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木聚糖酶酶活测定方法的研究 总被引：3，自引：0，他引：3
本试验研究了影响木聚糖酶测定的因素.结果表明不同底物、不同底物浓度、酶的稀释度和提取时间都会影响到酶活的测定结果,但蒸馏水及缓冲液作为提取液对酶活无显著影响.测定的吸光度在0.3左右(即0.25～0.5)时酶活的变异较小. 相似文献
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Pharmacologic activity of doxycycline 总被引：3，自引：0，他引：3
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H. Thomas 《New Zealand veterinary journal》2013,61(12):273-275
Febantel [N-2-([2,3-bis-(methoxycarbonyl)-guanidine] 5-(phenylthio)-phenyl)-2-methoxyacetamide] was found to inhibit the embryonic development of Trichuris muds and Haemonchus contortus ova. After oral treatment of T.muris-infected mice with 500 mg/kg febantel, the majority of eggs excreted from 31 hours after treatment did not develop into the larval stage. A more pronounced ovacidal effect was shown for H.contortus after treatment of sheep with low doses of febantel. The embryonic development of eggs had completely stopped from 24 hours after treatment with 2.5 mg/kg febantel. The commercially recommended dose-rate for febantel in sheep is 5 mg/kg. 相似文献
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Ochratoxin A (OTA) is an immunosuppressant fungal compound, produced by toxigenic species of Aspergillus and Penicillium fungi in a wide variety of climates and geographical regions. The contamination of food by this mycotoxin takes place primarily during preharvest periods. Almost all types of food can be contaminated. In addition, its chemical stability against heat and during industrial food processing makes OTA one of the most abundant food contaminating mycotoxins. Due in part to its long serum half-life in man, almost 100% of all human blood samples from some geographic regions may be positive for OTA. The immunosuppressant activity of OTA is characterized by size reduction of vital immune organs, such as thymus, spleen, and lymph nodes, depression of antibody responses, alterations in the number and functions of immune cells, and modulation of cytokine production. The immunotoxic activity of OTA probably results from degenerative changes and cell death following necrosis and apoptosis, in combination with slow replacement of affected immune cells, due to inhibition of protein synthesis. 相似文献
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Examination of the urease activity of 604 brucella strains showed a limited correlation with species. Most strains of B canis, B neotomae and B suis gave a positive urease reaction within 15 minutes, although some exceptions were noted. A substantial proportion of strains of B abortus and B melitensis also hydrolysed urea as rapidly as most B suis strains. Although most B ovis strains were negative to the urease test, 28.9 per cent of those examined gave positive reactions. 相似文献
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1. A survey of rhodanese activity (thiosulphate : cyanide sulphur transferase) in the tissues of the domestic fowl revealed that the highest activity occurred in the kidney, approximately twice that in the liver, 316 and 141 μmol SCN formed/min g protein, respectively.
2. In sparrows, pigeons and ducks, liver and kidney activities tended to be similar and increased with body size.
3. Relationships were found between enzyme activity and body weight to a fractional power, indicating relatively higher activity in smaller birds. 相似文献
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J Lukásová 《Veterinární medicína》1990,35(3):187-192
Factors influencing salmonella survival in fermented milk products were investigated. Filtrates of yoghurt and cream cultures and a filtrate from milk precipitated by lactic acid were inoculated by salmonellas. The pH value was adjusted within the range of 7.0 to 4.5. The content of nondissociated lactic acid was determined. The filtrates were incubated 24 and 48 hours at a temperature of 37 degrees C. In comparison with the milk filtrate, great inhibitory (at pH 6.5) and bactericidal (at pH 5.5) effects of the yoghurt culture on salmonellas were proved. The filtrate from the cream culture inactivated salmonellas at pH 4.5, the growth ceased at pH 5.5. The effects of lactic and acetic acids on salmonellas at a concentration of 0.5% and pH 3.3, and acetic acid at a concentration of 0.05% and pH 5.1 were also studied. 相似文献
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Culture supernatants from a number of Staphylococcus hyicus strains caused toxic effects to both murine fibroblast and porcine keratinocyte cells in culture. The extent of cytotoxicity was shown to differ between strains and may provide an indication of strain virulence. Purification of cytotoxic activity produced by S. hyicus (strain P119) using preparative isoelectric-focussing demonstrated it to be cytolytic, haemolytic and non-proteolytic. The cytotoxin demonstrates certain properties in common with the delta haemolysin of Staphylococcus aureus. 相似文献
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S. D. Folz B. L. Lee L. H. Nowakowski C. A. Winterrowd G. A. Conder 《Veterinary parasitology》1989,30(4):273-278
Sporozoites of Eimeria tenella, an important pathogen of poultry, were killed in vitro in a time- and concentration-dependent manner by exposure to diluted concentrations of normal human milk. Sodium cholate (bile salt stimulator) potentiated the anti-coccidial activity. The anti-coccidial activity was not found in the milk of lower mammals (cow, sheep, goat, dog). The component in human milk showing the activity was initially hypothesized to be a bile salt-stimulated lipase. However, testing of purified lipase (with or without sodium cholate) indicated no anticoccidial activity. Consequently, we theorize that the active component may be a free fatty acid. 相似文献
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Complement activity and conglutinin activity were measured in bovine sera stored under four conditions: phenolized (3 C), lyophilized (3 C), frozen (-23 C), and frozen (-57 C). The complement activity was lost after 12 weeks in phenol (3 C). The other three conditions, ranked in order of increasing effectiveness, are lyophilized (3 C) and frozen (-23 and -57 C). Conglutinin activity was lost after 23 weeks in phenol (3 C). The other three conditions, ranked in order of increasing effectiveness, are frozen (-23 C), lyophilized (3 C) and frozen (-57 C). Thus, the most effective condition to preserve complement and conglutinin simultaneously is freezing at -57 C. 相似文献
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1. The effect of stunning current on the time to recovery of physical activity, and on somatosensory evoked potentials (SEPs) in the brain, was examined in broiler chickens. 2. Increasing stunning current was associated with an increase in the time to recovery of tension in the neck muscles and with an increase in the incidence of loss of SEPs. 3. Currents greater than 105 mA per bird provided 52 s or more of apparent insensibility; currents greater than 120 mA were associated with absence of SEPs following the stun. 相似文献
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Y. Goto Y. Inaba Y. Tamura T. Hanaki H. Sazawa Y. Ito M. Matumoto 《Veterinary microbiology》1979,4(4):261-278
Akabane virus was shown to lyse as well as to agglutinate pigeon erythrocytes. The hemolytic activity of the virus was markedly enhanced by repeated freeze-thawing, but its hemagglutinating activity was not affected. Hemolysis (HL) with the virus, like its hemagglutination, was affected by the NaCl concentration as well as by the pH of the diluent. HL was markedly affected by the incubation temperature, but hemagglutination (HA) was not; HL activity was highest at 37°C, somewhat lower at 25°C, very low at 4°C, and did not occur at 0°C. While pigeon erythrocytes were positive for both HL and HA, goose erythrocytes were positive for HA but negative for HL. Erythrocytes from cattle, sheep, rabbits, guinea pigs, mice and day-old chickens were tested for HA as well as for HL activity with negative results. A linear relationship was shown, in a wide range of the virus concentrations, between the percent HL and the virus concentration, as expressed on a logarithmic scale. Based on these findings we developed an assay method for Akabane virus hemolysin. Analysis by CsCl equilibrium density gradient centrifugation indicated the hemolytic as well as the hemagglutinating activity to be structurally associated with the virion. Scanning electron microscopy of pigeon erythrocytes undergoing HL with the virus revealed the appearance of a depressed area with a hole on the cell surface. The hemolytic activity of the virus was specifically inhibited by antisera to the virus and an HL-inhibition test was developed. 相似文献
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