background: sertoli cells play a pivotal role in creating microenvironments essential for spermatogonial stem cells (sscs) self-renewal and commitment to differentiation. maintenance of sscs and or induction of in vitro spermiogenesis may provide a therapeutic strategy to treat male infertility. objective: this study investigated the role of luekemia inhibitory factor (lif) on the propagation o...

background: mesenchymal stem cells (mscs) possess a wide range of immunomodulatory functions mostly in immune cells including dendritic cells (dcs). dcs are the key cells in the immune response and play an important role in initiating cell-mediated immunity. objective: to evaluate the immunomodulatory effects of mscs supernatant on maturation and function of dcs. methods: bone marrow derived mi...

Proteins that modulate the activity of transcription factors, often called modulators, play a critical role in creating tissue- and context-specific gene expression responses to the signals cells receive. GEM (Gene Expression Modulation) is a probabilistic framework that predicts modulators, their affected targets and mode of action by combining gene expression profiles, protein-protein interac...

To study the function of specific cells or tissues using genomic tools like microarray analyses, it is highly desirable to obtain mRNA from a homogeneous source. However, this is particularly challenging for small organisms, like Caenorhabditis elegans and Drosophila melanogaster. We have optimized and applied a new technique, mRNA tagging, to isolate mRNA from specific tissues of D.melanogaste...

In this paper, we investigate the complexity of deciding determinism of unary languages. First, we give a method to derive a set of arithmetic progressions from a regular expression E over a unary alphabet, and establish relations between numbers represented by these arithmetic progressions and words in L(E). Next, we define a problem relating to arithmetic progressions and investigate the comp...

In a study of surface branched coverings, one can ask naturally: In how many different ways can a given surface be a branched covering of another given surface? This problem was studied by many authors in Quart. J. Math. Oxford Ser. 2 46 (1995) 485, Math. Scand. 84 (1999) 23, Discrete Math. 156 (1996) 141, Discrete Math. 183 (1998) 193, Discrete Math. (in press), European J. Combin. 22 (2001) 1...