Katarina Rajković

Morphology and classification of large neurons in the adult human dentate nucleus: A qualitative and quantitative analysis of 2D images

The dentate nucleus represents the most lateral of the four cerebellar nuclei that serve as major relay centres for fibres coming from the cerebellar cortex. Although many relevant findings regarding to the structure, neuronal morphology and cytoarchitectural development of the dentate nucleus have been presented so far, very little quantitative information has been collected on the types of large neurons in the human dentate nucleus. In the present study we qualitatively analyze our sample of large neurons according to their morphology and topology, and classify these cells into four types. Then, we quantify the morphology of such cell types taking into account seven morphometric parameters which describe the main properties of the cell soma, dendritic field and dendrite arborization. By performing appropriate statistics we prove out our classification of the large dentate neurons in the adult human. To the best of our knowledge, this study represents the first attempt of quantitative analysis of morphology and classification of the large neurons in the adult human dentate nucleus.

Application of fractal analysis to neuronal dendritic arborisation patterns of the monkey dentate nucleus.

The deep nuclei of the cerebellar cortex have not yet received adequate exploratory attention. An exception is represented by the pioneering work of Chan-Palay, published in 1977, on the dentate nucleus morphology. She has classified each individual cell in the dentatus of the monkey into one of six types. Although fractal analysis is presently the most prominent quantitative method for morphometric neuronal studies, no article referring to applications of this method to the analysis of cell types of the dentate nucleus has so far been published. In the present study we apply fractal analysis to this unsolved problem and calculate the fractal dimension for each dendritic arbour of a neuron. We will hereby prove that by application of fractal analysis to the dendritic arbours of these cells whilst ignoring other neuronal attributes allows for clear discrimination of only three cell types.

Quantitative analysis of dendritic morphology of the alpha and delta retinal ganglion cells in the rat: A cell classification study

Type I retinal ganglion cells in the rat have been classified into several groups based on the cell body size and dendritic morphology. Considerable overlap and heterogeneity within groups have been reported, which is especially obvious for the morphology of the dendritic tree. For that purpose, we analysed quantitatively the dendritic morphology of the alpha and delta rat retinal ganglion cells, using parameters which provide information on the dendritic field size, shape of the dendritic tree and dendritic branching complexity. We show that the alpha and delta cells have significantly different dendritic field sizes. Taking into account the level of stratification of the dendritic tree, we found a difference in the properties of the dendritic morphology between alpha inner and alpha outer cells, while the opposite result was obtained for the delta inner and delta outer delta cells. In this study we also call attention to the relationship between morphological parameters and retinal eccentricity. The significance of our quantitative results in terms of present alpha and delta rat retinal ganglion cell classification is discussed.

Morphology and cell classification of large neurons in the adult human dentate nucleus: a quantitative study.

The dentate nucleus represents the most lateral of the four cerebellar nuclei that serve as a major relay centres for fibres coming from the cerebellar cortex. Although many relevant findings regarding to the three-dimensional structure, the neuronal morphology and the cytoarchitectural development of the dentate nucleus have been presented so far, very little quantitative information has been collected to further explain several types of large neurons in the dentate nucleus. In this study we quantified the morphology of the large dentate neurons in the adult human taking, into account seven morphometric parameters that describe the main properties of the cell soma, the dendritic field and the dendritic branching pattern. Since the lateral cerebellar nucleus in the cat and other lower mammals is homologous to the dentate nucleus in primates and man, we have classified our sample of large neurons in accordance with the shape of the cell body, the dendritic arborization and their location within the dentate nucleus. By performing the appropriate statistical analysis, we have proved that our sample of human dentate neurons can be classified into four distinct types. In that sense, our quantitative analysis verifies the validity of previous qualitative conclusions concerning the large neurons in the developing human dentate nucleus. Furthermore, the present study represents the first attempt to perform a quantitative analysis and cell classification of the large projection neurons in the adult human dentate nucleus.

Mathematical Model of Neuronal Morphology: Prenatal Development of the Human Dentate Nucleus

The aim of the study was to quantify the morphological changes of the human dentate nucleus during prenatal development using mathematical models that take into account main morphometric parameters. The camera lucida drawings of Golgi impregnated neurons taken from human fetuses of gestational ages ranging from 14 to 41 weeks were analyzed. Four morphometric parameters, the size of the neuron, the dendritic complexity, maximum dendritic density, and the position of maximum density, were obtained using the modified Scholl method and fractal analysis. Their increase during the entire prenatal development can be adequately fitted with a simple exponential. The three parameters describing the evolution of branching complexity of the dendritic arbor positively correlated with the increase of the size of neurons, but with different rate constants, showing that the complex development of the dendritic arbor is complete during the prenatal period. The findings of the present study are in accordance with previous crude qualitative data on prenatal development of the human dentate nucleus, but provide much greater amount of fine details. The mathematical model developed here provides a sound foundation enabling further studies on natal development or analyzing neurological disorders during prenatal development.

Mathematical modeling of the neuron morphology using two dimensional images.

In this study mathematical analyses such as the analysis of area and length, fractal analysis and modified Sholl analysis were applied on two dimensional (2D) images of neurons from adult human dentate nucleus (DN). Using mathematical analyses main morphological properties were obtained including the size of neuron and soma, the length of all dendrites, the density of dendritic arborization, the position of the maximum density and the irregularity of dendrites. Response surface methodology (RSM) was used for modeling the size of neurons and the length of all dendrites. However, the RSM model based on the second-order polynomial equation was only possible to apply to correlate changes in the size of the neuron with other properties of its morphology. Modeling data provided evidence that the size of DN neurons statistically depended on the size of the soma, the density of dendritic arborization and the irregularity of dendrites. The low value of mean relative percent deviation (MRPD) between the experimental data and the predicted neuron size obtained by RSM model showed that model was suitable for modeling the size of DN neurons. Therefore, RSM can be generally used for modeling neuron size from 2D images.

In vitro Protease Inhibition and Cytotoxicity of Aspergillus fumigatus Biomolecules Secreted under Long-Term Aerated Conditions

The fatality rate of invasive aspergillosis (IA) is still very high, especially in prolonged and untreated pulmonary cases. Aspergillus fumigatus is the main causative agent of IA and investigation of its metabolites could provide valuable insight into virulence factor(s) associated with this organism. We evaluated the A. fumigatus culture filtrate (CF) products generated during short- and long-term aerated and non-aerated conditions and tested for (i) inhibition of cysteine or serine proteases and (ii) cytotoxicity. In addition, the mathematical model was determined using response surface methodology (RSM) to estimate the influence of different fermentation conditions on A. fumigatus CF characteristics, predict enzyme inhibition and make possible correlations with in vivo conditions. Biosynthesis of A. fumigatus low molecular weight proteinaceous products (from 6.4 to 15.4 kDa) was observed after 6 days of growth under aerated and alkaline conditions. Also, only these CFs showed significant reduction in cell lines survival (Caco-2 and WISH 35.6% and 54.6%, respectively). Obtained results provide solid starting point for further studies that would include: (i) detailed chemical characterization of A. fumigatus CF, (ii) activity relationships and in vivo correlation with pathogenicity of prolonged pulmonary IA and (iii) possible use of biomolecules as diagnostic or therapeutic markers.

Neurons of the Human Dentate Nucleus: Box-Count Method in the Quantitative Analysis of Cell Morphology

The morphology of neurons from the human dentate nucleus was analyzed estimating the size and shape of the dendritic field, shape of the neuron, space-filling property and the degree of dendrite aberrations. Among them, the last three morphological properties were investigated using the most popular technique of fractal analysis: the box-count method. The box dimensions of binary images and dendritic field area were statistically investigated in order to test whether the binary box dimension can quantify the size of the neuron. The same analysis was carried out using the box dimension of outline images and image circularity. The parameters, presented in this study have proved to be a useful means for quantifying the morphology of dentate neurons as they provide a robust means of differentiating between neuron subtypes in the dentate nucleus. The findings of the present study are in accordance with previous qualitative data.

Kinetic Profile of the Antioxidant Activity of Propolis Extract: 2,2-Diphenyl-1-Picrylhydrazyl Radical Bleaching Assay

Abstract The objective of this paper was to assess the antiradical effectiveness of propolis extract (PE) based on 2.2-diphenyl-1-picrylhydrazyl radical (DPPH•) bleaching assay kinetic profile. The kinetic profile of scavenging DPPH• for PE exhibited one kinetic period characterized by one kinetic constant. The second-order rate constant (k2) for the oxidation of PE by DPPH•, determined for the first time in this study, was 0.17 dm3g−1s−1. The obtained k2 value was compared to that of synthetic antioxidants and natural extracts used in the food industry. Kinetic analysis of PE antiradical effectiveness showed that the k2 was within the range values for natural colorants of fruit extracts and should be considered as a fast acting natural antioxidant source. The k2 parameter indicates the extent of oxidation inhibition that is based on all of the kinetic profiles of DPPH bleaching rather than single point measurements. For this reason, the kinetic analysis should become a necessary step for more precise antioxidative characterization of propolis.