Collagens in avian neural crest development: distribution in vivo and migration-promoting ability in vitro

This study examines the spatiotemporal distribution of collagen (Col) types I-V and IX during neural crest development in vivo and their ability to support neural crest cell movement in vitro. Col I, III and IV were widespread throughout the embryo, including the neural crest migratory pathways, whereas Col II, V and IX preferentially localized to regions from which migrating neural crest cells were absent. Col I-IV and IX occurred both in association with basement membranes and within interstitial matrices, whereas Col V only was detected in juxtaposition to basement membranes. Although initially distributed throughout the rostrocaudal extent of the somitic sclerotome, Col I and III rearranged to the caudal portion with progressive neural crest cell migration through the rostral portion of the sclerotome. This rearrangement does not occur in neural crest-ablated embryos, suggesting that it is a direct consequence of neural crest cell migration. The perinotochordal matrix, avoided by neural crest cells, contained a metameric Col II/IX immunoreactivity along the rostrocaudal axis which alternated with that of Col I and III. In contrast, Col IV and V were not observed in this matrix, but lined the basement membranes of the notochord and ventrolateral neural tube. To determine their functional significance for neural crest cell migration in vivo, purified collagens were tested for their ability to promote neural crest cell motility in vitro. Neural crest cell migration on isolated collagens was most pronounced on Col I and IV, whereas Col II, V and the triple-helical fragment of Col VII were unable to support cell motility. Substrata created by copolymerization of Col I and fibronectin, or Col I and laminin-nidogen, supported cell motility better than Col I alone, whereas both Col V and a cartilage-type chondroitin sulfate proteoglycan reduced cell movement on Col I. Fibronectin bound to pre-immobilized monomeric Col I, II or V had a reduced ability to support neural crest cell movement when compared to fibronectin alone. A similar reduction was seen for Col IV bound to the low density heparan sulfate proteoglycan from the EHS mouse tumor. The results demonstrate that Col I-IX are differentially distributed in the early avian embryo. During neural crest development several of these collagens undergo dynamic reorganizations that correlate with the migration of neural crest cells. Furthermore, various collagens possess distinct abilities to support neural crest cell migration in vitro, and their migration-promoting activity can be modulated by their conformation and/or association with other matrix components

Molecular mechanisms of neural crest cell attachment and migration on types I and IV collagen

We have examined the mechanisms involved in the interaction of avian neural crest cells with collagen types I and IV (Col I and IV) during their adhesion and migration in vitro. For this purpose native Col IV was purified from chicken tissues, characterized biochemically and ultrastructurally. Purified chicken Col I and Col IV, and various proteolytic fragments of the collagens, were used in quantitative cell attachment and migration assays in conjunction with domain-specific collagen antibodies and antibodies to avian integrin subunits. Neural crest cells do not distinguish between different macromolecular arrangements of Col I during their initial attachment, but do so during their migration, showing a clear preference for polymeric Col I. Interaction with Col I is mediated by the α1β1 integrin, through binding to a segment of the α1(I) chain composed of fragment CNBr3. Neural crest cell attachment and migration on Col IV involves recognition of conformation-dependent sites within the triple-helical region and the noncollagenous, carboxyl-terminal NC1 domain. This recognition requires integrity of inter- and intrachain disulfide linkages and correct folding of the molecule. Moreover, there also is evidence that interaction sites within the NC1 domain may be cryptic, being exposed during migration of the cells in the intact collagen as a result of the prolonged cell-substratum contact. In contrast to Col I, neural crest cell interaction with Col IV is mediated by β1-class integrins other than α1β1

Bike Athlete Performance, Blog 11

Student blog posts from the Great VCU Bike Race Book

Non separable Werner states in spontaneous parametric down-conversion

The multiphoton states generated by high-gain spontaneous parametric down-conversion (SPDC) in presence of large losses are investigated theoretically and experimentally. The explicit form for the two-photon output state has been found to exhibit a Werner structure very resilient to losses for any value of the gain parameter, g. The theoretical results are found in agreement with the experimental data. The last ones are obtained by quantum tomography of the state generated by a high-gain SPDC.Comment: 16 pages, 6 figure

A Grateful Testimonial to Doug Kahn

It is difficult for me to accept the reality that Doug Kahn is about to retire after a triumphant fifty-two year tenure as a professor at the University of Michigan Law School. For much of the nearly forty-seven years of my association with the Law School, first as a student and then as an alumnus, Doug has practically symbolized the Law School for me, as he went from being a revered teacher, to a valued mentor, to a dear friend, to a colleague and co-author, and, dare I say, to virtually a member of the family. But I am only one of many Michigan students whose lives and careers were touched and positively influenced by this extraordinary scholar, superb teacher, wise mentor, and very kind-hearted man. I am and always will be grateful beyond measure that our paths crossed, and am especially grateful that it happened early enough in Doug’s teaching career to give us the opportunity to also become colleagues, co-authors, and good friends in the years since I graduated

Memory for events during the first year of life.

PsychologyDoctor of Philosophy (Ph.D.

Chiune Sugihara: A Psychohistorical Study of a Rescuer of Jews during the Holocaust

This article seeks to analyze the actions of Japanese diplomat Chiune Sugihara, a rescuer of Jews during the Holocaust, utilizing a personality model developed by social scientists Samuel and Pearl Oliner. The Oliners’s altruistic personality model centers on the idea that individuals who became rescuers have a distinct personality that responds to the complex interaction between three components: 1) the external circumstances they are confronted with; 2) internal characteristics that goad them into action; and 3) their ultimate decision to take action. Although no two‐dimensional model is ever complex enough to capture the intimate complexity of a human personality, the Oliners’s model is ideal in “fleshing out” the personality of Sugihara as very little is known of the man beyond his rescue effort; he left scant written accounts of his life

Advanced Access: Creating an Infrastructure for Success in Primary Care

The Humboldt Independent Practice Association (IPA) has sought to improve the health of Humboldt County through practice transformation efforts. To date, Humboldt IPA’s primary care practice, the Priority Care Center, is building a foundation toward an Advanced Access model of care with an overarching aim of effectively improving access to quality care in Humboldt County. The 10 Building Blocks of High Performing Primary Care Practices framework set the stage for the intervention and was used as a roadmap to build an infrastructure for success. Team-based care was highlighted as the project relied on having systems and processes that empower the entire care team to expedite or provide care whenever possible. Without systems in place to support and guide staff in caring for patients, providers are held responsible for the bulk of patient care. This project posed a solution to the inefficient use of health care staff in a provider-centered model. We used a mixed-methods approach to measure success; aggregate data was collected in the form of Likert style surveys and staff were surveyed informally through face-to-face interviews. While the necessary steps were taken to create a robust infrastructure for team-based care, there is still much work to do to reach the overarching goal of Advanced Access. Innovative practices have demonstrated improved access, efficiency, and overall satisfaction among staff and patients, however, restructuring primary care practices to support a team-based model can be daunting. It is imperative that misconceptions about role and scope of practice are addressed, and that systems are put in place to safely allow for more expanded roles for healthcare staff