin-1 coendocytosis and fusion with Rab5 expressing endosomes, supporting a role for this receptor complex in HCV internalization. Receptor-specific antibodies and HCV particles increase CD81 and claudin-1 endocytosis, supporting a model wherein HCV stimulates receptor trafficking to promote particle internalization.

Clathrin-mediated endocytosis regulates occludin, and not focal adhesion, distribution during epithelial wound healing.

BACKGROUND INFORMATION: Vesicle trafficking has long been suggested to play mechanistic roles in regulating directed cell migration. Recent evidence demonstrates that specific cell types and modes of migration involve transport of particular cargo through particular pathways. Epithelial wound healing is essential in tissue repair. However, investigations into the mechanisms regulating cell migration have mainly focused upon other models such as fibroblast-derived cells. Roles for vesicle trafficking pathways in regulating directed cell migration have been identified in recent studies, but mechanisms through which endocytosis might be involved in epithelial wound healing have not been as well studied. Therefore, we analysed potential regulatory roles for endocytosis pathways during epithelial cell motility, with a particular focus on cell adhesion. RESULTS: Specifically, and in contrast to studies in fibroblasts, we find no evidence for a link between endocytosis and the distribution of focal adhesions. However, the localisation of occludin, an essential component of tight junctions, is regulated through endocytosis. We identified epithelial monolayer wounding as a stimulus for endocytosis of occludin and have shown that internalisation of occludin from the wound edge occurs through clathrin-mediated endocytosis (CME) into a rab5-positive compartment. CONCLUSIONS: Thus, these studies have evaluated mechanistic roles for dynamin-dependant, CME and caveolar endocytosis during epithelial wound healing and have provided contrasting observations between analyses of cell motility in fibroblast models and epithelial cells. In conclusion, these studies have identified a novel mechanism for regulation of occludin during wound healing.

The role of vesicle trafficking in epithelial cell motility.

Cell motility is important for many physiological and pathological processes including organ development, wound healing, cancer metastasis and correct immune responses. In particular, epithelial wound healing is both a medically relevant topic and a common experimental model. Mechanisms underlying generation of a polarized cell and maintenance of a motile phenotype during steady-state migration are not well understood. Polarized trafficking of bulk membrane and cell adhesion molecules has been implicated in regulation of cell motility. The present review focuses on the role of different trafficking pathways in epithelial cell migration, including clathrin-mediated endocytosis, caveolar endocytosis, exocytosis of biosynthetic cargo, 'short-loop' and 'long-loop' endosomal recycling.

Chronic eosinophilic leukemias and the myeloproliferative variant of the hypereosinophilic syndrome.

Among patients with hypereosinophilia, a myeloproliferative variant is recognized. In many of these patients a diagnosis of eosinophilic leukemia can be made. The molecular mechanism is often a fusion gene, incorporating part of PDGFRA or PDGFRB, encoding anaberrant tyrosine kinase. Prompt diagnosis of such cases is important since specific tyrosine kinase inhibitor therapy is indicated.

Eosinophilic leukaemia.

The last few years have seen much progress in our understanding of, and treatments for, eosinophilic leukaemia. In preparing this review, we used Pubmed and the archives of well-known Haematology journals to search for relevant research papers and reviews published in the last 5-10 years. In this article, we review the differential diagnosis and sub-classification of eosinophilic leukaemia, and go on to discuss clinical features, investigation and treatment of these disorders. We are increasingly able to classify clonal eosinophilias based on the underlying molecular genetic abnormalities, and prognosticate and treat patients according to this. The successful treatment of certain of these patients with imatinib, followed by a greater understanding of the mechanism of this treatment, has revolutionized the outlook for many patients with eosinophilic leukaemia. New similar tyrosine kinase inhibitors and other promising therapies are on the horizon.

Case 32. Eosinophilia: reactive or neoplastic?

A diagnosis of eosinophilic leukemia was suspected in a patient who presented with eosinophilia and a mild macrocytic anemia and was found to have trisomy 8. Further tests and the subsequent clinical course permitted an accurate diagnosis.