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121.
Increased acidic phospholipids in rat brain membranes after chronic ethanol administration 总被引:2,自引:0,他引:2
Two types of plasma membranes isolated from rat brain cortex were used to study the membrane-perturbing properties of ethanol. Rats administered ethanol in the form of a liquid diet showed an increase in levels of phosphatidylserines, phosphatidylinositols and phosphatidic acids as compared to controls. The results present evidence that chronic ethanol treatment results in an increase in the acidic phospholipids in brain membranes. This type of membrane modification may have important implications for the function of membrane transport enzymes such as (Na+, K+)-ATPase, which also increases in activity upon chronic ethanol administration. 相似文献
122.
IgE immune complexes induce immediate and prolonged release of leukotriene C4 (LTC4) from rat alveolar macrophages 总被引:2,自引:0,他引:2
J A Rankin M Hitchcock W W Merrill S S Huang J R Brashler M K Bach P W Askenase 《Journal of immunology (Baltimore, Md. : 1950)》1984,132(4):1993-1999
Alveolar macrophages obtained by lung lavage from rats were incubated with monoclonal mouse anti-DNP IgE and specific antigen (DNP-HSA) and were found to release a slow reacting substance (SRS), which was characterized by high performance liquid chromatography as leukotriene C4 (LTC)4. Alveolar macrophages incubated with 1 microM A23187 (calcium ionophore) released similar amounts of SRS (6.0 +/- 2.2 and 5.7 +/- 3.7 X 10(-10) mol of LTC4 per 5 X 10(6) alveolar macrophages, respectively). The optimal conditions and mechanism of LTC release by IgE and antigen were examined. LTC4 release was maximal when freshly retrieved alveolar macrophages were incubated for 20 min with 10 micrograms/ml IgE and then for 20 min with 100 ng/ml antigen or for 20 min with IgE and antigen that had been preincubated together for 30 min at room temperature. In addition, LTC4 release was maximal when cells were challenged with IgE and antigen in a protein-free balanced salt solution and when the cells were tumbled to prevent adherence. Dose response experiments revealed that macrophages released LTC4 when stimulated with as little as 10 ng IgE and 100 ng DNP-HSA. Alveolar macrophages did not release LTC when challenged with IgE or DNP-HSA alone. Activation of LTC4 release by IgE and antigen was rapid in onset (2.5 to 5 min), and washing to remove fluid phase IgE and antigen revealed that once activated, alveolar macrophages were capable of prolonged and continuous release of LTC4. Peritoneal lavage cells stimulated with IgE and antigen did not release SRS but could release SRS when incubated with A23187 (5.7 +/- 1.3 X 10(-10) mol LTC4/5 X 10(6) macrophages). A large variability existed between individual rats in the ability of their alveolar macrophages to be activated by IgE and antigen to release LTC4. DNP-HSA labeled with 125I was used to show formation of immune complexes of IgE and antigen when IgE and antigen were incubated together before macrophage challenge. IgE immune complexes containing as little as 2 ng of antigen elicited the release of LTC4 from alveolar macrophages. These data indicate that rat alveolar macrophages release primarily LTC4 when challenged with IgE immune complexes, and that the alveolar macrophage may differ in this respect from peritoneal macrophages that do not release detectable quantities of LTC4 when challenged under identical conditions. 相似文献
123.
PRCII is an avian retrovirus whose oncogene (v-fps) induces fibrosarcomas in birds. The viral gene v-fps arose by transduction of an undetermined portion of a cellular gene known as c-fps. PRCII is weakly oncogenic when compared with Fujinami sarcoma virus, another transforming virus containing v-fps. As a first step in the elucidation of the molecular basis for the decreased virulence of PRCII, we have determined the entire nucleotide sequence of v-fps in the PRCII genome. The v-fps domain in PRCII encodes a polypeptide with a molecular weight of ca. 60,500 fused to a portion of the polyprotein encoded by the viral structural gene gag. The hybrid gag-fps polyprotein of PRCII would have a molecular weight of ca. 98,100, in accord with results of previous studies of the protein encoded by the PRCII genome. The leftward junctions between fps and gag in Fujinami sarcoma virus and PRCII are located at the same position in fps, but at different positions in gag. A sequence of 1,020 nucleotides, bounded by direct repeats of 6 nucleotides, is present in v-fps of Fujinami sarcoma virus but absent from PRCII. Our data should permit further explorations of the relationship between structure and function in the transforming protein encoded by v-fps. 相似文献
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蚕豆根、茎和叶含有0.31~0.70 μmol酰脲·g~(-1)FW,并受结瘤和生长发育的影响。摘除正在生长的器官可观察到同腋位叶片酞脲含量暂时升高现象。 叶片中酰脲主要是尿囊酸。尿囊素酶和脲酶活性分别为0.30 μmol尿囊酸·g~(-1)FW·h~(-1)和0.19 μmol NH_3·g~(-1)FW·h~(-1)。尿囊酸含量和尿囊素酶活性日变化相似,只是后者峰值比前者出现早。 相似文献
126.
The activation of yeast proteinase B at pH 5 has been suggested to be due to the degradation of a specific inhibitor for the enzyme, IB, by proteinase A. However, we found that when pepstatin, which completely inhibits proteinase A, was included in the pH 5 activation mixture, the same time-dependent activation of proteinase B was observed. Furthermore, proteinase B preparations that were void of proteinase A activity were still activated by incubation at pH 5. We found that the activation of proteinase B at pH 5 was due primarily to the irreversible loss of inhibitory effect of IB, which can be resolved by isoelectrofocusing into four distinct bands with isoelectric points of 4.6, 6.1, 6.8 and 7.6. These four forms of IB showed varying degrees of stability at pH 5, which may explain some of the differing observations reported in the past. 相似文献
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