An integrative bioinformatic approach for identifying subtypes and subtype-specific drivers in cancer

Cancer is a complex disease and within a cancer, subtypes of patients with distinct behaviors often exist. The subtypes might have been caused by different hits, such as copy number aberrations (CNAs) and point mutations, on different pathways/cells-of-origin in a common tissue/organ. Identifying the subtypes with subtype-specific drivers, i.e., hits, is key to the understanding of cancer and development of novel treatments. Here, we report the development of an integrative method to identify the subtypes of cancer. Specifically, we consider CNAs and their impact on gene expressions. Based on these relations, we propose an iterative approach that alternates between kernel based gene expression clustering and gene signature selection. We applied the method to datasets of the pediatric cancer medulloblastoma (MB). The consensus number of clusters quickly converges to three; and for each of these three subtypes, the signature detection also converges to a consistent set of a few hundred highly functionally related genes. For each of the subtypes, we correlate its signature with the set of within-subtype recurrent CNA-affected genes for identifying drivers. The top-ranked driver candidates are found to be enriched with known pathways in certain subtypes of MB as well as containing novel genes that might reveal new understandings for other subtypes.published_or_final_versionThe 2012 IEEE Symposium on Computational Intelligence in Bioinformatics and Computational Biology (CIBCB’12), San Diego, CA., 9-12 May 2012. In IEEE CIBCB Proceedings, 2012, p. 169-17

Temporal genetic variation in populations of the limpet Cellana grata from Hong Kong shores

Variations in the relative contributions of gene flow and spatial and temporal variation in recruitment are considered the major determinants of population genetic structure in marine organisms. Such variation can be assessed through repeated measures of the genetic structure of a species over time. To test the relative importance of these two phenomena, temporal variation in genetic composition was measured in the limpet Cellana grata, among four annual cohorts over 10 years at four rocky shores in Hong Kong. A total of 408 limpets, comprising individuals from 1998, 1999, 2006 and 2007 cohorts were screened for genetic variation using five microsatellite loci. Minor but significant genetic differentiation was detected among samples from the 1998/1999 collection (FST = 0.0023), but there was no significant differentiation among the 2006/2007 collection (FST = 0.0008). Partitioning of genetic variation among shores was also significant in 1998/1999 but not in the 2006/2007 collection, although there was no correlation between genetic and geographic distances. There was no significant difference between collections made in 1998/1999 and 2006/2007. This lack of clear structure implies a high level of gene flow, but differentiation with time may be the result of stochastic recruitment variation among shores. Estimates of effective population size were not high (599, 95% C. L. 352-11397), suggesting the potential susceptibility of the populations to genetic drift, although a significant bottleneck effect was not detected. These findings indicate that genetic structuring between populations of C. grata in space and time may result from spatio-temporal variation in recruitment, but the potential development of biologically significant differentiation is suppressed by a lack of consistency in recruitment variability and high connectivity among shores. © Springer-Verlag 2009.postprin

Segment and track neurons in 3D by repulsive snake method

We present a snake (active contour) model based on repulsive force to segment neurons obtained from microscopy. Based on these segmentation results, we track the neurons in 3D image to look for its branch structure. These segmentation results allow user to study morphology of neurons to further investigate neuronal function and connectivity. This repulsive snake model can successfully segment two or multiple neurons that are close to each other by some alternating repulsive force generated from the neighboring objects. We apply our results on real data to demonstrate the performance of our method. © 2005 IEEE.published_or_final_versio

A gene signature based method for identifying subtypes and subtype-specific drivers in cancer with an application to medulloblastoma

published_or_final_versio

Midwifery 2030: A woman's pathway to health. What does this mean?

© 2015 The Authors. The 2014 State of the World's Midwifery report included a new framework for the provision of woman-centred sexual, reproductive, maternal, newborn and adolescent health care, known as the Midwifery2030 Pathway. The Pathway was designed to apply in all settings (high-, middle- and low-income countries, and in any type of health system). In this paper, we describe the process of developing the Midwifery2030 Pathway and explain the meaning of its different components, with a view to assisting countries with its implementation.The Pathway was developed by a process of consultation with an international group of midwifery experts. It considers four stages of a woman's reproductive life: (1) pre-pregnancy, (2) pregnancy, (3) labour and birth, and (4) postnatal, and describes the care that women and adolescents need at each stage. Underpinning these four stages are ten foundations, which describe the systems, services, workforce and information that need to be in place in order to turn the Pathway from a vision into a reality. These foundations include: the policy and working environment in which the midwifery workforce operates, the effective coverage of sexual, reproductive, maternal, newborn and adolescent services (i.e. going beyond availability and ensuring accessibility, acceptability and high quality), financing mechanisms, collaboration between different sectors and different levels of the health system, a focus on primary care nested within a functional referral system when needed, pre- and in-service education for the workforce, effective regulation of midwifery and strengthened leadership from professional associations. Strengthening of all of these foundations will enable countries to turn the Pathway from a vision into reality

Skin- and gut-homing molecules on human circulating gamma delta T cells and their dysregulation in inflammatory bowel disease

Changes in phenotype and function of γδ T cells have been reported in inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). Dysregulation of lymphocyte migration plays a key role in IBD pathogenesis; however, data on migratory properties of γδ T cells are scarce. Human circulating γδ T cells from healthy controls (n = 27), patients with active CD (n = 15), active UC (n = 14) or cutaneous manifestations of IBD (n = 2) were characterized by flow cytometry. Circulating γδ T cells in healthy controls were CD3(hi) and expressed CD45RO. They expressed gut-homing molecule β7 but not gut-homing molecule corresponding chemokine receptors (CCR)9, or skin-homing molecules cutaneous lymphocyte-associated antigen (CLA) and CCR4, despite conventional T cells containing populations expressing these molecules. CCR9 expression was increased on γδ T cells in CD and UC, while skin-homing CLA was expressed aberrantly on γδ T cells in patients with cutaneous manifestations of IBD. Lower levels of CD3 expression were found on γδ T cells in CD but not in UC, and a lower proportion of γδ T cells expressed CD45RO in CD and UC. Enhanced expression of gut-homing molecules on circulating γδ T cells in IBD and skin-homing molecules in cutaneous manifestations of IBD may be of clinical relevance