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1.
The UKAEA and the Joint Research Centre, Euratom, Ispra are engaged in a collaborative experimental programme carrying out a series of small scale, well instrumented tests aimed at providing high quality data of the stresses, strains and loads occurring when a well characterized source is released within a fluid in a containment vessel. In the UK the data are being used to validate the computer codes ASTARTE and SEURBNUK which are used in studies of the response of the fast reactor primary containment system in the event of a hypothetical reactor excursion. This paper describes the UK experimental programme and the development of the low density explosive which is used as the energy source; the rationale of the code development programme is presented together with a report on the progress that has been made in validating the two codes against the experimental data.  相似文献   
2.
Polyclonal T lymphocyte populations can be stimulated with anti-CD3 antibody to proliferate, secrete cytokines, and mediate MHC-unrestricted cytotoxic activity against a wide range of tumor target cells. Because anti-CD3-activated killer-T (AK-T) cells may be useful in the immunotherapy of human cancers, it is important to understand the signaling pathways and cell-surface structures involved in the induction and tumoricidal effector function of AK-T cells. Studies in the mouse model system have characterized the cytokines, signal transduction pathways, and costimulatory molecules involved in AK-T cell development. The recognition/adhesion and subsequent signaling events which lead to tumoricidal activity by mouse AK-T cells have also been defined. These findings, providing they translate accurately to the human system, may allow for the design of effective strategies to use AK-T cells for the treatment of human cancers. However, to date, the encouraging results obtained with anti-CD3 antibody/AK-T cell-based immunotherapies in mouse models of cancer have not been duplicated in clinical trials. The most likely explanation for this dis-appointing result is that tumor-reactive T lymphocytes in long term tumor-bearers fail to function correctly in the tumor microenvironment due to tumor-induced immune suppression and defects in key signal transduction molecules. It is clear that a detailed understanding of the inhibitory effect of established tumors on host T cells and the means to overcome tumor-induced immunosuppression are needed before anti-CD3 antibody/AK-T cell-based immunotherapies can be expected to succeed in the clinical setting.  相似文献   
3.
This study aimed to evaluate intake, body growth, and the development of the rumen, mammary gland, and immune system in Holstein Friesian calves reared for 100 d on the commercially available feed FiberStart (conserved alfalfa, Medicago sativa; Fiber Fresh Feeds Ltd., Reporoa, New Zealand) and fed calf milk replacer (CMR) for either 56 or 91 d. Eighty calves (40 bulls and 40 heifer calves) were reared indoors in groups (n = 5 of the same sex/pen). All calves were fed 4 L of CMR/d (175 g/L of CMR) in 2 feeds/d for the first 10 d and then 1 feed/d until d 49 or 84. The calves were gradually weaned by d 56 (earlier weaned; n = 8 pens) and d 91 (later weaned; n = 8 pens). All calves were fed FiberStart ad libitum as the only solid feed source from d 1 to 100 of the study. Irrespective of treatment, all calves had similar body weights at d 0 (40.9 ± 3.0 kg) and d 49 (74.2 ± 5.1 kg) of the study. Calf sex had no effect on intake, growth, blood, and immune system parameters. Earlier-weaned calves consumed 18% more solid feed dry matter but had 16% lower body weight gain (28.9 vs. 38.5 kg, respectively) from d 56 to 100 relative to later-weaned calves, resulting in different body weight at 100 d (104 vs. 121 ± 1.3 kg). Although earlier-weaned calves could compensate for the loss of CMR dry matter and crude protein intake from d 56 to 100 by increasing forage intake, they were unable to compensate for the loss of energy from the CMR by increasing solid feed consumption. Plasma β-hydroxybutyrate concentrations were 52% greater in earlier-weaned calves than in later-weaned calves at d 84, indicating greater metabolic activity of the rumen wall. The duration of CMR feeding had no influence on humoral or cell-mediated immune functions of the calves, as evidenced by a lack of effect on antivaccine antibody responses as well as on immune gene expression. Earlier- versus later-weaned heifer calves had 5% lower mammary gland mass, indicating that greater energy supply increased mammary mass. The results of this experiment demonstrate the ability to artificially rear dairy calves on a conserved alfalfa as the only solid feed. Furthermore, earlier weaning off CMR promotes solid feed intake and an associated increase in blood β-hydroxybutyrate, an indicator of rumen development, but increasing the duration of CMR feeding improves growth and mammary gland mass by d 100. The implications of these findings on lifetime growth, health, and milk production in dairy heifers warrant further investigation.  相似文献   
4.
The yeast Hansenula polymorpha is able to grow on vanadate concentrations that are toxic to other organisms. Transmission electron microscopy analysis showed that H. polymorpha cells growing on a vanadate-containing medium undergo a significant increase in cell vacuolation and a thickening of the cell wall; the presence of small cytoplasmic vesicles and an increase in cristae at the level of the plasma membrane were also observed. These ultrastructural modifications were accompanied by a change in the intracellular polyphosphate level, as shown by in vivo 31P-NMR. The involvement of these observed changes in vanadium detoxification is discussed.  相似文献   
5.
Homage to the page, the colour of the text: An ancient metaphor: thought is a thread, and the raconteur is a spinner of yarns—but the true storyteller, the poet, is a weaver. The scribes made this old and audible abstraction into a new and visible fact. After long practice, their work took on such an even, flexible texture that they called the written page a textus, which means cloth.1 ?1. Robert Bringhurst, The Elements of Typographic Style, 3rd edn., Point Roberts, WA: Hartley & Marks, 2004, 25.   相似文献   
6.
PURPOSE: Since the routine use of storage phosphor systems for mammography has been limited by its inadequate spatial resolution of 5 linepairs/mm, a combination of a magnification mammography technique with storage phosphor plates was investigated to detect microcalcifications. MATERIAL AND METHODS: A new mammography system with a microfocus tube using an anode of 0.05-0.12 mm allowed to obtain survey views of the breast with 1.7x magnification (m), and spot views with 4x magnification. The digital image receptor comprised a high resolution storage phosphor plate. To determine spatial resolution, contrast transfer curves were obtained, and the detection of microcalcifications was investigated by ROC (receiver operating characteristic) analysis. RESULTS: Spatial resolution for digital survey views (m = 1.7) was 8 linepairs/mm and for spot views (m = 4) was 18 linepairs/mm. ROC analysis demonstrated a significantly higher performance of the digital magnification technique compared to the conventional screen-film mammography technique. CONCLUSIONS: The limitations of digital mammography with respect to spatial resolution can be overcome by using a high magnification technique.  相似文献   
7.
Pentoxifylline (PTX), rapamycin (RAP), and leflunomide are potent immunomodulatory drugs with differing modes of action. In order to develop new drug combinations for immunotherapy, we tested the effects of PTX in combination with RAP or A77 1726 (the active metabolite of leflunomide) on in vitro T cell activation in a mouse model system. T lymphocytes in spleen cell preparations were stimulated with anti-CD3 monoclonal antibody alone, or in the presence of PTX (25-200 microg/ml), RAP (0.5-5.0 ng/ml), A77 1726 (2.5-10.0 microM), PTX/RAP (25-200 microg/ml and 0.5-5.0 ng/ml, respectively), or PTX/A77 1726 (25-200 microg/ml and 2.5-10.0 microM, respectively). Anti-CD3-induced T cell proliferation was inhibited in a dose-dependent fashion by the individual drugs. An additive inhibitory effect was observed in cultures treated with PTX/RAP or PTX/A77 1726. The effects of PTX, RAP, A77 1726, PTX/RAP, or PTX/A77 1726 (at concentrations approximating the IC50 of individual drugs for inhibition of lymphoproliferation) on anti-CD3-activated killer (AK) cell induction, CD25 expression, and interleukin (IL)-2 synthesis in anti-CD3-activated spleen cell cultures were also determined. Alone, each drug was able to suppress AK cell induction to varying degrees. PTX plus RAP exhibited strong synergism, while the combination of PTX and A77 1726 had an additive inhibitory effect on AK cell induction. CD25 expression was only weakly inhibited by A77 1726, but the percentage of CD25-expressing cells was greatly reduced in cultures treated with PTX or RAP. The combination of PTX and RAP had an additive inhibitory effect on CD25 expression while PTX and A77 1726 together had an effect equivalent to PTX alone. IL-2 synthesis was inhibited by PTX but was unaffected by RAP or A77 1726. Treatment with PTX plus RAP led to a further reduction in IL-2 production but co-treatment with PTX and A77 1726 approximated the inhibitory effect of PTX alone. We conclude that the combination of PTX and RAP is noteworthy for its potent immunomodulatory activity and may be of use in clinical situations where it is desirable to prevent T cell activation.  相似文献   
8.
    
BACKGROUND: Leaves of forage chicory break down rapidly in the rumen despite little or no rumination. Because chicory cell walls contain high concentrations of pectin, degradation of leaf midrib and leaf lamina tissues by pectinolytic enzymes was investigated. RESULTS: Treatment with endopolygalacturonase (endo‐PG) degraded fresh intact chicory leaves to particles of less than 1 mm in length and solubilised more than 70% of the dry matter within 16 h. Uronic acids were released more extensively than neutral monosaccharides. In similar treatments, 77% of white clover leaflets and 12% of perennial ryegrass leaf blades were solubilised or broken down to particles with a size of less than 1 mm. The degradation of pectic polysaccharides in chicory midribs was monitored by immunofluorescence labelling with monoclonal antibodies JIM5 and JIM7 which target partially methyl‐esterified epitopes of the homogalacturonan (HG) domain of pectin. Examination by fluorescence microscopy revealed that cell separation in the cortical parenchyma of chicory midrib following endo‐PG treatment was associated with loss of HG from the middle lamella, the corners of intercellular spaces and from the tricellular junctions. CONCLUSION: The results of the current study suggest that one of the main contributions to chicory breakdown in the rumen may be cell separation caused by degradation of HG by pectinolytic enzymes from rumen bacteria. Copyright © 2007 Society of Chemical Industry  相似文献   
9.
Objective: To study the money management ability of people with acquired brain dysfunction (ABD) and its relationship to neuropsychological test performance. Subjects or Other Participants: 35 people with ABD and 15 matched controls without ABD. Main Outcome Measures: Case managers completed an experimenter-designed Money Management Survey (MMS), a staff-rating measure of the client's money management abilities. Results: In addition to the problems identified by controls, the group with ABD had other difficulties such as not leaving money aside for essentials and using automatic teller machines. Neuropsychological assessment demonstrated a modest ability to predict the overall MMS, however, the prediction of specific behaviors (problematic impulsive spending and paying the bills or rent late) was more successful. Conclusion: These results provide support for the use of the MMS and indicate that people with ABD have greater problems with specific aspects of money management than do controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
10.
In this study, we examined the prevalence of Salmonella and coliform bacteria on shrimp aquaculture farms to develop guidelines or preventative measures for reducing Salmonella and fecal contamination on products harvested from these farms. The U.S. Food and Drug Administration, in conjunction with foreign government regulatory agencies, the aquaculture industry, and academia affiliates, analyzed 1,234 samples from 103 shrimp aquaculture farms representing six countries between July 2001 and June 2003 for fecal coliforms, Escherichia coli, and Salmonella. A significant relationship was found (P = 0.0342) between the log number of fecal bacteria and the probability that any given sample would contain Salmonella. The likelihood of any given sample containing Salmonella was increased by 1.2 times with each 10-fold increase in either fecal coliform or E. coli concentration. The statistical relationship between Salmonella concentration and that of both fecal coliforms and E. coli was highest in grow-out pond water (P = 0.0042 for fecal coliforms and P = 0.0021 for E. coli). The likelihood of finding Salmonella in grow-out pond water increased 2.7 times with each log unit increase in fecal coliform concentration and 3.0 times with each log unit increase in E. coli concentration. Salmonella is not part of the natural flora of the shrimp culture environment nor is it inherently present in shrimp grow-out ponds. The occurrence of Salmonella bacteria in shrimp from aquaculture operations is related to the concentration of fecal bacteria in the source and grow-out pond water.  相似文献   
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