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251.
Guerra F. A.; Savich R. D.; Wallen L. D.; Lee C. H.; Clyman R. I.; Mauray F. E.; Kitterman J. A. 《Journal of applied physiology》1988,64(5):2160-2166
To test the hypothesis that prostaglandin (PG) E2 is a respiratory depressant in the newborn lamb, 12 chronically catheterized, unanesthetized lambs (age 2-6 days) were infused with progressively increasing doses of PGE2 (0.1, 0.5, 1.0, and 5.0 micrograms.kg-1.min-1; 30 min for each dose) into the ascending aorta. PGE2 caused significant progressive decreases in ventilation (due to decreased tidal volume and breathing rate), heart rate, blood pressure, and percent of the time spent in low-voltage electrocortical activity (LVA). PGE2 also caused respiratory acidosis, hypoxemia, and increased frequency and duration of apneic events (greater than 3 s). During the infusion there was a dose-related increase in plasma concentration of PGE2. At 30 min postinfusion, all measured variables showed recovery, although arterial pH, CO2 tension, and plasma PGE2 remained significantly different from control values, and the percent time in LVA was even higher than during control. Infusion of the vehicle alone (n = 5) caused no significant changes in any of the measured variables. The results, taken in combination with previous fetal studies, indicate that PGE2 has marked inhibitory effects on breathing movements both before and after birth. 相似文献
252.
Effect of epinephrine on neutrophil kinetics in rabbit lungs 总被引:1,自引:0,他引:1
Doerschuk C. M.; Allard M. F.; Lee S.; Brumwell M. L.; Hogg J. C. 《Journal of applied physiology》1988,65(1):401-407
The effect of epinephrine on neutrophil (PMN) kinetics in rabbit lungs was evaluated by measuring the retention of radiolabeled PMN's in the lung, the exchange rate between the marginated and circulating pools of PMN's, and the erythrocyte (RBC) transit time. Epinephrine treatment decreased RBC transit times and increased exchange rates in the regions with the shortest transit times but did not change the pulmonary recovery of radiolabeled PMN's. When regions of similar RBC transit time were compared, epinephrine did not affect PMN retention at short transit times but did produce greater retention at long transit times. These data suggest that the major effect of epinephrine was to increase the proportion of the lung having short RBC transit times and fast exchange rates between the marginated and circulating pools. However, this effect did not decrease the overall retention of PMN's most likely because it was balanced by recruitment of additional capillary segments, which increased PMN retention in regions with longer transit times. 相似文献
253.
Protoplasts were isolated from mesophyll of axenic cultures of grape, Vitis rotundifolia cv. Summit and V. vinifera cv. Cabernet Sauvignon. Enzymes effective for protoplast isolation were Macerozyme R-10 (0.5% and 0.1%) and Cellulase Onozuka R-10 (1.0% and 0.5%) for V. rotundifolia and V. vinifera, respectively. Polyvinylpyrrolidone and 2-(N-morpholino)ethanesulfonic acid were essential in the isolation media. Protoplasts were purified using flotation/centrifugation. The protoplasts of V. rotundifolia cultured in Gamborg's B5 basal medium with 2.2 M 6-benzyladenine, 4.5 M 2,4-dichlorophenoxyacetic acid and 0.4% agarose gave the best plating efficiency of conditions tried in this study. Cell division occurred within 5 to 6 days and visible microcalli developed within one month. After 6 weeks in culture, microcalli transferred to liquid medium exhibited active callus growth. Protoplasts of V. vinifera cultured under these conditions had similar results.Abbreviations MES
2-(N-morpholino)ethanesulfonic acid monohydrate
- PVP
polyvinylpyrrolidone
- PDS
potassium dextran sulfate
- BA
6-benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- FDA
fluorescein diacetate 相似文献
254.
Tau protein has been shown to be an integral component of Alzheimer paired helical filaments (PHF). However, the extent to which tau is incorporated into PHF has not been clear because the antibodies used to label PHF generally do not have precisely defined epitopes. Here we define the antigenic sites for five monoclonal antibodies that react with tau and cross-react with SDS-extracted neurofibrillary tangles. The reactive sites were determined by screening a lambda gt11 sublibrary expressing small fragments of the tau sequence. The mapped epitopes were found to span almost the entire length of tau, suggesting that PHF contains tau in its entirety or nearly in its entirety. One antibody was found to cross-react with microtubule-associated protein 2, implying some degree of homology between the two proteins. 相似文献
255.
J R Hageman J Zemaitis R B Holtzman S E Lee L J Smith C E Hunt 《Prostaglandins, leukotrienes, and essential fatty acids》1988,32(3):145-153
We have previously reported that bronchoalveolar lavage fluid cyclo-oxygenase products of arachidonic acid (AA) metabolism increase prior to the development of significant hyperoxic lung injury. To further assess the role of AA metabolites in the development of hyperoxic lung injury, we have utilized this same model of hyperoxic lung injury and administered either indomethacin (an inhibitor of the cyclo-oxygenase pathway of AA metabolism) or dexamethasone (inhibitor of AA release). A total of 46 adult rabbits were exposed to greater than 95% oxygen for 65 hours. Fourteen animals were given either 2 or 3 mg/kg/day indomethacin, 7 served as controls: 18 animals were given either 0.5 or 1.0 mg/kg/day of dexamethasone, 7 served as controls. The surviving animals were sacrificed after 65 hours of hyperoxia and bronchoalveolar lavage of the left lung was done; the right lung was examined by light microscopy. Treatment with indomethacin or dexamethasone failed to ameliorate the hyperoxic lung injury process. However, in both the indomethacin and dexamethasone treatment groups, significant suppression of 6-keto-PGF1 alpha, a PGI2 metabolite, was observed. Some suppression of TXB2 production was observed, but there was no evidence of any decrease in leukotriene production. We postulate that failure to ameliorate hyperoxic lung injury with either indomethacin or dexamethasone therapy was related to significant suppression of PGI2, a potentially protective AA metabolite, and/or to failure to significantly decrease production of potential pathogenic participants, such as TXA2 or LTB4.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
256.
257.
258.
本文用凝胶直读法、末端鉴定法等相配合,测定了樗蚕(Philosamia cynthia)絲腺5SrRNA的核苷酸顺序:AGACAACGUCCAUACCACGUUGAAAACACCGGUUCUCGUCCGAUCACCGAAGUCAAGCAACGUCGGGCGCGGUCAGUACUUGGAUGGGUGACCGCCUGGGAACACCGCGUGCUGUUGGCUU比较了樗蚕、蓖麻蚕、柞蚕、家蚕、果蝇等5SrRNA结构差异,在分子水平上探讨了昆虫的分化。 相似文献
259.
Culture conditions for arresting and stimulating the proliferation of a rainbow trout fibroblast cell line,RTG-2 总被引:1,自引:0,他引:1
L. E. J. Lee A. Martinez N. C. Bols 《In vitro cellular & developmental biology. Plant》1988,24(8):795-802
Summary Conditions for arresting and stimulating the proliferation of the rainbow trout fibroblast cell line RTG-2 have been examined
and the time course of events after stimulation determined. Quiescent populations were achieved in two ways. Cultures grown
to confluency without a medium change for at least 7 d had fewer than 5% of the cells in S phase and few mitotic figures.
Cultures deprived of serum, which could be done for up to 3 d without a loss in cell number, also achieved quiescence. After
3 d without serum, less than 1% of cells were in S phase and mitotic figures were infrequent. Addition to these cultures of
fresh serum-containing medium brought about the synchronous entry of cells into S phase and mitosis. For cultures in which
either the medium had been changed after 7 d without a change or serum-containing medium had been added after 3 d of serum
deprivation, DNA synthesis increased after a lag period of 20 to 24 h, was pronounced between 30 and 45 h, and then declined.
This was followed by a peak in the mitotic index. These protocols for arresting and subsequently stimulating RTG-2 proliferation
should allow the G1-S transition to be studied in a representative of teleosts.
This research was supported by Natural Sciences and Engineering Research Council of Canada grant to N. C. B. 相似文献
260.
Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching. 相似文献