Synthesis and characterization of the colistin peptide polymyxin E1 and related antimicrobial peptides.

Two strategies were developed to synthesize the acylated cyclic peptides know as polymyxins. Synthesis of polymyxin E1 and several analogs enabled us to evaluate the minimum inhibitory concentration of individual compounds against Gram-negative bacteria. In this study we also report the first identification of two component peptides in the complex polymyxin fermentation product colistin, a Thr2Ser isoform and an acyl group isomer. Both of these peptides, as well as a known component peptide, Leu7Ile, were similar to polymyxin E1 in potency, suggesting that conservative mutations in the colistin family are functionally inconsequential. In contrast, the acyclic analogs of all of these peptides were inactive, indicating that the characteristic lariat structure of the polymyxins is necessary for antimicrobial activity.

In vitro maintenance, cooling and cryopreservation of red wolf (Canis rufus) spermatozoa.

A current priority for the preservation of the endangered red wolf (Canis rufus) is the development of a sperm-based genome resource bank. The aims of this study were to examine the effects of (i) holding temperature on the motility of spermatozoa over time, and (ii) cooling methods on the characteristics of spermatozoa after cooling and cryopreservation. Electroejaculates (n = 11; fresh) were evaluated for the percentage of motile spermatozoa, cell and acrosome morphology (Spermac (Meditech 1st Canada Inc, Montreal, Ontario) and fluorescein isothiocyanate-labelled Pisum sativum agglutinin lectin (PSA/FITC; Sigma Diagnostics, Oakville, Ontario) staining), and zona penetration. Semen samples were then divided into two equal samples and centrifuged to remove seminal plasma. One half of the ejaculate sample was re-suspended in sperm-Tyrode's albumin lactate pyruvate (TALP), divided into three aliquots and maintained either at room temperature (approximately 21-23 degrees C), 0 degree C or 37 degrees C. Sperm motility was examined at 0.5 and 1.0 h, and subsequently every hour for 10 h. Motility of spermatozoa decreased after 2 h, but was consistently greater at room temperature than at 37 degrees C or 0 degree C. The other half of the ejaculate sample was re-suspended in an egg yolk-based extender and divided into two aliquots. One aliquot was cooled in a refrigerator (5 degrees C) for 30 min, whereas the second aliquot was put into a beaker containing water at 37 degrees C, which was then placed into an ice bath until the sample reached 0 degree C (approximately 120 min). Spermatozoa were evaluated after cooling and after freezing and thawing treatments. No differences were observed between cooling treatments either after cooling or freezing and thawing. However, marked decreases in intact acrosomes, post-thaw motility and normal morphology of spermatozoa after treatment demonstrate that further investigations are necessary to improve cryopreservation methods in this species.

Piecing together the puzzle of carnivore reproduction.

Recent advances in feline and canine reproductive studies demonstrate how methodically piecing this information together is beginning to reap rewards for wildlife conservation programs. Non-invasive endocrinology can be used to monitor female reproductive function, time con-specific introductions or AI, and diagnose pregnancy. Sperm morphology characteristics and cell membrane function may be genetically inherited and differ between genetically diverse and inbred species/populations in felids. It is not clear if the same is true for the endangered red wolf. While standards exist for freezing feline and canine sperm, new information using fluorescent staining and zona penetration assays (ZPA) indicates that significant damage can occur during pre-freeze cooling, and may also be related to a species' genetic diversity. Posthumous gamete salvage from genetically valuable animals not only provides a means to study sperm and oocyte physiology but also to assist with genetic management of populations. Using the knowledge gained, IVM/IVF and ICSI have been successful in the domestic cat and AI has resulted in offspring in numerous non-domestic felids. However, understanding the processes of IVM/IVF is still not well understood in canids. New information reveals that sperm and the cumulus cells may be integral to oocyte maturation and that canine epididymal sperm are not capable of undergoing fertilization. The acquisition of knowledge and application of biotechnologies lags behind for non-domestic canid conservation programs.

Mercury levels in Great Lakes herring gull (Larus argentatus) eggs, 1972-1992.

Since 1971, the herring gull (Larus argentatus) has been used as a sentinel species for monitoring the levels of persistent contaminants in the Great Lakes ecosystem. In this study, 21 herring gull colonies in the Great Lakes and connecting channels were sampled during 1972-1976, 1981-1983, 1985 and 1992. For each year, 10 eggs (usually) were collected from each colony site and analyzed for total mercury (microg/g, wet wt). Results indicated that eggs from Lake Ontario displayed the highest lake-wide mercury levels (0.28-0.73 microg/g), followed by Lake Superior (0.21-0.50 microg/g). Lake Erie typically displayed the lowest mercury levels (0.18-0.24 microg/g). Overall, mercury levels ranged from 0.12 microg/g in 1985 to 0.88 microg/g in 1982 for Channel Shelter Island (Lake Huron) and Pigeon Island (Lake Ontario), respectively. Generally, all colony sites showed peak egg mercury levels in 1982. A significant decline in egg mercury levels was observed in five colony sites for the period 1972-1992 and in three different colony sites for the period 1981-1992. Mercury levels in the eggs of herring gulls for the period of this study were below levels associated with acute toxic effects in this species but were within a range, for certain years, which potentially reduces hatchability in other avian species.

Hospital of the Future--not just technology "talk".

Technology is gaining increasing attention and competitive importance in the healthcare industry, but healthcare administrators need more than just talk to make effective technology investments. Andersen Consulting and the American College of Healthcare Executives have created Hospital of the FutureSM, in Dallas, Texas, as a dynamic, evolving research and demonstration forum that allows healthcare administrators and providers to see potential technology solutions in action--in healthcare settings specifically designed to look and feel like the real thing. This article discusses the functionality and technical structure of Hospital of the Future, as well as the integration issues among disparate healthcare systems addressed in developing the display.

The Survey of Achievement Responsibility (SOAR): reliability and validity data on an academic attribution scale.

The Survey of Achievement Responsibility (SOAR) was designed to assess students' causal attributions of success and failure in school-related situations. Unlike other measures of locus of control and attributions, the SOAR simultaneously distinguishes among three broad subject areas--math/science, language arts/social studies, and physical education--and between two possible outcomes--success and failure. Data on the psychometric characteristics of the SOAR came from two samples from each of two large school districts, one suburban and one metropolitan. A five-stage study of the psychometric qualities of this new instrument revealed: (a) Content validity is high--judges independently classified items into the attribution categories intended by the authors; (b) internal consistency reliabilities are in a range adequate for group research purposes and are comparable to the reliabilities of other measures of attributions; (c) test-retest reliabilities showed attribution profiles to be stable over a 2-month interval; (d) correlations between the SOAR scales and students' self-reports of ability in various subject areas showed differential relationships in theoretically predicted directions; and (e) correlations between the SOAR scales and achievement tests were statistically significant, though low in magnitude, consistent with reports on other instruments. Finally, use of the SOAR in a spectrum of studies has demonstrated its research utility and indicated directions for further instrument development and research.