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101.
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Prolonged exposure to host immunity was studied for its effect on several characteristics of a cloned 3-methylcholanthrene-induced fibrosarcoma. One million cells of a clone 10-O were injected subcutaneously into normal C3H/HeJ mice (clone 10-N) or tumor-immune mice (clone 10-I). After 10 passages in immune mice, 1 X 10(6) cells from 10-I tumor were transferred back into normal mice (clone 10-R). After 5 to 10 additional in vivo passages, clone 10-O, 10-N, 10-I, and 10-R tumors were transplanted into normal mice and observed for tumor growth rate, tumorigenicity, antigen specificity, metastatic potential, and plating efficiency. Clone 10-I after 10 passages in immunized mice grew significantly more slowly than did 10-O or 10-N clones, required more tumor cells to cause 50% tumor incidence in normal mice (tumorigenicity), and completely lost its capacity to metastasize spontaneously or experimentally. The plating efficiency in vitro of 10-I was also less than that of 10-O or 10-N. All these changes reversed after 5 to 10 passages of 10-I clone back into normal mice (10-R). Although immune pressure induced qualitative antigenic changes, as demonstrated by a tumor-rejection assay, and resulted in no cross-reactivity with control tumor clones (antigen specificity), the degree of immune response to its autologous clone in immune mice (immunogenicity) remained constant. These results suggest that several unrelated characteristics of this clone 10 can be phenotypically changed during the same period by immune pressure. 相似文献
105.
Yu. B. Lishmanov L. V. Maslova L. N. Maslov E. N. Dan'shina 《Bulletin of experimental biology and medicine》1993,116(2):974-976
Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N
o
8, pp. 175–176, August, 1993 相似文献
106.
研究消炎痛及乙胺嗪对家兔肺、脑血管和大鼠脑微动脉缺氧反应的影响。发现吸入10%氧使家兔肺血管阻力(PVR)增加,脑血管阻力(CVR)降低,大鼠脑微动脉扩张。用消炎痛明显增强家兔缺氧性肺、脑血管反应。△PVR%由用药前26.6±16.7%增至44.2±7.7%;△CVR%则由一12.9±4.5%减至-30.7±4.7%;大鼠微动脉直径增大率(△D%)由用药前28.2±2.0%增至41.3±5.8%;用乙胺嗪则使缺氧时△PVR%由 84.6±18.1%降至 23.8±8.5%;△CVR%由-16.7±4.5%变为 6.9±2.8%;△D%由 29.7±5.8%减至 25.6±5.0%。结果表明前列腺素在缺氧性肺血管收缩反应及脑血管扩张反应中起调节作用,而白三烯则在缺氧性肺血管收缩反应中起介导作用。 相似文献
107.
108.
Penetration of Schistosoma japonicum cercaria into host skin. 总被引:1,自引:0,他引:1
The anterior part of Schistosoma japonicum cercaria is a specialized head organ which can slightly stretch out and retract. There are three different types of large unicellular glands in cercarial body, consisting of one head gland, 2 pairs of pre- and 3 pairs of postacetabular glands. These glands differ in position, gross feature, histochemistry and functions. Both polysaccharase and protease activities are demonstrated in the secretions from these glands. Mode of cercarial penetration is described in detail and the penetration is effected by a combination of lytic secretions and mechanical movements. The schematic representation of the process of cercarial penetration is presented. The dynamic distributions of schistosomula in skin at different time intervals after skin penetration in various mammalian hosts are shown. Some newly transformed schistosomula die while penetrating into the skin of 7 mammalian species and the mortality rate varies with the host species, and that can also be affected by the age of cercariae following emergence from the snail. Some physiological aspects between cercariae and newly transformed schistosomula are compared. In contrast to cercariae, schistosomula are saline-adapted and water-intolerant. They were modified histochemically and antigenically.
相似文献
109.
110.
You M. Lu Bu F. Lu Yu L. Yan Tin H. Yan Xiaon P. Ho Wen J. Wang 《The European journal of neuroscience》1993,5(10):1334-1338
The activation of membrane-associated phospholipase C is rapidly and transiently induced in the central nervous system by a variety of stimuli. Ischaemic brain injury is one of the situations that leads to a dramatic increase in polyphosphoinositide (PPI) turnover. In this study, stimulation of PPI hydrolysis by glutamate (500 μM) was measured in hippocampal slices from rats up to 21 days after an ischaemic insult of 30 min. Ischaemia was induced using the four-vessel occlusion method. PPI hydrolysis elicited by glutamate was significantly increased in the slices prepared from ischaemic rats 24 h after reperfusion, the accumulation of inositol phosphates (InsPs ) and inositol 1,4,5-trisphosphate (InsP3 ) was 614±74% ( n = 8) and 182±11% ( n = 9) of the basal level respectively. This potentiation was also observed 21 days after ischaemia. Hyper-responsiveness to glutamate was also accompanied by an increase in AIF− 4 -stimulated formation of [3 H]inositol phosphates. In addition, global ischaemia did not change either high-affinity [3 H]glutamate binding in hippocampal membranes or the stimulation of PPI hydrolysis by carbachol or noradrenaline in hippocampal slices. The present results suggest that the increased responsiveness to glutamate is the result, at least in part, of functional changes at the G-protein level, and may contribute to the pathophysiology of ischaemic brain injury or to the regenerative phenomena that accompany ischaemic damage. 相似文献