Skeletal shape varies widely across species as adaptation to specialized modes of feeding and locomotion, but how skeletal shape is established is unknown. An example of extreme diversity in the shape of a skeletal structure can be seen in the sternum, which varies considerably across species. Here we show that the Dchs1–Fat4 planar cell polarity pathway controls cell orientation in the early skeletal condensation to define the shape and relative dimensions of the mouse sternum. These changes fit a model of cell intercalation along differential Dchs1–Fat4 activity that drives a simultaneous narrowing, thickening and elongation of the sternum. Our results identify the regulation of cellular polarity within the early pre-chondrogenic mesenchyme, when skeletal shape is established, and provide the first demonstration that Fat4 and Dchs1 establish polarized cell behaviour intrinsically within the mesenchyme. Our data also reveal the first indication that cell intercalation processes occur during ventral body wall elongation and closure.

<h4>ABSTRACT</h4> <P>A generational age transformation is occurring in nursing classrooms across the United States. Nurse educators need to prepare for the different values and expectations of students from Generation X and the newly emerging Generation Y in the educational environment. This quantitative, descriptive research begins to examine the preferences and expectations of these generations regarding teaching methods. </P> <h4>AUTHORS</h4> <P>Received: September 29, 2004</P> <P>Accepted: May 20, 2005</P> <P>Dr. Walker and Dr. Elliott are Associate Professors, Dr. Martin, Ms. Norwood, Mr. Mangum, and Dr. Haynie are Assistant Professors, and Ms. White is Instructor, The University of Mississippi Medical Center, School of Nursing, Jackson, Mississippi. </P> <P>Address correspondence to Jean T. Walker, PhD, RN, Associate Professor, The University Mississippi Medical Center, School of Nursing, 2500 North State Street, Jackson, MS 39216; e-mail: <a href="mailto:jwalker@son.umsmed.edu">jwalker@son.umsmed.edu</a>. </P>

The protocadherins Fat4 and Dchs1 act as a receptor-ligand pair to regulate many developmental processes in mice and humans, including development of the vertebrae. Based on conservation of function between Drosophila and mammals, Fat4-Dchs1 signalling has been proposed to regulate planar cell polarity (PCP) and activity of the Hippo effectors Yap and Taz, which regulate cell proliferation, survival and differentiation. There is strong evidence for Fat regulation of PCP in mammals but the link with the Hippo pathway is unclear. In Fat4 −/− and Dchs1 −/− mice, many vertebrae are split along the midline and fused across the anterior-posterior axis, suggesting that these defects might arise due to altered cell polarity and/or changes in cell proliferation/differentiation. We show that the somite and sclerotome are specified appropriately, the transcriptional network that drives early chondrogenesis is intact, and that cell polarity within the sclerotome is unperturbed. We find that the key defect in Fat4 and Dchs1 mutant mice is decreased proliferation in the early sclerotome. This results in fewer chondrogenic cells within the developing vertebral body, which fail to condense appropriately along the midline. Analysis of Fat4;Yap and Fat4;Taz double mutants, and expression of their transcriptional target Ctgf, indicates that Fat4-Dchs1 regulates vertebral development independently of Yap and Taz. Thus, we have identified a new pathway crucial for the development of the vertebrae and our data indicate that novel mechanisms of Fat4-Dchs1 signalling have evolved to control cell proliferation within the developing vertebrae.

Studies report that students in health care professions do not retain knowledge of infection control and demonstrate poor hand hygiene compliance. This study describes the effect of a multifaceted approach (education, skills training, and monitoring) on nursing students' knowledge of infection control principles, opinions, hand hygiene practices, and value of nursing research in evidence-based practice. Students participated in hand hygiene monitoring of health care workers with 900 observations. Students demonstrated strong knowledge of hand hygiene principles: 63% reported that hand hygiene monitoring positively influenced their own compliance. Although posters have been identified as effective prompts, students did not perceive poster reminders as effective in prompting handwashing. Students reported that hand hygiene activities helped them value the role of the nurse in research and evidence-based practice. This study may help educators clarify misconceptions that result in student noncompliance in hand hygiene practices.

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