The ALL-1 gene is directly involved in 5-10% of acute lymphoblastic leukemias (ALLs) and acute myeloid leukemias (AMLs) by fusion to other genes or through internal rearrangements. DNA microarrays were used to determine expression profiles of ALLs and AMLs with ALL-1 rearrangements. These profiles distinguish those tumors from other ALLs and AMLs. The expression patterns of ALL-1-associated tumors, in particular ALLs, involve oncogenes, tumor suppressors, antiapoptotic genes, drug-resistance genes, etc., and correlate with the aggressive nature of the tumors. The genes whose expression differentiates between ALLs with and without ALL-1 rearrangement were further divided into several groups, enabling separation of ALL-1-associated ALLs into two subclasses. One of the groups included 43 genes that exhibited expression profiles closely linked to ALLs with ALL-1 rearrangements. Further, there were evident differences between the expression profiles of AMLs in which ALL-1 had undergone fusion to other genes and AMLs with partial duplication of ALL-1. The extensive analysis described here pinpointed genes that might have a direct role in pathogenesis.C hromosome band 11q23 is a region of recurrent rearrangements in human acute leukemias. These rearrangements, usually in the form of reciprocal chromosome translocations, affect 5-10% of children and adults with acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML). The most common translocations are t(4;11) and t(9;11), accounting for 40% and 27%, respectively, of all 11q23 rearrangements. There is a strong association between leukemia phenotype and particular rearrangements. Thus, t(4;11) occurs nearly exclusively in ALL, and 85% of cases with t(9;11) are AMLs (1, 2). Essentially all 11q23 abnormalities involve the ALL-1 gene (also termed MLL, HRX, or HTRX), which rearranges with Ͼ30 partner genes to produce fusion proteins composed of ALL-1 N terminus and the C terminus of the partner protein (3, 4). A second and less frequent type of ALL-1 rearrangement does not involve partner genes but rather partial duplications of ALL-1 N-terminal segments (5). ALL-1-associated leukemias show some unusual and intriguing features (reviewed in refs. 6 and 7). First, they predominate infant acute leukemias, amounting to 80% of infants with ALL and 65% of those with AML. Second, they account for the majority of therapyrelated (secondary) leukemias, developing in 5-15% of primary cancer patients treated with drugs, such as etoposide (VP16), that inhibit DNA topoisomerase II. Third, in infant leukemia and in therapy-related leukemia the disease arises after a brief latency. In fact, studies of monozygotic twins and newborns with leukemia and analysis of neonatal blood spots from children who were diagnosed with leukemia indicate that in most or all infant leukemias ALL-1 rearrangements occur in utero. The short latency suggests that ALL-1 fusion proteins induce leukemia with few, if any, additional mutations. Fourth, prognosis of patients with 11q23 abnormalities is ...
We study networks constructed from gene expression data obtained from many types of cancers. The networks are constructed by connecting vertices that belong to each others' list of K nearest neighbors, with K being an a priori selected non-negative integer. We introduce an order parameter for characterizing the homogeneity of the networks. On minimizing the order parameter with respect to K, degree distribution of the networks shows power-law behavior in the tails with an exponent of unity. Analysis of the eigenvalue spectrum of the networks confirms the presence of the power-law and small-world behavior. We discuss the significance of these findings in the context of evolutionary biological processes.
We show that in the loop-erased random walk problem, the exponent characterizing probability distribution of areas of erased loops is superuniversal. In d-dimensions, the probability that the erased loop has an area A varies as A −2 for large A, independent of d, for 2 ≤ d ≤ 4. We estimate the exponents characterizing the distribution of perimeters and areas of erased loops in d = 2 and 3 by large-scale Monte Carlo simulations. Our estimate of the fractal dimension z in two-dimensions is consistent with the known exact value 5/4. In three-dimensions, we get z = 1.6183 ± 0.0004. The exponent for the distribution of durations of avalanche in the three-dimensional abelian sandpile model is determined from this by using scaling relations. 64.60.Ak, 05.40.+j, 75.10.Hk
Face is a complex multidimensional visual model and developing a computational model for face recognition is difficult. The paper presents a methodology for face recognition based on information theory approach of coding and decoding the face image. Proposed methodology is connection of two stages-Feature extraction using principle component analysis and recognition using the feed forward back propagation Neural Network. The algorithm has been tested on 400 images (40 classes). A recognition score for test lot is calculated by considering almost all the variants of feature extraction. The proposed methods were tested on Olivetti and Oracle Research Laboratory (ORL) face database. Test results gave a recognition rate of 97.018%
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