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991.
Mononuclear phagocytes release interleukin-1 (IL-1), a 17-kDa polypeptide with diverse biological activities. IL-1 is synthesized as a precursor (31 kDa) which lacks a signal sequence or hydrophobic domains that could facilitate transmembrane translocation. Possible postsynthetic modifications of IL-1 that might account for its cellular transport were examined. We found that lipopolysaccharide stimulated, but not unstimulated, murine macrophages incorporated 32PO4 into the IL-1 alpha precursor (31 kDa) predominantly at residue serine 90. Released IL-1 alpha (17 kDa) is not phosphorylated in agreement with peptide sequence data that the site of 32P incorporation is in the amino-terminal one-third of the precursor. Approximately 10% of the phosphorylated IL-1 alpha precursor is membrane bound and associated with a fraction enriched in lysosomal vesicles. Together these data suggest mechanisms by which the postsynthetic proteolysis of the IL-1 alpha precursor may be modified and cellular transport of IL-1 alpha is accomplished. 相似文献
992.
993.
The immunological network at the site of tumor rejection 总被引:4,自引:0,他引:4
R Evans 《Biochimica et biophysica acta》1986,865(1):1-11
The tumor mass irrespective of its type or location in the body has long been shrouded in mystery and even today we still have only a tentative handle on its secrets. Attempts to manipulate either the tumor cells per se or host-derived leukocytes have, on the whole, not been successful or at best questionable. The ability of the host to respond immunologically to TSTA is well documented, yet again attempts to manipulate this response have been disappointing. One of the problems has been a lack of knowledge concerning the tumor mass and its constituents, such as the intratumor leukocytes, and the significance of their presence to the biological properties of the neoplasm [8,9,80]. The purpose in studying the immunological network is, in part, to try to assign a function to these cells on the premise that lymphoid elements and macrophages have a potential role to play in recognition of TSTA. The advantage of adoptive immunotherapy model systems is that tumor rejection can be achieved under controlled conditions and this allows an analysis of the immunological network and its individual circuits. At the same time, valuable information on the mechanisms of action during adoptive immunotherapy and how best to improve therapeutic protocols is acquired. 相似文献
994.
995.
996.
Several human studies have shown an inverse relation between vitamin A intake (and serum concentrations of retinol and carotene) and cancer. Serum cholesterol concentrations have also been reported in inverse relation to cancer. In a study of 3102 people in Evans County, Georgia, who were followed for over 12-14 years to assess the incidence of cancer there was an inverse association between the risk of cancer and both serum retinol and serum cholesterol concentrations. The data also showed an unexpectedly strong correlation between serum retinol and total cholesterol concentrations. The inverse relationship with cancer was stronger with serum retinol than with cholesterol, which suggested that the association with cholesterol might be secondary. This suggestion may also explain the cholesterol-cancer association reported in several other cohort studies. Further studies of the relation between serum concentrations of cholesterol, retinol, and carotene and the incidence of cancer are needed. 相似文献
997.
998.
Philip R. Larson 《American journal of botany》1962,49(2):132-137
Larson , Philip R. (Lake States Forest Experiment Station, Rhinelander, Wis.) The indirect effect of photoperiod on tracheid diameter in Pinus resinosa. Amer. Jour. Bot. 49 (2) : 132–137. Illus. 1962.—The influence of photoperiod on tracheid diameter was studied by independently exposing the buds and needles to different photoperiods. Long days promoted needle elongation and large-diameter tracheid production, whereas short days brought about cessation of needle elongation and the transition to narrow-diameter tracheids. The response to photoperiod varied with the stage of plant development. During active extension growth of the shoot, the bud exerted a decisive regulatory influence on tracheid diameter, but the needles became the principal source of the stimulus contributing to tracheid diameter when extension growth terminated. It is suggested that the effect of photoperiod on tracheid diameter is indirect and associated with auxin production and distribution of the terminal meristems. 相似文献
999.
1000.
Comparison of the internal proteins of the T-even bacteriophages 总被引:2,自引:0,他引:2