In situ analysis of neuronal dynamics and positional cues in the patterning of nerve connections

Recently developed imaging techniques permit individual cells to be uniquely labeled and followed over time as development proceeds in intact vertebrate embryos. Small groups of cells in the developing eye rudiment of the frog Xenopus have been labeled with the vital dyes DiI, lysinated fluorescein dextran (LFD) or lysinated rhodamine dextran (LRD). Individual optic axons and their growth cones were clearly visible in the intact living animal using confocal microscopy or epifluorescence microscopy with a low light level video camera and computer-based video image enhancement. To follow the dynamics of single optic nerve fiber terminal arborizations, small groups of cells, or even single retinal ganglion cells, were labeled with DiI, and the resulting labeled optic nerve fibers were imaged using a confocal microscope. The images show a profound alteration in morphology from day to day, demonstrating that optic nerve terminal arborizations are dynamic structures constantly extending and retracting branches. To follow the topography of the developing projection and analyze the cues that guide its formation, small groups of eyebud cells from LFD- and LRD-labeled donor embryos were grafted to an unlabeled host in either a location equivalent to that from which they had been removed (homotopic grafts) or a non-equivalent location (heterotopic grafts). Axons from homotopic grafts projected to the tectum as expected from the adult topography of the retinotectal projection. Dorsoventral topography was present from the time that the optic nerve fibers were observable in the tectum, in agreement with previous work. Nasotemporal topography was subtle or absent for the first few days, and then slowly refined. The importance of positional cues was tested by performing heterotopic eyebud grafts, in which the labeled eyebud cells are grafted to inappropriate places in the host eyebud. The heterotopic grafts appeared to integrate with the ectopic site in the eyebud in a functional manner. They should, therefore, project to the tectum together with their new neighbors if neighbor interactions or activity-based cues were of primary importance in the initial patterning of the map. However, the experiments showed that the axons from heterotopic grafts always behaved in a fashion appropriate to their position of origin in the donor, regardless of their final position in the host. These observations indicate that small groups of eyebud cells (as small as a single cell) possess positional information that plays a dominant role in guiding the optic nerve fibers to their target sites in the tectum

EFFECTS OF A VISUAL BARRIER FENCE ON THE BEHAVIOR AND MOVEMENTS OF BLACK-TAILED PRAIRIE DOGS

Prairie dogs prefer an open view of their surroundings and may abandon an area with visual obstructions. We examined the effects of a visual barrier fence, which had a see-through visibility of 60%, on the foraging, vigilance, and aggressive behaviors of adult female black-tailed prairie dogs (Cynomys ludovicianus) in central Nebraska. We expected animals near a visual barrier to spend more time in vigilance and less time foraging. Adult female prairie dogs exposed to a visual barrier spent a greater amount of time foraging and less time in a headbob position than those not exposed to a fence (P = 0.087, P = 0.015). We also examined changes in prairie dog home ranges and use of an area in response to these visual barrier fences, expecting that prairie dogs would move away from fences over a 54-day period. If they invaded other territories, we expected to see more aggression on colonies with a fence. The size, shape, and location of home ranges and core activity areas of adult females did not change over time as a result of the presence of a visual barrier fence. We observed only 1 act of aggression during the study period. This apparent lack of aggression is likely due to the fidelity of study animals to established home ranges. The number of prairie dogs using areas at various distances from a visual barrier fence also did not change over this time (P \u3e 0.90). These results indicate that the visual barrier fence tested did not cause prairie dogs to be more vigilant and aggressive, nor did it affect their pre-established spatial use within the colony

Responses of a Spotted Turtle (\u3cem\u3eClemmys guttata\u3c/em\u3e) Population to Creation of Early-successional Habitat

The maintenance or creation of early successional habitat is commonly employed by natural resource managers, often for the benefit of native wildlife. In southern New England, USA, forest succession has reduced the amount of early successional habitat on the landscape making the creation of such habitat a management priority in the region. However, questions remain regarding the impacts of the creation of early successional habitat on certain species, especially those that are associated with late successional habitats. We conducted a radio-telemetry study of Spotted Turtles (Clemmys guttata) in Rhode Island, USA, for one year before, and one year after a 3-ha forest clear-cut in close proximity to wetlands known to contain a resident population of the species. The annual home range size of turtles was 18.5% larger post-cut, possibly due to changes in the distribution of resources and suitable habitat after the harvest. However, turtles exhibited fidelity to hibernacula and communal overwintering, despite nearby disturbance, and patterns of activity and habitat use were similar in both years and were generally consistent with those of other Spotted Turtle populations. Our results suggest that timber harvesting of this spatial scale and management approach may not have any short-term effects on the spatial ecology or habitat use of populations of Spotted Turtles, but further research is needed to understand longer-term effects. We strongly recommend that the timing of clear-cut harvesting be restricted to outside of the region-specific activity season of this species and that land managers avoid significant disturbance to wetlands containing Spotted Turtles, especially those containing hibernacula

The pharmacokinetics of nebulized nanocrystal budesonide suspension in healthy volunteers.

Nanocrystal budesonide (nanobudesonide) is a suspension for nebulization in patients with steroid-responsive pulmonary diseases such as asthma. The pharmacokinetics and safety of the product were compared to those of Pulmicort Respules. Sixteen healthy volunteers were administered nanobudesonide 0.5 and 1.0 mg, Pulmicort Respules 0.5 mg, and placebo in a four-way, randomized crossover design. All nebulized formulations were well tolerated, with no evidence of bronchospasm. Nebulization times were significantly shorter for nanobudesonide compared to Pulmicort Respules. Because of a low oral bioavailability, plasma concentration of budesonide is a good marker of lung-delivered dose. The pharmacokinetics of nanobudesonide 0.5 and 1.0 mg were approximately dose proportional with respect to Cmax, AUC(0-t), and AUC(0-infinity). Nanobudesonide 0.5 mg and Pulmicort Respules 0.5 mg exhibited similar AUCs, suggesting a similar extent of pulmonary absorption. A higher Cmax was noted with nanobudesonide 0.5 mg, and the tmax was significantly different, suggesting a more rapid rate of drug delivery of nanobudesonide 0.5 mg than Pulmicort Respules. In conclusion, nebulized nanobudesonide 0.5 mg was safe in healthy volunteers, with a similar extent of absorption as Pulmicort Respules

Nurses\u27 Alumnae Association Bulletin, May 1963

President\u27s Letter Alumnae Meetings, 1962 Building Fund Mediocrity Hospital Report Alumnae Notes Social Committee Student Activities Marriages, New Arrivals and Necrology Annual Giving Fund Driv

Working Partnerships, Partnerships Working

Involvement in community partnerships at Virginia Commonwealth University has its roots in the institution\u27s history. The Medical College of Virginia, founded in1838, and the Richmond Professional Institute, founded in 1917, both sought to extend knowledge into the community to change peoples\u27 lives for the better. Today, the VCU campuses are even more entwined with the City of Richmond -- physically, and increasingly so as a partner in the economic and social challenges and opportunities facing the City

Increasing Aging Content within the Social Work Curriculum: Perceptions of Key Constituents

This mixed methodology study examines the perceptions of key constituents regarding methods for effectively integrating aging content into the foundation curriculum of the BSW and MSW program at the University of Georgia School of Social Work. Students were asked to complete a survey to determine their perception of geriatric content that existed within the foundation coursework. Following an analysis of the survey results, eight semi-structured focus group discussions were conducted with a purposeful sample of students, faculty, field instructors, social work alumni, older adults from the community, and representatives from aging agencies. The intention of these focus groups was to find out what aging content should be infused within the curriculum. The focus group meetings were held in various locations throughout Northeast Georgia and in one remote location in South Georgia. Participants were interviewed about the necessary skills and knowledge for social workers practicing with an aging population in the areas of: essential intervention skills, program policies and regulations, critical information needed to develop client service plans, strategies for addressing service delivery fragmentation, and community collaboration to support intergenerational family needs. The results of this study will be discussed to provide suggestions on how existing foundation courses can integrate aging content

Polaris: Mass and Multiplicity

Polaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide ($18''$) physical companion, the F-type dwarf Polaris B. Polaris itself is a single-lined spectroscopic binary with an orbital period of 30 years (Kamper, 1996, JRASC, 90, 140). By combining {\it Hipparcos} measurements of the instantaneous proper motion with long-term measurements and the Kamper radial-velocity orbit, Wielen et al. (2000, A&A, 360, 399) have predicted the astrometric orbit of the close companion. Using the {\it Hubble Space Telescope} and the Advanced Camera for Surveys' High-Resolution Channel with an ultraviolet (F220W) filter, we have now directly detected the close companion. Based on the Wielen et al. orbit, the {\it Hipparcos} parallax, and our measurement of the separation ($0.176''$ $\pm$ $0.002''$), we find a preliminary mass of 5.0 $\pm$ 1.5 M$_{\odot}$ for the Cepheid and 1.38 $\pm$ 0.61 M$_{\odot}$ for the close companion. These values will be refined by additional {\it HST} observations scheduled for the next 3 years. We have also obtained a {\it Chandra} ACIS-I image of the Polaris field. Two distant companions C and D are not X-rays sources and hence are not young enough to be physical companions of the Cepheid. There is one additional stellar X-ray source in the field, located $253''$ from Polaris A, which is a possible companion. Further investigation of such a distant companion is valuable to confirm the full extent of the system.Comment: submitted to Conference Proceedings of IAU Symp. 24