BCFD - a Visual Basic program for calculation of the fractal dimension of digitized geological image data using a box-counting technique

The BCFD program was develped for the analysis of digitized objects using a box-counting algorithm, which has the largest number of applications among the fractal methods in the geosciences. Counting is performed by scanning of image pixels in boxes of different sizes, and the number of boxes is determined automatically from the image resolution. The program calculates the fractal dimension D of theobjects in the image, along with the coefficient of determination R2. Input files are thus transferred to ubiquitous BMP images, in a 1-bit monochrome for mat. The pro gram out puts the re sults on screen, into a text file and op tion ally also di rectly into MS Ex cel, where the data can be fur ther used in charts or other cal cu la tions. It was tested with three fractal and three Eu clid ean ob jects with known the o ret i cal val - ues, plus three geo log i cal im age data (a nat u ral river net work and two frac ture net works), and gave re sults with very high or per fect the o - ret i cal ac cu racy. Ap pli ca tion of data val ues ob tained is pre sented with sev eral ex am ples. BCFD is writ ten in Vi sual Ba sic 6.0. The source code is freely avail able, and is open for any mod i fi ca tions or in te gra tion with other soft ware pack ages that are pow ered by Vi sual Ba sic for Ap pli ca tions (VBA) or its equiv a lent

Quantitative analysis of randomness exhibited by river channels using chaos game technique: Mississippi, Amazon, Sava and Danube case studies

This paper presents a numerical evaluation of the randomness which can be observed in the geometry of major river channels. The method used is based upon that of generating a Sierpinski triangle via the chaos game technique, played with the sequence representing the river topography. The property of the Sierpinski triangle is that it can be constructed only by playing a chaos game with random values. Periodic or chaotic sequences always produce an incomplete triangle. The quantitative data about the scale of the random behaviour of the river channel pathway was evaluated by determination of the completeness of the triangle, generated on the basis of sequences representing the river channel, and measured by its fractal dimension. The results show that the most random behaviour is observed for the Danube River when sampled every 715 m. By comparing the maximum dimension of the obtained Sierpinski triangle with the gradient of the river we can see a strong correlation between a higher gradient corresponding to lower random behaviour. Another connection can be seen when comparing the length of the segment where the river shows the most random flow with the total length of the river. The shorter the river, the denser the sampling rate of observations has to be in order to obtain a maximum degree of randomness. From the comparison of natural rivers with the computer-generated pathways the most similar results have been produced by a complex superposition of different sine waves. By adding a small amount of noise to this function, the fractal dimensions of the generated complex curves are the most similar to the natural ones, but the general shape of the natural curve is more similar to the generated complex one without the noise

Complexity of cancer protease biology: Cathepsin K expression and function in cancer progression

Proteases, including lysosomal cathepsins, are functionally involved in many processes in cancer progression from its initiation to invasion and metastatic spread. Only recently, cathepsin K (CatK), the cysteine protease originally reported as a collagenolytic protease produced by osteoclasts, appeared to be overexpressed as well in various types of cancers. In this review, the physiological functions of CatK are presented and compared to its potential role in pathobiolology of processes associated with tumour growth, invasion and metastasis of cancer cells and their interactions with the tumour microenvironment. CatK activity is either indirectly affecting signalling pathways, or directly degrading extracellular matrix (ECM) proteins, for example in bone metastases. Recently, CatK was also found in glioma, possibly regulating cancer stem-like cell mobilisation and modulating recently found physiological CatK substrates, including chemokines and growth factors. Moreover, CatK may be useful in differential diagnosis and may have prognostic value. Finally, the application of CatK inhibitors, which are already in clinical trials for treatment of osteoporosis, has a potential to attenuate cancer aggressivenes

La Vigie marocaine

08 avril 19361936/04/08 (A27,N8879)-1936/04/08

Scheme of cellular processes and activities involving overexpressed protease and protease inhibitor genes in GBM.

<p>The overexpressed protease and inhibitor genes in GBM tissues and cells were queried by the Biomine search engine which identified processes and activities ascribed with KEGG and GO identifiers (in circles) in which selected genes (in bold caption) are involved.</p

Cathepsin K cleavage of SDF-1α inhibits its chemotactic activity towards glioblastoma stem-like cells

Glioblastoma (GBM) is the most aggressive primary brain tumor with poor patient survival that is at least partly caused by malignant and therapy-resistant glioma stem-like cells (GSLCs) that are protected in GSLC niches. Previously, we have shown that the chemo-attractant stromal-derived factor-1α (SDF-1α), its C-X-C receptor type 4 (CXCR4) and the cysteine protease cathepsin K (CatK) are localized in GSLC niches in glioblastoma. Here, we investigated whether SDF-1α is a niche factor that through its interactions with CXCR4 and/or its second receptor CXCR7 on GSLCs facilitates their homing to niches. Furthermore, we aimed to prove that SDF-1α cleavage by CatK inactivates SDF-1α and inhibits the invasion of GSLCs. We performed mass spectrometric analysis of cleavage products of SDF-1α after proteolysis by CatK. We demonstrated that CatK cleaves SDF-1α at 3 sites in the N-terminus, which is the region of SDF-1α that binds to its receptors. Confocal imaging of human GBM tissue sections confirmed co-localization of SDF-1α and CatK in GSLC niches. In accordance, 2D and 3D invasion experiments using CXCR4/CXCR7-expressing GSLCs and GBM cells showed that SDF-1α had chemotactic activity whereas CatK cleavage products of SDF-1α did not. Besides, CXCR4 inhibitor plerixafor inhibited invasion of CXCR4/CXCR7-expressing GSLCs. In conclusion, CatK can cleave and inactivate SDF-1α. This implies that CatK activity facilitates migration of GSLCs out of niches. We propose that activation of CatK may be a promising strategy to prevent homing of GSLCs in niches and thus render these cells sensitive to chemotherapy and radiation

Signaling pathways in which the candidate genes are involved.

<p>An extensive literature search revealed that the candidate genes are cross-linked to 3 signaling pathways: NF-κB, Akt and MAPK, which all play a role in cancer. NF-κB signaling pathway has a crucial role in regulating immune responses, whereas Akt signaling has been shown to inhibit the growth of GBM cells and GBM stem-like cells that may also be impaired by MAPK signaling disruption. Because of the RT-qPCR results, <i>CTSK</i>'s role has been examined and it was found via cross linking to other candidate genes obtained via osteopontin (<i>OPN</i>) gene functions.</p