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571.
Tanja Sigl Gregor Schlamberger Hermine Kienberger Steffi Wiedemann Heinrich HD Meyer Martin Kaske 《Acta veterinaria Scandinavica》2010,52(1):32
Background
Conjugated linoleic acid (CLA) is a collective term for isomers of octadecadienoic acid with conjugated double-bond system. Thus, it was the objective to investigate whether milk composition and metabolic key parameters are affected by adding CLA to the diet of dairy cows in the first four weeks of lactation. 相似文献572.
The concept of critical load (CL) was defined to express the tolerance of natural and semi‐natural habitats for anthropogenic air pollution. Correct evaluation of the exceedance of critical loads is fundamental for the long‐term protection of ecosystems by limiting emissions of potential acidifying and eutrophying pollutants. For forest ecosystems, the exceedance of critical loads is often calculated using deposition data measured in the forest interior. However, several studies report forest edges acting as ‘hotspots’ of acidifying and nitrogen deposition, showing up to fourfold increases in atmospheric deposition compared to the forest interior. This paper estimates the relevance of considering the higher deposition load in forest edges for calculating exceedance of critical loads for nitrogen and potential acidifying deposition. If measures to control and reduce atmospheric deposition are based on mean deposition fluxes within forest stands, deposition reductions will not be enough for preventing adverse effects. In fact, emission reductions should be adjusted to deposition values at the forest edge, since these zones are most threatened. We thus conclude that there is an urgent need to reconsider the calculation of exceedance of critical loads, taking into account edge enhancement of deposition. This is an issue of high relevance, particularly in highly fragmented regions, such as Flanders (Belgium). 相似文献
573.
Better discrimination was possible between phenylthiocarbamide (PTC)
solutions and the pure solvent when the solvent was a tasteless low-
concentration NaCl solution to which the subject had adapted than when the
solvent was purified water. The reverse was true for 6-n- propylthiouracil
(PROP). The differences in discrimination for PROP and PTC in the different
solvents were caused by differences in the intensity and persistence of
aftertastes, rather than a more intense perception of the PTC and PROP
tastes per se. This has consequences for traditional approaches to
measuring taste sensitivity, as well as indicating that PTC and PROP are
not necessarily equivalent indicators of 'taster' versus 'non-taster'
status.
相似文献
574.
Constitutional chromosome instability and cancer risk 总被引:5,自引:0,他引:5
Acquired, clonal chromosome abnormalities are thought to be of pathogenetic importance in human cancer; at the cellular level, neoplasia is best viewed as a genetic disease. It is therefore logical to suggest that cancer risk must somehow be related to individual variations in genomic stability. Those persons whose chromosomes are less stable will, on average, be the ones who are most likely to develop cancer. The testing of this hypothesis shows that, apart from the autosomal recessive chromosome breakage syndromes, only patients with adenomatosis of the colon and rectum have, consistently and by different groups, been found to display elevated spontaneous and clastogen-induced chromosome breakage frequencies. Some evidence indicates a similar tendency in patients with dysplastic nevus syndrome, basal cell carcinoma, cervix cancer, and Kaposi's sarcoma. For several other cancers the data strongly argue against any inherent genomic instability. Although most results thus fail to support constitutional chromosome fragility as a factor of importance in tumorigenesis, conclusive falsification of the hypothesis cannot be said to have been obtained. The possibility remains that variations in chromosome stability and clastogen sensitivity between different cell types, and also difficulties in selecting the most appropriate carcinogens in clastogen-exposure tests, may have masked systematic constitutional differences between patients and controls in the breakage assays. 相似文献
575.
F. Mertens E. Pålsson Anders Lindstrand Sören Toksvig-Larsen Sakari Knuutila Marcelo L. Larramendy Wa`el El-Rifai Janusz Limon Felix Mitelman Nils Mandahl 《Human genetics》1996,98(6):651-656
We examined, cytogenetically and by in situ hybridization (ISH) techniques, the synovia, osteophytes, and articular cartilage
from 32 patients with pronounced osteoarthritis (OA), a prevalent form of arthropathy characterized by progressive reduction
of articular cartilage, and synovial samples from 17 control patients. In short-term cultures, clonal chromosome aberrations,
in particular the gain of chromosomes 7 (+7) and 5 (+5), were found to be strongly associated with OA. These aberrations were
found in almost 90% of the cultures from synovia and osteophytes, whereas only 1/11 synovial samples from joints unequivocally
unaffected by OA had cells with +5 or +7. The in vivo nature of trisomy 7 was demonstrated by ISH on uncultured cells, and
serial passaging showed that cells with +7 had a proliferative advantage in vitro. Thus, the combined data indicate that cells
with somatic mutations appear early and may be influential in the disease process leading to OA.
Received: 7 June 1996 / Revised: 9 August 1996 相似文献