Wyniki wyszukiwania - BazTech

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Grafowa metoda segmentacji obiektów w postaci skupisk na przykładzie obrazów kometowych

Bal A.

Pomiary Automatyka Kontrola

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2012

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R. 58, nr 4

313-315

PL

W pracy przedstawiono propozycję metody segmentacji obiektów będących skupiskami - przykładem takich obiektów są tzw. komety, które są wynikiem jednokomórkowej elektroforezy żelowej. Opracowana metoda działa dwuetapowo: etap 1. to segmentacja służąca wyznaczeniu elementów składowych należących do obiektów, etap 2 wykorzystuje minimalne drzewo rozpinające do określenia zbioru elementów tworzących poszczególne obiekty, obszar poszczególnych obiektów wyznaczany jest jako otoczka wypukła odpowiedniego drzewa rozpinającego.

EN

This paper deals with a problem of segmentation of aggregate objects, that is objects which are formed by a set of unconnected elements smaller than the object itself. Images of such a type of objects are very difficult for segmentation. An example of this type of objects are "comets" (Fig. 1, left column) from Single Cell Gel Electrophoresis images (also called comet assay images). In comet assay images the comet region is formed by unconnected fragments of DNA. Because of not satisfying results of comet segmentation with use of the standard methods, a new method for segmentation of such images was developed. The new method works in two stages. The first stage is the image segmentation-for comets the Bernsen binarization method (Eqs. (1) and (2)) with median filtering of the obtained results was chosen-the result of this stage is a set of comet elements ei which represent DNA fragments (Fig. 1, the 2nd column). In the second stage the minimum spanning trees Tp are created (Fig. 1, 3th column)-graph vertexes vi represent elements ei, and length dij of edge eij between vertexes vi and vj is equal to the closest distance between pixels of elements ei and ej-then for each connected tree Tp its convex hull which defines the region of comet Kp (Fig. 1, the 4th column) is created. In case of defects appearing in comet images, the incorrect region can be rejected e.g. by use of geometrical or photometrical features of the regions.

2

Comparison of the effects of bleomycin and ionizing radiation in two sublines of murine lymphoma L5178Y

Kruszewski M., Zaim J., Grądzka I., Szumiel I.

Nukleonika

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2001

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Vol. 46, nr 3

81-86

EN

We compared the effects of bleomycin (BLM) and ionizing radiation on two sublines of murine lymphoma L5178Y (LY): LY-R, radiation resistant and LY-S, radiation sensitive. This radiosensitivity difference is related to the ability to rejoin DNA double strand breaks. LY-S cells were about two times more sensitive to BLM than LY-R, similarly as in the case of sensitivity to X rays. Since there was no difference in the P-glycoprotein-related drug transport system between the sublines, it could be expected that the enhanced sensitivity of LY-S cells to BLM was caused by the DNA repair defect. Growth disturbances in BLM treated cell populations were proportional to the lethal effect and their duration was observed until elimination of dead cells (3-6 days after 50 ěM BLM, 1 h at 37oC). There was no slow growth phase accompanied by normal viability, as previously described for X-irradiated LY-S cells. Initial DNA damage, estimated with the single cell gel electrophoresis method was linearly related to BLM dose in LY-S cells; in LY-R cells - in the low dose range (up to 10 ěM) - there was more damage than in LY-S cells, however, at higher doses the dose - effect curves became identical. The doseeffect relationship for ă rays was linear and identical in both cell sublines. DNA damage distribution in BLM treated cells was much less uniform as compared to that in irradiated cells and indicated the presence of cells with severely damaged DNA, a feature typical for BLM action in vitro.

3

On the segmentation of the Comet Assay images

Smolka B., Szczepański M., Świerniak A., Palus H., Plataniotis K. N.

Journal of Medical Informatics & Technologies

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2001

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Vol. 2, Part. 1

MI29--MI39

EN

The single cell gel electrophoresis, called Comet Assay is a microelectrophoretic technique of direct visualization of DNA damage at the cell level. In the comet assay, the cells suspended in an agarose gel on a microscope slide are subjected to lysis, unwinding of DNA and electrophoresis. After staining with fluorescent DNA binding dye, cells with DNA damage display increased migration of genetic material from the cell nucleus. Under the influence of weak, statics electric field, charged DNA migrates away from the nucleus forming a so called comet. The damage is quantified by measuring the amound of the genetic material, which migrates from the nucleus to form the comet tail. The foremost advantage of the comet assay is that it analyses individual cells, thus allowing the measurement of the heterogeneity of response within a cell population. In this paper we present three novel method of the comet tail and head extraction.