P systems with control nuclei: The concept

AbstractWe describe an extension of P systems where each membrane has an associated control nucleus responsible with the generation of the rules to be applied in that membrane. The nucleus exports a set of rules which are applied in the membrane region (only for one step, but in the usual maximal-parallel way), then the rules are removed and a new iteration of this process takes place. This way, powerful control mechanisms may be included in P systems themselves, as opposed to using the level of “strategies” previously exploited for simulating P systems. The nuclei may contain general programs for generating rules, ranging from those using information on the full system, to more restricted programs where only local information in the nuclei themselves and the associated membranes is used. The latter approach, mixed with a particular mechanism for the representation of the control programs, the rules, and the export procedure is powerful enough for modeling complex biological applications, e.g., to develop a detailed model for cell growth and division in normal and abnormal (tumoral) evolution of biological systems

Computer Aided Diagnosis for Confocal Laser Endomicroscopy in Advanced Colorectal Adenocarcinoma

Introduction: Confocal laser endomicroscopy (CLE) is becoming a popular method for optical biopsy of digestive mucosa for both diagnostic and therapeutic procedures. Computer aided diagnosis of CLE images, using image processing and fractal analysis can be used to quantify the histological structures in the CLE generated images. The aim of this study is to develop an automatic diagnosis algorithm of colorectal cancer (CRC), based on fractal analysis and neural network modeling of the CLE-generated colon mucosa images. Materials and Methods We retrospectively analyzed a series of 1035 artifact-free endomicroscopy images, obtained during CLE examinations from normal mucosa (356 images) and tumor regions (679 images). The images were processed using a computer aided diagnosis (CAD) medical imaging system in order to obtain an automatic diagnosis. The CAD application includes image reading and processing functions, a module for fractal analysis, grey-level co-occurrence matrix (GLCM) computation module, and a feature identification module based on the Marching Squares and linear interpolation methods. A two-layer neural network was trained to automatically interpret the imaging data and diagnose the pathological samples based on the fractal dimension and the characteristic features of the biological tissues. Results: Normal colon mucosa is characterized by regular polyhedral crypt structures whereas malignant colon mucosa is characterized by irregular and interrupted crypts, which can be diagnosed by CAD. For this purpose, seven geometric parameters were defined for each image: fractal dimension, lacunarity, contrast correlation, energy, homogeneity, and feature number. Of the seven parameters only contrast, homogeneity and feature number were significantly different between normal and cancer samples. Next, a two-layer feed forward neural network was used to train and automatically diagnose the malignant samples, based on the seven parameters tested. The neural network operations were cross-entropy with the results: training: 0.53, validation: 1.17, testing: 1.17, and percent error, resulting: training: 16.14, validation: 17.42, testing: 15.48. The diagnosis accuracy error was 15.5%. Conclusions: Computed aided diagnosis via fractal analysis of glandular structures can complement the traditional histological and minimally invasive imaging methods. A larger dataset from colorectal and other pathologies should be used to further validate the diagnostic power of the method

Diagram of the NAVICAD diagnosis application.

<p>Diagram of the NAVICAD diagnosis application.</p

Average CAD parameter values ± standard deviation.

<p>Average CAD parameter values ± standard deviation.</p

Normal colon mucosa.

<p><b>a.</b> Normal colon mucosa with round shaped crypts (blue circle), situated at relatively equal distance one from another, dark goblet cells (yellow circles), and narrow and regular blood vessels surrounding the crypts (red arrows). <b>b.</b> Normal colon mucosa image processed: Fractal dimension = 1.732; Lacunarity = 0.13; Contrast = 0.26; Correlation = 0.97; Energy = 0.24; Homogeneity = 0.89; Features No = 14.</p

The neural network operation.

<p>The neural network operation.</p