Uterine defences against bacterial challenge are more efficient during oestrus than during dioestrus. The exact reasons and mechanisms responsible for this difference are, however, still incompletely understood. The leukocyte reaction is one of the defence mechanisms that has been cited as being able to respond better to a bacterial challenge during oestrus than during dioestrus. The aim of the present study was to test the hypothesis that the magnitude of endometrial leukocyte migration following the instillation of semen into the uterine lumen is greater during oestrus than during dioestrus. Eight Nooitgedacht mares of normal fertility, aged between 8 and 16 years (11.5 ± 2.7; mean ± SD), were used in the study. Each mare received a different treatment during each of four oestrous cycles, with a rest cycle after each treatment. Two treatments were performed during dioestrus and two during oestrus. One treatment for each stage of the cycle was a control treatment without challenge to the endometrium. At time zero of challenged cycles a single aliquot of 13 ml raw semen, frozen-thawed without addition of any cryoprotectant or extender, was instilled into the uterus. An endometrial biopsy was taken 6 and 48 h after time zero and a swab for cytology and culture (if cytology was positive) was collected 48 and 120 h after time zero. An image analyzer was used to record the total number of cells, round cells, neutrophils and eosinophils per unit surface area of epithelium, stratum compactum (SC) and stratum spongiosum (SS). The relative number of round cells, neutrophils and eosinophils were expressed as proportions of the number of each cell type to the total number of cells. The use of an image analyser made the collection of quantitative data from histologic sections possible. However, the operator still had to make some critical decisions, namely to choose the field of the section for analysis and to assign individual cells to a chosen category. The total numbers of cells in the epithelium and the SS were greater during dioestrus than during oestrus, while no such difference could be demonstrated for the SC. The stage of the oestrous cycle had no meaningful influence on any other (measured or calculated) variable. During challenged cycles, absolute and relative numbers of neutrophils were significantly greater in the epithelium, SC and SS than during control cycles. There was an interaction (not always reaching significance) between treatment and time with regard to the absolute and relative numbers of neutrophils in epithelium and SS and round cells in the epithelium. Numbers of neutrophils and round cells were significantly higher 6 h after treatment than 48 h after treatment in challenged cycles, but did not differ during control cycles. During challenged cycles, the stage of the oestrous cycle when treatment occurred had no effect on the duration of the induced endometritis, the occurrence of positive cytology or culture results, or the type of bacteria that were cultured. Regardless of the stage of their cycles when they were challenged, all mares rid themselves of the opportunistic pathogens placed into the uterine lumen within one oestrous cycle. The hypothesis was rejected and it is therefore concluded that the stage of the oestrous cycle did not influence the magnitude of the endometrial leukocyte response to a standardized challenge with semen in these reproductively sound mares. A similar study will be required to test whether this conclusion also holds true for mares that are susceptible to endometritis. / Dissertation (MMedVet (Gyn))--University of Pretoria, 2006. / Production Animal Studies / unrestricted

Borrelia burgdorferi is the etiological agent of Lyme disease. Not much is known about the susceptibility of this organism to chemical disinfection. Current antimicrobial susceptibility test methods, such as those published by the American Society for Testing and Materials (ASTM), usually require assessment of the number of colony forming units (cfu) of growing organisms on plates following exposure to an agent. For fast-growing organisms, plates are ready for counting 1-2 days post plating, while several weeks may be needed for slower growing organisms. Spirochetes, like B. burgdorferi are difficult to grow on solid media and typically require long incubation periods, sometimes up to several weeks, to generate visible colonies. These issues make B. burgdorferi cfu assessment by plate counting difficult and unreliable. Furthermore, Borrelia have a demonstrated capacity for pleomorphic forms, and can exist in spirochete, round body, or biofilm forms, depending on culture conditions. Plate counts, by nature, do not allow for assessment of morphological form changes. Additionally, the susceptibility of B. burgdorferi pleomorphic forms to chemical disinfectants has not been tested. In this study, we used the SYBR GREEN I/Propidium Iodide (SG I/PI) viability assay to rapidly estimate the percent kill of B. burgdorferi pleomorphic forms to chemical disinfection. Planktonic spirochete populations in 30-second treated samples showed viability percent values of: >95% for Hanks balanced salt solution (HBSS), ~60% for distilled deionized H2O (dd H2O), <5% for ACS 200, and 1% for 1% glutaraldehyde (GTA). Solutions containing 70% ethanol (ETH) and 1% hypochlorite (HC) showed no viable spirochetes following treatment. The percent of live round body cells following different treatments were: >99% for HBSS and <25% for dd H2O. ACS 200, 1% GTA, and 70% ETH treatments resulted in <1% live round body forms, whereas HC showed no live round cell forms. The susceptibility of B. burgdorferi biofilms to various treatments was also assayed using a SG I/PI viability stain after 30-minute contact times. The percent of viable organisms (green) in the treated biofilms was estimated by microscopic observations. HBSS controls showed >98% of bacteria in the biofilm were alive, while treated biofilms showed the following percent viabilities: ACS 200 - ~2%, 1% HC - <1%, 5% HC - <1%, 1% GTA - ~10%, 70% ETH - ~ 2%, and dd H2O ~40%. These techniques merged standardized assessment of antimicrobial activity in liquid culture using an ASTM-type kill-time procedure with viability techniques used in antibiotic susceptibility testing to rapidly evaluate the percent kill of B. burgdorferi pleomorphic forms in vitro following disinfectant exposure. These results showed that B. burgdorferi biofilm forms are orders of magnitude more resistant to chemical disinfection than other morphological forms of this organism.

The purpose of this study was to examine multi-track Year-Round Education (YRE) elementary school principals' perceptions of the effects of YRE on their instructional leadership activities. A review of the related literature revealed that principals perceived that multi-track YRE has increased their management activities. A questionnaire was developed and sent to a selected sample of 105 principals who served at multi-track (60-20 calendar) YRE elementary schools with grade level configurations of K-5 and K-6. In addition. the principals selected for this study had prior experience as principal s of traditional calendar schools and were assigned full-time administrative assistance (e.g., vice-principal. assistant principal, or equivalent). Ten of 64 principals who returned completed questionnaires were interviewed.

The Round Barn is a novel in two parts that tells the story of two Iowa farm families during the period 1915 to 1929, a volatile time in the history of the American farm. The first part of the novel tells the story of Joe Marshall, a young man in conflict with his hard-working farmer father. At sixteen-years-old, Joe must choose whether to leave the farm to pursue his own desires or to stay where he is needed to help keep his financially strapped family afloat. Part two of the novel focuses on Mae Allinson, a woman in her early twenties, who has willingly accepted the responsibility of raising her sister's child after her sister dies in childbirth. By doing so, Mae forsakes the man she was to marry, the man who would take her to Chicago and away from farm life. The round barn, built by Joe Marshall's father in the opening chapter of the novel, serves as a through line linking all the chapters and connecting characters to a specific place. The round barn, in addition to being a stage setting for the action of the novel, has its own story arc, rising out of the Iowa soil in the first chapter, functioning as a working barn through the central part of the novel, then finally falling into disrepair by the end. In the novel, Joe and Mae each seek their own identities within their families, identities that put them in conflict with a family dynamic that is focused on the survival and prosperity of the family as a whole. This conflict forces each character to define for themselves what love, power, freedom, and obligation mean and how far they are willing to go inpursuit of these things. In addition to functioning within their own families, the main characters must also contend with the larger issues that put pressure on the American farm of the time (economics, war, social change, and migration to the urban areas), factors that push and pull the characters in different directions. By telling the story from the positions of two different characters and by spanning the number of years that it does, the novel seeks to show how events and the passage of time transform the individual characters, their families, and the American farm.

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