Dscam Switches Slit Repulsion To Mild Attraction Via Robo Receptors

Axon guidance is a critical part of neural development, the process thatgenerates and shapes the nervous system, from the earliest stages ofembryogenesis to the last years of life. Axons navigate to reach their correcttargets via different axon guidance cues, such as Netrins and Slits. The axonalgrowth cone contains receptors that distinguish these guidance molecules andtranslates them into attractive or repulsive responses. Slit repels axons from theCNS midline by binding to the Robo (Roundabout) receptor. Netrin acts as anattractant through fra/DCC/Unc-40 and Dscam (Down syndrome cell adhesionmolecule) receptors. However, genetic evidence shows that Dscam alsoresponds to other ligand(s).We have identified Slit as an additional ligand for Dscam using both celloverlay and immunoprecipitation assays. Our results show that the Dscam onlybinds to the Slit N-terminal fragment (Slit-N), in a domain distinct from the Robobinding site. I have demonstrated that Robo preferentially binds full length Slit(Slit-FL), but in the presence of Dscam binds Slit-N. We believe that this Slit-Ndependent Dscam-Robo complex modifies Robo signaling.In vivo, slit-FL and slit-N transgenes have differential effects on motorneuron innervation of muslces that are mediated by Dscam. Overexpression ofslit-FL and slit-N at the CNS midline in a robo mutant background leads to anincrease in axon attraction to the midline. We interpret this result as evidencethat Slit has an attractive as well as a repulsive function. To test the hypothesisiithat Dscam can act as an attractive receptor for Slit, we employed a range of slittransgenes to analyze attractive functions of slit in axon guidance. Our dataargues that Slit needs to be processed to act as an axonal attractant in vivo. Weexamined the consequence of removing the Robo binding domain (LRR2) fromSlit in vivo, hoping to observe the attractive function masked by Slit’s repulsiveactivity. Instead, the transgene appears only to inhibit Dscam activity, supportinga model that Dscam requires Robo as a co-receptor.Our data suggests that Dscam binds to proteolytically processed Slit andconverts repulsion to mild attraction in the presence of Robo receptors. Our workalso suggests that, as seen for other ligands, Slit can act as both an attractantand repellent via distinct receptors, and indicates how the complexity of thenervous system can arise through a relatively small number of ligands

PANEL 4 ORGANIZATIONAL TRANSFORMATION IN THE INFORMATION AGE

The issues addressed by this panel are complex but urgent. Large multinational companies and public agencies are reaching a limit of structural complexity but not of growth. This is evidenced by increases in layers of management and staff, administrative overhead, and more formal control and reporting systems. Redesign of organizations via information technologies offers the chance to create or restore organizational simplicity. Furthermore, information technologies can provide an opportunity for creating organizational structures that are more adaptive, responsive, and flexible. This will be essential for any organization to be able to deal with increasing environmental turbulence in terms of intense cost pressures, internationalization across industries, and the breaking down of traditional industry boundaries. This panel aims at answering the question How can information technologies be effectively used as a base for organizational redesign and reclustering? More specifically, the panel will focus on: Emerging New Organizational Forms New models are needed for organizational redesign and structuring aimed at achieving adaptability and responsiveness. These models must provide the freedom to respond to increasing complexity in a new business era. Business teams and interorganizational relationships represent examples of new organizational approaches. The panel focuses on the new approaches and the role of information technologies in their implementation. Role of Information Technologies as an Enabling or Inhibiting Factor This panel also addresses how an organization\u27s existing base of technology impacts the implementation of new organizational forms. Organizations must become more flexible to survive in today\u27s hostile business environment. This flexibility allows companies to respond to threats in a timely fashion and be proactive in business. Information technologies can play a key role in enabling the next generation of organizational structures by providing a flexible and responsive infrastructure, but, in fact, these infrastructures are often not flexible and have become a barrier to organizational change. New Paradigm for Study of Organizations in Action The traditional concept of an organization is no longer useful to managers or students of organizations. It is dominated by models of structure and physical identity. New distinctions to describe organizations in action are needed. The Panel discusses possibilities of implementing plans for organizational design that involve information technologies. This panel will enhance the attendees understanding of the issues and intricacies of organizational transformation in the information age

Electronic Mail Usage Pattern of Emergent Leaders in Distributed Teams

We conducted an exploratory study to examine the unique electronic mail usage patterns exhibited by the emergent leaders in seven teams of senior executives of a federal government agency. The team members worked together over ten weeks via electronic mail in the context of an executive development program. The goal of the analysis was to identify the distinct patterns of communication behaviors among emergent leaders in distributed teams that differentiate them from other team members. To this end, we conducted a content analysis of 327 electronic mail messages that were sent to the list-serve, using a coding scheme developed based on the existing leadership and small group literature. We examined the communication frequency, the message type (task-oriented, people-oriented, and technology-oriented), and the message length. Our results provide four main observations regarding emergent leadership in distributed teams: (1) overall, the emergent leaders sent more messages than other members did; (2) the emergent leaders sent more task-related messages than other members did; (3) the emergent leaders sent longer messages than other members did; and (4) demographic variables such as age, job experience, and experience at the current position did not affect emergent leadership

Information Technology and Organizational Learning: An Investigation of Exploitation and Exploration Processes

This study investigates the effects of information technology on exploration and exploitation in organizational learning. We extend an earlier computational model of organizational learning and introduce learning between individuals through three distinct mechanisms: face-to-face exchange, IT-enabled communication support, and knowledge repositories. Each of these mechanisms has a distinct effect upon the exploration and exploitation dynamics in organizational learning, and we conclude that these capabilities offer firms a more robust ability to manage the exploration and exploitation balance in organizational learning

Knowledge Management Systems: Issues, Challenges, and Benefits

The knowledge-based theory of the firm suggests that knowledge is the organizational asset that enables sustainable competitive advantage in hyper-competitive environments. The emphasis on knowledge in today\u27s organizations is based on the assumption that barriers to the transfer and replication of knowledge endow it with strategic importance. Many organizations are developing information systems designed specifically to facilitate the sharing and integration of knowledge. Such systems are referred to as Knowledge Management System (KMS). Because KMS are just beginning to appear in organizations, little research and field data exists to guide the development and implementation of such systems or to guide expectations of the potential benefits of such systems. This study provides an analysis of current practices and outcomes of KMS and the nature of KMS as they are evolving in fifty organizations. The findings suggest that interest in KMS across a variety of industries is very high, the technological foundations are varied, and the major concerns revolve around achieving the correct amount and type of accurate knowledge and garnering support for contributing to the KMS. Implications for practice and suggestions for future research are drawn from the study findings

Casting the Net: A Multimodal Network Perspective on Knowledge Management

Recent information systems research has challenged the tendency of researchers to focus upon single information system (Vertegaal 2003) or upon individuals simply as users of those systems (Lamb and Kling 2003). Responding to these critiques, this paper forwards a new paradigm through which to study knowledge management: the multimodal knowledge network. Drawing heavily upon the field of social network research, we argue that the way in which multiple individuals interact with one another and with multiple information management systems will have significant implications for organizational knowledge sharing outcomes. In this study, we conduct a comparative case study through which to begin building a theory of multimodal knowledge networks. We study five health care teams in a large health maintenance organization and find that, although these teams have identical portfolios of information management systems and a similar complement of employees, each team configures its knowledge resources differently to complete similar tasks. We find that the structures that result from these multiple interpersonal and human–systems interactions have implications on knowledge outcomes for the network. We develop propositions as a result of this analysis and outline directions for future research

Efficacy and side effects of distal vein ligation in arterio-venous fistulas of the snuff-box region in chronic renal failure patients

چکیده: زمینه و هدف: فیستول شریانی وریدی در ناحیه Snuff box یکی از تکنیک های رایج فیستول گذاری در بیماران دیالیزی می باشد. هدف از این مطالعه مقایسه کارآیی و عوارض بستن و نبستن دیستال ورید در فیستول های شریانی وریدی در ناحیهSnuff box در بیماران مبتلا به نارسایی مزمن کلیه بود. روش بررسی: در این مطالعه کارآزمایی بالینی 60 بیمار ( 30 مرد، 30 زن) با نارسایی مزمن کلیه که برای فیستول گذاری مراجعه کرده بودند به روش آسان انتخاب و به طور تصادفی به دو گروه 30 نفره تقسیم شدند. در گروه اول پس از گذاشتن فیستول شریانی وریدی (AVF) دیستال ورید بسته شد و در گروه دوم بسته نشد. بیماران در روزهای 1، 30 و 90 پس از جراحی از نظر عملکرد فیستول و عوارض مورد بررسی قرار گرفتند. داده ها به کمک آزمون های آماری t دانشجویی و کای دو تجزیه و تحلیل شد. یافته ها: کارآیی زودرس در دو گروه لیگاتور شده و لیگاتور نشده به ترتیب 100 و 7/96 درصد و کارآیی دیررس به ترتیب 90 و 4/83 درصد بود (05/0P). هایپرتانسیون وریدی و ادم در دو بیمار (هر دو در گروه لیگاتور نشده) و عفونت محل عمل تنها در یک بیمار مشاهده شد. نتیجه گیری: با توجه به کارآیی بالا و عوارض اندک، فیستول های شریانی وریدی، ناحیه Snuff-box یکی از راه های ارجح عروقی ممکن برای بیماران همودیالیزی است. بستن دیستال ورید سبب می شود که عارضه هایپرتانسیون وریدی در فیستول ایجاد نشود

THE ECOLOGY OF MIS RESEARCH: A TWENTY YEAR STATUS REVIEW

The debate concerning the legitimacy of MIS as a field of research has endured over the last decade. The absence of theories and lack of a cumulative research tradition have been areas of particular concern. The research reported in this article provides evidence on these important issues. The study systematically analyzed MIS articles in seven core journals over the period 1968-1988. The resulting database, consisting of 792 articles, was analyzed for themes and topics, and on the basis of type of article (empirical/non-empirical). The findings indicate that MIS research efforts have refocused in some areas, while much remains to be done in others. This study provides the opportunity to pause and reflect on the last twenty years of research in MIS and to take stock so that the research of the coming twenty years will extend and build upon the existing foundations