Many paths lead to immunology.

While some people pore over the textbook and train through the classics of the field, many scientists come to immunology when they discover it intersecting with their "first love" interests. Five of these "accidental immunologists" tell us how they found their way to a fascination with the immune system.

Novel meriolin derivatives activate the mitochondrial apoptosis pathway in the presence of antiapoptotic Bcl-2.

Meriolin derivatives represent a new class of kinase inhibitors with a pronounced cytotoxic potential. Here, we investigated a newly synthesized meriolin derivative (termed meriolin 16) that displayed a strong apoptotic potential in Jurkat leukemia and Ramos lymphoma cells. Meriolin 16 induced apoptosis in rapid kinetics (within 2-3 h) and more potently (IC50: 50 nM) than the previously described derivatives meriolin 31 and 36 [1]. Exposure of Ramos cells to meriolin 16, 31, or 36 for 5 min was sufficient to trigger severe and irreversible cytotoxicity. Apoptosis induction by all three meriolin derivatives was independent of death receptor signaling but required caspase-9 and Apaf-1 as central mediators of the mitochondrial death pathway. Meriolin-induced mitochondrial toxicity was demonstrated by disruption of the mitochondrial membrane potential (ΔΨm), mitochondrial release of proapoptotic Smac, processing of the dynamin-like GTPase OPA1, and subsequent fragmentation of mitochondria. Remarkably, all meriolin derivatives were able to activate the mitochondrial death pathway in Jurkat cells, even in the presence of the antiapoptotic Bcl-2 protein. In addition, meriolins were capable of inducing cell death in imatinib-resistant K562 and KCL22 chronic myeloid leukemia cells as well as in cisplatin-resistant J82 urothelial carcinoma and 2102EP germ cell tumor cells. Given the frequent inactivation of the mitochondrial apoptosis pathway by tumor cells, such as through overexpression of antiapoptotic Bcl-2, meriolin derivatives emerge as promising therapeutic agents for overcoming treatment resistance.

A guideline on the molecular ecosystem regulating ferroptosis.

Ferroptosis, an intricately regulated form of cell death characterized by uncontrolled lipid peroxidation, has garnered substantial interest since this term was first coined in 2012. Recent years have witnessed remarkable progress in elucidating the detailed molecular mechanisms that govern ferroptosis induction and defence, with particular emphasis on the roles of heterogeneity and plasticity. In this Review, we discuss the molecular ecosystem of ferroptosis, with implications that may inform and enable safe and effective therapeutic strategies across a broad spectrum of diseases.

7-Dehydrocholesterol is an endogenous suppressor of ferroptosis.

Ferroptosis is a form of cell death that has received considerable attention not only as a means to eradicate defined tumour entities but also because it provides unforeseen insights into the metabolic adaptation that tumours exploit to counteract phospholipid oxidation1,2. Here, we identify proferroptotic activity of 7-dehydrocholesterol reductase (DHCR7) and an unexpected prosurvival function of its substrate, 7-dehydrocholesterol (7-DHC). Although previous studies suggested that high concentrations of 7-DHC are cytotoxic to developing neurons by favouring lipid peroxidation3, we now show that 7-DHC accumulation confers a robust prosurvival function in cancer cells. Because of its far superior reactivity towards peroxyl radicals, 7-DHC effectively shields (phospho)lipids from autoxidation and subsequent fragmentation. We provide validation in neuroblastoma and Burkitt's lymphoma xenografts where we demonstrate that the accumulation of 7-DHC is capable of inducing a shift towards a ferroptosis-resistant state in these tumours ultimately resulting in a more aggressive phenotype. Conclusively, our findings provide compelling evidence of a yet-unrecognized antiferroptotic activity of 7-DHC as a cell-intrinsic mechanism that could be exploited by cancer cells to escape ferroptosis.

Left atrial strain in adults after the arterial switch operation for transposition of the great arteries.

BACKGROUND: No study has focused on left atrial (LA) function assessed by echocardiography in adult patients with simple D-TGA after arterial switch operation (ASO). We aimed to describe LA strain parameters in these patients. METHODS: A prospective cohort study including 42 adult patients with simple D-TGA after ASO and 33 aged-matched controls. Phasic LA and LV global longitudinal strain (GLS) were obtained by transthoracic 2D-speckle tracking echocardiography (STE). Volumetric and functional analysis of LA and LV were also evaluated by 2D and 3D analysis. A multivariable model was performed to investigate the variables that best differentiate patients with D-TGA from healthy controls. RESULTS: LA strain parameters in D-TGA patients were within the normal range described for healthy subjects. However, the three LA strain parameters (Reservoir, Conduit, and Contraction) were lower in patients (LASr: 31.13 ± 7.67 vs. 49.71 ± 8.38; LAS cd: -22.91 ± 5.69 vs. -34.55 ± 6.54; LASct: -8.14 ± 4.93 vs. -15.15 ± 6.07, p < .001 for all three comparisons). LA volumes were similar between patients and controls. LV-GLS remained significantly lower in the D-TGA group than in controls (-17.29 ± 2.68 vs. -21.98 ± 1.84, p < .001). D-TGA patients had evidence of worse LV ejection fraction measured by the Teichholz method (63.38 ± 8.23 vs. 69.28 ± 5.92, p = .001) and 3D analysis (57.97% ± 4.16 vs. 60.67 ± 3.39, p = .011) and diastolic dysfunction as compared to healthy controls. LV-GLS and conduit LAS were the variables best differentiating patients with D-TGA from healthy controls. CONCLUSIONS: LA strain is impaired in young adults with simple D-TGA late after the ASO, probably in agreement with some degree of LV dysfunction previously described.

Level of professional quality of life and coping with death competence in healthcare professionals exposed to perinatal loss: A cross-sectional study.

Perinatal loss is a traumatic and stressful experience with a significant emotional toll on the physical and psychological wellbeing of the healthcare professionals. We included 216 healthcare professionals working in an obstetrics-gynecology service or neonatal intensive care unit in a cross-sectional study and aimed to analyze the possible association between the healthcare professionals' level of professional quality of life, their coping with death competence, and their personal and work-related characteristics. Compassion fatigue and burnout did not correlate significantly with healthcare professionals' personal and work-related characteristics. Formal training was strongly associated with high levels of compassion satisfaction and coping with death competence. A low level of coping with death competence was found in women and in younger healthcare professionals, those who are single, and with little professional experience. Self-care activities and hospital support systems can be effective resources in coping with death.

Expanding roles of BCL-2 proteins in apoptosis execution and beyond.

The proteins of the BCL-2 family are known as key regulators of apoptosis, with interactions between family members determining permeabilisation of the mitochondrial outer membrane (MOM) and subsequent cell death. However, the exact mechanism through which they form the apoptotic pore responsible for MOM permeabilisation (MOMP), the structure and specific components of this pore, and what roles BCL-2 proteins play outside of directly regulating MOMP are incompletely understood. Owing to the link between apoptosis dysregulation and disease, the BCL-2 proteins are important targets for drug development. With the development and clinical use of drugs targeting BCL-2 proteins showing success in multiple haematological malignancies, enhancing the efficacy of these drugs, or indeed developing novel drugs targeting BCL-2 proteins is of great interest to treat cancer patients who have developed resistance or who suffer other disease types. Here, we review our current understanding of the molecular mechanism of MOMP, with a particular focus on recently discovered roles of BCL-2 proteins in apoptosis and beyond, and discuss what implications these functions might have in both healthy tissues and disease.

Exploring the Binding Affinity of the ARR2 GARP DNA Binding Domain via Comparative Methods.

Plants have evolved signaling mechanisms such as the multi-step phosphorelay (MSP) to respond to different internal and external stimuli. MSP responses often result in gene transcription regulation that is modulated through transcription factors such as B-type Arabidopsis response regulator (ARR) proteins. Among these proteins, ARR2 is a key component that is expressed ubiquitously and is involved in many aspects of plant development. Although it has been noted that B-type ARRs bind to their cognate genes through a DNA-binding domain termed the GARP domain, little is known about the structure and function of this type of DNA-binding domain; thus, how ARRs bind to DNA at a structural level is still poorly understood. In order to understand how the MSP functions in planta, it is crucial to unravel both the kinetics as well as the structural identity of the components involved in such interactions. For this reason, this work focusses on resolving how the GARP domain of ARR2 (GARP2) binds to the promoter region of ARR5, one of its native target genes in cytokinin signaling. We have established that GARP2 specifically binds to the ARR5 promoter with three different bi-molecular interaction systems-qDPI-ELISA, FCS, and MST-and we also determined the KD of this interaction. In addition, structural modeling of the GARP2 domain confirms that GARP2 entails a HTH motif, and that protein-DNA interaction most likely occurs via the α3-helix and the N-terminal arm of this domain since mutations in this region hinder ARR2's ability to activate transcription.

Pyroptosis Induction and Visualization at the Single-Cell Level Using Optogenetics.

Pyroptosis has been identified as a pro-inflammatory form of programmed cell death. It can be triggered by different stimuli including pathogen invasion or cell stress/danger signals releasing hundreds of proteins upon lysis that cause complex responses in neighboring cells. Pyroptosis is executed by the gasdermin (GSDM) family of proteins which, upon cleavage by caspases, form transmembrane pores that release cytokines to induce inflammation. However, despite the importance of gasdermins in the development of inflammatory diseases and cancer, a lot is still to be understood in the downstream consequences of this cell death pathway. Currently, conventional methods, such as drug treatments or chemically forced oligomerization, are limited in the spatiotemporal analysis of pyroptosis signaling in the cellular population, since all cells are primed for undergoing pyroptosis. Here, we provide a protocol for the application of a novel optogenetics tool called NLS_PhoCl_N-GSDMD_mCherry that enables precise temporal and spatial pyroptosis induction in a confocal microscopy setup, followed by imaging of the cell death process and subsequent quantitative analysis of the experiment. This tool opens new opportunities for the study of pyroptosis activation and of its effects on the bystander cell responses.

Mechanisms of BCL-2 family proteins in mitochondrial apoptosis.

The proteins of the BCL-2 family are key regulators of mitochondrial apoptosis, acting as either promoters or inhibitors of cell death. The functional interplay and balance between the opposing BCL-2 family members control permeabilization of the outer mitochondrial membrane, leading to the release of activators of the caspase cascade into the cytosol and ultimately resulting in cell death. Despite considerable research, our knowledge about the mechanisms of the BCL-2 family of proteins remains insufficient, which complicates cell fate predictions and does not allow us to fully exploit these proteins as targets for drug discovery. Detailed understanding of the formation and molecular architecture of the apoptotic pore in the outer mitochondrial membrane remains a holy grail in the field, but new studies allow us to begin constructing a structural model of its arrangement. Recent literature has also revealed unexpected activities for several BCL-2 family members that challenge established concepts of how they regulate mitochondrial permeabilization. In this Review, we revisit the most important advances in the field and integrate them into a new structure-function-based classification of the BCL-2 family members that intends to provide a comprehensive model for BCL-2 action in apoptosis. We close this Review by discussing the potential of drugging the BCL-2 family in diseases characterized by aberrant apoptosis.

Calcium as a master regulator of ferroptosis and other types of regulated necrosis.

Regulation of proliferation and cell death is fundamental for organismal development and for restoring tissue homeostasis after biological stress. During the last years, several forms of regulated cell death have been discovered that share the loss of plasma membrane integrity as a common hallmark and that are collectively known as regulated necrosis (RN) pathways. During RN, plasma membrane damage is sensed by the cell by increases in the levels of intracellular calcium. Interestingly, cytosolic calcium influx can either lead to cell death or survival, given the versatile role of this ion in regulating multiple signaling processes. Among them, membrane repair enables the cells to tolerate the injury and, even in some conditions, survive. Here, we review calcium signaling in the context of RN pathways, with a focus on ferroptosis, a type of RN in which plasma membrane damage is elicited by the accumulation of oxidized lipids. In contrast, other forms of RN such as necroptosis and pyroptosis require dedicated pore-forming proteins for plasma membrane damage and cell death. We first focus on the current knowledge regarding the contribution of calcium to ferroptosis, and then illustrate the similarities and differences in calcium signaling with necroptosis and pyroptosis. Calcium signaling emerges as a key event in the cellular responses to membrane damage and in the regulation of cell death.

Incidence and Risk Factors for Development of Cardiac Toxicity in Adult Patients with Newly Diagnosed Acute Myeloid Leukemia.

The incidence of cardiac morbimortality in acute myeloid leukemia (AML) is not well known. We aim to estimate the cumulative incidence (CI) of cardiac events in AML patients and to identify risk factors for their occurrence. Among 571 newly diagnosed AML patients, 26 (4.6%) developed fatal cardiac events, and among 525 treated patients, 19 (3.6%) experienced fatal cardiac events (CI: 2% at 6 months; 6.7% at 9 years). Prior heart disease was associated with the development of fatal cardiac events (hazard ratio (HR) = 6.9). The CI of non-fatal cardiac events was 43.7% at 6 months and 56.9% at 9 years. Age ≥ 65 (HR = 2.2), relevant cardiac antecedents (HR = 1.4), and non-intensive chemotherapy (HR = 1.8) were associated with non-fatal cardiac events. The 9-year CI of grade 1-2 QTcF prolongation was 11.2%, grade 3 was 2.7%, and no patient had grade 4-5 events. The 9-year CI of grade 1-2 cardiac failure was 1.3%, grade 3-4 was 15%, and grade 5 was 2.1%; of grade 1-2, arrhythmia was 1.9%, grade 3-4 was 9.1%, and grade 5 was 1%. Among 285 intensive therapy patients, median overall survival decreased in those experiencing grade 3-4 cardiac events (p < 0.001). We observed a high incidence of cardiac toxicity associated with significant mortality in AML.

Intensive nurse-led follow-up in primary care to improve self-management and compliance behaviour after myocardial infarction.

AIMS AND OBJECTIVES: To assess the effects of intensive follow-up by primary care nurses on cardiovascular disease self-management and compliance behaviours after myocardial infarction. BACKGROUND: Although cardiovascular disease prevention and cardiac rehabilitation take place in hospital settings, a nurse-led approach is necessary in primary care during the first few months after a myocardial infarction. Therefore, it is important to assess self-management of cardiovascular disease and levels of compliance with the prescribed diet, physical activity, and medication. DESIGN: The study used a multicentre, quasi-experimental, pre-post design without a control group. METHODS: Patients with acute coronary syndrome from 40 healthcare facilities were included in the study. A total of 212 patients participated in a programme including 11 interventions during the first 12-18 months after myocardial infarction. The following Nursing Outcomes Classification (NOC) outcomes were assessed at baseline and at the end of the intervention: Self-management: Cardiac Disease (1617) and Compliance Behaviour: Prescribed Diet (1622), Compliance Behaviour: Prescribed Activity (1632), and Compliance Behaviour: Prescribed Medication (1623). Marjory Gordon's functional health patterns and a self-care notebook were used in each intervention. Pre-post intervention means were compared using Student's t-tests for related samples. The results of the study are reported in compliance with the TREND Statement. RESULTS: A total of 132 patients completed the intervention. The indicators for each NOC outcome and the variations in scores before and after the intensive follow-up showed a statistically significant improvement (p-value = 0.000). Compliance Behaviour: Prescribed Diet (pre = 3.7; post = 4.1); Compliance Behaviour: Prescribed Activity (pre = 3.9; post = 4.3); Compliance Behaviour: Prescribed Medication (pre = 3.9; post = 4.7). CONCLUSION: Intensive, immediate follow-up after myocardial infarction improves compliance behaviours and self-management of heart disease. A combined self-care and family care approach should be encouraged to empower post-myocardial infarction patients. To facilitate patients' self-efficacy, the use of health education tools such as a cardiovascular self-care notebook can also be helpful. RELEVANCE TO CLINICAL PRACTICE: This study highlights the benefits of intensive, protocolised, comprehensive patient follow-up in primary care during the first few months after an acute myocardial infarction (AMI). Primary care nurses train patients in cardiovascular self-care. PATIENT OR PUBLIC CONTRIBUTION: Patients were not involved in either the design or the carrying out of the study. However, at the end of the study, they participated in an evaluation process about the utility of the research study and their satisfaction with it. This process was carried out using an ad hoc survey consisting of 10 questions assessing the nursing care and follow-up inputs that were received.

Real-Time Growth Kinetics Analysis of Macromolecular Assemblies in Cells with Single Molecule Resolution.

Single molecule fluorescence microscopy has the unique advantage to provide real-time information on the spatiotemporal assembly of individual protein complexes in cellular membranes. This includes the assembly of proteins into oligomer species of numerous copy numbers. However, there is a need for improved tracing analysis of the real-time growth kinetics of these assemblies in cells with single molecule resolution. Here, we present an automated analysis software to accurately measure the real-time kinetics of assembly of individual high-order oligomer complexes. Our software comes with a simple Graphical User Interface (GUI), is available as a source code and an executable, and can analyze a full data set of several hundred to thousand molecules in less than 2 minutes. Importantly, this software is suitable for the analysis of intracellular protein oligomers, whose stoichiometry is usually more difficult to quantify due to variability in signal detection in the different areas of the cell. We validated our method with simulated ground-truth data and time-lapse images of diffraction-limited oligomeric assemblies of BAX and BAK proteins on mitochondria of cells undergoing apoptosis. Our approach provides the broad community of biologists with a fast, user-friendly tool to trace the compositional evolution of macromolecular assemblies, and potentially model their growth for a deeper understanding of the structural and biophysical mechanisms underlying their functions.

Mitochondrial pores at the crossroad between cell death and inflammatory signaling.

Mitochondria are cellular organelles with a major role in many cellular processes, including not only energy production, metabolism, and calcium homeostasis but also regulated cell death and innate immunity. Their proteobacterial origin makes them a rich source of potent immune agonists, normally hidden within the mitochondrial membrane barriers. Alteration of mitochondrial permeability through mitochondrial pores thus provides efficient mechanisms not only to communicate mitochondrial stress to the cell but also as a key event in the integration of cellular responses. In this regard, eukaryotic cells have developed diverse signaling networks that sense and respond to the release of mitochondrial components into the cytosol and play a key role in controlling cell death and inflammatory pathways. Modulating pore formation at mitochondria through direct or indirect mechanisms may thus open new opportunities for therapy. In this review, we discuss the current understanding of the structure and molecular mechanisms of mitochondrial pores and how they function at the interface between cell death and inflammatory signaling to regulate cellular outcomes.

Editor Profile: Ana García Sáez.

In this special interview series, we profile members of The FEBS Journal editorial board to highlight their research focus, perspectives on the journal and future directions in their field. Ana García-Sáez is Professor at the CECAD Research Center, Institute for Genetics, University of Cologne (Germany). She has served as an Editorial Board Member of The FEBS Journal since 2021.

Structural Insights into Polymer-Bounded Lipid Nanodiscs.

Membrane proteins are an essential part of signaling and transport processes and are targeted by multiple drugs. To isolate and investigate them in their native state, polymer-bounded nanodiscs have become valuable tools. In this study, we investigate the lipid model system dimyristoyl-phosphocholine (DMPC) with the nanodisc-forming copolymers styrene maleic acid (SMA) and diisobutylene maleic acid (DIBMA). Using small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS), we studied the influence of polymer concentration and temperature on the nanodisc structure. In Tris buffer, the size of nanodiscs formed with SMA is smaller compared to DIBMA at the same polymer ratio. In both cases, the size decreases monotonically with increasing polymer concentration, and this effect is more pronounced when using SMA. Measurements at temperatures (T) between 5 and 30 °C in phosphate buffer showed an incomplete solubilization at high T even at polymer/lipid ratios above that required for complete lipid solubilization. For DIBMA, the nanodiscs developed at lower temperatures are stable and the net repulsion increases, while for SMA, the individual nanodiscs possess smaller sizes and are less affected by T. However, using DLS, one can observe SMA agglomerates at low T. Interestingly, for both polymers, no drastic changes of the observable parameters (radius and bilayer thickness) are seen upon cooling, which would indicate a sharp (first-order) phase transition from liquid-crystalline to gel, but only gradual changes. Hence, we conclude that the transition from a gel toward a liquid-crystalline lipid phase proceeds over a broad T-range compared to a continuous lipid bilayer. These results can pave the way toward the development of better protocols for studying membrane proteins stabilized in this type of membrane mimics.

Reversible Live-Cell Labeling with Retro-engineered HaloTags Enables Long-Term High- and Super-Resolution Imaging.

Self-labeling enzymes (SLE) such as the HaloTag have emerged as powerful tools in high and super-resolution fluorescence microscopy. Newly developed fluorogenic SLE substrates enable imaging in the presence of excess dye. To exploit this feature for reversible labeling, we engineered two variants of HaloTag7 with restored dehalogenase activity. Kinetic studies in vitro showed different turnover kinetics for reHaloTagS (≈0.006 s-1 ) and reHaloTagF (≈0.055 s-1 ). Imaging by confocal and stimulated emission depletion microscopy yielded 3-5-time enhanced photostability of reHaloTag labeling. Prominently, single molecule imaging with reHaloTags enabled controlled and stable labeling density over extended time periods. By combination with structured illumination, simultaneous visualization of single molecule diffusion and organellar dynamics was achieved. These applications highlight the potential of reHaloTag labeling for pushing the limits of advanced fluorescence microscopy techniques.

CA125 como nuevo biomarcador en pacientes con circulación de Fontan / CA125: a new biomarker in patients with Fontan circulation

Introducción y objetivos Los pacientes con circulación de Fontan (CF) presentan una gran incidencia de complicaciones y ningún biomarcador estratifica el riesgo. El objetivo es analizar la asociación de biomarcadores con un perfil clínico de disfunción de la CF, incluyendo por primera vez el antígeno carbohidrato 125 (CA125), y proponer una estimación del riesgo basada en la combinación de biomarcadores. Métodos Estudio transversal de adultos con CF. Se consideró perfil clínico desfavorable el combinado de insuficiencia cardiaca, arritmias auriculares, fístulas venovenosas, enteropatía pierdeproteínas o bronquitis plástica. Se analizaron variables clínicas y analíticas, incluidos CA125, NT-proBNP, función renal y hepática y amplitud de distribución eritrocitaria (ADE). Se realizó un estudio univariado y multivariado de la relación de dichas complicaciones clínicas y curvas ROC para obtener puntos de corte. Resultados Se incluyó a 56 pacientes (media de edad, 27,4±7,8 años). El 34% tenía un perfil clínico desfavorable, con valores de CA125 significativamente mayores (30,1 frente a 12,6 UI/ml; p=0,001). LnCA125 (OR=5,1; IC95%, 1,2-22), ADE (OR=1,8; IC95%, 1,1-3.1) y FIB4 (OR=38; IC95%, 1,7-855) se asociaron con un perfil de disfunción clínica. Los puntos de corte fueron CA125 ≥ 20 U/ml, FIB4 ≥ 0,75 y ADE ≥ 14,5%, y la probabilidad de un perfil clínico desfavorable fue del 81% con 2 o más biomarcadores elevados. Conclusiones El aumento de CA125 se asocia con mayor prevalencia de complicaciones en pacientes con CF. Los valores de CA125 ≥ 20 U/ml, FIB4 ≥ 0,75 y ADE ≥ 14,5% identifican con alta probabilidad fracaso clínico de la CF. (AU)

Introduction and objectives Patients with Fontan circulation (FC) have a high incidence of clinical complications. However, no biomarker is able to accurately stratify risk. The aim of this study was to analyze the relationship between biomarkers and clinical complications, including carbohydrate antigen 125 (CA125) for the first time, and to propose a risk estimation based on a combination of biomarkers. Methods Cross-sectional study of patients with FC. The clinical endpoint was the combination of heart failure, atrial arrhythmias, veno-venous fistulae, protein-losing enteropathy, or plastic bronchitis. Demographic, clinical, and laboratory variables were analyzed, including CA125, NT-proBNP, renal and liver function, and red cell distribution width (RDW). We performed univariate and multivariate analyses of the relationship between these variables and the composite endpoint. Cutoff values were calculated by ROC curves. Results We included 56 patients (27.4±7.8 years). A total of 34% showed the composite endpoint, with significantly higher CA125 levels (30.1 IU/mL vs 12.6 IU/mL; P=.001). In the multivariate model, the biomarkers related to the endpoint were LnCA125 (OR, 5.1; 95%CI, 1.2-22), RDW (OR, 1.8; 95%CI, 1.1-3.1), and FIB4 (OR, 38, 95%CI, 1.7-855). The cutoff points were CA125 ≥ 20 U/mL, FIB4 ≥ 0.75, and RDW ≥ 14.5%, and the probability of the occurrence of the endpoint was 81% if ≥ 2 biomarkers were elevated. Conclusions CA125 elevation is associated with a higher prevalence of complications in patients with Fontan-type circulation. CA125 levels ≥ 20U/mL, FIB4 ≥ 0.75 and RDW ≥ 14.5% identify with a high probability the clinical failure of FC. (AU)