1,120 research outputs found

    Enhancing the yield of target tissue and secondary metabolites in Calendula officinalis L., a medicinal plant.

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    Medicinal crops can be usefully studied in controlled hydroponic systems in which various factors can be manipulated to increase target plant tissue yield and secondary metabolite production. In this project floral tissue and other plant organs of the medicinal plant Calendula officinalis and four important secondary metabolites: quercetin, rutin, isorhamnetin-3-O-glucoside and isorhamnetin-3-rutinoside were quantified under contrasting conditions in terms of phosphorus concentration, rate of nutrient supply and simulated foliar herbivory in a factorial experimental design. The objectives were to identify conditions that will maximize the yield of target plant tissue, maximize the production of secondary metabolites and minimize the variation in that value. Phosphorus concentration was varied because this nutrient is important for plant growth, particularly during flower production. Nutrient supply rates used in this study sought to minimize nutrient deficiencies and growth fluctuations. Selected plants in the study were also subjected to a clipping treatment, as numerous studies have shown that herbivory can induce increased growth ( overcompensation ) and potentially to stimulate secondary metabolite production. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .S74. Source: Masters Abstracts International, Volume: 42-01, page: 0150. Adviser: Lesley Lovett-Doust. Thesis (M.Sc.)--University of Windsor (Canada), 2003

    The 2004 Claremont Debate: Lipsey vs. Scriven

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    While there is little disagreement about the need for, and value of, program evaluation, there remain major disagreements in the field about best practices (Donaldson & Lipsey, in press). For example, Donaldson and Scriven (2003) invited a diverse group of evaluators to Claremont in 2001 to share their visions for “how we should practice evaluation” in the new millennium. Theorists and practitioners discussed a wide range of views and evaluation approaches, many at odds with one another, on how best to improve evaluation practice (e.g., the experimental paradigm, evaluation as a transdiscipline, results-oriented management, empowerment evaluation, fourth generation evaluation, inclusive evaluation, theory-driven evaluation and the like). In response to some of the heated exchanges, Mark (2003) noted “it seems ironic when evaluators who espouse inclusion, empowerment, and participation would like to exclude, disempower, and see no participation by evaluators who hold different views.” Hefurther concluded that whatever peace has been achieved in the so-call quantitative-qualitative paradigm wars remains an uneasy peace

    Universal screening for meticillin-resistant Staphylococcus aureus : interim results from the NHS Scotland pathfinder project

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    Following recommendations from a Health Technology Assessment (HTA), a prospective cohort study of meticillin-resistant Staphylococcus aureus (MRSA) screening of all admissions (N = 29 690) to six acute hospitals in three regions in Scotland indicated that 7.5% of patientswere colonised on admission to hospital. Factors associated with colonisation included re-admission, specialty of admission (highest in nephrology, care of the elderly, dermatology and vascular surgery), increasing age, and the source of admission (care home or other hospital). Three percent of all those who were identified as colonised developed hospital-associated MRSA infection, compared with only 0.1% of those not colonised. Specialtieswith a high rate of colonisation on admission also had higher rates of MRSA infection. Very few patients refused screening (11 patients, 0.03%) or had treatment deferred (14 patients, 0.05%). Several organisational issues were identified, including difficulties in achieving complete uptake of screening (88%) or decolonisation (41%); the latter was largely due to short duration of stay and turnaround time for test results. Patient movement resulted in a decision to decontaminate all positive patients rather than just those in high risk specialties as proposed by the HTA. Issues also included a lack of isolation facilities to manage patients with MRSA. The study raises significant concerns about the contribution of decolonisation to reducing risks in hospital due to short duration of stay, and reinforces the central role of infection control precautions. Further study is required before the HTA model can be re-run and conclusions redrawn on the cost and clinical effectiveness of universal MRSA screening

    The N-methyl-d-aspartate receptor antagonist CPP alters synapse and spine structure and impairs long-term potentiation and long-term depression induced morphological plasticity in dentate gyrus of the awake rat

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    Long-term morphological synaptic changes associated with homosynaptic long-term potentiation (LTP) and heterosynaptic long-term depression (LTD) in vivo, in awake adult rats were analyzed using three-dimensional (3-D) reconstructions of electron microscope images of ultrathin serial sections from the molecular layer of the dentate gyrus. For the first time in morphological studies, the specificity of the effects of LTP and LTD on both spine and synapse ultrastructure was determined using an N-methyl-d-aspartate (NMDA) receptor antagonist CPP (3-[(R)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid). There were no differences in synaptic density 24 h after LTP or LTD induction, and CPP alone had no effect on synaptic density. LTP increased significantly the proportion of mushroom spines, whereas LTD increased the proportion of thin spines, and both LTP and LTD decreased stubby spine number. Both LTP and LTD increased significantly spine head evaginations (spinules) into synaptic boutons and CPP blocked these changes. Synaptic boutons were smaller after LTD, indicating a pre-synaptic effect. Interestingly, CPP alone decreased bouton and mushroom spine volumes, as well as post-synaptic density (PSD) volume of mushroom spines.These data show similarities, but also some clear differences, between the effects of LTP and LTD on spine and synaptic morphology. Although CPP blocks both LTP and LTD, and impairs most morphological changes in spines and synapses, CPP alone was shown to exert effects on aspects of spine and synaptic structure
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