Next-generation reference intervals for pediatric hematology

Background Interpreting hematology analytes in children is challenging due to the extensive changes in hematopoiesis that accompany physiological development and lead to pronounced sex- and age-specific dynamics. Continuous percentile charts from birth to adulthood allow accurate consideration of these dynamics. However, the ethical and practical challenges unique to pediatric reference intervals have restricted the creation of such percentile charts, and limitations in current approaches to laboratory test result displays restrict their use when guiding clinical decisions. Methods We employed an improved data-driven approach to create percentile charts from laboratory data collected during patient care in 10 German centers (9,576,910 samples from 358,292 patients, 412,905-1,278,987 samples per analyte). We demonstrate visualization of hematology test results using percentile charts and z-scores (www.pedref.org/hematology) and assess the potential of percentiles and z-scores to support diagnosis of different hematological diseases. Results We created percentile charts for hemoglobin, hematocrit, red cell indices, red cell count, red cell distribution width, white cell count and platelet count in girls and boys from birth to 18 years of age. Comparison of pediatricians evaluating complex clinical scenarios using percentile charts versus conventional/tabular representations shows that percentile charts can enhance physician assessment in selected example cases. Age-specific percentiles and z-scores, compared with absolute test results, improve the identification of children with blood count abnormalities and the discrimination between different hematological diseases. Conclusions The provided reference intervals enable precise assessment of pediatric hematology test results. Representation of test results using percentiles and z-scores facilitates their interpretation and demonstrates the potential of digital approaches to improve clinical decision-making.

Parkinsonian rest tremor can be detected accurately based on neuronal oscillations recorded from the subthalamic nucleus

OBJECTIVE

To investigate the possibility of tremor detection based on deep brain activity.

METHODS

We re-analyzed recordings of local field potentials (LFPs) from the subthalamic nucleus in 10 PD patients (12 body sides) with spontaneously fluctuating rest tremor. Power in several frequency bands was estimated and used as input to Hidden Markov Models (HMMs) which classified short data segments as either tremor-free rest or rest tremor. HMMs were compared to direct threshold application to individual power features.

RESULTS

Applying a threshold directly to band-limited power was insufficient for tremor detection (mean area under the curve [AUC] of receiver operating characteristic: 0.64, STD: 0.19). Multi-feature HMMs, in contrast, allowed for accurate detection (mean AUC: 0.82, STD: 0.15), using four power features obtained from a single contact pair. Within-patient training yielded better accuracy than across-patient training (0.84vs. 0.78, p=0.03), yet tremor could often be detected accurately with either approach. High frequency oscillations (>200Hz) were the best performing individual feature.

CONCLUSIONS

LFP-based markers of tremor are robust enough to allow for accurate tremor detection in short data segments, provided that appropriate statistical models are used.

SIGNIFICANCE

LFP-based markers of tremor could be useful control signals for closed-loop deep brain stimulation.

Evaluation of an Interactive Visualization Tool for the Interpretation of Pediatric Laboratory Test Results

The physiological age-related development of pediatric laboratory results interferes with pathological derangements, which can complicate the interpretation of test results. Recently proposed continuous reference intervals (RIs) promise to be beneficial, although their clinical use may depend on graphical presentations. To estimate the clinical utility of continuous RIs, we developed and evaluated an interactive visualization tool, and examined the differentiation of hemoglobinopathies that is attainable based on the underlying innovative RI model. The implemented web application allows users to easily enter laboratory test results, and displays various visualizations in conjunction with the corresponding RIs, such as charts and personalized Z-scores. To evaluate the usability of the visualization tool, we conducted concurrent think-aloud sessions with four physicians, who were prompted to solve a set of typical interpretation tasks, and acquired additional information through a questionnaire including the System Usability Scale (SUS). We used 85 de-identified clinical cases for an exemplified assessment of how well model-based interpretations of blood count parameters reproduced previously diagnosed hemoglobinopathies. Usability tests as well as questionnaire responses indicated that the developed tool was well received by the physicians. Results from the think-aloud evaluation revealed only minor problems and the tool reached an average SUS score of 86.9, suggesting good usability. Hemoglobinopathy discrimination depended on the considered subtype, although the overall performance of the novel method rivaled the one of the conventional approach. The interactive visualization of innovative continuous reference intervals demonstrated promising results, which justifies further testing on the path towards clinical routine.

High-mobility ZnO nanorod field-effect transistors by self-alignment and electrolyte-gating

High mobility, solution-processed field-effect transistors are important building blocks for flexible electronics. Here we demonstrate the alignment of semiconducting, colloidal ZnO nanorods by a simple solvent evaporation technique and achieve high electron mobilities in field-effect transistors at low operating voltages by electrolyte-gating with ionic liquids. The degree of alignment varies with nanorod length, concentration and solvent evaporation rate. We find a strong dependence of electron mobility on the degree of alignment but less on the length of the nanorods. Maximum field-effect mobilities reach up to 9 cm(2) V(-1) s(-1) for optimal alignment. Because of the low process temperature (150 °C), ZnO nanorod thin films are suitable for application on flexible polymer substrates.

Differential modulation of STN-cortical and cortico-muscular coherence by movement and levodopa in Parkinson's disease

Previous research suggests that oscillatory coupling between cortex, basal ganglia and muscles plays an important role in motor behavior. Furthermore, there is evidence that oscillatory coupling is altered in patients with movement disorders such as Parkinson's disease (PD). In this study, we performed simultaneous magnetoencephalography (MEG), local field potential (LFP) and electromyogram (EMG) recordings in PD patients selected for therapeutic subthalamic nucleus (STN) stimulation. Patients were recorded (i) after withdrawal of anti-parkinsonian medication (OFF) and (ii) after levodopa administration (ON). We analyzed STN-cortical and cortico-muscular coherence during static forearm contraction and repetitive hand movement in order to evaluate modulations of coherence by movement and medication. Based on previous results from studies investigating resting state coherence in PD patients, we selected primary motor cortex (M1) and superior temporal gyrus (STG) as regions of interest. We found beta coherence between M1 and STN to be suppressed by administration of levodopa. M1-muscular coherence was strongly reduced in the alpha and beta band during repetitive movement compared to static contraction, but was unaffected by administration of levodopa. Strong STG-STN but not STG-muscular coherence could be observed in the alpha band. Coherence with STG was modulated neither by movement nor by medication. Finally, we found both M1-STN and M1-muscular beta coherence to be negatively correlated with UPDRS akinesia and rigidity sub-scores in the OFF state. The present study provides new insights into the functional roles of STN-cortical and cortico-muscular coherence and their relationship to PD symptoms. The results indicate that STN-cortical and cortico-muscular coupling are correlated, but can be modulated independently. Moreover, they show differences in their frequency-specific topography. We conclude that they represent partly independent sub-loops within the motor system. Given their negative correlation with akinesia, neither can be considered "antikinetic".

Impact of oxygen plasma treatment on the device performance of zinc oxide nanoparticle-based thin-film transistors

Thin-films of zinc oxide nanoparticles were investigated by photoluminescence spectroscopy and a broad defect-related yellow-green emission was observed. Oxygen plasma treatment was applied in order to reduce the number of defects, and the emission intensity was quenched to 4% of the initial value. Thin-film transistors that incorporate the nanoparticles as active semiconducting layers show an improved device performance after oxygen plasma treatment. The maximum drain current and the charge carrier mobility increased more than 1 order of magnitude up to a nominal value of 23 cm(2) V(-1) s(-1) and the threshold voltage was lowered.

Concept of a thin film memory transistor based on ZnO nanoparticles insulated by a ligand shell

In this work, we report on the synthesis and the electrical properties of ZnO nanoparticles, which differ in their organic shell. The introduction of a 2-ethylhexanoate shell instead of a common acetate shell has an impact on the accessible size of the ZnO nanoparticles and changes the electrical properties of thin films in transistors. While acetate covered ZnO particles behave as a semiconductor with an electron mobility of 0.38 cm(2) V(-1) s(-1), the 2-ethylhexanoate ligand shell inhibits a charge transport resulting in insulating films (with an average ε(r) = 9.4). These films can be reconverted to semiconductive layers by removing the ligand shell with oxygen plasma treatment or they can be used as a solution processed dielectric layer in organic transistors. Its use as dielectric allows low voltage device operation and shows potential application as a charge storage layer as needed in non-volatile memory transistors.

Cationic proteins inhibit L-arginine uptake in rat alveolar macrophages and tracheal epithelial cells. Implications for nitric oxide synthesis

Eosinophil-derived cationic proteins play an essential role in the pathogenesis of bronchial asthma. We tested whether cationic proteins interfere with the cationic amino-acid transport in alveolar macrophages (AMPhi) and tracheal epithelial cells, and whether L-arginine-dependent pathways were affected. The effect of cationic polypeptides on cellular uptake of [(3)H]-L-arginine, nitrite accumulation, and the turnover of [(3)H]-L-arginine by nitric oxide (NO) synthase and arginase (formation of [(3)H]-L-citrulline and [(3)H]-L-ornithine, respectively) were studied. Poly-L-arginine reduced [(3)H]-L-arginine uptake in rat AMPhi and tracheal epithelial cells in a concentration-dependent manner (at 300 microgram/ml by 70%). Poly-L-lysine, protamine, and major basic protein (each up to 300 microgram/ml) tested in rat AMPhi inhibited [(3)H]-L-arginine uptake by 35 to 50%. During 6 h incubation in amino acid-free Krebs solution, rat AMPhi, precultured in the absence or presence of LPS (1 microgram/ml), accumulated 1.4 and 3.5 nmol/10(6) cells nitrite, respectively. Addition of 100 microM L-arginine increased nitrite accumulation by 70 and 400% in control and lipopolysaccharide-treated AMPhi, respectively. Nitrite accumulation in the presence of L-arginine was reduced by poly-L-arginine and poly-L-lysine (100 and 300 microgram/ml) by 60 to 85% and 20 to 30%, respectively. Poly-L-arginine, but not poly-L-lysine, inhibited nitrite accumulation already in the absence of extracellular L-arginine. Poly-L-arginine (300 microgram/ml) inhibited [(3)H]-L-citrulline formation by AMPhi stronger than that of [(3)H]-L-ornithine. We conclude that cationic proteins can inhibit cellular transport of L-arginine and this can limit NO synthesis. Poly-L-arginine inhibits L-arginine uptake more effectively than other cationic proteins and exerts additional direct inhibitory effects on NO synthesis.

[Multiple sclerosis--disclosing the diagnosis. Attitude of patients: when? How? Disclose at all?]

MS patient members of the German Multiple Sclerosis Society were asked about their opinions concerning time and circumstances of getting to know the diagnosis, based on their personal experiences. Citations from 126 answers to a questionnaire, which had been published in the newsletter of the society, are presented to illustrate typical statements. Two thirds of the patients insisted on being informed about the diagnosis as early and as extensively as possible. One third, however, was more reluctant and stated that extensive information about the diagnosis should be timed individually depending on expected development of the disease and disabilities. Information should be extensive, constructive, and tailored to the individual needs of each patient so that he could deal more effectively with his disease. Most contributions voiced severe criticism as to the practice of information experienced. The study was initiated to prepare a more systematic approach to a field which has not been investigated to a degree matching its importance and impact in everyday neurological practice.