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Venezia, Italy

Alafeefy A.M.,DAIS | Ahmad R.,King Saud University | Abdulla M.,Egyptian Russian University | Eldehna W.M.,P.A. College | And 7 more authors.
European Journal of Medicinal Chemistry | Year: 2016

Carbonic anhydrases (CA I, II, IX and XII) are known to be highly expressed in various human malignancies. CA IX is overexpressed in colorectal cancer specifically in hereditary nonpolyposis colorectal cancer. Inhibition of CA activity by small molecular CA inhibitor like sulphonamides, sulphonamide derivative (SU.D2) or HIF1a inhibitor Chetomin leads to inhibition of tumorigenesis. Eighteen new quinazolin-4-sulfonamide derivatives were prepared and characterized by means of IR, NMR and mass spectra. Certain selected derivatives were tested for their ability to inhibit four isoforms of the metalloemzyme CA, namely, CA I, CA II, CA IX and CA XII. Compound 3c was found to be highly effective in inhibiting the cancer cell proliferation. 3c decreased cell viability of human HT-29 cells in dose and time dependent manner and with IC50 of 5.45 mM. Moreover, it was tested on metastatic colon cancer cell SW-620 where it was found to be equally effective on human SW-620 cells. This novel compound inhibited the CA IX and CA XII protein expression in HT-29 cells without affecting CA I and CA II expression. These findings indicate that 3c inhibits cellular proliferation in two human colon cancer cells by specifically targeting the CA IX and CA XII expression. © 2016 Published by Elsevier Masson SAS. Source

Nourbakhsh F.,DAIS | Bulo S.R.,FBK | Pelillo M.,DAIS
Proceedings - International Conference on Pattern Recognition | Year: 2014

We address the problem of encoding a graph of order n into a graph of order k x8B; n in a way to minimize reconstruction error. We characterize this encoding in terms of a particular factorization of the adjacency matrix of the original graph. The factorization is determined as the solution of a discrete optimization problem, which is for convenience relaxed into a continuous, but equivalent, one. We propose a new multiplicative update rule for the optimization task. Experiments are conducted to assess the effectiveness of the proposed approach. © 2014 IEEE. Source

Lourenco A.,Polytechnic Institute of Lisbon | Lourenco A.,Telecommunications Institute of Portugal | Rota Bulo S.,DAIS | Rebagliati N.,VTT Technical Research Center of Finland | And 5 more authors.
Machine Learning | Year: 2013

Clustering ensemble methods produce a consensus partition of a set of data points by combining the results of a collection of base clustering algorithms. In the evidence accumulation clustering (EAC) paradigm, the clustering ensemble is transformed into a pairwise co-association matrix, thus avoiding the label correspondence problem, which is intrinsic to other clustering ensemble schemes. In this paper, we propose a consensus clustering approach based on the EAC paradigm, which is not limited to crisp partitions and fully exploits the nature of the co-association matrix. Our solution determines probabilistic assignments of data points to clusters by minimizing a Bregman divergence between the observed co-association frequencies and the corresponding co-occurrence probabilities expressed as functions of the unknown assignments. We additionally propose an optimization algorithm to find a solution under any double-convex Bregman divergence. Experiments on both synthetic and real benchmark data show the effectiveness of the proposed approach. © 2013, The Author(s). Source

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