Investigating two mobile just-in-time adaptive interventions to foster psychological resilience: research protocol of the DynaM-INT study.

BACKGROUND: Stress-related disorders such as anxiety and depression are highly prevalent and cause a tremendous burden for affected individuals and society. In order to improve prevention strategies, knowledge regarding resilience mechanisms and ways to boost them is highly needed. In the Dynamic Modelling of Resilience - interventional multicenter study (DynaM-INT), we will conduct a large-scale feasibility and preliminary efficacy test for two mobile- and wearable-based just-in-time adaptive interventions (JITAIs), designed to target putative resilience mechanisms. Deep participant phenotyping at baseline serves to identify individual predictors for intervention success in terms of target engagement and stress resilience. METHODS: DynaM-INT aims to recruit N = 250 healthy but vulnerable young adults in the transition phase between adolescence and adulthood (18-27 years) across five research sites (Berlin, Mainz, Nijmegen, Tel Aviv, and Warsaw). Participants are included if they report at least three negative burdensome past life events and show increased levels of internalizing symptoms while not being affected by any major mental disorder. Participants are characterized in a multimodal baseline phase, which includes neuropsychological tests, neuroimaging, bio-samples, sociodemographic and psychological questionnaires, a video-recorded interview, as well as ecological momentary assessments (EMA) and ecological physiological assessments (EPA). Subsequently, participants are randomly assigned to one of two ecological momentary interventions (EMIs), targeting either positive cognitive reappraisal or reward sensitivity. During the following intervention phase, participants' stress responses are tracked using EMA and EPA, and JITAIs are triggered if an individually calibrated stress threshold is crossed. In a three-month-long follow-up phase, parts of the baseline characterization phase are repeated. Throughout the entire study, stressor exposure and mental health are regularly monitored to calculate stressor reactivity as a proxy for outcome resilience. The online monitoring questionnaires and the repetition of the baseline questionnaires also serve to assess target engagement. DISCUSSION: The DynaM-INT study intends to advance the field of resilience research by feasibility-testing two new mechanistically targeted JITAIs that aim at increasing individual stress resilience and identifying predictors for successful intervention response. Determining these predictors is an important step toward future randomized controlled trials to establish the efficacy of these interventions.

Semi-quantitative assessment of ischemia with rubidium-82 PET myocardial perfusion imaging.

PURPOSE: Semi-quantitative scores can be used as an adjunct to visual assessment in rubidium-82 positron emission tomography (82Rb PET). The semi-quantitative cut-off values used in 82Rb PET are derived from single-photon emission computed tomography (SPECT). It is unknown whether these cut-off values can be extrapolated to 82Rb PET. We compared the semi-quantitative with the visual assessment of ischemia and determined which summed difference score (SDS) score predicts ischemia best. METHODS: We included 108 patients who underwent 82Rb PET imaging and performed visual and semi-quantitative assessment. A scan with a SDS ≥ 2 and a summed stress score (SSS) ≥ 4 was considered to demonstrate ischemia. We compared the semi-quantitative with the visual assessment. RESULTS: 41 (38%) Normal scans, and 67 (62%) scans with ischemia and/or an irreversible defect were included. The semi-quantitative assessment showed ischemia more often than the visual assessment (51% vs 29%, P < .001). Patients with a low or intermediate pre-test probability of coronary artery disease (CAD) and a SDS < 4 did not demonstrate ischemia by visual assessment. CONCLUSION: Semi-quantitative assessment in 82Rb PET imaging clearly demonstrates the presence of ischemia. Ischemia is unlikely in patients with low and intermediate pre-test probability of CAD and a SDS < 4.

Value of SiPM PET in myocardial perfusion imaging using Rubidium-82.

BACKGROUND: PET scanners using silicon photomultipliers with digital readout (SiPM PET) have an improved temporal and spatial resolution compared to PET scanners using conventional photomultiplier tubes (PMT PET). However, the effect on image quality and visibility of perfusion defects in myocardial perfusion imaging (MPI) is unknown. Our aim was to determine the value of a SiPM PET scanner in MPI. METHODS: We prospectively included 30 patients who underwent rest and regadenoson-induced stress Rubidium-82 (Rb-82) MPI on the D690 PMT PET (GE Healthcare) and within three weeks on the Vereos SiPM PET (Philips Healthcare). Two expert readers scored the image quality and assessed the existence of possible defects. In addition, interpreter's confidence, myocardial blood flow (MBF), and myocardial flow reserve (MFR) values were compared. RESULTS: Image quality improved (P = 0.03) using the Vereos as compared to the D690. Image quality of the Vereos and the D690 was graded fair in 20% and 10%, good in 60% and 50%, and excellent in 20% and 40%, respectively. Defect interpretation and interpreter's confidence did not differ between the D690 and the Vereos (P > 0.50). There were no significant differences in rest MBF (P ≥ 0.29), stress MBF (P ≥ 0.11), and MFR (P ≥ 0.51). CONCLUSION: SiPM PET provides an improved image quality in comparison with PMT PET. Defect interpretation, interpreter's confidence, and absolute blood flow measurements were comparable between both systems. SiPM PET is therefore a reliable technique for MPI using Rb-82. TRIAL REGISTRATION: ToetsingOnline NL63853.075.17. Registered 13 November, 2017.

The impact and challenges of implementing CTCA according to the 2019 ESC guidelines on chronic coronary syndromes: a survey and projection of CTCA services in the Netherlands.

BACKGROUND: The 2019 ESC-guidelines on chronic coronary syndromes (ESC-CCS) recommend computed tomographic coronary angiography (CTCA) or non-invasive functional imaging instead of exercise ECG as initial test to diagnose obstructive coronary artery disease. Since impact and challenges of these guidelines are unknown, we studied the current utilisation of CTCA-services, status of CTCA-protocols and modeled the expected impact of these guidelines in the Netherlands. METHODS AND RESULTS: A survey on current practice and CTCA utilisation was disseminated to every Dutch hospital organisation providing outpatient cardiology care and modeled the required CTCA capacity for implementation of the ESC guideline, based on these national figures and expert consensus. Survey response rate was 100% (68/68 hospital organisations). In 2019, 63 hospital organisations provided CTCA-services (93%), CTCA was performed on 99 CTCA-capable CT-scanners, and 37,283 CTCA-examinations were performed. Between the hospital organisations, we found substantial variation considering CTCA indications, CTCA equipment and acquisition and reporting standards. To fully implement the new ESC guideline, our model suggests that 70,000 additional CTCA-examinations would have to be performed in the Netherlands. CONCLUSIONS: Despite high national CTCA-services coverage in the Netherlands, a substantial increase in CTCA capacity is expected to be able to implement the 2019 ESC-CCS recommendations on the use of CTCA. Furthermore, the results of this survey highlight the importance to address variations in image acquisition and to standardise the interpretation and reporting of CTCA, as well as to establish interdisciplinary collaboration and organisational alignment.

Expression ratio of the TGFß-inducible gene MYO10 is prognostic for overall survival of squamous cell lung cancer patients and predicts chemotherapy response.

In lung cancer a deregulation of Transforming Growth Factor-ß (TGFß) signaling has been observed. Yet, the impact of TGFß in squamous cell carcinoma of the lung (LUSC) remained to be determined. We combined phenotypic and transcriptome-wide studies and showed that the stimulation of the LUSC cell line SK-MES1 with TGFß results in an increase of migratory invasive properties. The analysis of the dynamics of gene expression by next-generation sequencing revealed that TGFß stimulation orchestrates the upregulation of numerous motility- and actin cytoskeleton-related genes. Among these the non-muscle myosin 10 (MYO10) showed the highest upregulation in a LUSC patient cohort of the Cancer Genome Atlas (TCGA). Knockdown of MYO10 abrogated TGFß-induced collagen gel invasion of SK-MES1 cells. The analysis of MYO10 mRNA expression in paired tissues of 151 LUSC patients with corresponding 80-month clinical follow-up data showed that the mRNA expression ratio of MYO10 in tumor and tumor-free tissue is prognostic for overall survival of LUSC patients and predictive for the response of these patients to adjuvant chemotherapy. Thus, MYO10 represents a new clinical biomarker for this aggressive disease and due to its role in cellular motility and invasion could serve as a potential molecular target for therapeutic interventions in patients with LUSC.

Predictors of severe stenosis at invasive coronary angiography in patients with normal myocardial perfusion imaging.

PURPOSE: Normal myocardial perfusion imaging (MPI) is associated with excellent prognosis. However, in patients with persisting symptoms, it may be difficult to determine the patients in whom invasive angiography is justified to rule out false negative MPI. We evaluated predictors for severe stenosis at invasive angiography in patients with persisting symptoms after normal MPI. METHODS: 229 consecutive patients with normal MPI, without previous bypass surgery, underwent invasive angiography within 6 months. Older age was defined as >65 years. Multivariable analyses were performed to adjust for differences in baseline variables. RESULTS: Mean age was 62 ± 11 years, 48% were women. Severe stenosis was observed in 34%, and of these patients 60% had single-vessel disease (not left main coronary artery disease). After adjusting for several variables, including diabetes, smoking status, hypertension and hypercholesterolaemia, predictors of severe stenosis were male gender, odds ratio (OR) 2.7 (95% confidence interval (CI) 1.5-4.9), older age, OR 1.9 (95% CI 1.02-3.54) previous PCI, OR 2.0 (95% CI 1.0-4.3) and typical angina, OR 2.5 (95% CI 1.4-4.6). CONCLUSIONS: Increasing age, male gender, previous PCI and typical symptoms are predictors of severe stenosis at invasive coronary angiography in patients with normal MPI. The majority of these patients have single-vessel disease.

Partial break in tolerance of NKG2A-/LIR-1- single KIR+ NK cells early in the course of HLA-matched, KIR-mismatched hematopoietic cell transplantation.

Natural killer (NK) cell subpopulations from 8 HLA-matched but killer cell immunoglobulin-like receptor (KIR)/HLA-ligand-mismatched patient-donor pairs were analyzed in the course of allogeneic hematopoietic stem cell transplantation (HCT). The patients' post-transplantation NKG2A-/LIR-1- NK cells, which expressed only inhibitory KIRs for which the patient had no HLA class I ligands, showed higher cytotoxic capacity than the NKG2A-/LIR-1- NK cells lacking any inhibitory KIRs that remained tolerant throughout the course of HCT. The NKG2A+ NK cell subpopulations displayed the highest levels of cytotoxic activation, which appeared to be significantly enhanced in comparison with that in allogeneic graft's donors. LIR-1- NK cells were much more frequent after HCT than LIR-1+ NK cells and LIR-1 expression on NKG2A+ or NKG2A- NK cells was associated with significantly lower cytotoxic activities. Thus NKG2A-/LIR-1- NK cells expressing only HLA-mismatched KIRs show a partial break in tolerance in the first year following HCT. The failure to exclude LIR-1+ cells within the NKG2A- NK cell subset in previous studies could explain the earlier conflicting results. Thus systemic immune activation in patients following HCT augments the GvL effect through both increasing overall NK cell activities and partially breaking tolerance of unlicensed NK cells.

MRSA Infections in HIV-Infected People Are Associated with Decreased MRSA-Specific Th1 Immunity.

People with HIV infection are at increased risk for community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections (SSTIs). Lower CD4 T-cell counts, higher peak HIV RNA levels and epidemiological factors may be associated with increased risk but no specific immune defect has been identified. We aimed to determine the immunologic perturbations that predispose HIV-infected people to MRSA SSTIs. Participants with or without HIV infection and with MRSA SSTI, MRSA colonization or negative for MRSA were enrolled. Peripheral blood and skin biopsies from study participants were collected. Flow cytometry, flow cytometry with microscopy, multiplex assays of cell culture supernatants and immunohistochemistry were used to evaluate the nature of the immune defect predisposing HIV-infected people to MRSA infections. We found deficient MRSA-specific IFNγ+ CD4 T-cell responses in HIV-infected people with MRSA SSTIs compared to MRSA-colonized participants and HIV-uninfected participants with MRSA SSTIs. These IFNγ+ CD4 T cells were less polyfunctional in HIV-infected participants with SSTIs compared to those without SSTIs. However, IFNγ responses to cytomegalovirus and Mycobacterium avium antigens and MRSA-specific IL-17 responses by CD4 T cells were intact. Upon stimulation with MRSA, peripheral blood mononuclear cells from HIV-infected participants produced less IL-12 and IL-15, key drivers of IFNγ production. There were no defects in CD8 T-cell responses, monocyte responses, opsonization, or phagocytosis of Staphylococcus aureus. Accumulation of CD3 T cells, CD4 T cells, IL-17+ cells, myeloperoxidase+ neutrophils and macrophage/myeloid cells to the skin lesions were similar between HIV-infected and HIV-uninfected participants based on immunohistochemistry. Together, these results indicate that MRSA-specific IFNγ+ CD4 T-cell responses are essential for the control of initial and recurrent MRSA infections in HIV-infected people.

Visual estimation of coronary calcium on computed tomography for attenuation correction.

BACKGROUND: The coronary calcium score (CCS) provides independent diagnostic and prognostic information on top of myocardial perfusion imaging (MPI) in patients suspected for coronary artery disease, but requires an additional computed tomography (CT) scan. OBJECTIVE: We investigated the accuracy and inter-reader reproducibility of visual estimation of the CCS on the CT used for attenuation correction. METHODS: 250 patients undergoing single photon emission computed tomography MPI and Agatston CCS were included. The CCS was also visually estimated on the CT for attenuation correction by two separate readers blinded to the Agatston CCS, and was categorized into a six-point scale (0, 1-10, 11-100, 101-400, 401-1000 and > 1000). RESULTS: The median Agatston CCS was 82 [25th-75th percentile: 0-562], with a range from 0 to 7287. Of the visually estimated CCS, 60% (reader 1) and 65% (reader 2) were classified correctly into the 6 categories. 93% (reader 1) and 88% (reader 2) of the visually estimated CCS did not vary by more than one category from the Agatston CCS. The intraclass correlation coefficient for agreement between the Agatston CCS and the visually estimated CCS was 0.95 for reader 1 and 0.94 for reader 2. The intraclass correlation coefficient for inter-reader reproducibility of the visually estimated CCS was 0.96. CONCLUSION: The CCS can be accurately estimated on the CT for attenuation correction, as high agreement is demonstrated with the Agatston CCS and inter-reader reproducibility is excellent. If no traditional Agatston CCS is performed, the degree of atherosclerosis should be assessed by means of estimating CCS on the CT for attenuation correction.

Timing of intervention in high-risk non-ST-elevation acute coronary syndromes in PCI versus non-PCI centres : Sub-group analysis of the ELISA-3 trial.

AIMS: To compare the effect of timing of intervention in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) in percutaneous coronary intervention (PCI) versus non-PCI centres. METHODS AND RESULTS: A post-hoc sub-analysis was performed of the ELISA III trial, a randomised multicentre trial investigating outcome of early (< 12 h) versus late (> 48 h) angiography and revascularisation in 542 patients with high-risk NSTE-ACS. 90 patients were randomised in non-PCI centres and tended to benefit more from an early invasive strategy than patients included in the PCI centre (relative risk 0.23 vs. 0.85 [p for interaction = 0.089] for incidence of the combined primary endpoint of death, reinfarction and recurrent ischaemia after 30 days of follow-up). This was largely driven by reduction in recurrent ischaemia. In non-PCI centres, patients randomised to the late group had a 4 and 7 day longer period until PCI or coronary artery bypass grafting, respectively. This difference was less pronounced in the PCI centre. CONCLUSIONS: This post-hoc analysis from the ELISA-3 trial suggests that NSTE-ACS patients initially hospitalised in non-PCI centres show the largest benefit from early angiography and revascularisation, associated with a shorter waiting time to revascularisation. Improved patient logistics and transfer between non-PCI and PCI centres might therefore result in better clinical outcome.

Data2Dynamics: a modeling environment tailored to parameter estimation in dynamical systems.

UNLABELLED: Modeling of dynamical systems using ordinary differential equations is a popular approach in the field of systems biology. Two of the most critical steps in this approach are to construct dynamical models of biochemical reaction networks for large datasets and complex experimental conditions and to perform efficient and reliable parameter estimation for model fitting. We present a modeling environment for MATLAB that pioneers these challenges. The numerically expensive parts of the calculations such as the solving of the differential equations and of the associated sensitivity system are parallelized and automatically compiled into efficient C code. A variety of parameter estimation algorithms as well as frequentist and Bayesian methods for uncertainty analysis have been implemented and used on a range of applications that lead to publications. AVAILABILITY AND IMPLEMENTATION: The Data2Dynamics modeling environment is MATLAB based, open source and freely available at http://www.data2dynamics.org. CONTACT: andreas.raue@fdm.uni-freiburg.de SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Zero coronary calcium in the presence of three-vessel and left main coronary artery disease in a Hodgkin lymphoma survivor.

We describe a 45-year-old male survivor of Hodgkin lymphoma, treated with mediastinal radiation therapy, referred for single-photon emission computed tomography (SPECT) myocardial perfusion imaging in combination with coronary artery calcium (CAC) scoring. SPECT demonstrated a reversible moderate-sized lateral perfusion defect, and the CAC score was zero. A calcium score of zero markedly reduces the probability of having coronary artery disease (CAD) and is associated with a very low risk of future cardiovascular events. However, a CAC score of zero does not completely rule out obstructive CAD. In this case, invasive coronary angiography revealed three-vessel CAD with left main involvement. Whether mediastinal radiation therapy in general is associated with CAD without accompanying CAC is yet unclear.

The Interplay Between Host Genetic Variation, Viral Replication, and Microbial Translocation in Untreated HIV-Infected Individuals.

Systemic immune activation, a major determinant of human immunodeficiency virus (HIV) disease progression, is the result of a complex interplay between viral replication, dysregulation of the immune system, and microbial translocation due to gut mucosal damage. Although human genetic variants influencing HIV load have been identified, it is unknown how much the host genetic background contributes to interindividual differences in other determinants of HIV pathogenesis such as gut damage and microbial translocation. Using samples and data from 717 untreated participants in the Swiss HIV Cohort Study and a genome-wide association study design, we searched for human genetic determinants of plasma levels of intestinal fatty acid-binding protein (I-FABP/FABP2), a marker of gut damage, and of soluble CD14 (sCD14), a marker of lipopolysaccharide bioactivity and microbial translocation. We also assessed the correlations between HIV load, sCD14, and I-FABP. Although we found no genome-wide significant determinant of the tested plasma markers, we observed strong associations between sCD14 and both HIV load and I-FABP, shedding new light on the relationships between processes that drive progression of untreated HIV infection.

El regadenosón como nuevo agente de estrés para la adquisición de imágenes SPECT de perfusión miocárdica. Experiencia inicial en Holanda / Regadenoson as a new stress agent in myocardial perfusion imaging. Initial experience in The Netherlands

Objetivo. El regadenosón es un agonista selectivo para los receptores adenosínicos-2A recién aprobado para inducir estrés farmacológico con una sola inyección en bolo para la adquisición de imágenes SPECT de perfusión miocárdica (IPM). Material y Métodos. Se incluyeron 123 pacientes sucesivos referidos para IPM por sospecha de enfermedad arterial coronaria (EAC). A 66 pacientes se les hizo una prueba de estrés con regadenosón y a 57 con adenosina, ambas seguidas por SPECT de manera estándar. A los técnicos, médicos y los pacientes mismos se les pidió que reportaran sus experiencias mediante cuestionarios. Resultados. En comparación con la adenosina, el regadenosón no produjo ningún bloqueo auriculoventricular (frente al 10% tras adenosina), pero produjo una taquicardia menor y cambios de la presión arterial pequeños. Todos los síntomas tras el regadenosón fueron más leves y de duración más corta. Hubo menos pacientes que tenían síntomas graves tras el regadenosón (17% vs. 32%, p < 0,01). El efecto secundario reportado más frecuentemente fue la disnea, seguido por rubefacción y angina, pero todos estos efectos se resolvieron rápidamente. La puntuación global de los síntomas, que incluye tanto la severidad como la duración, fue significativamente más baja después del regadenosón que después de la adenosina (6,7 ± 6,3 vs. 10,0 ± 7,9, respectivamente, p < 0,01). Las imágenes SPECT fueron similares. El procedimiento con el regadenosón fue más rápido y práctico. Conclusión. El regadenosón es un nuevo agente de estrés conveniente para IPM con un perfil muy favorable para los pacientes y los departamentos de cardiología nuclear (AU)

Objective. Regadenoson is a recently approved selective adenosine-2A receptor agonist to induce pharmacological stress in myocardial perfusion imaging (MPI) procedures using a single bolus injection. Material and Methods. We included 123 patients referred for MPI because of suspected coronary arterial disease (CAD). Of these, 66 patients underwent a regadenoson stress test and 57 patients underwent an adenosine stress test preceding standard myocardial SPECT imaging. Technicians, physicians and patients were asked to report their experience using questionnaires. Results. As compared to adenosine, regadenoson did not produce any atrio-ventricular block (0 vs. 10% with adenosine), but did produce minor tachycardia and minimal blood pressure changes while all other side effects were milder and shorter. There were fewer patients with severe complaints after taking regadenoson than adenosine (17% vs. 32%, respectively, p < 0.01). The most frequent complaint reported was dyspnea, followed by flushing and chest pain. However, when they did occur, they usually disappeared rapidly. The overall symptom score, including severity and duration of side effects, was significantly lower after regadenoson than after adenosine (6.7 ± 6.3 vs. 10.0 ± 7.9, respectively; p < 0.01.) SPECT imaging results were similar. The regadenoson procedure was faster and more practical. Conclusion. Regadenoson, the new selective adenosine-2A receptor agonist, is a stress agent for MPI with a patient- and department friendly profile (AU)

Type I interferon responses in rhesus macaques prevent SIV infection and slow disease progression.

Inflammation in HIV infection is predictive of non-AIDS morbidity and death, higher set point plasma virus load and virus acquisition; thus, therapeutic agents are in development to reduce its causes and consequences. However, inflammation may simultaneously confer both detrimental and beneficial effects. This dichotomy is particularly applicable to type I interferons (IFN-I) which, while contributing to innate control of infection, also provide target cells for the virus during acute infection, impair CD4 T-cell recovery, and are associated with disease progression. Here we manipulated IFN-I signalling in rhesus macaques (Macaca mulatta) during simian immunodeficiency virus (SIV) transmission and acute infection with two complementary in vivo interventions. We show that blockade of the IFN-I receptor caused reduced antiviral gene expression, increased SIV reservoir size and accelerated CD4 T-cell depletion with progression to AIDS despite decreased T-cell activation. In contrast, IFN-α2a administration initially upregulated expression of antiviral genes and prevented systemic infection. However, continued IFN-α2a treatment induced IFN-I desensitization and decreased antiviral gene expression, enabling infection with increased SIV reservoir size and accelerated CD4 T-cell loss. Thus, the timing of IFN-induced innate responses in acute SIV infection profoundly affects overall disease course and outweighs the detrimental consequences of increased immune activation. Yet, the clinical consequences of manipulation of IFN signalling are difficult to predict in vivo and therapeutic interventions in human studies should be approached with caution.

[Regadenoson as a new stress agent in myocardial perfusion imaging. Initial experience in The Netherlands]. / El regadenosón como nuevo agente de estrés para la adquisición de imágenes SPECT de perfusión miocárdica. Experiencia inicial en Holanda.

OBJECTIVE: Regadenoson is a recently approved selective adenosine-2A receptor agonist to induce pharmacological stress in myocardial perfusion imaging (MPI) procedures using a single bolus injection. MATERIAL AND METHODS: We included 123 patients referred for MPI because of suspected coronary arterial disease (CAD). Of these, 66 patients underwent a regadenoson stress test and 57 patients underwent an adenosine stress test preceding standard myocardial SPECT imaging. Technicians, physicians and patients were asked to report their experience using questionnaires. RESULTS: As compared to adenosine, regadenoson did not produce any atrio-ventricular block (0 vs. 10% with adenosine), but did produce minor tachycardia and minimal blood pressure changes while all other side effects were milder and shorter. There were fewer patients with severe complaints after taking regadenoson than adenosine (17% vs. 32%, respectively, p<0.01). The most frequent complaint reported was dyspnea, followed by flushing and chest pain. However, when they did occur, they usually disappeared rapidly. The overall symptom score, including severity and duration of side effects, was significantly lower after regadenoson than after adenosine (6.7±6.3 vs. 10.0±7.9, respectively; p<0.01.) SPECT imaging results were similar. The regadenoson procedure was faster and more practical. CONCLUSION: Regadenoson, the new selective adenosine-2A receptor agonist, is a stress agent for MPI with a patient- and department friendly profile.

[Differential diagnosis of myeloproliferative neoplasms. Quantitative NF-E2 immunohistochemistry for differentiating between essential thrombocythemia and primary myelofibrosis]. / Differenzialdiagnose myelproliferativer Neoplasien. Quantitative NF-E2-Immunhistochemie zur Unterscheidung zwischen essenzieller Thrombozythämie und primärer Myelofibrose.

BACKGROUND: Besides essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF) the myeloproliferative neoplasms (MPN) defined by the World Health Organization (WHO) comprise the entity of unclassifiable MPNs (MPN, U). The exact differential diagnosis of the specific MPN entities can be challenging particularly at early stages of the diseases. So far, pathologists have had to rely only on histomorphological evaluation of bone marrow biopsies in combination with laboratory data because helpful ancillary tests are not yet available. Even molecular tests, such as JAK2 mutation analysis are not helpful particularly in the differential diagnosis of ET and PMF because both entities are associated with the V617F mutation in 50 % of the cases. Recently overexpression of the transcription factor NF-E2 in MPN was described. MATERIALS AND METHODS: A collective of samples consisting of 163 bone marrow biopsies including 139 MPN cases was stained immunohistochemically for NF-E2 and analyzed regarding the subcellular localization of NF-E2 in erythroid progenitor cells. The results were compared between the MPN entities as well as the controls and statistical analyses were conducted. RESULTS AND DISCUSSION: This study showed that NF-E2 immunohistochemistry and analysis of the proportion of nuclear positive erythroblasts of all erythroid precursor cells can help to distinguish between ET and PMF even in early stages of the diseases. An MPN, U case showing a proportion of more than 20 % nuclear positive erythroblasts can be classified as a PMF with 92 % accuracy.

High-dimensional Bayesian parameter estimation: case study for a model of JAK2/STAT5 signaling.

In this work we present results of a detailed Bayesian parameter estimation for an analysis of ordinary differential equation models. These depend on many unknown parameters that have to be inferred from experimental data. The statistical inference in a high-dimensional parameter space is however conceptually and computationally challenging. To ensure rigorous assessment of model and prediction uncertainties we take advantage of both a profile posterior approach and Markov chain Monte Carlo sampling. We analyzed a dynamical model of the JAK2/STAT5 signal transduction pathway that contains more than one hundred parameters. Using the profile posterior we found that the corresponding posterior distribution is bimodal. To guarantee efficient mixing in the presence of multimodal posterior distributions we applied a multi-chain sampling approach. The Bayesian parameter estimation enables the assessment of prediction uncertainties and the design of additional experiments that enhance the explanatory power of the model. This study represents a proof of principle that detailed statistical analysis for quantitative dynamical modeling used in systems biology is feasible also in high-dimensional parameter spaces.

Influence of cell-to-cell variability on spatial pattern formation.

Many spatial patterns in biology arise through differentiation of selected cells within a tissue, which is regulated by a genetic network. This is specified by its structure, parameterisation and the noise on its components and reactions. The latter, in particular, is not well examined because it is rather difficult to trace. The authors use suitable local mathematical measures based on the Voronoi diagram of experimentally determined positions of epidermal plant hairs (trichomes) to examine the variability or noise in pattern formation. Although trichome initiation is a highly regulated process, the authors show that the experimentally observed trichome pattern is substantially disturbed by cell-to-cell variations. Using computer simulations, they find that the rates concerning the availability of the protein complex that triggers trichome formation plays a significant role in noise-induced variations of the pattern. The focus on the effects of cell noise yields further insights into pattern formation of trichomes. The authors expect that similar strategies can contribute to the understanding of other differentiation processes by elucidating the role of naturally occurring fluctuations in the concentration of cellular components or their properties.

Comprehensive estimation of input signals and dynamics in biochemical reaction networks.

MOTIVATION: Cellular information processing can be described mathematically using differential equations. Often, external stimulation of cells by compounds such as drugs or hormones leading to activation has to be considered. Mathematically, the stimulus is represented by a time-dependent input function. Parameters such as rate constants of the molecular interactions are often unknown and need to be estimated from experimental data, e.g. by maximum likelihood estimation. For this purpose, the input function has to be defined for all times of the integration interval. This is usually achieved by approximating the input by interpolation or smoothing of the measured data. This procedure is suboptimal since the input uncertainties are not considered in the estimation process which often leads to overoptimistic confidence intervals of the inferred parameters and the model dynamics. RESULTS: This article presents a new approach which includes the input estimation into the estimation process of the dynamical model parameters by minimizing an objective function containing all parameters simultaneously. We applied this comprehensive approach to an illustrative model with simulated data and compared it to alternative methods. Statistical analyses revealed that our method improves the prediction of the model dynamics and the confidence intervals leading to a proper coverage of the confidence intervals of the dynamic parameters. The method was applied to the JAK-STAT signaling pathway. AVAILABILITY: MATLAB code is available on the authors' website http://www.fdmold.uni-freiburg.de/~schelker/. CONTACT: max.schelker@fdm.uni-freiburg.de SUPPLEMENTARY INFORMATION: Additional information is available at Bioinformatics Online.