The paper presents an application of a clustering technique inspired by ant colony metaheuristics. The paper addresses the problem of long-term (Holter) electrocardiogram data processing. Long-term recording produces a huge amount of biomedical data, which must be preprocessed prior to its presentation to the specialist. The paper also discusses relevant aspects improving the robustness, stability and convergence criteria of the method. The method is compared with well known clustering techniques (both classical and nature-inspired), first testing on the known dataset and finally applying them to the real ECG data records from the MIT-BIH database and outperforms the standard methods. Electrocardiogram data clustering can effectively reduce the amount of data presented to the cardiologist: cardiac arrhythmia and significant morphology changes in the ECG can be visually emphasized in a reasonable time. The final evaluation of the ECG recording must still be made by an expert.

• MeSH
• algoritmy MeSH
• biomimetika metody   MeSH
• chování zvířat MeSH
• diagnóza počítačová metody   MeSH
• elektrokardiografie ambulantní metody   MeSH
• Formicidae fyziologie   MeSH
• lidé MeSH
• počítačové zpracování signálu * MeSH
• reprodukovatelnost výsledků MeSH
• rozpoznávání automatizované metody   MeSH
• senzitivita a specificita MeSH
• shluková analýza * MeSH
• srdeční arytmie diagnóza   patofyziologie   MeSH
• srdeční frekvence * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH

BACKGROUND: Hierarchical clustering is an exploratory data analysis method that reveals the groups (clusters) of similar objects. The result of the hierarchical clustering is a tree structure called dendrogram that shows the arrangement of individual clusters. To investigate the row/column hierarchical cluster structure of a data matrix, a visualization tool called 'cluster heatmap' is commonly employed. In the cluster heatmap, the data matrix is displayed as a heatmap, a 2-dimensional array in which the colour of each element corresponds to its value. The rows/columns of the matrix are ordered such that similar rows/columns are near each other. The ordering is given by the dendrogram which is displayed on the side of the heatmap. RESULTS: We developed InCHlib (Interactive Cluster Heatmap Library), a highly interactive and lightweight JavaScript library for cluster heatmap visualization and exploration. InCHlib enables the user to select individual or clustered heatmap rows, to zoom in and out of clusters or to flexibly modify heatmap appearance. The cluster heatmap can be augmented with additional metadata displayed in a different colour scale. In addition, to further enhance the visualization, the cluster heatmap can be interconnected with external data sources or analysis tools. Data clustering and the preparation of the input file for InCHlib is facilitated by the Python utility script inchlib_clust. CONCLUSIONS: The cluster heatmap is one of the most popular visualizations of large chemical and biomedical data sets originating, e.g., in high-throughput screening, genomics or transcriptomics experiments. The presented JavaScript library InCHlib is a client-side solution for cluster heatmap exploration. InCHlib can be easily deployed into any modern web application and configured to cooperate with external tools and data sources. Though InCHlib is primarily intended for the analysis of chemical or biological data, it is a versatile tool which application domain is not limited to the life sciences only.

• Klíčová slova
• Big data, Client-side scripting, Cluster heatmap, Data clustering, Exploration, JavaScript library, Scientific visualization, Web integration,
• Publikační typ
• časopisecké články MeSH

The spatial distribution of neutral lipids and semiochemicals on the surface of six-day-old separately reared naive Drosophila melanogaster flies has been visualized and studied using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and laser-assisted desorption/ionization (LDI)-TOF imaging (MSI). Metal targets were designed for two-dimensional MSI of the surface of 3-D biological objects. Targets with either simple grooves or profiled holes designed to accurately accommodate the male and female bodies were fabricated. These grooves and especially holes ensured correct height fixation and spatial orientation of the flies on the targets after matrix application and sample drying. For LDI-TOF to be used, the flies were arranged into holes and fixed to a plane of the target using fast-setting glue. In MALDI-TOF mode, the flies were fixed as above and sprayed with a lithium 2,5-dihydroxybenzoate matrix using up to 100 airbrush spray cycles. The scanning electron microscopy images revealed that the deposits of matrix were homogenous and the matrix formed mostly into the clusters of crystals (40-80 µm) that were separated from each other by an uncovered cuticle surface (30-40 µm). The MSI using target with profiled holes provided superior results to the targets with simple grooves, eliminating the ion suppression/mass deviation due to the 3-D shape of the flies. Attention was paid to neutral lipids and other compounds including the male anti-attractant 11-cis-vaccenyl acetate for which the expected distribution with high concentration on the tip of the male abdomen was confirmed. The red and blue mass shift (PlusMinus1 colour scale) was observed associated with mass deviation predominantly between ±0.2 and 0.3 Da. We use in-house developed software for mass recalibration, to eliminate the mass deviation effects and help with the detection of low-intensity mass signals.

• Klíčová slova
• MALDI, fruit flies, laser desorption, mass shift correction, mass spectrometric imaging, neutral lipids, sex pheromones,
• MeSH
• Drosophila melanogaster chemie   MeSH
• feromony analýza   chemie   MeSH
• hmotnostní spektrometrie metody   MeSH
• lipidy analýza   chemie   MeSH
• molekulární zobrazování metody   MeSH
• počítačové zpracování obrazu metody   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• feromony MeSH
• lipidy MeSH